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Two Seas for One Great Diversity: Checklist of the Marine Heterobranchia (Mollusca; Gastropoda) from the Salento Peninsula (South-East Italy)

Two Seas for One Great Diversity: Checklist of the Marine Heterobranchia (Mollusca; Gastropoda)... diversity Article Two Seas for One Great Diversity: Checklist of the Marine Heterobranchia (Mollusca; Gastropoda) from the Salento Peninsula (South-East Italy) 1 , 2 , 3 2 , 4 5 Giulia Furfaro * , Fabio Vitale , Cataldo Licchelli and Paolo Mariottini Department of Biological and Environmental Sciences and Technologies—DiSTeBA, University of Salento, I-73100 Lecce, Italy Salento Sommerso Association, I-73100 Lecce, Italy; fabio_vitale@tin.it (F.V.); cataldo.licchelli@gmail.com (C.L.) Museum of Natural History of Salento, I-73021 Calimera-Lecce, Italy Cooperativa Hydra, I-73100 Lecce, Italy Department of Science, University of Roma Tre, I-00146 Rome, Italy; paolo.mariottini@uniroma3.it * Correspondence: giulia.furfaro@unisalento.it Received: 18 March 2020; Accepted: 24 April 2020; Published: 26 April 2020 Abstract: The Salento peninsula is a portion of the Italian mainland separating two distinct Mediterranean basins, the Ionian and the Adriatic seas. Several authors have studied the marine Heterobranchia (Mollusca, Gastropoda) fauna composition living in the Ionian Sea, but to date further knowledge regarding this interesting group of mollusks is still needed. Recent studies have corroborated the peculiarity of the Mediterranean Sea showing high levels of endemism and cryptic diversity. On the other hand, marine sea slugs have been revealed to be important indicators of the marine ecosystem’s health, due to their species-specific diet that consist of a vast variety of sessile and benthic invertebrates. A baseline study of the marine Heterobranchia diversity is therefore a necessary step to reveal the hidden diversity and to monitor the possible presence of alien species. The present study shows results from approximately 600 scientific dives carried out during a nine-year period in all of the main submarine habitats of the studied area, while accounting for the marine Heterobranchia from both the Ionian and Adriatic Seas. With this contribution, the list of marine Heterobranchia inhabiting the Salento Peninsula rises to 160. Furthermore, it also reports, for the first time, the presence of one alien species and three new records for Italian waters. Ecological notes and geographical distribution for each added species are provided together with animal iconography, consisting mainly of in situ photographs, for species identification. Keywords: diversity; sea slugs; nudibranchs; Mediterranean Sea; monitoring 1. Introduction The Salento Peninsula (South-East Italy) in Puglia is a strip of land right on the border of the eastern Mediterranean Sea, made up of a large variety of habitats: rocky formations, open sandy beaches, marine caves, etc. The Salento Peninsula is a physically well-identified region, encompassing 0 00  0 00 the innermost point of the Gulf of Taranto (40 31 17.8 N 17 06 10.7 E) and the beach of Torre 0 00  0 00 Santa Sabina di Ostuni (40 45 52.3 N 17 41 20.1 E), with a length of 138 kilometers, calculated 0 00  0 00 on the axis between Martina Franca (40 42 17.7 N 17 20 20.9 E) and the Cape of Santa Maria di 0 00  0 00 Leuca (39 47 40.4 N 18 22 05.0 E). The maximum and minimum width are 54 and 33 kilometers, respectively, and the total coastal length is 365 kilometers [1–5]. This peninsula protrudes between two ecoregions of the Mediterranean Sea [6], the Northern Ionian, and the Southern Adriatic seas, which are conventionally separated by the dividing line passing through Otranto (according to the Diversity 2020, 12, 171; doi:10.3390/d12050171 www.mdpi.com/journal/diversity Diversity 2020, 12, 171 2 of 24 biogeographical zones described by Bianchi [7], i.e., zones 6 and 7, respectively). These two basins are characterised by peculiar and distinct main currents and submarine morphologies, resulting in very complex and dynamic ecosystems a ected by seasonal fluctuations, which influences both the shallow and deep communities [8,9]. Therefore, this marine area could potentially host a high abundance of Heterobranchia species, due to their pelagic larval stage and diversified diet. Knowledge on diversity is a basic requisite to identify targets and to monitor species composition shifts over time, caused by natural or anthropogenic factors. In fact, the change in marine Heterobranchia fauna composition over time is considered a good ecological indicator of potential environmental modifications [10–14] and this peculiarity is particularly interesting in such a heterogeneous area of the Mediterranean. Furthermore, the capability of marine Heterobranchia to host biological compounds that are potentially interesting for biomedical applications, provides additional value to the study of this particular group of mollusks [14]. In fact, many species of marine Heterobranchia display aposematic vivacious warning colors to indicate that they contain defensive secondary metabolites that are sequestered, transformed from dietary sources, or synthesized de novo [15]. These compounds are used, mainly by nudibranchs, as a chemical defense from predation [16,17] and have revealed to be an important source of diverse bioactive products used as e ective analgesic, anti-inflammatory, antiviral, and anticancer drugs [18,19]. The Mediterranean marine diversity is therefore revealed to be interesting, mainly due to the presence of cryptic or endemic species. In fact, several species once considered to be widespread across the Atlantic and the Mediterranean were shown to be a complex of cryptic species, many of which are endemic to the Mediterranean (e.g., [20–23]). This trend is also true for marine Heterobranchia, as demonstrated by recent molecular papers that helped to unravel such cryptic diversity [24–29]. In this context, studies focused on the production of species lists from di erent geographical areas are needed as an essential starting point to unveil this hidden diversity. In the past decade, the key works on marine Heterobranchia in the area under investigation have been published by Perrone [30–37], who mainly provided data regarding the species inhabiting the Ionian side of the Salento peninsula (Gulf of Taranto), and only provided ecological notes on a small number of species. Recently, Onorato and Belmonte [38] reviewed the biodiversity assessment of the marine submerged caves in the Salento peninsula, which includes some heterobranchs, while Micaroni et al. [39] published a check-list of Heterobranchia from the Ionian locality of Tricase, adding 20 species to Perrone’s previous lists [30–37]. Finally, several published papers that did not have proper checklists, added new records of single species sampled from the Salento Peninsula [29,40–44], contributing to the increase of lists of species known from this Apulian area. However, to date, there is no published checklist of marine Heterobranchia fauna from the Adriatic side of the Salento peninsula. During the last ten years, there has been an increasing interest in marine observation by underwater photographers [45,46]. This has allowed the possibility to extend the research on fauna, to detect lesser known species, and to create a collaboration network between scientists and amateurs who are experts in this field. The so-called Citizen Science dedicated to the Heterobranchia is an important support in expanding the body of knowledge on this group of gastropods, by providing field observations on bathymetric distribution, seasonality [47], egg deposition, reproductive behavior and trophic niche, and by making the data immediately available to the scientific community through web-based social networks [48]. In the last decade, due to the combined e orts of professional underwater photographers and acknowledged systematic experts in sea slugs, many new records and ecological observations on the Salento Peninsula marine Heterobranchia have been collected. Taking all of these points into account, the present study had the following aims to: (i) contribute to the Salento Peninsula marine Heterobranchia checklist with new records from the sublittoral waters, considering both sides of this Peninsula, the Ionian and the Adriatic sides, for the first time; (ii) provide ecological notes and local distribution for each new recorded species; (iii) show in situ photographs of the live animals to document species identification. Diversity 2020, 12, 171 3 of 24 2. Materials and Methods The geographical area under investigation was a stretch of more than 270 km of coastline around the Salento Peninsula in Southern Italy (Figure 1). With 600 scuba dives in the past 9 years, di erent benthic habitats were surveyed, some of which were included in the European legislative context (EU WFD, EU Habitat Directive, EU MSFD): pre-coralligenous and coralligenous assemblages, soft-bottom substrates, Posidonia oceanica (Linnaeus) Delile, 1813 meadows, and algal biocoenosis on rocky substrates. All sampled sites were georeferenced (Table 1) to provide accurate data of the studied locations for future monitoring and comparison. When possible, ecological observation and in situ photographs of the individuals recorded were performed and catalogued for species identification. The Scuba dives (0–40 m depth) took place all year round, almost every week, during daylight and at night, between 2011 and 2019. Specimens between 2 and 5 mm in length were photographed alive in the laboratory, in Petri capsules illuminated by a series of low voltage LED lamps, with 6500 K bulbs. The camera used for filming was a tripod mounted Nikon D7100, with 60 mm micro Nikkor or 105 mm micro Nikkor optics, a series of extension rings and additional lenses. The underwater photographic or videography equipment (F.V.) was a Nikon D7000 body, 60 mm micro Nikkor, or 105 mm micro Nikkor optics, extension rings inside an Isotta housing, as well as additional wet lenses SubSee +10 diopter, two underwater flashes Inon z240, and two LED lamps of great luminous power. Or alternatively, (C.L.) a Canon 600D body in a Nauticam 600D housing, equipped with the following lenses—for macro photography and in some cases for micro subjects, the Canon 60 mm USM Macro, and Canon 100 mm USM Macro were used, in addition to wet lenses SubSee +5 and +10 diopter; for wide angle photography, the Tokina 10–17 mm fisheye lens was used. The light source was provided by a couple of Inon strobes z240 and a single focus light I-Torch Video Pro 3. The systematics and the validity of names were checked with the help of the Word Register of Marine Species [49]. Species identification was obtained by morphological investigation and a subsequent consultation of the existent literature ([29,41,44] and other references cited in the present work), guide books [50,51] and websites [48,52,53]. In the case of Berthellina cf. edwardsii, the shell from an individual (Voucher RM3_1865) was extracted and used to confirm the identification as this anatomical feature is commonly considered to be diagnostic for this species. The shell was removed and dissolved in a 10% NaOH solution, then rinsed in water, dried, and mounted for examination by optical microscopy, following the same protocol described by Furfaro et al. [54]. Voucher numbers were assigned to the collected individuals that were selected for future molecular analyses; samples were preserved in 95% alcohol and stored in the Department of Science at the Roma Tre University (Rome, Italy) (Table 2). Finally, a comparison between species as recorded by previous authors (Perrone [30–37] (A), Onorato and Belmonte [38] (B), Micaroni et al. [39] (C)) and the present study (D) was carried out and reported in Table 2 with new records highlighted in bold letters. An ethical approach in this research was also carried out by complying with the restrictions in term of collected sample size, environmental survey of the collection sites, use of hand-net picking of specimens (harmless and not destructive) as well as complying with local, regional, national, and international rules, and regulations for access to biodiversity, sustainable use, and benefit sharing (Convention on Biological Diversity and its Nagoya Protocol, national regulations). Diversity 2020, 12, 171 4 of 24 Diversity 2020, 12, x FOR PEER REVIEW 4 of 23 Figure 1. Map of the Salento Peninsula indicating the sampling localities; the box highlights the Figure 1. Map of the Salento Peninsula indicating the sampling localities; the box highlights the Salento Salento Peninsula at a higher magnification. Numbers refer to sampling stations reported in Table 1. Peninsula at a higher magnification. Numbers refer to sampling stations reported in Table 1. Table 1. Number, name, geographic coordinates (latitude and longitude), and the depth range of the Table 1. Number, name, geographic coordinates (latitude and longitude), and the depth range of the sampled stations. sampled stations. N Station Latitude Longitude Depth N° Station Latitude Longitude Depth 0 00  0 00 1 1 Mar Mar P Piccolo, iccolo, Taranto Taran (Ionian to (IonSea) ian Sea) 40 40° 28 28′53.62 53.62′′N N 17°16′17 00.9 16 1′′E 00.91 1–10 m E 1–10 m 0 00  0 00 2 Capo S. Vito, Taranto (Ionian Sea) 40 24 35.85 N 17 12 06.07 E 1–20 m 2 Capo S. Vito, Taranto (Ionian Sea) 40°24′35.85′′N 17°12′06.07′′E 1–20 m 0 00  0 00 3 3 Porto Pirrone, Taranto (Ionian Sea) 40 21 27.79 N 17 19 40.93 E 4–20 m Porto Pirrone, Taranto (Ionian Sea) 40°21′27.79′′N 17°19′40.93′′E 4–20 m 0 00  0 00 4 Torre Ovo, Taranto (Ionian Sea) 40 17 29.18 N 17 30 11.20 E 1–20 m 4 Torre Ovo, Taranto (Ionian Sea) 40°17′29.18′′N 17°30′11.20′′E 1–20 m 0 00  0 00 5 Campomarino, Taranto (Ionian Sea) 40 17 34.76 N 17 31 41.48 E 1–20 m 5 Campomarino, Taranto (Ionian Sea) 40°17′34.76′′N 17°31′41.48′′E 1–20 m 0 00  0 00 6 Porto Cesareo I. Conigli, Lecce (Ionian Sea) 40 15 32.15 N 17 52 57.59 E 1–15 m 6 Porto Cesareo I. Conigli, Lecce (Ionian Sea) 40°15′32.15′′N 17°52′57.59′′E 1–15 m 0 00  0 00 7 Porto Cesareo, Lecce (Ionian Sea) 40 14 51.48 N 17 54 33.51 E 0–1 m 7 Porto Cesareo, Lecce (Ionian Sea) 40°14′51.48′′N 17°54′33.51′′E 0–1 m 0 00  0 00 8 S. Isidoro, Lecce (Ionian Sea) 40 13 15.51 N 17 55 29.27 E 1–5 m 8 S. Isidoro, Lecce (Ionian Sea) 40°13′15.51′′N 17°55′29.27′′E 1–5 m 0 00  0 00 9 Torre Inserraglio, Lecce (Ionian Sea) 40 10 41.44 N 17 55 51.53 E 1–20 m 9 Torre Inserraglio, Lecce (Ionian Sea) 40°10′41.44′′N 17°55′51.53′′E 1–20 m 0 00  0 00 10 Santa Caterina di Nardò, Lecce (Ionian Sea) 40 08 05.87 N 17 59 15.53 E 1–15 m 10 Santa Caterina di Nardò, Lecce (Ionian Sea) 40°08′05.87′′N 17°59′15.53′′E 1–15 m 0 00  0 00 11 Santa Maria al Bagno, Lecce (Ionian Sea) 40 07 30.58 N 17 59 46.43 E 0–6 m 11 Santa Maria al Bagno, Lecce (Ionian Sea) 40°07′30.58′′N 17°59′46.43′′E 0–6 m 0 00  0 00 12 O.R. Gallipoli, Lecce (Ionian Sea) 40 06 04.68 N 17 58 04.22 E 36 m 12 O.R. Gallipoli, Lecce (Ionian Sea) 40°06′04.68′′N 17°58′04.22′′E 36 m 0 00  0 00 13 Gallipoli, Lecce (Ionian Sea) 40 04 34.70 N 17 59 50.25 E 1–20 m 13 Gallipoli, Lecce (Ionian Sea) 40°04′34.70′′N 17°59′50.25′′E 1–20 m 0 00  0 00 14 Gallipoli - Isola S. Andrea, Lecce (Ionian Sea) 40 02 36.77 N 17 57 01.64 E 5–20 m 14 Gallipoli - Isola S. Andrea, Lecce (Ionian Sea) 40°02′36.77′′N 17°57′01.64′′E 5–20 m 0 00  0 00 15 Gallipoli Pizzo, Lecce (Ionian Sea) 39 59 57.64 N 17 59 27.36 E 1–15 m 15 Gallipoli Pizzo, Lecce (Ionian Sea) 39°59′57.64′′N 17°59′27.36′′E 1–15 m 0 00  0 00 16 Marina Mancaversa, Lecce (Ionian Sea) 39 58 58.04 N 18 00 18.58 E 1–5 m 16 Marina Mancaversa, Lecce (Ionian Sea) 39°58′58.04′′N 18°00′18.58′′E 1–5 m 0 00  0 00 17 Torre Suda, Lecce (Ionian Sea) 39 56 27.95 N 18 02 17.36 E 1–5 m 17 Torre Suda, Lecce (Ionian Sea) 39°56′27.95′′N 18°02′17.36′′E 1–5 m 0 00  0 00 18 Ugento, Lecce (Ionian Sea) 39 52 36.70 N 18 05 25.14 E 5–30 m 18 Ugento, Lecce (Ionian Sea) 39°52′36.70′′N 18°05′25.14′′E 5–30 m 0 00  0 00 19 Santa Maria di Leuca, Lecce (Ionian Sea) 39 48 18.38 N 18 22 42.56 E 1–20 m 19 Santa Maria di Leuca, Lecce (Ionian Sea) 39°48′18.38′′N 18°22′42.56′′E 1–20 m 0 00  0 00 20 Tricase, Lecce (Adriatic Sea) 39 55 51.31 N 18 23 47.92 E 1–30 m 20 Tricase, Lecce (Adriatic Sea) 39° 550′51.310′′0N 18°23′47 .92′′0E 1–30 00 m 21 Porto Miggiano, Lecce (Adriatic Sea) 40 01 46.72 N 18 27 01.30 E 1–25 m 21 Porto Miggiano, Lecce (Adriatic Sea) 40° 010′46.720′′0N 18°27′01 .30′′0E 1–25 m 00 22 Otranto, Lecce (Adriatic Sea) 40 08 18.52 N 18 30 47.65 E 1–40 m 0 00  0 00 22 Otranto, Lecce (Adriatic Sea) 40°08′18.52′′N 18°30′47.65′′E 1–40 m 23 Roca, Lecce (Adriatic Sea) 40 17 50.18 N 18 24 49.69 E 1–6 m 23 Roca, Lecce (Adriatic Sea) 40° 170′50.180′′0N 18°24′49 .69′′0E 1–6 m 00 24 Frigole, Lecce (Adriatic Sea) 40 26 20.52 N 18 14 46.56 E 0–1 m 0 00  0 00 24 Frigole, Lecce (Adriatic Sea) 40°26′20.52′′N 18°14′46.56′′E 0–1 m 25 Brindisi (Adriatic Sea) 40 39 54.11 N 17 57 34.81 E 1–8 m 25 Brindisi (Adriatic Sea) 40°39′54.11′′N 17°57′34.81′′E 1–8 m Table 2. List of species of Heterobranchia occurring around the Salento peninsula; localities are numbered according to Figure 1, with new records in column D, highlighted in bold. Column A = Perrone [30–37]; B = Onorato and Belmonte [38]; C = Micaroni et al. [39]; and D = Present study. Taxonomy A B C D Vouchers Pleurobranchida Family Pleurobranchidae Gray, 1827 Pleurobranchus membranaceus (Montagu, 1803) 16 Pleurobranchus testudinarius Cantraine, 1835 1,17 Diversity 2020, 12, 171 5 of 24 Table 2. List of species of Heterobranchia occurring around the Salento peninsula; localities are numbered according to Figure 1, with new records in column D, highlighted in bold. Column A = Perrone [30–37]; B = Onorato and Belmonte [38]; C = Micaroni et al. [39]; and D = Present study. Taxonomy A B C D Vouchers Pleurobranchida Family Pleurobranchidae Gray, 1827 Pleurobranchus membranaceus (Montagu, 1803) 16 Pleurobranchus testudinarius Cantraine, 1835 1,17 Berthellina cf. edwardsii 1,4,6,10,13,15 RM3_1865 Berthella aurantiaca (Risso, 1818) 8,9,19,23 Berthella elongata (Cantraine, 1836) 16 Berthella ocellata (delle Chiaje, 1830) 8 5,6 Berthella plumula (Montagu, 1803) 16 Berthella stellata (Risso, 1826) 9 22 Berthellina citrina (Rüppell & Leuckart, 1828) 18 Family Pleurobranchaeidae Pilsbry, 1896 Pleurobranchaea meckeli (Blainville, 1825) 16 11 5,6 Nudibranchia - Doridina Family Calycidorididae Roginskaya, 1972 Diaphorodoris luteocincta (M. Sars, 1870) 6 Diaphorodoris papillata Portmann & Sandmeier, 1960 11 5,6,10 Family Onchidorididae Gray, 1927 Adalaria proxima (Alder & Hancock, 1854) 21 Knoutsodonta albonigra (Pruvot-Fol, 1951) 20,24 Family Goniodorididae H. & A. Adams, 1854 Goniodoris castanea Alder & Hancock, 1845 20 1 Okenia longiductis Pola M, Paz-Sedano S, Macali A, 1,4 Minchin D, Marchini A, Vitale F, 2019 [41] Okenia mediterranea (von Ihering, 1886) [41] 6 Okenia problematica Pola M, Paz-Sedano S, Macali A, Minchin D, Marchini A, Vitale F, 2019 [41] RM3_1042, Trapania lineata Haefelfinger, 1960 4–6,10,13,15 RM3_1048, RM3_1077 Trapania maculata Haefelfinger, 1960 4–6,10,13,15 RM3_1076 Family Polyceridae Alder & Hancock, 1845 Crimora papillata Alder & Hancock, 1862 5,6,11 Kaloplocamus ramosus (Cantraine, 1835) 11 Polycera elegans (Bergh, 1894) 1 Polycera hedgpethi Marcus, 1964 1 Polycera quadrilineata (O. F. Müller, 1776) 3,16 11 1,3–6,10,13,15 RM3_1065 Thecacera pennigera (Montagu, 1815) 1 Family Aegiridae P. Fischer, 1883 Aegires punctilucens (d’Orbigny, 1837) 4 Family Cadlinidae Bergh, 1891 Aldisa banyulensis Pruvot-Fol, 1951 23,24 6 Family Chromodorididae Bergh, 1891 RM3_1039, RM3_1040, Felimare fontandraui (Pruvot-Fol, 1951) 6,8 RM3_1099, RM3_1100 Felimare orsinii (Vérany, 1846) 8,12,13,15 RM3_1041, 1,4–6, Felimare picta (Philippi, 1836) 19 13 11 RM3_1052, 8,10,12,13,15 RM3_1053 1,4–6, RM3_1074, Felimare tricolor (Cantraine, 1835) 5 11 8,10,12,13,15 RM3_1075 RM3_1231, Felimare villafranca (Risso, 1818) 16 11 1,5,6 RM3_1232 Diversity 2020, 12, 171 6 of 24 Table 2. Cont. Taxonomy A B C D Vouchers Felimida binza (Ev. Marcus & Er. Marcus, 1963) 15 RM3_1061, Felimida krohni (Vérany, 1846) 13 11 4–6,13 RM3_1068 Felimida luteorosea (Rapp, 1827) 16 11 1,6 Felimida purpurea (Risso, 1831) 4 6 Family Dorididae Rafinesque, 1815 Doris ocelligera (Bergh, 1881) 11 3 Doris pseudoargus Rapp, 1827 19 Doris verrucosa Linnaeus, 1758 19 1 Family Discodorididae Bergh, 1891 Atagema rugosa Pruvot-Fol, 1951 19 Baptodoris cinnabarina Bergh, 1884 8,20 22, 6 Discodoris stellifera (Vayssière, 1903) 9,19 15 Gargamella perezi (Llera & Ortea, 1982) 19,24 Geitodoris bonosi Ortea & Ballesteros, 1981 3 Geitodoris portmanni (Schmekel, 1972) 20 Jorunna tomentosa (Cuvier, 1804) 3,10,20 1, 13 Paradoris indecora (Bergh, 1881) 3,24 RM3_1054, Peltodoris atromaculata Bergh, 1880 8 11 ALL RM3_1056, RM3_1057 Peltodoris sordii Perrone, 1989 3 Platydoris argo (Linnaeus, 1767) 8 11 5,6,10,13 Rostanga anthelia Perrone, 1991 4 Rostanga rubra (Risso, 1818) 20,23 Taringa armata Swennen, 1961 22 Taringa pinoi Perrone, 1985 20,24 Tayuva lilacina (Gould, 1852) 3 1,22 Family Phyllidiidae Rafinesque, 1814 RM3_1049, Phyllidia flava Aradas, 1847 19 11 4–6,9,10,13 RM3_1055, RM3_1058 Family Dendrodorididae O’Donoghue, 1924 Dendrodoris grandiflora (Rapp, 1827) 16 11 1,3,5,6 1,16, Dendrodoris limbata (Cuvier, 1804) 1,3,5,6 Doriopsilla areolata Bergh, 1880 17,23 3,4,6 Nudibranchia - Cladobranchia Family Tritoniidae Lamarck, 1809 Marionia blainvillea (Risso, 1818) 9 19 Tritonia manicata Deshayes, 1853 8,16 11 5,6 Tritonia nilsodhneri Marcus Ev., 1983 9 Tritonia striata Haefelfinger, 1963 16 5,6 Family Hancockiidae MacFarland, 1923 Hancockia uncinata (Hesse, 1872) 16 Family Scyllaeidae Alder & Hancock, 1855 Scyllaea pelagica Linnaeus, 1758 19 Family Tethydidae Rafinesque, 1815 Melibe viridis Kelaart, 1858 [55] 1,5,6 Tethys fimbria Linnaeus, 1767 16 6,13 Family Dotidae Gray, 1853 Doto acuta Schmekel & Kress, 1977 11 Doto cervicenigra Ortea & Bouchet, 1989 3,6 Doto floridicola Simroth, 1888 13 Doto fragaria Ortea & Bouchet, 1989 [56] 6 Doto koenneckeri Lemche, 1976 11 13 Doto paulinae Trinchese, 1881 11 6 Doto pygmaea Bergh, 1871 11 Diversity 2020, 12, 171 7 of 24 Table 2. Cont. Taxonomy A B C D Vouchers Family Proctonotidae Gray, 1853 Antiopella cristata (Delle Chiaje, 1841) 9 1,3,5,6 Family Arminidae Iredale & O’Donoghue, 1841 Armina tigrina Rafinesque, 1814 18 5 Dermatobranchus cf. rubidus (Gould, 1852) [40] 2 Family Coryphellidae Bergh, 1889 Fjordia lineata (Lovén, 1846) 16 6,7 Family Flabellinidae Bergh, 1889 RM3_354, RM3_481, RM3_482, RM3_484, RM3_1079, RM3_1080, RM3_1081, RM3_1082, RM3_1083, RM3_1084, Calmella cavolini (Vérany, 1846) 8 11 5,6,13,15 RM3_1085, RM3_1086, RM3_1087, RM3_1088, RM3_1089, RM3_1090, RM3_1091, RM3_1092, RM3_1093, RM3_1095 RM3_1046, RM3_1047, Edmundsella pedata (Montagu, 181) 8 13 ALL RM3_1059, RM3_1067 RM3_1050, RM3_1043, RM3_1060, RM3_1063, Flabellina anis (Gmelin, 1791) 8 13 11 ALL RM3_1064, RM3_1070, RM3_1071, RM3_1073 Paraflabellina gabinierei (Vicente, 1975) 1,4,5,13 RM3_345, Paraflabellina ischitana (Hirano & T. E. RM3_346, 13 2,4–6,9,10,13,15 Thompson, 1990) RM3_532, RM3_533 Family Samlidae Korshunova, Martynov, Bakken, Evertsen, Fletcher, Mudianta, Saito, Lundin, Schrödl & Picton, 2017 Luisella babai (Schmekel, 1972) 13 11 13 RM3_1069 Family Piseinotecidae Edmunds, 1970 RM3_862, Piseinotecus soussi Tamsouri, Carmona, Moukrim & 6 RM3_863, Cervera, 2014 [57] RM3_1236 Family Aeolidiidae Gray, 1827 Aeolidiella alderi (Cocks, 1852) 16,20 1,3 Aeolidiella glauca (Alder & Hancock, 1845) 16 Berghia coerulescens (Laurillard, 1832) 16 11 5,6,13,15,18 Berghia verrucicornis (A. Costa, 1867) 19 13,6 Limenandra nodosa Haefelfinger & Stamm, 1958 2 Spurilla neapolitana (Delle Chiaje, 1841) 16 11 1,3,4 Family Facelinidae Berg, 1889 Caloria elegans (Alder & Hancock, 1845) 4,5,6 RM3_1051 Diversity 2020, 12, 171 8 of 24 Table 2. Cont. Taxonomy A B C D Vouchers RM3_1038, RM3_1045, RM3_1062, Cratena peregrina (Gmelin, 1791) 11 ALL RM3_1066, RM3_1072, RM3_1078, RM3_1094 Dicata odhneri (Schmekel, 1967) 1,4,6 Dondice banyulensis Portmann & Sandmeier, 1960 6,8,13,19 Facelina annulicornis (Chamisso & Eysenhardt, 1821) 11 5,6,13–15 RM3_1201, Facelina fusca Schmekel, 1966 3 RM3_1235 Facelina rubrovittata (A. Costa, 1866) 2,4–6,12,13,15 Facelina vicina (Bergh, 1882) 6 RM3_1202 Favorinus branchialis (Rathke, 1806) 16,20 1,3,5,6,13,15 Family Eubranchidae Odhner, 1934 Eubranchus andra (Korshunova, Malmberg, Prkic, ´ 1, 3, 6 Petani, Fletcher, Lundin, Martynov, 2020) [44] Eubranchus cf. farrani (Alder & Hancock, 1844) 1,3,10,13,15,21 Eubranchus cf. linensis Garcia-Gomez, Cervera & 1,6 Garcia, 1990 Eubranchus cf. exiguus (Alder & Hancock, 1848) 11 10,6 Family Fionidae Gray, 1857 RM3_1097, Fiona pinnata (Eschscholtz, 1831) 11 RM3_1098 Family Trinchesiidae F. Nordsieck, 1972 Catriona maua Ev. Marcus & Er. Marcus, 1960 4 Rubramoena amoena (Alder & Hancock, 1845) 13 Trinchesia genovae (O’Donoghue, 1926) 3,5,6,13 Trinchesia morrowae Korshunova, Picton, Furfaro, Mariottini, Pontes, Prkic, ´ Fletcher, Malmberg, 6 Lundin & Martynov, 2019 Trinchesia cf. miniostriata Schmekel, 1968 13 Trinchesia ocellata Schmekel, 1966 5 Umbraculida Family Tylodinidae Gray, 1847 Tylodina perversa (Gmelin, 1791) 4,16 5,6 Family Umbraculidae Dall, 1889 Umbraculum umbraculum (Lightfoot, 1786) 16 13 11 3,5,6,13,15 RM3_1037 Runcinida Family Runcinidae H. & A. Adams, 1854 Runcina adriatica T. E. Thompson, 1980 [42] 11 3,5,6,13 Runcina brenkoae T. E. Thompson, 1980 11 Runcina cf. ferruginea Kress, 1977 13 Runcina cf. ornata (Quatrefages, 1844) 11 Cephalaspidea Family Philinidae Gray, 1850 Philine punctata (J. Adams, 1800) 4 Philine quadripartita Ascanius, 1772 1 Family Aglajidae Pilsbry, 1895 Aglaja tricolorata Renier, 1807 11 5,6 Camachoaglaja africana (Pruvot-Fol, 1953) 3,5,6,13 Philinopsis depicta (Renier, 1807) 5,6 Melanochlamys wildpretii Ortea, Bacallado & Moro, 2003 Family Bullidae Gray, 1827 Bulla striata Bruguière, 1792 11 1, 4 Family Haminoeidae Pilsbry, 1895 Diversity 2020, 12, 171 9 of 24 Table 2. Cont. Taxonomy A B C D Vouchers Haminoea cf. orteai Talavera, Murillo & 3,13 Templado, 1987 Weinkaua turgidula (Forbes, 1844) 11 4 Aplysiida Family Aplysiidae Lamarck, 1809 Aplysia dactylomela Rang, 1828 [58] 5,6,13 Aplysia depilans Gmelin, 1791 16 13 11 ALL Aplysia fasciata Poiret, 1789 16 11 ALL Aplysia parvula Mörch, 1863 16 11 ALL Aplysia punctata (Cuvier, 1803) 16 13 ALL Bursatella leachii Blainville, 1817 2,16,19 1 Notarchus punctatus Philippi, 1836 16 Petalifera petalifera (Rang, 1828) 16,23 5,13 Phyllaplysia lafonti (P. Fischer, 1870) 19 Sacoglossa Family Oxynoida Stoliczka, 1868 Lobiger serradifalci (Calcara, 1840) 2 Oxynoe olivacea Rafinesque, 1814 2 Family Plakobranchidae Gray, 1840 Bosellia mimetica Trinchese, 1891 8,16,19 11 3,6,10 Elysia flava Verrill, 1901 19,20 6 Elysia gordanae T. E. Thompson & Jaklin, 1988 3,6,10,13,15 Elysia hetta Perrone, 1990 9,19 15 Elysia margaritae Fez, 1962 6 Elysia timida (Risso, 1818) 16 11 ALL Elysia translucens Pruvot-Fol, 1957 19 Elysia viridis (Montagu, 1804) 16 11 1,22 RM3_1096 Elysia rubeni Martín-Hervás, Carmona, Jensen, 5,6,13 Licchelli, Vitale & Cervera, 2019 [29] Thuridilla hopei (Vérany, 1853) 16,19,20 11 ALL RM3_1044 Family Hermaeidae H. & A. Adams, 1854 Aplysiopsis elegans Deshayes, 1853 1 Cyerce cristallina (Trinchese, 1881) 19 2, 13 Cyerce graeca T. E. Thompson, 1988 6 RM3_1165, Hermaea bifida (Montagu, 1816) 1 RM3_1166, RM3_1167 Hermaea paucicirra Pruvot-Fol, 1953 3,6 Hermaea variopicta (A. Costa, 1869) 24 6 Family Limapontiidae Gray, 1847 Calliopaea bellula d’Orbigny, 1837 16,19 Ercolania coerulea Trinchese, 1892 3 Ercolania viridis (A. Costa, 1866) 11 3,14 Limapontia capitata (O. F. Müller, 1774) 25 Placida cremoniana (Trinchese, 1892) 1,6 Placida dendritica (Alder & Hancock, 1843) 9 3 Abbreviation cf. is from the Latin confer/conferatur, both meaning compare. 3. Results The present checklist reports 160 marine Heterobranchia species from the Salento Peninsula (Table 2) consisting of: 10 Pleurobranchida, 9 Cephalaspidea, 4 Runcinida, 2 Umbraculida, 9 Aplisiida, 24 Sacoglossa, and 102 Nudibranchia (50 Doridina, 52 Cladobranchia). This contribution added 45 species (Tables 2 and 3) to the marine heterobranchs fauna known from this area, so far, and in particular, 2 species belonging to Pleurobranchida, 6 Cephalaspidea, 1 Runcinida, 9 Sacoglossa, and 27 Nudibranchia (9 Doridina, 18 Cladobranchia). One alien species, Polycera hedgpethi Er. (Marcus, 1964), was reported for the first time in the studied area. This work reported for the first time the presence of Elysia margaritae (Fez, 1962), Haminoea cf. orteai (Talavera, Murillo and Templado, 1987), and Rubramoena amoena (Alder & Hancock, 1845), in Italian waters. Table 3 provides the species list with Diversity 2020, 12, 171 10 of 24 ecological remarks of all added species. Furthermore, an extensive photographic catalogue mainly consisting of pictures taken in situ is provided in Figures 2–9. Table 3. List of the newly recorded Heterobranchia from the Salento peninsula; species names, relative figure numbers, ecological notes, and phenotypical variability for each added species are reported. Abundance is indicated as number of specimens. Phenotypical Species Name Figure Ecological Notes Abundance Variability Pleurobranchus On soft bottom during diurnal dive. 1 testudinarius Figure 2A - 1–2 Depth: 25 m Cantraine, 1835 Usually living singularly or in groups Body color ranging Berthellina cf. under stones, in small shaded from light 2 edwardsii (Vayssière, Figure 2B,C >100 crevices or in dark caves. creamy-yellow to 1897) Depth: 0–15 m reddish-orange The specimens of this This sedentary species usually lives Diaphorodoris species show the red near bryozoan colonies (cf. Nolella 3 luteocincta Figure 2D spot on the dorsum 3–10 stipata Gosse, 1855). (M. Sars, 1870) which varies in shape Depth: 0–3 m and size Often in clusters, feeding on Trapania lineata Entoprocta spp. covering black 4 Figure 2E - >100 Haefelfinger, 1960 sponges. Recorded all year long. Depth: 0–30 m Often sympatric with the congeneric Trapania maculata 5 Figure 2F T. lineata. - >100 Haefelfinger, 1960 Depth: 0–30 m Found all year long, in shady pre-coralligenous shallow waters or Crimora papillata Color of the notum coastal caves. Often in association 6 Alder & Hancock, Figure 2G,H variable from light >100 with encrusting bryozoans on which 1862 yellow to ochre their egg masses are laid. Depth: 0–10 m Very typical body color Observed during the winter months, pattern, showing blue Polycera elegans 7 Figure 3A,B in shallow waters. spots di ering in size 11–30 (Bergh, 1894) Depth: 5 m and number between individuals Observed during winter season, in Polycera hedgpethi 8 Figure 3C,D shallow waters. - 3–10 Er. Marcus, 1964 Depth: 5 m Even if this species Observed in large assemblages at the shows a variable Felimare fontandraui end of spring, associated with the phenotype [26], the 9 Figure 3E,F 31–100 (Pruvot-Fol, 1951) sponge Dysidea avara (Schmidt, 1862). Salentine specimens Depth: 7 m have constant body color pattern In large groups mating and feeding Felimare orsinii on black sponges. Found between 10 Figure 3G - 31–100 (Vérany, 1846) April and July. Depth: 0–15 m Felimida binza On a rocky substrates. Found during 11 (Ev. Marcus & Er. Figure 3H September. - 1–2 Marcus, 1963) Depth: 5–7 m Very mimetic Found on the yellow gorgonian morphotype that can Tritonia nilsodhneri 12 Figure 4A Eunicella cavolinii Koch, 1887. consistently vary from 1–2 Marcus Ev., 1983 Depth: 30 m dark brown to pale yellow or white This small species (few millimetres) is Doto cervicenigra found from winter to early spring on 13 Ortea & Bouchet, Figure 4B hydrozoans colonies of Aglaophenia - 11–30 1989 Lamouroux, 1812. Depth: 0–3 m Diversity 2020, 12, 171 11 of 24 Table 3. Cont. Phenotypical Species Name Figure Ecological Notes Abundance Variability The average size of specimens observed is ca. 5 mm. Its host Doto floridicola 14 Figure 4C,D hydrozoan colonies belonging to - 11–30 Simroth, 1888 Aglaophenia. Depth: 8–12 m Paraflabellina The body colors vary On hard substrates. 15 gabinierei Figure 4E from white to opaque 3–10 Depth: 0–25 m (Vicente, 1975) pinkish Limenandra nodosa Found on Padina pavonica (Linnaeus) 16 Haefelfinger & Figure 4F Thivy, 1960 in summer. - 1–2 Stamm, 1958 Depth 6 m Body pattern with Caloria elegans Usually observed on hard substrata. cerata brightly colored 17 (Alder & Hancock, Figure 4G 11–30 Depth: 0–15 m from white to light 1845) orange Dicata odhneri Found in shallow waters. 18 Figure 4H - 11–30 Schmekel, 1967 Depth: 0–15 m Dondice banyulensis Conspicuous in size and brightly 19 Portmann & Figure 5A coloured. - 11–30 Sandmeier, 1960 Depth: 0- to more than 30 m Found in a tidal pool in association Facelina fusca with the green algae Anadyomene 20 Figure 5B - 1–2 Schmekel, 1966 stellata (Wulfen) C. Agardh, 1823. Depth: 0.5 m Observed all year long in shady Facelina rubrovittata 21 Figure 5C pre-coralligenous habitats. - 31–100 (A. Costa, 1866) Depth: 0–15 m. The color of the digestive gland visible Facelina vicina (Bergh, 22 Figure 5D,E Depth: 0–15 m through cerata vary 3–10 1882) from light orange/pink to dark violet This species shows Eubranchus cf. farrani Found at shallow depth on di erences in the shape 23 (Alder & Hancock, Figure 5F hydrozoans colonies. 11–30 and the number of the 1844) Depth: 0–15 m dorsal yellow spots Eubranchus cf. linensis 24 Garcia-Gomez, Figure 5G,H Depth: 0–5 m. - 11–30 Cervera & Garcia, Catriona maua Recorded in shallow water on 25 Ev. Marcus & Er. Figure 6A hydrozoans colonies. - 1–2 Marcus, 1960 Depth: 0.5 m Rubramoena amoena Found in April in shallow water. 26 (Alder & Hancock, Figure 6B Temperature 15 C. - 1–2 1845) Depth: 8 m Occurs in shallow water on algae, Trinchesia genovae 27 Figure 6C,D bryozoan, and hydrozoans substrates. - 11–30 (O’Donoghue, 1926) Depth: 0–20 m Trinchesia cf. On rocky substrates. 28 miniostriata Figure 6E - 1–2 Depth: 9 m Schmekel, 1968 Trinchesia morrowae The typical color of the Common in March-April and in July Korshunova, Picton, apical portion of the when it is possible to observe several Furfaro, Mariottini, rhinophores and the specimens living and laying eggs on 29 Pontes, Prkic, ´ Figure 6F oral tentacles varies >100 hydroid of the genus Sertularella Fletcher, Malmberg, from orange to yellow Gray, 1848. Lundin & or it could Depth: 0–15 m Martynov, 2019 completely lack. Diversity 2020, 12, 171 12 of 24 Table 3. Cont. Phenotypical Species Name Figure Ecological Notes Abundance Variability Very small species 1.5–2 mm, as Runcina cf. ferruginea 30 Figure 6G expected for Runcina species. - 3–10 Kress, 1977 Depth: 8 m. Found only as single and very small Philine punctata (J. 31 Figure 6H specimen, ca. 1 mm, on Posidonia - 1–2 Adams, 1800) oceanica rhizomes. Philine quadripartita Recorded on soft bottoms. 32 Figure 7A - 1–2 Ascanius, 1772 Depth: 8 m Its body color pattern varies from a dark Camachoaglaja Recorded on soft bottoms or on algae. form to another much 33 africana Figure 7B,C 11–30 Depth: 0–20 m lighter and densely (Pruvot-Fol, 1953) covered by whitish tiny dots Found on soft bottoms or on algae Philinopsis depicta mainly during winter season and in 34 Figure 7D - 11–30 (Renier, 1807) shallow water. Depth: 0–15 m Melanochlamys wildpretii Found in winter in shallow water. 35 Figure 7E - 1–2 Ortea, Bacallado & Depth: 0–3 m Moro, 2003 Haminoea cf. orteai Found on green algae. 36 Talavera, Murillo & Figure 7F - 31–100 Depth: 0–3 m Templado, 1987 Very mimetic species, usually in Elysia gordanae association with the green alga Figure 7G,H 37 T. E. Thompson & Flabellia petiolata (Turra) Nizamuddin, - >100 and Figure 8A Jaklin, 1988 1987. Depth: 0–15 m On Dictyota dichotoma (Hudson) J.V. Elysia margaritae 38 Figure 8B Lamouroux, 1809. - 1–2 Fez, 1962 Depth: 0–2 m Aplysiopsis elegans 39 Figure 8C Depth: 0–12 m - 3–10 Deshayes, 1853 Found on April. 18 C water The body color patter Cyerce graeca 40 Figure 8D temperature. varies from withe to 1–2 T. E. Thompson, 1988 Depth: 3 m light yellow Hermaea Found mainly in spring and summer 41 Figure 8E - 3–10 bifida(Montagu, 1816) on green algae. Depth: 5–6 m Hermaea paucicirra Found on algae in shallow waters. 42 Figure 8F - 1–2 Pruvot-Fol, 1953 Depth: 0–1 m Ercolania coerulea Found on algae in shallow waters. 43 Figure 8G,H - 3–10 Trinchese, 1892 Depth: 0–5 m Limapontia capitata (O. Found on algae in shallow waters. 44 Figure 9A - 11–30 F. Müller, 1774) Depth: 0.5 m Placida cremoniana 45 Figure 9B Depth: 0–12 m - 11–30 (Trinchese, 1892) Diversity 2020, 12, 171 13 of 24 Diversity 2020, 12, x FOR PEER REVIEW 12 of 23 Figure 2. (A) Pleurobranchus testudinarius. St. 3 (B) Berthellina cf. edwardsii. St. 11. In the right-low Figure 2. A. Pleurobranchus testudinarius. St. 3 B. Berthellina cf. edwardsii. St. 11. In the right-low corner, corner, the internal shell (length: 4.2 mm). (C) Berthellina cf. edwardsii. St. 11 (D) Diaphorodoris the internal shell (length: 4.2 mm). C. Berthellina cf. edwardsii. St. 11 D. Diaphorodoris luteocincta. St. 11 luteocincta. St. 11 (E) Trapania lineata, mating individuals. St. 11 (F) Trapania maculata. St. 11 (G) Crimora E. Trapania lineata, mating individuals. St. 11 F. Trapania maculata. St. 11 G. Crimora papillata. St. 11 H. papillata. St. 11 (H) Crimora papillata, with spawn. St. 11. Crimora papillata, with spawn. St. 11. Diversity 2020, 12, 171 14 of 24 Diversity 2020, 12, x FOR PEER REVIEW 13 of 23 Figure 3. (A) Polycera elegans. St. 1 (B) Polycera elegans. St. 1 (C) Polycera hedgpethi. St. 1 (D) Polycera Figure 3. A. Polycera elegans. St. 1 B. Polycera elegans. St. 1 C. Polycera hedgpethi. St. 1 D. Polycera hedgpethi. Two individuals after mating. The reproductive openings are clearly visible in the specimen hedgpethi. Two individuals after mating. The reproductive openings are clearly visible in the specimen on the upper portion. St. 1 (E) Felimare fontandraui. St. 11 (F) Felimare fontandraui, mating individuals on the upper portion. St. 1 E. Felimare fontandraui. St. 11 F. Felimare fontandraui, mating individuals with spawn. St. 11 (G) Felimare orsinii, mating individuals. St. 14 (H) Felimida binza. St. 25. with spawn. St. 11 G. Felimare orsinii, mating individuals. St. 14 H. Felimida binza. St. 25. Diversity 2020, 12, 171 15 of 24 Diversity 2020, 12, x FOR PEER REVIEW 14 of 23 Figure 4. (A) Tritonia nilsodhneri. St. 18 (B) Doto cervicenigra. St. 11 (C) Doto floridicola. St. 22 (D) Spawn Figure 4. A. Tritonia nilsodhneri. St. 18 B. Doto cervicenigra. St. 11 C. Doto floridicola. St. 22 D. Spawn of of Doto floridicola. St. 22 (E) Paraflabellina gabinierei. St. 11 (F) Limenandra nodosa. St. 3 (G) Caloria elegans. Doto floridicola. St. 22 E. Paraflabellina gabinierei. St. 11 F. Limenandra nodosa. St. 3 G. Caloria elegans. St. St. 11 (H) Dicata odhneri St. 11. 11 H. Dicata odhneri St. 11. Diversity 2020, 12, 171 16 of 24 Diversity 2020, 12, x FOR PEER REVIEW 15 of 23 Figure 5. (A) Dondice banyulensis. St. 13 (B) Facelina fusca. St. 7 (C) Facelina rubrovittata. St. 11 (D,E) Figure 5. A. Dondice banyulensis. St. 13 B. Facelina fusca. St. 7 C. Facelina rubrovittata. St. 11 D. E. Facelina Facelina vicina. St. 11 (F) Eubranchus cf. farrani. St. 11 (G,H) Eubranchus cf. linensis St. 11. vicina. St. 11 F. Eubranchus cf. farrani. St. 11 G. H. Eubranchus cf. linensis St. 11. Diversity 2020, 12, 171 17 of 24 Diversity 2020, 12, x FOR PEER REVIEW 16 of 23 Figure 6. (A) Catriona maua. St. 9 (B) Rubramoena amoena. St. 22 (C) Trinchesia genovae. St. 11 Figure 6. A. Catriona maua. St. 9 B. Rubramoena amoena. St. 22 C. Trinchesia genovae. St. 11 D. Trinchesia (D) Trinchesia genovae. St. 7 (E) Trinchesia cf. miniostriata St. 22 (F) Trinchesia morrowae. St. 11 (G) Runcina genovae. St. 7 E. Trinchesia cf. miniostriata St. 22 F. Trinchesia morrowae. St. 11 G. Runcina cf. ferruginea. cf. ferruginea. St. 22 (H) Philine punctata St. 9. St. 22 H. Philine punctata St. 9. Diversity 2020, 12, 171 18 of 24 Diversity 2020, 12, x FOR PEER REVIEW 17 of 23 Figure 7. (A) Philine quadripartita. St. 1 (B) Camachoaglaja africana. St. 7 (C) Camachoaglaja africana. St. 22 Figure 7. A. Philine quadripartita. St. 1 B. Camachoaglaja africana. St. 7 C. Camachoaglaja africana. St. 22 D. (D) Philinopsis depicta. St. 10 (E) Melanochlamys wildpretii. St. 7 (F) Haminoea cf. orteai. St. 22 (G) Elysia Philinopsis depicta. St. 10 E. Melanochlamys wildpretii. St. 7 F. Haminoea cf. orteai. St. 22 G. Elysia gordanae. gordanae. St. 11 (H) Elysia gordanae. St. 11. St. 11 H. Elysia gordanae. St. 11. Diversity 2020, 12, 171 19 of 24 Diversity 2020, 12, x FOR PEER REVIEW 18 of 23 Figure 8. (A) Spawn of Elysia gordanae. St. 22 (B) Elysia margaritae. St. 11 (C) Aplysiopsis elegans. St. 1 Figure 8. A. Spawn of Elysia gordanae. St. 22 B. Elysia margaritae. St. 11 C. Aplysiopsis elegans. St. 1 D. (D) Cyerce graeca. St. 11 (E) Hermaea bifida. St. 1 (F) Hermaea paucicirra. St. 7 (G,H) Ercolania coerulea. Cyerce graeca. St. 11 E. Hermaea bifida. St. 1 F. Hermaea paucicirra. St. 7 G. H. Ercolania coerulea. St. 7. St. 7. Diversity 2020, 12, 171 20 of 24 Diversity 2020, 12, x FOR PEER REVIEW 19 of 23 Figure 9. (A) Limapontia capitata. St. 24 (B) Placida cremoniana. St. 1. Figure 9. A. Limapontia capitata. St. 24 B. Placida cremoniana. St. 1. 4. Discussion 4. Discussion This study reported 160 marine Heterobranchia species from the Salento Peninsula giving the most up to date list of marine heterobranchs inhabiting this area of the Apulian coasts. This was This study reported 160 marine Heterobranchia species from the Salento Peninsula giving the particularly remarkable considering that the total number of registered species belonging to this most up to date list of marine heterobranchs inhabiting this area of the Apulian coasts. This was mollusks group for the whole Mediterranean Sea was approximately 550 [51]. The composition of the particularly remarkable considering that the total number of registered species belonging to this main groups of marine heterobranchs living in the Salento Peninsula reported in this work is shown mollusks group for the whole Mediterranean Sea was approximately 550 [51]. The composition of the in Figure 10. The groups with the largest numbers of species added were Cladobranchia (18) and main groups of marine heterobranchs living in the Salento Peninsula reported in this work is shown Doridina (9), as expected, these nudibranchs belonged to the groups with the richest variety of taxa. in Figure 10. The groups with the largest numbers of species added were Cladobranchia (18) and Surprisingly, with the present contribution, 6 species of Cephalaspidea were added to the ones reported Doridina (9), as expected, these nudibranchs belonged to the groups with the richest variety of taxa. previously. Another interesting consideration was concerning the superorder Sacoglossa, which almost Surprisingly, with the present contribution, 6 species of Cephalaspidea were added to the ones doubled after this study. Finally, some species were noteworthy because they are currently under reported previously. Another interesting consideration was concerning the superorder Sacoglossa, studied or because the validity of the species is still in doubt. This was the case for Berthellina cf. which almost doubled after this study. Finally, some species were noteworthy because they are edwardsii, Eubranchus cf. exiguus, E. cf. farrani, E. cf. linensis, Facelina fusca, Haminoea cf. orteai, Runcina currently under studied or because the validity of the species is still in doubt. This was the case for cf. ferruginea and Trinchesia cf. miniostriata. In particular, in the case of Berthellina cf. edwardsii we Berthellina cf. edwardsii, Eubranchus cf. exiguus, E. cf. farrani, E. cf. linensis, Facelina fusca, Haminoea cf. depicted (Figure 2B) the internal shell (4.2 mm long), since it fits the standard average length of the orteai, Runcina cf. ferruginea and Trinchesia cf. miniostriata. In particular, in the case of Berthellina cf. shell commonly used as diagnostic for this species, albeit we preferred to keep an uncertainty (cf.) edwardsii we depicted (Figure 2B) the internal shell (4.2 mm long), since it fits the standard average before a further molecular study would allow a clear-cut identification. The studied marine area, length of the shell commonly used as diagnostic for this species, albeit we preferred to keep an deeply influenced by two di erent seas and characterized by a variety of submarine habitats, hosts uncertainty (cf.) before a further molecular study would allow a clear-cut identification. The studied a high variety of species, which makes it an important geographical area for this sea slug diversity. marine area, deeply influenced by two different seas and characterized by a variety of submarine In fact, with this work we report that the total number of marine Heterobranchia living in the Salento habitats, hosts a high variety of species, which makes it an important geographical area for this sea Peninsula is 160, which is about a third of the total number of currently accepted species reported slug diversity. In fact, with this work we report that the total number of marine Heterobranchia living for the whole Mediterranean Sea. This is quite an important finding, also considering the fact that a in the Salento Peninsula is 160, which is about a third of the total number of currently accepted species high diversity in heterobranchs composition indirectly reflects a high structuring and diversification reported for the whole Mediterranean Sea. This is quite an important finding, also considering the of the habitats involved, and consequently, of the biodiversity that they contribute to maintain [14]. fact that a high diversity in heterobranchs composition indirectly reflects a high structuring and Studying and monitoring the marine Heterobranchia diversity in the Salento Peninsula is valuable for diversification of the habitats involved, and consequently, of the biodiversity that they contribute to highlighting the consequences of the global marine changes reported in the last decade [10–12,59,60], maintain [14]. Studying and monitoring the marine Heterobranchia diversity in the Salento Peninsula such as warming and acidification of waters or invasion of alien species. An additional detailed is valuable for highlighting the consequences of the global marine changes reported in the last decade and constantly updated iconography is available on the website of the Salento Sommerso group [10–12,59,60], such as warming and acidification of waters or invasion of alien species. An additional (http://www.salentosommerso.it/index_opi.php), a non-profit association devoted to the preservation detailed and constantly updated iconography is available on the website of the Salento Sommerso and documentation of the underwater biodiversity of the Salento Peninsula. group (http://www.salentosommerso.it/index_opi.php), a non-profit association devoted to the preservation and documentation of the underwater biodiversity of the Salento Peninsula. Diversity 2020, 12, x FOR PEER REVIEW 20 of 23 Diversity 2020, 12, 171 21 of 24 Figure 10. Comparison between the main heterobranch groups; the graph shows the comparison Figure 10. Comparison between the main heterobranch groups; the graph shows the comparison between the total species of the Salento Peninsula, clustered into the main groups. between the total species of the Salento Peninsula, clustered into the main groups. 5. Conclusions Author Contributions: F.V. and C.L. conceived the project and performed most of the SCUBA diving and took in situ pictures. G.F. and P.M. analysed the data and carried out the SCUBA diving. F.V., C.L., G.F., and P.M. The study of marine diversity is a fundamental topic especially if focused on areas like wrote the manuscript. All authors read and approved the final manuscript. Mediterranean Sea, which is characterised by a high rate of endemic and cryptic species. In this study we have investigated the presence of marine Heterobranchia in the Salento Peninsula (Apulia, Funding: Authors sincerely acknowledge the University of Roma Tre for financial support (CAL/2018 and South-Italy) CAL/2019). considering for the first time both Ionian and Adriatic coasts. Results of a nine-year study reports 160 species inhabiting the studied area with new records from the sublittoral waters, Acknowledgments: Special thanks to Prof. Genuario Belmonte (University of Salento, Italy), Prof. Lucas Cervera ecological notes, local distribution and systematic remarks. This inventory of marine Heterobranchia Currado (University of Cadiz, Spain), and Egidio Trainito (Sardinia, Italy) for their useful suggestions. The encountered in the Salento Peninsula adds 45 species to the previously known for this area. For all authors wish to thank Elena Mazzone (Rome, Italy) for the revision of the English text. We would also like to the added species, we have figured live animals mostly by in situ photographs to document species thank Paolo D'Ambrosio, Director of the Porto Cesareo AMP, for permission to carry out research in the Marine identification Protected Area and of Porto Ce reported sareo (Le data on cce) ecology . The authors are , phenotypical greatly variability indebtedand to Prof. abundance. Marco Oliverio This inventory (Rome, Ita of ly) for the revision of the English text. A very special thanks to our diving companions Marcella D'Elia, Domenico marine Heterobranchia provides a baseline for future monitoring of both coastal sides and could serve Licchelli, Cesare Bortone, and Pierantonio Cicirillo, with whom we shared many dives. We thank Antonello as a starting point for further molecular studies aiming to unveil Mediterranean cryptic diversity. Perrone for suggestions and criticism. We thank Gianfranco Alemanno, Andrea Astore, Gianni Colucci, Piero Author Lenoci, Vi Contributions: ncenzo Marra, E F.V. n and rico P C.L. aticonceived , and Gianl the uca pr Roma oject no, for and performed supporting us with most of the many photographic images, SCUBA diving and took in situ pictures. G.F. and P.M. analysed the data and carried out the SCUBA diving. F.V., C.L., G.F., and P.M. wrote specimens, and for sharing some of their data with us. Thanks to Manuel Ballesteros from the University of the manuscript. All authors have read and agreed to the published version of the manuscript. Barcelona (Spain), Marta Pola from the University of Madrid (Spain), Enric Madrenas and Miquel Pontes (Spain), Manuel Malaquias of the University of Bergen (Norway), and Jakov Prkić (Croatia) for the many suggestions Funding: Authors sincerely acknowledge the University of Roma Tre for financial support (CAL/2018 and CAL/2019). and constructive exchanges of ideas and experiences. The authors are greatly indebted to the four anonymous reviewers, who provided many valuable comments, and improved the English. Acknowledgments: Special thanks to Genuario Belmonte (University of Salento, Italy), Lucas Cervera Currado (University of Cadiz, Spain), and Egidio Trainito (Sardinia, Italy) for their useful suggestions. The authors wish Conflicts of Interest: The authors declare no conflict of interest. The funders had no role in the design of the to thank Elena Mazzone (Rome, Italy) for the revision of the English text. We would also like to thank Paolo study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to D’Ambrosio, Director of the Porto Cesareo AMP, for permission to carry out research in the Marine Protected Area of pu Porto blish the res Cesareou(Lecce). lts. The authors are greatly indebted to Marco Oliverio (Rome, Italy) for the revision of the English text. A very special thanks to our diving companions Marcella D’Elia, Domenico Licchelli, Cesare Bortone, and Pierantonio Cicirillo, with whom we shared many dives. We thank Antonello Perrone for suggestions and References criticism. We thank Gianfranco Alemanno, Andrea Astore, Gianni Colucci, Piero Lenoci, Vincenzo Marra, Enrico Pati, and Gianluca Romano, for supporting us with many photographic images, specimens, and for sharing some 1. Dainelli, G. Appunti Geologici sulla Parte Meridionale del Capo di Leuca; Tipografia della Pace di Filippo of their data with us. Thanks to Manuel Ballesteros from the University of Barcelona (Spain), Marta Pola from the Cuggiani: Rome, Italy, 1901. University of Madrid (Spain), Enric Madrenas and Miquel Pontes (Spain), Manuel Malaquias of the University of 2. De Giorgi, C. La Serie Geologica dei Terreni nella Penisola Salentina; Tipografia della Pace di Filippo Cuggiani: Bergen (Norway), and Jakov Prkic ´ (Croatia) for the many suggestions and constructive exchanges of ideas and experiences. The authors are greatly indebted to the four anonymous reviewers, who provided many valuable Rome, Italy, 1903. comments, and improved the English. 3. Biasutti, R. Note morfologiche ed idrografiche sulla Terra d’Otranto. Riv. Geogr. It 1911, 18, 508–531. Conflicts of Interest: The authors declare no conflict of interest. The funders had no role in the design of the 4. Sacco, F. La geotettonica dell’Appennino meridionale. Boll. Soc. Geol. Ital. 1912, 31, 379–387. study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to 5. Colamonico, C. La Geografia della Puglia: Profilo Monografico Regionale:(Con una Carta Geografica a Colori); publish the results. Cressati: Bari, Italy, 1926. 6. Spalding, M.D.; Fox, H.E.; Allen, G.R.; Davidson, N.; Ferdaña, Z.A.; Finlayson, M.; Halpern, B.S.; Jorge, References M.A.; Lombana, A.; Lourie, S.A.; et al. Notes Marine Ecoregions of the World: A Bioregionalization of 1. Dainelli, G. Appunti Geologici sulla Parte Meridionale del Capo di Leuca; Tipografia della Pace di Filippo Cuggiani: Coastal and Shelf Areas. BioScience 2007, 57, 573–583. Rome, Italy, 1901. 7. Bianchi, C.N. Proposta di suddivisione dei mari italiani in Settori Biogeografici. Not. Soc. Biol. Mar. 2004, 2. De Giorgi, C. La Serie Geologica dei Terreni nella Penisola Salentina; Tipografia della Pace di Filippo Cuggiani: 46, 57–59. Rome, Italy, 1903. Diversity 2020, 12, 171 22 of 24 3. Biasutti, R. Note morfologiche ed idrografiche sulla Terra d’Otranto. Riv. Geogr. It 1911, 18, 508–531. 4. Sacco, F. La geotettonica dell’Appennino meridionale. Boll. Soc. Geol. Ital. 1912, 31, 379–387. 5. Colamonico, C. 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Two Seas for One Great Diversity: Checklist of the Marine Heterobranchia (Mollusca; Gastropoda) from the Salento Peninsula (South-East Italy)

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Abstract

diversity Article Two Seas for One Great Diversity: Checklist of the Marine Heterobranchia (Mollusca; Gastropoda) from the Salento Peninsula (South-East Italy) 1 , 2 , 3 2 , 4 5 Giulia Furfaro * , Fabio Vitale , Cataldo Licchelli and Paolo Mariottini Department of Biological and Environmental Sciences and Technologies—DiSTeBA, University of Salento, I-73100 Lecce, Italy Salento Sommerso Association, I-73100 Lecce, Italy; fabio_vitale@tin.it (F.V.); cataldo.licchelli@gmail.com (C.L.) Museum of Natural History of Salento, I-73021 Calimera-Lecce, Italy Cooperativa Hydra, I-73100 Lecce, Italy Department of Science, University of Roma Tre, I-00146 Rome, Italy; paolo.mariottini@uniroma3.it * Correspondence: giulia.furfaro@unisalento.it Received: 18 March 2020; Accepted: 24 April 2020; Published: 26 April 2020 Abstract: The Salento peninsula is a portion of the Italian mainland separating two distinct Mediterranean basins, the Ionian and the Adriatic seas. Several authors have studied the marine Heterobranchia (Mollusca, Gastropoda) fauna composition living in the Ionian Sea, but to date further knowledge regarding this interesting group of mollusks is still needed. Recent studies have corroborated the peculiarity of the Mediterranean Sea showing high levels of endemism and cryptic diversity. On the other hand, marine sea slugs have been revealed to be important indicators of the marine ecosystem’s health, due to their species-specific diet that consist of a vast variety of sessile and benthic invertebrates. A baseline study of the marine Heterobranchia diversity is therefore a necessary step to reveal the hidden diversity and to monitor the possible presence of alien species. The present study shows results from approximately 600 scientific dives carried out during a nine-year period in all of the main submarine habitats of the studied area, while accounting for the marine Heterobranchia from both the Ionian and Adriatic Seas. With this contribution, the list of marine Heterobranchia inhabiting the Salento Peninsula rises to 160. Furthermore, it also reports, for the first time, the presence of one alien species and three new records for Italian waters. Ecological notes and geographical distribution for each added species are provided together with animal iconography, consisting mainly of in situ photographs, for species identification. Keywords: diversity; sea slugs; nudibranchs; Mediterranean Sea; monitoring 1. Introduction The Salento Peninsula (South-East Italy) in Puglia is a strip of land right on the border of the eastern Mediterranean Sea, made up of a large variety of habitats: rocky formations, open sandy beaches, marine caves, etc. The Salento Peninsula is a physically well-identified region, encompassing 0 00  0 00 the innermost point of the Gulf of Taranto (40 31 17.8 N 17 06 10.7 E) and the beach of Torre 0 00  0 00 Santa Sabina di Ostuni (40 45 52.3 N 17 41 20.1 E), with a length of 138 kilometers, calculated 0 00  0 00 on the axis between Martina Franca (40 42 17.7 N 17 20 20.9 E) and the Cape of Santa Maria di 0 00  0 00 Leuca (39 47 40.4 N 18 22 05.0 E). The maximum and minimum width are 54 and 33 kilometers, respectively, and the total coastal length is 365 kilometers [1–5]. This peninsula protrudes between two ecoregions of the Mediterranean Sea [6], the Northern Ionian, and the Southern Adriatic seas, which are conventionally separated by the dividing line passing through Otranto (according to the Diversity 2020, 12, 171; doi:10.3390/d12050171 www.mdpi.com/journal/diversity Diversity 2020, 12, 171 2 of 24 biogeographical zones described by Bianchi [7], i.e., zones 6 and 7, respectively). These two basins are characterised by peculiar and distinct main currents and submarine morphologies, resulting in very complex and dynamic ecosystems a ected by seasonal fluctuations, which influences both the shallow and deep communities [8,9]. Therefore, this marine area could potentially host a high abundance of Heterobranchia species, due to their pelagic larval stage and diversified diet. Knowledge on diversity is a basic requisite to identify targets and to monitor species composition shifts over time, caused by natural or anthropogenic factors. In fact, the change in marine Heterobranchia fauna composition over time is considered a good ecological indicator of potential environmental modifications [10–14] and this peculiarity is particularly interesting in such a heterogeneous area of the Mediterranean. Furthermore, the capability of marine Heterobranchia to host biological compounds that are potentially interesting for biomedical applications, provides additional value to the study of this particular group of mollusks [14]. In fact, many species of marine Heterobranchia display aposematic vivacious warning colors to indicate that they contain defensive secondary metabolites that are sequestered, transformed from dietary sources, or synthesized de novo [15]. These compounds are used, mainly by nudibranchs, as a chemical defense from predation [16,17] and have revealed to be an important source of diverse bioactive products used as e ective analgesic, anti-inflammatory, antiviral, and anticancer drugs [18,19]. The Mediterranean marine diversity is therefore revealed to be interesting, mainly due to the presence of cryptic or endemic species. In fact, several species once considered to be widespread across the Atlantic and the Mediterranean were shown to be a complex of cryptic species, many of which are endemic to the Mediterranean (e.g., [20–23]). This trend is also true for marine Heterobranchia, as demonstrated by recent molecular papers that helped to unravel such cryptic diversity [24–29]. In this context, studies focused on the production of species lists from di erent geographical areas are needed as an essential starting point to unveil this hidden diversity. In the past decade, the key works on marine Heterobranchia in the area under investigation have been published by Perrone [30–37], who mainly provided data regarding the species inhabiting the Ionian side of the Salento peninsula (Gulf of Taranto), and only provided ecological notes on a small number of species. Recently, Onorato and Belmonte [38] reviewed the biodiversity assessment of the marine submerged caves in the Salento peninsula, which includes some heterobranchs, while Micaroni et al. [39] published a check-list of Heterobranchia from the Ionian locality of Tricase, adding 20 species to Perrone’s previous lists [30–37]. Finally, several published papers that did not have proper checklists, added new records of single species sampled from the Salento Peninsula [29,40–44], contributing to the increase of lists of species known from this Apulian area. However, to date, there is no published checklist of marine Heterobranchia fauna from the Adriatic side of the Salento peninsula. During the last ten years, there has been an increasing interest in marine observation by underwater photographers [45,46]. This has allowed the possibility to extend the research on fauna, to detect lesser known species, and to create a collaboration network between scientists and amateurs who are experts in this field. The so-called Citizen Science dedicated to the Heterobranchia is an important support in expanding the body of knowledge on this group of gastropods, by providing field observations on bathymetric distribution, seasonality [47], egg deposition, reproductive behavior and trophic niche, and by making the data immediately available to the scientific community through web-based social networks [48]. In the last decade, due to the combined e orts of professional underwater photographers and acknowledged systematic experts in sea slugs, many new records and ecological observations on the Salento Peninsula marine Heterobranchia have been collected. Taking all of these points into account, the present study had the following aims to: (i) contribute to the Salento Peninsula marine Heterobranchia checklist with new records from the sublittoral waters, considering both sides of this Peninsula, the Ionian and the Adriatic sides, for the first time; (ii) provide ecological notes and local distribution for each new recorded species; (iii) show in situ photographs of the live animals to document species identification. Diversity 2020, 12, 171 3 of 24 2. Materials and Methods The geographical area under investigation was a stretch of more than 270 km of coastline around the Salento Peninsula in Southern Italy (Figure 1). With 600 scuba dives in the past 9 years, di erent benthic habitats were surveyed, some of which were included in the European legislative context (EU WFD, EU Habitat Directive, EU MSFD): pre-coralligenous and coralligenous assemblages, soft-bottom substrates, Posidonia oceanica (Linnaeus) Delile, 1813 meadows, and algal biocoenosis on rocky substrates. All sampled sites were georeferenced (Table 1) to provide accurate data of the studied locations for future monitoring and comparison. When possible, ecological observation and in situ photographs of the individuals recorded were performed and catalogued for species identification. The Scuba dives (0–40 m depth) took place all year round, almost every week, during daylight and at night, between 2011 and 2019. Specimens between 2 and 5 mm in length were photographed alive in the laboratory, in Petri capsules illuminated by a series of low voltage LED lamps, with 6500 K bulbs. The camera used for filming was a tripod mounted Nikon D7100, with 60 mm micro Nikkor or 105 mm micro Nikkor optics, a series of extension rings and additional lenses. The underwater photographic or videography equipment (F.V.) was a Nikon D7000 body, 60 mm micro Nikkor, or 105 mm micro Nikkor optics, extension rings inside an Isotta housing, as well as additional wet lenses SubSee +10 diopter, two underwater flashes Inon z240, and two LED lamps of great luminous power. Or alternatively, (C.L.) a Canon 600D body in a Nauticam 600D housing, equipped with the following lenses—for macro photography and in some cases for micro subjects, the Canon 60 mm USM Macro, and Canon 100 mm USM Macro were used, in addition to wet lenses SubSee +5 and +10 diopter; for wide angle photography, the Tokina 10–17 mm fisheye lens was used. The light source was provided by a couple of Inon strobes z240 and a single focus light I-Torch Video Pro 3. The systematics and the validity of names were checked with the help of the Word Register of Marine Species [49]. Species identification was obtained by morphological investigation and a subsequent consultation of the existent literature ([29,41,44] and other references cited in the present work), guide books [50,51] and websites [48,52,53]. In the case of Berthellina cf. edwardsii, the shell from an individual (Voucher RM3_1865) was extracted and used to confirm the identification as this anatomical feature is commonly considered to be diagnostic for this species. The shell was removed and dissolved in a 10% NaOH solution, then rinsed in water, dried, and mounted for examination by optical microscopy, following the same protocol described by Furfaro et al. [54]. Voucher numbers were assigned to the collected individuals that were selected for future molecular analyses; samples were preserved in 95% alcohol and stored in the Department of Science at the Roma Tre University (Rome, Italy) (Table 2). Finally, a comparison between species as recorded by previous authors (Perrone [30–37] (A), Onorato and Belmonte [38] (B), Micaroni et al. [39] (C)) and the present study (D) was carried out and reported in Table 2 with new records highlighted in bold letters. An ethical approach in this research was also carried out by complying with the restrictions in term of collected sample size, environmental survey of the collection sites, use of hand-net picking of specimens (harmless and not destructive) as well as complying with local, regional, national, and international rules, and regulations for access to biodiversity, sustainable use, and benefit sharing (Convention on Biological Diversity and its Nagoya Protocol, national regulations). Diversity 2020, 12, 171 4 of 24 Diversity 2020, 12, x FOR PEER REVIEW 4 of 23 Figure 1. Map of the Salento Peninsula indicating the sampling localities; the box highlights the Figure 1. Map of the Salento Peninsula indicating the sampling localities; the box highlights the Salento Salento Peninsula at a higher magnification. Numbers refer to sampling stations reported in Table 1. Peninsula at a higher magnification. Numbers refer to sampling stations reported in Table 1. Table 1. Number, name, geographic coordinates (latitude and longitude), and the depth range of the Table 1. Number, name, geographic coordinates (latitude and longitude), and the depth range of the sampled stations. sampled stations. N Station Latitude Longitude Depth N° Station Latitude Longitude Depth 0 00  0 00 1 1 Mar Mar P Piccolo, iccolo, Taranto Taran (Ionian to (IonSea) ian Sea) 40 40° 28 28′53.62 53.62′′N N 17°16′17 00.9 16 1′′E 00.91 1–10 m E 1–10 m 0 00  0 00 2 Capo S. Vito, Taranto (Ionian Sea) 40 24 35.85 N 17 12 06.07 E 1–20 m 2 Capo S. Vito, Taranto (Ionian Sea) 40°24′35.85′′N 17°12′06.07′′E 1–20 m 0 00  0 00 3 3 Porto Pirrone, Taranto (Ionian Sea) 40 21 27.79 N 17 19 40.93 E 4–20 m Porto Pirrone, Taranto (Ionian Sea) 40°21′27.79′′N 17°19′40.93′′E 4–20 m 0 00  0 00 4 Torre Ovo, Taranto (Ionian Sea) 40 17 29.18 N 17 30 11.20 E 1–20 m 4 Torre Ovo, Taranto (Ionian Sea) 40°17′29.18′′N 17°30′11.20′′E 1–20 m 0 00  0 00 5 Campomarino, Taranto (Ionian Sea) 40 17 34.76 N 17 31 41.48 E 1–20 m 5 Campomarino, Taranto (Ionian Sea) 40°17′34.76′′N 17°31′41.48′′E 1–20 m 0 00  0 00 6 Porto Cesareo I. Conigli, Lecce (Ionian Sea) 40 15 32.15 N 17 52 57.59 E 1–15 m 6 Porto Cesareo I. Conigli, Lecce (Ionian Sea) 40°15′32.15′′N 17°52′57.59′′E 1–15 m 0 00  0 00 7 Porto Cesareo, Lecce (Ionian Sea) 40 14 51.48 N 17 54 33.51 E 0–1 m 7 Porto Cesareo, Lecce (Ionian Sea) 40°14′51.48′′N 17°54′33.51′′E 0–1 m 0 00  0 00 8 S. Isidoro, Lecce (Ionian Sea) 40 13 15.51 N 17 55 29.27 E 1–5 m 8 S. Isidoro, Lecce (Ionian Sea) 40°13′15.51′′N 17°55′29.27′′E 1–5 m 0 00  0 00 9 Torre Inserraglio, Lecce (Ionian Sea) 40 10 41.44 N 17 55 51.53 E 1–20 m 9 Torre Inserraglio, Lecce (Ionian Sea) 40°10′41.44′′N 17°55′51.53′′E 1–20 m 0 00  0 00 10 Santa Caterina di Nardò, Lecce (Ionian Sea) 40 08 05.87 N 17 59 15.53 E 1–15 m 10 Santa Caterina di Nardò, Lecce (Ionian Sea) 40°08′05.87′′N 17°59′15.53′′E 1–15 m 0 00  0 00 11 Santa Maria al Bagno, Lecce (Ionian Sea) 40 07 30.58 N 17 59 46.43 E 0–6 m 11 Santa Maria al Bagno, Lecce (Ionian Sea) 40°07′30.58′′N 17°59′46.43′′E 0–6 m 0 00  0 00 12 O.R. Gallipoli, Lecce (Ionian Sea) 40 06 04.68 N 17 58 04.22 E 36 m 12 O.R. Gallipoli, Lecce (Ionian Sea) 40°06′04.68′′N 17°58′04.22′′E 36 m 0 00  0 00 13 Gallipoli, Lecce (Ionian Sea) 40 04 34.70 N 17 59 50.25 E 1–20 m 13 Gallipoli, Lecce (Ionian Sea) 40°04′34.70′′N 17°59′50.25′′E 1–20 m 0 00  0 00 14 Gallipoli - Isola S. Andrea, Lecce (Ionian Sea) 40 02 36.77 N 17 57 01.64 E 5–20 m 14 Gallipoli - Isola S. Andrea, Lecce (Ionian Sea) 40°02′36.77′′N 17°57′01.64′′E 5–20 m 0 00  0 00 15 Gallipoli Pizzo, Lecce (Ionian Sea) 39 59 57.64 N 17 59 27.36 E 1–15 m 15 Gallipoli Pizzo, Lecce (Ionian Sea) 39°59′57.64′′N 17°59′27.36′′E 1–15 m 0 00  0 00 16 Marina Mancaversa, Lecce (Ionian Sea) 39 58 58.04 N 18 00 18.58 E 1–5 m 16 Marina Mancaversa, Lecce (Ionian Sea) 39°58′58.04′′N 18°00′18.58′′E 1–5 m 0 00  0 00 17 Torre Suda, Lecce (Ionian Sea) 39 56 27.95 N 18 02 17.36 E 1–5 m 17 Torre Suda, Lecce (Ionian Sea) 39°56′27.95′′N 18°02′17.36′′E 1–5 m 0 00  0 00 18 Ugento, Lecce (Ionian Sea) 39 52 36.70 N 18 05 25.14 E 5–30 m 18 Ugento, Lecce (Ionian Sea) 39°52′36.70′′N 18°05′25.14′′E 5–30 m 0 00  0 00 19 Santa Maria di Leuca, Lecce (Ionian Sea) 39 48 18.38 N 18 22 42.56 E 1–20 m 19 Santa Maria di Leuca, Lecce (Ionian Sea) 39°48′18.38′′N 18°22′42.56′′E 1–20 m 0 00  0 00 20 Tricase, Lecce (Adriatic Sea) 39 55 51.31 N 18 23 47.92 E 1–30 m 20 Tricase, Lecce (Adriatic Sea) 39° 550′51.310′′0N 18°23′47 .92′′0E 1–30 00 m 21 Porto Miggiano, Lecce (Adriatic Sea) 40 01 46.72 N 18 27 01.30 E 1–25 m 21 Porto Miggiano, Lecce (Adriatic Sea) 40° 010′46.720′′0N 18°27′01 .30′′0E 1–25 m 00 22 Otranto, Lecce (Adriatic Sea) 40 08 18.52 N 18 30 47.65 E 1–40 m 0 00  0 00 22 Otranto, Lecce (Adriatic Sea) 40°08′18.52′′N 18°30′47.65′′E 1–40 m 23 Roca, Lecce (Adriatic Sea) 40 17 50.18 N 18 24 49.69 E 1–6 m 23 Roca, Lecce (Adriatic Sea) 40° 170′50.180′′0N 18°24′49 .69′′0E 1–6 m 00 24 Frigole, Lecce (Adriatic Sea) 40 26 20.52 N 18 14 46.56 E 0–1 m 0 00  0 00 24 Frigole, Lecce (Adriatic Sea) 40°26′20.52′′N 18°14′46.56′′E 0–1 m 25 Brindisi (Adriatic Sea) 40 39 54.11 N 17 57 34.81 E 1–8 m 25 Brindisi (Adriatic Sea) 40°39′54.11′′N 17°57′34.81′′E 1–8 m Table 2. List of species of Heterobranchia occurring around the Salento peninsula; localities are numbered according to Figure 1, with new records in column D, highlighted in bold. Column A = Perrone [30–37]; B = Onorato and Belmonte [38]; C = Micaroni et al. [39]; and D = Present study. Taxonomy A B C D Vouchers Pleurobranchida Family Pleurobranchidae Gray, 1827 Pleurobranchus membranaceus (Montagu, 1803) 16 Pleurobranchus testudinarius Cantraine, 1835 1,17 Diversity 2020, 12, 171 5 of 24 Table 2. List of species of Heterobranchia occurring around the Salento peninsula; localities are numbered according to Figure 1, with new records in column D, highlighted in bold. Column A = Perrone [30–37]; B = Onorato and Belmonte [38]; C = Micaroni et al. [39]; and D = Present study. Taxonomy A B C D Vouchers Pleurobranchida Family Pleurobranchidae Gray, 1827 Pleurobranchus membranaceus (Montagu, 1803) 16 Pleurobranchus testudinarius Cantraine, 1835 1,17 Berthellina cf. edwardsii 1,4,6,10,13,15 RM3_1865 Berthella aurantiaca (Risso, 1818) 8,9,19,23 Berthella elongata (Cantraine, 1836) 16 Berthella ocellata (delle Chiaje, 1830) 8 5,6 Berthella plumula (Montagu, 1803) 16 Berthella stellata (Risso, 1826) 9 22 Berthellina citrina (Rüppell & Leuckart, 1828) 18 Family Pleurobranchaeidae Pilsbry, 1896 Pleurobranchaea meckeli (Blainville, 1825) 16 11 5,6 Nudibranchia - Doridina Family Calycidorididae Roginskaya, 1972 Diaphorodoris luteocincta (M. Sars, 1870) 6 Diaphorodoris papillata Portmann & Sandmeier, 1960 11 5,6,10 Family Onchidorididae Gray, 1927 Adalaria proxima (Alder & Hancock, 1854) 21 Knoutsodonta albonigra (Pruvot-Fol, 1951) 20,24 Family Goniodorididae H. & A. Adams, 1854 Goniodoris castanea Alder & Hancock, 1845 20 1 Okenia longiductis Pola M, Paz-Sedano S, Macali A, 1,4 Minchin D, Marchini A, Vitale F, 2019 [41] Okenia mediterranea (von Ihering, 1886) [41] 6 Okenia problematica Pola M, Paz-Sedano S, Macali A, Minchin D, Marchini A, Vitale F, 2019 [41] RM3_1042, Trapania lineata Haefelfinger, 1960 4–6,10,13,15 RM3_1048, RM3_1077 Trapania maculata Haefelfinger, 1960 4–6,10,13,15 RM3_1076 Family Polyceridae Alder & Hancock, 1845 Crimora papillata Alder & Hancock, 1862 5,6,11 Kaloplocamus ramosus (Cantraine, 1835) 11 Polycera elegans (Bergh, 1894) 1 Polycera hedgpethi Marcus, 1964 1 Polycera quadrilineata (O. F. Müller, 1776) 3,16 11 1,3–6,10,13,15 RM3_1065 Thecacera pennigera (Montagu, 1815) 1 Family Aegiridae P. Fischer, 1883 Aegires punctilucens (d’Orbigny, 1837) 4 Family Cadlinidae Bergh, 1891 Aldisa banyulensis Pruvot-Fol, 1951 23,24 6 Family Chromodorididae Bergh, 1891 RM3_1039, RM3_1040, Felimare fontandraui (Pruvot-Fol, 1951) 6,8 RM3_1099, RM3_1100 Felimare orsinii (Vérany, 1846) 8,12,13,15 RM3_1041, 1,4–6, Felimare picta (Philippi, 1836) 19 13 11 RM3_1052, 8,10,12,13,15 RM3_1053 1,4–6, RM3_1074, Felimare tricolor (Cantraine, 1835) 5 11 8,10,12,13,15 RM3_1075 RM3_1231, Felimare villafranca (Risso, 1818) 16 11 1,5,6 RM3_1232 Diversity 2020, 12, 171 6 of 24 Table 2. Cont. Taxonomy A B C D Vouchers Felimida binza (Ev. Marcus & Er. Marcus, 1963) 15 RM3_1061, Felimida krohni (Vérany, 1846) 13 11 4–6,13 RM3_1068 Felimida luteorosea (Rapp, 1827) 16 11 1,6 Felimida purpurea (Risso, 1831) 4 6 Family Dorididae Rafinesque, 1815 Doris ocelligera (Bergh, 1881) 11 3 Doris pseudoargus Rapp, 1827 19 Doris verrucosa Linnaeus, 1758 19 1 Family Discodorididae Bergh, 1891 Atagema rugosa Pruvot-Fol, 1951 19 Baptodoris cinnabarina Bergh, 1884 8,20 22, 6 Discodoris stellifera (Vayssière, 1903) 9,19 15 Gargamella perezi (Llera & Ortea, 1982) 19,24 Geitodoris bonosi Ortea & Ballesteros, 1981 3 Geitodoris portmanni (Schmekel, 1972) 20 Jorunna tomentosa (Cuvier, 1804) 3,10,20 1, 13 Paradoris indecora (Bergh, 1881) 3,24 RM3_1054, Peltodoris atromaculata Bergh, 1880 8 11 ALL RM3_1056, RM3_1057 Peltodoris sordii Perrone, 1989 3 Platydoris argo (Linnaeus, 1767) 8 11 5,6,10,13 Rostanga anthelia Perrone, 1991 4 Rostanga rubra (Risso, 1818) 20,23 Taringa armata Swennen, 1961 22 Taringa pinoi Perrone, 1985 20,24 Tayuva lilacina (Gould, 1852) 3 1,22 Family Phyllidiidae Rafinesque, 1814 RM3_1049, Phyllidia flava Aradas, 1847 19 11 4–6,9,10,13 RM3_1055, RM3_1058 Family Dendrodorididae O’Donoghue, 1924 Dendrodoris grandiflora (Rapp, 1827) 16 11 1,3,5,6 1,16, Dendrodoris limbata (Cuvier, 1804) 1,3,5,6 Doriopsilla areolata Bergh, 1880 17,23 3,4,6 Nudibranchia - Cladobranchia Family Tritoniidae Lamarck, 1809 Marionia blainvillea (Risso, 1818) 9 19 Tritonia manicata Deshayes, 1853 8,16 11 5,6 Tritonia nilsodhneri Marcus Ev., 1983 9 Tritonia striata Haefelfinger, 1963 16 5,6 Family Hancockiidae MacFarland, 1923 Hancockia uncinata (Hesse, 1872) 16 Family Scyllaeidae Alder & Hancock, 1855 Scyllaea pelagica Linnaeus, 1758 19 Family Tethydidae Rafinesque, 1815 Melibe viridis Kelaart, 1858 [55] 1,5,6 Tethys fimbria Linnaeus, 1767 16 6,13 Family Dotidae Gray, 1853 Doto acuta Schmekel & Kress, 1977 11 Doto cervicenigra Ortea & Bouchet, 1989 3,6 Doto floridicola Simroth, 1888 13 Doto fragaria Ortea & Bouchet, 1989 [56] 6 Doto koenneckeri Lemche, 1976 11 13 Doto paulinae Trinchese, 1881 11 6 Doto pygmaea Bergh, 1871 11 Diversity 2020, 12, 171 7 of 24 Table 2. Cont. Taxonomy A B C D Vouchers Family Proctonotidae Gray, 1853 Antiopella cristata (Delle Chiaje, 1841) 9 1,3,5,6 Family Arminidae Iredale & O’Donoghue, 1841 Armina tigrina Rafinesque, 1814 18 5 Dermatobranchus cf. rubidus (Gould, 1852) [40] 2 Family Coryphellidae Bergh, 1889 Fjordia lineata (Lovén, 1846) 16 6,7 Family Flabellinidae Bergh, 1889 RM3_354, RM3_481, RM3_482, RM3_484, RM3_1079, RM3_1080, RM3_1081, RM3_1082, RM3_1083, RM3_1084, Calmella cavolini (Vérany, 1846) 8 11 5,6,13,15 RM3_1085, RM3_1086, RM3_1087, RM3_1088, RM3_1089, RM3_1090, RM3_1091, RM3_1092, RM3_1093, RM3_1095 RM3_1046, RM3_1047, Edmundsella pedata (Montagu, 181) 8 13 ALL RM3_1059, RM3_1067 RM3_1050, RM3_1043, RM3_1060, RM3_1063, Flabellina anis (Gmelin, 1791) 8 13 11 ALL RM3_1064, RM3_1070, RM3_1071, RM3_1073 Paraflabellina gabinierei (Vicente, 1975) 1,4,5,13 RM3_345, Paraflabellina ischitana (Hirano & T. E. RM3_346, 13 2,4–6,9,10,13,15 Thompson, 1990) RM3_532, RM3_533 Family Samlidae Korshunova, Martynov, Bakken, Evertsen, Fletcher, Mudianta, Saito, Lundin, Schrödl & Picton, 2017 Luisella babai (Schmekel, 1972) 13 11 13 RM3_1069 Family Piseinotecidae Edmunds, 1970 RM3_862, Piseinotecus soussi Tamsouri, Carmona, Moukrim & 6 RM3_863, Cervera, 2014 [57] RM3_1236 Family Aeolidiidae Gray, 1827 Aeolidiella alderi (Cocks, 1852) 16,20 1,3 Aeolidiella glauca (Alder & Hancock, 1845) 16 Berghia coerulescens (Laurillard, 1832) 16 11 5,6,13,15,18 Berghia verrucicornis (A. Costa, 1867) 19 13,6 Limenandra nodosa Haefelfinger & Stamm, 1958 2 Spurilla neapolitana (Delle Chiaje, 1841) 16 11 1,3,4 Family Facelinidae Berg, 1889 Caloria elegans (Alder & Hancock, 1845) 4,5,6 RM3_1051 Diversity 2020, 12, 171 8 of 24 Table 2. Cont. Taxonomy A B C D Vouchers RM3_1038, RM3_1045, RM3_1062, Cratena peregrina (Gmelin, 1791) 11 ALL RM3_1066, RM3_1072, RM3_1078, RM3_1094 Dicata odhneri (Schmekel, 1967) 1,4,6 Dondice banyulensis Portmann & Sandmeier, 1960 6,8,13,19 Facelina annulicornis (Chamisso & Eysenhardt, 1821) 11 5,6,13–15 RM3_1201, Facelina fusca Schmekel, 1966 3 RM3_1235 Facelina rubrovittata (A. Costa, 1866) 2,4–6,12,13,15 Facelina vicina (Bergh, 1882) 6 RM3_1202 Favorinus branchialis (Rathke, 1806) 16,20 1,3,5,6,13,15 Family Eubranchidae Odhner, 1934 Eubranchus andra (Korshunova, Malmberg, Prkic, ´ 1, 3, 6 Petani, Fletcher, Lundin, Martynov, 2020) [44] Eubranchus cf. farrani (Alder & Hancock, 1844) 1,3,10,13,15,21 Eubranchus cf. linensis Garcia-Gomez, Cervera & 1,6 Garcia, 1990 Eubranchus cf. exiguus (Alder & Hancock, 1848) 11 10,6 Family Fionidae Gray, 1857 RM3_1097, Fiona pinnata (Eschscholtz, 1831) 11 RM3_1098 Family Trinchesiidae F. Nordsieck, 1972 Catriona maua Ev. Marcus & Er. Marcus, 1960 4 Rubramoena amoena (Alder & Hancock, 1845) 13 Trinchesia genovae (O’Donoghue, 1926) 3,5,6,13 Trinchesia morrowae Korshunova, Picton, Furfaro, Mariottini, Pontes, Prkic, ´ Fletcher, Malmberg, 6 Lundin & Martynov, 2019 Trinchesia cf. miniostriata Schmekel, 1968 13 Trinchesia ocellata Schmekel, 1966 5 Umbraculida Family Tylodinidae Gray, 1847 Tylodina perversa (Gmelin, 1791) 4,16 5,6 Family Umbraculidae Dall, 1889 Umbraculum umbraculum (Lightfoot, 1786) 16 13 11 3,5,6,13,15 RM3_1037 Runcinida Family Runcinidae H. & A. Adams, 1854 Runcina adriatica T. E. Thompson, 1980 [42] 11 3,5,6,13 Runcina brenkoae T. E. Thompson, 1980 11 Runcina cf. ferruginea Kress, 1977 13 Runcina cf. ornata (Quatrefages, 1844) 11 Cephalaspidea Family Philinidae Gray, 1850 Philine punctata (J. Adams, 1800) 4 Philine quadripartita Ascanius, 1772 1 Family Aglajidae Pilsbry, 1895 Aglaja tricolorata Renier, 1807 11 5,6 Camachoaglaja africana (Pruvot-Fol, 1953) 3,5,6,13 Philinopsis depicta (Renier, 1807) 5,6 Melanochlamys wildpretii Ortea, Bacallado & Moro, 2003 Family Bullidae Gray, 1827 Bulla striata Bruguière, 1792 11 1, 4 Family Haminoeidae Pilsbry, 1895 Diversity 2020, 12, 171 9 of 24 Table 2. Cont. Taxonomy A B C D Vouchers Haminoea cf. orteai Talavera, Murillo & 3,13 Templado, 1987 Weinkaua turgidula (Forbes, 1844) 11 4 Aplysiida Family Aplysiidae Lamarck, 1809 Aplysia dactylomela Rang, 1828 [58] 5,6,13 Aplysia depilans Gmelin, 1791 16 13 11 ALL Aplysia fasciata Poiret, 1789 16 11 ALL Aplysia parvula Mörch, 1863 16 11 ALL Aplysia punctata (Cuvier, 1803) 16 13 ALL Bursatella leachii Blainville, 1817 2,16,19 1 Notarchus punctatus Philippi, 1836 16 Petalifera petalifera (Rang, 1828) 16,23 5,13 Phyllaplysia lafonti (P. Fischer, 1870) 19 Sacoglossa Family Oxynoida Stoliczka, 1868 Lobiger serradifalci (Calcara, 1840) 2 Oxynoe olivacea Rafinesque, 1814 2 Family Plakobranchidae Gray, 1840 Bosellia mimetica Trinchese, 1891 8,16,19 11 3,6,10 Elysia flava Verrill, 1901 19,20 6 Elysia gordanae T. E. Thompson & Jaklin, 1988 3,6,10,13,15 Elysia hetta Perrone, 1990 9,19 15 Elysia margaritae Fez, 1962 6 Elysia timida (Risso, 1818) 16 11 ALL Elysia translucens Pruvot-Fol, 1957 19 Elysia viridis (Montagu, 1804) 16 11 1,22 RM3_1096 Elysia rubeni Martín-Hervás, Carmona, Jensen, 5,6,13 Licchelli, Vitale & Cervera, 2019 [29] Thuridilla hopei (Vérany, 1853) 16,19,20 11 ALL RM3_1044 Family Hermaeidae H. & A. Adams, 1854 Aplysiopsis elegans Deshayes, 1853 1 Cyerce cristallina (Trinchese, 1881) 19 2, 13 Cyerce graeca T. E. Thompson, 1988 6 RM3_1165, Hermaea bifida (Montagu, 1816) 1 RM3_1166, RM3_1167 Hermaea paucicirra Pruvot-Fol, 1953 3,6 Hermaea variopicta (A. Costa, 1869) 24 6 Family Limapontiidae Gray, 1847 Calliopaea bellula d’Orbigny, 1837 16,19 Ercolania coerulea Trinchese, 1892 3 Ercolania viridis (A. Costa, 1866) 11 3,14 Limapontia capitata (O. F. Müller, 1774) 25 Placida cremoniana (Trinchese, 1892) 1,6 Placida dendritica (Alder & Hancock, 1843) 9 3 Abbreviation cf. is from the Latin confer/conferatur, both meaning compare. 3. Results The present checklist reports 160 marine Heterobranchia species from the Salento Peninsula (Table 2) consisting of: 10 Pleurobranchida, 9 Cephalaspidea, 4 Runcinida, 2 Umbraculida, 9 Aplisiida, 24 Sacoglossa, and 102 Nudibranchia (50 Doridina, 52 Cladobranchia). This contribution added 45 species (Tables 2 and 3) to the marine heterobranchs fauna known from this area, so far, and in particular, 2 species belonging to Pleurobranchida, 6 Cephalaspidea, 1 Runcinida, 9 Sacoglossa, and 27 Nudibranchia (9 Doridina, 18 Cladobranchia). One alien species, Polycera hedgpethi Er. (Marcus, 1964), was reported for the first time in the studied area. This work reported for the first time the presence of Elysia margaritae (Fez, 1962), Haminoea cf. orteai (Talavera, Murillo and Templado, 1987), and Rubramoena amoena (Alder & Hancock, 1845), in Italian waters. Table 3 provides the species list with Diversity 2020, 12, 171 10 of 24 ecological remarks of all added species. Furthermore, an extensive photographic catalogue mainly consisting of pictures taken in situ is provided in Figures 2–9. Table 3. List of the newly recorded Heterobranchia from the Salento peninsula; species names, relative figure numbers, ecological notes, and phenotypical variability for each added species are reported. Abundance is indicated as number of specimens. Phenotypical Species Name Figure Ecological Notes Abundance Variability Pleurobranchus On soft bottom during diurnal dive. 1 testudinarius Figure 2A - 1–2 Depth: 25 m Cantraine, 1835 Usually living singularly or in groups Body color ranging Berthellina cf. under stones, in small shaded from light 2 edwardsii (Vayssière, Figure 2B,C >100 crevices or in dark caves. creamy-yellow to 1897) Depth: 0–15 m reddish-orange The specimens of this This sedentary species usually lives Diaphorodoris species show the red near bryozoan colonies (cf. Nolella 3 luteocincta Figure 2D spot on the dorsum 3–10 stipata Gosse, 1855). (M. Sars, 1870) which varies in shape Depth: 0–3 m and size Often in clusters, feeding on Trapania lineata Entoprocta spp. covering black 4 Figure 2E - >100 Haefelfinger, 1960 sponges. Recorded all year long. Depth: 0–30 m Often sympatric with the congeneric Trapania maculata 5 Figure 2F T. lineata. - >100 Haefelfinger, 1960 Depth: 0–30 m Found all year long, in shady pre-coralligenous shallow waters or Crimora papillata Color of the notum coastal caves. Often in association 6 Alder & Hancock, Figure 2G,H variable from light >100 with encrusting bryozoans on which 1862 yellow to ochre their egg masses are laid. Depth: 0–10 m Very typical body color Observed during the winter months, pattern, showing blue Polycera elegans 7 Figure 3A,B in shallow waters. spots di ering in size 11–30 (Bergh, 1894) Depth: 5 m and number between individuals Observed during winter season, in Polycera hedgpethi 8 Figure 3C,D shallow waters. - 3–10 Er. Marcus, 1964 Depth: 5 m Even if this species Observed in large assemblages at the shows a variable Felimare fontandraui end of spring, associated with the phenotype [26], the 9 Figure 3E,F 31–100 (Pruvot-Fol, 1951) sponge Dysidea avara (Schmidt, 1862). Salentine specimens Depth: 7 m have constant body color pattern In large groups mating and feeding Felimare orsinii on black sponges. Found between 10 Figure 3G - 31–100 (Vérany, 1846) April and July. Depth: 0–15 m Felimida binza On a rocky substrates. Found during 11 (Ev. Marcus & Er. Figure 3H September. - 1–2 Marcus, 1963) Depth: 5–7 m Very mimetic Found on the yellow gorgonian morphotype that can Tritonia nilsodhneri 12 Figure 4A Eunicella cavolinii Koch, 1887. consistently vary from 1–2 Marcus Ev., 1983 Depth: 30 m dark brown to pale yellow or white This small species (few millimetres) is Doto cervicenigra found from winter to early spring on 13 Ortea & Bouchet, Figure 4B hydrozoans colonies of Aglaophenia - 11–30 1989 Lamouroux, 1812. Depth: 0–3 m Diversity 2020, 12, 171 11 of 24 Table 3. Cont. Phenotypical Species Name Figure Ecological Notes Abundance Variability The average size of specimens observed is ca. 5 mm. Its host Doto floridicola 14 Figure 4C,D hydrozoan colonies belonging to - 11–30 Simroth, 1888 Aglaophenia. Depth: 8–12 m Paraflabellina The body colors vary On hard substrates. 15 gabinierei Figure 4E from white to opaque 3–10 Depth: 0–25 m (Vicente, 1975) pinkish Limenandra nodosa Found on Padina pavonica (Linnaeus) 16 Haefelfinger & Figure 4F Thivy, 1960 in summer. - 1–2 Stamm, 1958 Depth 6 m Body pattern with Caloria elegans Usually observed on hard substrata. cerata brightly colored 17 (Alder & Hancock, Figure 4G 11–30 Depth: 0–15 m from white to light 1845) orange Dicata odhneri Found in shallow waters. 18 Figure 4H - 11–30 Schmekel, 1967 Depth: 0–15 m Dondice banyulensis Conspicuous in size and brightly 19 Portmann & Figure 5A coloured. - 11–30 Sandmeier, 1960 Depth: 0- to more than 30 m Found in a tidal pool in association Facelina fusca with the green algae Anadyomene 20 Figure 5B - 1–2 Schmekel, 1966 stellata (Wulfen) C. Agardh, 1823. Depth: 0.5 m Observed all year long in shady Facelina rubrovittata 21 Figure 5C pre-coralligenous habitats. - 31–100 (A. Costa, 1866) Depth: 0–15 m. The color of the digestive gland visible Facelina vicina (Bergh, 22 Figure 5D,E Depth: 0–15 m through cerata vary 3–10 1882) from light orange/pink to dark violet This species shows Eubranchus cf. farrani Found at shallow depth on di erences in the shape 23 (Alder & Hancock, Figure 5F hydrozoans colonies. 11–30 and the number of the 1844) Depth: 0–15 m dorsal yellow spots Eubranchus cf. linensis 24 Garcia-Gomez, Figure 5G,H Depth: 0–5 m. - 11–30 Cervera & Garcia, Catriona maua Recorded in shallow water on 25 Ev. Marcus & Er. Figure 6A hydrozoans colonies. - 1–2 Marcus, 1960 Depth: 0.5 m Rubramoena amoena Found in April in shallow water. 26 (Alder & Hancock, Figure 6B Temperature 15 C. - 1–2 1845) Depth: 8 m Occurs in shallow water on algae, Trinchesia genovae 27 Figure 6C,D bryozoan, and hydrozoans substrates. - 11–30 (O’Donoghue, 1926) Depth: 0–20 m Trinchesia cf. On rocky substrates. 28 miniostriata Figure 6E - 1–2 Depth: 9 m Schmekel, 1968 Trinchesia morrowae The typical color of the Common in March-April and in July Korshunova, Picton, apical portion of the when it is possible to observe several Furfaro, Mariottini, rhinophores and the specimens living and laying eggs on 29 Pontes, Prkic, ´ Figure 6F oral tentacles varies >100 hydroid of the genus Sertularella Fletcher, Malmberg, from orange to yellow Gray, 1848. Lundin & or it could Depth: 0–15 m Martynov, 2019 completely lack. Diversity 2020, 12, 171 12 of 24 Table 3. Cont. Phenotypical Species Name Figure Ecological Notes Abundance Variability Very small species 1.5–2 mm, as Runcina cf. ferruginea 30 Figure 6G expected for Runcina species. - 3–10 Kress, 1977 Depth: 8 m. Found only as single and very small Philine punctata (J. 31 Figure 6H specimen, ca. 1 mm, on Posidonia - 1–2 Adams, 1800) oceanica rhizomes. Philine quadripartita Recorded on soft bottoms. 32 Figure 7A - 1–2 Ascanius, 1772 Depth: 8 m Its body color pattern varies from a dark Camachoaglaja Recorded on soft bottoms or on algae. form to another much 33 africana Figure 7B,C 11–30 Depth: 0–20 m lighter and densely (Pruvot-Fol, 1953) covered by whitish tiny dots Found on soft bottoms or on algae Philinopsis depicta mainly during winter season and in 34 Figure 7D - 11–30 (Renier, 1807) shallow water. Depth: 0–15 m Melanochlamys wildpretii Found in winter in shallow water. 35 Figure 7E - 1–2 Ortea, Bacallado & Depth: 0–3 m Moro, 2003 Haminoea cf. orteai Found on green algae. 36 Talavera, Murillo & Figure 7F - 31–100 Depth: 0–3 m Templado, 1987 Very mimetic species, usually in Elysia gordanae association with the green alga Figure 7G,H 37 T. E. Thompson & Flabellia petiolata (Turra) Nizamuddin, - >100 and Figure 8A Jaklin, 1988 1987. Depth: 0–15 m On Dictyota dichotoma (Hudson) J.V. Elysia margaritae 38 Figure 8B Lamouroux, 1809. - 1–2 Fez, 1962 Depth: 0–2 m Aplysiopsis elegans 39 Figure 8C Depth: 0–12 m - 3–10 Deshayes, 1853 Found on April. 18 C water The body color patter Cyerce graeca 40 Figure 8D temperature. varies from withe to 1–2 T. E. Thompson, 1988 Depth: 3 m light yellow Hermaea Found mainly in spring and summer 41 Figure 8E - 3–10 bifida(Montagu, 1816) on green algae. Depth: 5–6 m Hermaea paucicirra Found on algae in shallow waters. 42 Figure 8F - 1–2 Pruvot-Fol, 1953 Depth: 0–1 m Ercolania coerulea Found on algae in shallow waters. 43 Figure 8G,H - 3–10 Trinchese, 1892 Depth: 0–5 m Limapontia capitata (O. Found on algae in shallow waters. 44 Figure 9A - 11–30 F. Müller, 1774) Depth: 0.5 m Placida cremoniana 45 Figure 9B Depth: 0–12 m - 11–30 (Trinchese, 1892) Diversity 2020, 12, 171 13 of 24 Diversity 2020, 12, x FOR PEER REVIEW 12 of 23 Figure 2. (A) Pleurobranchus testudinarius. St. 3 (B) Berthellina cf. edwardsii. St. 11. In the right-low Figure 2. A. Pleurobranchus testudinarius. St. 3 B. Berthellina cf. edwardsii. St. 11. In the right-low corner, corner, the internal shell (length: 4.2 mm). (C) Berthellina cf. edwardsii. St. 11 (D) Diaphorodoris the internal shell (length: 4.2 mm). C. Berthellina cf. edwardsii. St. 11 D. Diaphorodoris luteocincta. St. 11 luteocincta. St. 11 (E) Trapania lineata, mating individuals. St. 11 (F) Trapania maculata. St. 11 (G) Crimora E. Trapania lineata, mating individuals. St. 11 F. Trapania maculata. St. 11 G. Crimora papillata. St. 11 H. papillata. St. 11 (H) Crimora papillata, with spawn. St. 11. Crimora papillata, with spawn. St. 11. Diversity 2020, 12, 171 14 of 24 Diversity 2020, 12, x FOR PEER REVIEW 13 of 23 Figure 3. (A) Polycera elegans. St. 1 (B) Polycera elegans. St. 1 (C) Polycera hedgpethi. St. 1 (D) Polycera Figure 3. A. Polycera elegans. St. 1 B. Polycera elegans. St. 1 C. Polycera hedgpethi. St. 1 D. Polycera hedgpethi. Two individuals after mating. The reproductive openings are clearly visible in the specimen hedgpethi. Two individuals after mating. The reproductive openings are clearly visible in the specimen on the upper portion. St. 1 (E) Felimare fontandraui. St. 11 (F) Felimare fontandraui, mating individuals on the upper portion. St. 1 E. Felimare fontandraui. St. 11 F. Felimare fontandraui, mating individuals with spawn. St. 11 (G) Felimare orsinii, mating individuals. St. 14 (H) Felimida binza. St. 25. with spawn. St. 11 G. Felimare orsinii, mating individuals. St. 14 H. Felimida binza. St. 25. Diversity 2020, 12, 171 15 of 24 Diversity 2020, 12, x FOR PEER REVIEW 14 of 23 Figure 4. (A) Tritonia nilsodhneri. St. 18 (B) Doto cervicenigra. St. 11 (C) Doto floridicola. St. 22 (D) Spawn Figure 4. A. Tritonia nilsodhneri. St. 18 B. Doto cervicenigra. St. 11 C. Doto floridicola. St. 22 D. Spawn of of Doto floridicola. St. 22 (E) Paraflabellina gabinierei. St. 11 (F) Limenandra nodosa. St. 3 (G) Caloria elegans. Doto floridicola. St. 22 E. Paraflabellina gabinierei. St. 11 F. Limenandra nodosa. St. 3 G. Caloria elegans. St. St. 11 (H) Dicata odhneri St. 11. 11 H. Dicata odhneri St. 11. Diversity 2020, 12, 171 16 of 24 Diversity 2020, 12, x FOR PEER REVIEW 15 of 23 Figure 5. (A) Dondice banyulensis. St. 13 (B) Facelina fusca. St. 7 (C) Facelina rubrovittata. St. 11 (D,E) Figure 5. A. Dondice banyulensis. St. 13 B. Facelina fusca. St. 7 C. Facelina rubrovittata. St. 11 D. E. Facelina Facelina vicina. St. 11 (F) Eubranchus cf. farrani. St. 11 (G,H) Eubranchus cf. linensis St. 11. vicina. St. 11 F. Eubranchus cf. farrani. St. 11 G. H. Eubranchus cf. linensis St. 11. Diversity 2020, 12, 171 17 of 24 Diversity 2020, 12, x FOR PEER REVIEW 16 of 23 Figure 6. (A) Catriona maua. St. 9 (B) Rubramoena amoena. St. 22 (C) Trinchesia genovae. St. 11 Figure 6. A. Catriona maua. St. 9 B. Rubramoena amoena. St. 22 C. Trinchesia genovae. St. 11 D. Trinchesia (D) Trinchesia genovae. St. 7 (E) Trinchesia cf. miniostriata St. 22 (F) Trinchesia morrowae. St. 11 (G) Runcina genovae. St. 7 E. Trinchesia cf. miniostriata St. 22 F. Trinchesia morrowae. St. 11 G. Runcina cf. ferruginea. cf. ferruginea. St. 22 (H) Philine punctata St. 9. St. 22 H. Philine punctata St. 9. Diversity 2020, 12, 171 18 of 24 Diversity 2020, 12, x FOR PEER REVIEW 17 of 23 Figure 7. (A) Philine quadripartita. St. 1 (B) Camachoaglaja africana. St. 7 (C) Camachoaglaja africana. St. 22 Figure 7. A. Philine quadripartita. St. 1 B. Camachoaglaja africana. St. 7 C. Camachoaglaja africana. St. 22 D. (D) Philinopsis depicta. St. 10 (E) Melanochlamys wildpretii. St. 7 (F) Haminoea cf. orteai. St. 22 (G) Elysia Philinopsis depicta. St. 10 E. Melanochlamys wildpretii. St. 7 F. Haminoea cf. orteai. St. 22 G. Elysia gordanae. gordanae. St. 11 (H) Elysia gordanae. St. 11. St. 11 H. Elysia gordanae. St. 11. Diversity 2020, 12, 171 19 of 24 Diversity 2020, 12, x FOR PEER REVIEW 18 of 23 Figure 8. (A) Spawn of Elysia gordanae. St. 22 (B) Elysia margaritae. St. 11 (C) Aplysiopsis elegans. St. 1 Figure 8. A. Spawn of Elysia gordanae. St. 22 B. Elysia margaritae. St. 11 C. Aplysiopsis elegans. St. 1 D. (D) Cyerce graeca. St. 11 (E) Hermaea bifida. St. 1 (F) Hermaea paucicirra. St. 7 (G,H) Ercolania coerulea. Cyerce graeca. St. 11 E. Hermaea bifida. St. 1 F. Hermaea paucicirra. St. 7 G. H. Ercolania coerulea. St. 7. St. 7. Diversity 2020, 12, 171 20 of 24 Diversity 2020, 12, x FOR PEER REVIEW 19 of 23 Figure 9. (A) Limapontia capitata. St. 24 (B) Placida cremoniana. St. 1. Figure 9. A. Limapontia capitata. St. 24 B. Placida cremoniana. St. 1. 4. Discussion 4. Discussion This study reported 160 marine Heterobranchia species from the Salento Peninsula giving the most up to date list of marine heterobranchs inhabiting this area of the Apulian coasts. This was This study reported 160 marine Heterobranchia species from the Salento Peninsula giving the particularly remarkable considering that the total number of registered species belonging to this most up to date list of marine heterobranchs inhabiting this area of the Apulian coasts. This was mollusks group for the whole Mediterranean Sea was approximately 550 [51]. The composition of the particularly remarkable considering that the total number of registered species belonging to this main groups of marine heterobranchs living in the Salento Peninsula reported in this work is shown mollusks group for the whole Mediterranean Sea was approximately 550 [51]. The composition of the in Figure 10. The groups with the largest numbers of species added were Cladobranchia (18) and main groups of marine heterobranchs living in the Salento Peninsula reported in this work is shown Doridina (9), as expected, these nudibranchs belonged to the groups with the richest variety of taxa. in Figure 10. The groups with the largest numbers of species added were Cladobranchia (18) and Surprisingly, with the present contribution, 6 species of Cephalaspidea were added to the ones reported Doridina (9), as expected, these nudibranchs belonged to the groups with the richest variety of taxa. previously. Another interesting consideration was concerning the superorder Sacoglossa, which almost Surprisingly, with the present contribution, 6 species of Cephalaspidea were added to the ones doubled after this study. Finally, some species were noteworthy because they are currently under reported previously. Another interesting consideration was concerning the superorder Sacoglossa, studied or because the validity of the species is still in doubt. This was the case for Berthellina cf. which almost doubled after this study. Finally, some species were noteworthy because they are edwardsii, Eubranchus cf. exiguus, E. cf. farrani, E. cf. linensis, Facelina fusca, Haminoea cf. orteai, Runcina currently under studied or because the validity of the species is still in doubt. This was the case for cf. ferruginea and Trinchesia cf. miniostriata. In particular, in the case of Berthellina cf. edwardsii we Berthellina cf. edwardsii, Eubranchus cf. exiguus, E. cf. farrani, E. cf. linensis, Facelina fusca, Haminoea cf. depicted (Figure 2B) the internal shell (4.2 mm long), since it fits the standard average length of the orteai, Runcina cf. ferruginea and Trinchesia cf. miniostriata. In particular, in the case of Berthellina cf. shell commonly used as diagnostic for this species, albeit we preferred to keep an uncertainty (cf.) edwardsii we depicted (Figure 2B) the internal shell (4.2 mm long), since it fits the standard average before a further molecular study would allow a clear-cut identification. The studied marine area, length of the shell commonly used as diagnostic for this species, albeit we preferred to keep an deeply influenced by two di erent seas and characterized by a variety of submarine habitats, hosts uncertainty (cf.) before a further molecular study would allow a clear-cut identification. The studied a high variety of species, which makes it an important geographical area for this sea slug diversity. marine area, deeply influenced by two different seas and characterized by a variety of submarine In fact, with this work we report that the total number of marine Heterobranchia living in the Salento habitats, hosts a high variety of species, which makes it an important geographical area for this sea Peninsula is 160, which is about a third of the total number of currently accepted species reported slug diversity. In fact, with this work we report that the total number of marine Heterobranchia living for the whole Mediterranean Sea. This is quite an important finding, also considering the fact that a in the Salento Peninsula is 160, which is about a third of the total number of currently accepted species high diversity in heterobranchs composition indirectly reflects a high structuring and diversification reported for the whole Mediterranean Sea. This is quite an important finding, also considering the of the habitats involved, and consequently, of the biodiversity that they contribute to maintain [14]. fact that a high diversity in heterobranchs composition indirectly reflects a high structuring and Studying and monitoring the marine Heterobranchia diversity in the Salento Peninsula is valuable for diversification of the habitats involved, and consequently, of the biodiversity that they contribute to highlighting the consequences of the global marine changes reported in the last decade [10–12,59,60], maintain [14]. Studying and monitoring the marine Heterobranchia diversity in the Salento Peninsula such as warming and acidification of waters or invasion of alien species. An additional detailed is valuable for highlighting the consequences of the global marine changes reported in the last decade and constantly updated iconography is available on the website of the Salento Sommerso group [10–12,59,60], such as warming and acidification of waters or invasion of alien species. An additional (http://www.salentosommerso.it/index_opi.php), a non-profit association devoted to the preservation detailed and constantly updated iconography is available on the website of the Salento Sommerso and documentation of the underwater biodiversity of the Salento Peninsula. group (http://www.salentosommerso.it/index_opi.php), a non-profit association devoted to the preservation and documentation of the underwater biodiversity of the Salento Peninsula. Diversity 2020, 12, x FOR PEER REVIEW 20 of 23 Diversity 2020, 12, 171 21 of 24 Figure 10. Comparison between the main heterobranch groups; the graph shows the comparison Figure 10. Comparison between the main heterobranch groups; the graph shows the comparison between the total species of the Salento Peninsula, clustered into the main groups. between the total species of the Salento Peninsula, clustered into the main groups. 5. Conclusions Author Contributions: F.V. and C.L. conceived the project and performed most of the SCUBA diving and took in situ pictures. G.F. and P.M. analysed the data and carried out the SCUBA diving. F.V., C.L., G.F., and P.M. The study of marine diversity is a fundamental topic especially if focused on areas like wrote the manuscript. All authors read and approved the final manuscript. Mediterranean Sea, which is characterised by a high rate of endemic and cryptic species. In this study we have investigated the presence of marine Heterobranchia in the Salento Peninsula (Apulia, Funding: Authors sincerely acknowledge the University of Roma Tre for financial support (CAL/2018 and South-Italy) CAL/2019). considering for the first time both Ionian and Adriatic coasts. Results of a nine-year study reports 160 species inhabiting the studied area with new records from the sublittoral waters, Acknowledgments: Special thanks to Prof. Genuario Belmonte (University of Salento, Italy), Prof. Lucas Cervera ecological notes, local distribution and systematic remarks. This inventory of marine Heterobranchia Currado (University of Cadiz, Spain), and Egidio Trainito (Sardinia, Italy) for their useful suggestions. The encountered in the Salento Peninsula adds 45 species to the previously known for this area. For all authors wish to thank Elena Mazzone (Rome, Italy) for the revision of the English text. We would also like to the added species, we have figured live animals mostly by in situ photographs to document species thank Paolo D'Ambrosio, Director of the Porto Cesareo AMP, for permission to carry out research in the Marine identification Protected Area and of Porto Ce reported sareo (Le data on cce) ecology . The authors are , phenotypical greatly variability indebtedand to Prof. abundance. Marco Oliverio This inventory (Rome, Ita of ly) for the revision of the English text. A very special thanks to our diving companions Marcella D'Elia, Domenico marine Heterobranchia provides a baseline for future monitoring of both coastal sides and could serve Licchelli, Cesare Bortone, and Pierantonio Cicirillo, with whom we shared many dives. We thank Antonello as a starting point for further molecular studies aiming to unveil Mediterranean cryptic diversity. Perrone for suggestions and criticism. We thank Gianfranco Alemanno, Andrea Astore, Gianni Colucci, Piero Author Lenoci, Vi Contributions: ncenzo Marra, E F.V. n and rico P C.L. aticonceived , and Gianl the uca pr Roma oject no, for and performed supporting us with most of the many photographic images, SCUBA diving and took in situ pictures. G.F. and P.M. analysed the data and carried out the SCUBA diving. F.V., C.L., G.F., and P.M. wrote specimens, and for sharing some of their data with us. Thanks to Manuel Ballesteros from the University of the manuscript. All authors have read and agreed to the published version of the manuscript. Barcelona (Spain), Marta Pola from the University of Madrid (Spain), Enric Madrenas and Miquel Pontes (Spain), Manuel Malaquias of the University of Bergen (Norway), and Jakov Prkić (Croatia) for the many suggestions Funding: Authors sincerely acknowledge the University of Roma Tre for financial support (CAL/2018 and CAL/2019). and constructive exchanges of ideas and experiences. The authors are greatly indebted to the four anonymous reviewers, who provided many valuable comments, and improved the English. Acknowledgments: Special thanks to Genuario Belmonte (University of Salento, Italy), Lucas Cervera Currado (University of Cadiz, Spain), and Egidio Trainito (Sardinia, Italy) for their useful suggestions. The authors wish Conflicts of Interest: The authors declare no conflict of interest. The funders had no role in the design of the to thank Elena Mazzone (Rome, Italy) for the revision of the English text. We would also like to thank Paolo study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to D’Ambrosio, Director of the Porto Cesareo AMP, for permission to carry out research in the Marine Protected Area of pu Porto blish the res Cesareou(Lecce). lts. The authors are greatly indebted to Marco Oliverio (Rome, Italy) for the revision of the English text. A very special thanks to our diving companions Marcella D’Elia, Domenico Licchelli, Cesare Bortone, and Pierantonio Cicirillo, with whom we shared many dives. We thank Antonello Perrone for suggestions and References criticism. We thank Gianfranco Alemanno, Andrea Astore, Gianni Colucci, Piero Lenoci, Vincenzo Marra, Enrico Pati, and Gianluca Romano, for supporting us with many photographic images, specimens, and for sharing some 1. Dainelli, G. Appunti Geologici sulla Parte Meridionale del Capo di Leuca; Tipografia della Pace di Filippo of their data with us. Thanks to Manuel Ballesteros from the University of Barcelona (Spain), Marta Pola from the Cuggiani: Rome, Italy, 1901. University of Madrid (Spain), Enric Madrenas and Miquel Pontes (Spain), Manuel Malaquias of the University of 2. De Giorgi, C. 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Published: Apr 26, 2020

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