A new gastrotrich species of the genus ptychostomella (macrodasyida, thaumastodermatidae) from South Korea
A new gastrotrich species of the genus ptychostomella (macrodasyida, thaumastodermatidae) from...
Lee, Ji
Min; WookHwang, Ui; Chang, Cheon
Young
2009-01-01 00:00:00
Animal Cells and Systems 13: 25-30, 2009 A New Gastrotrich Species of the Genus Ptychostomella (Macrodasyida, Thaumastodermatidae) from South Korea 1 2, Ji Min Lee, Ui W ook Hwang , and Cheon Y oung Chang * Institute of Basic Science, Daegu University; Department of Biology, Teachers College, Kyungpook National University, Daegu 702-701, Kor ea; Department of Biological Science, College of Natural Sciences, Daegu University, Gyeongsan 712-714, Korea Ab s t ra ct : A new marine gastrotrich species, Ptychostomella crumbles from subtidal bottom at about 6-7 m depth. By the j e ju ensis n. sp. belonging to the family Thaumastodermatidae, detailed scannin g electronic microsco py , we confirmed that is described on the basis of the specimens from subtidal this species is characteristic in having the numerous sand bottom at about 6-7 m depth of Jeju Island, South cuticular gland openings mostly flanking a bristle on the Kor ea. Ptychostomella jejuensis n. sp. is distinguished from dorsal and dorsolateral surfaces. As the character is consistent its congeneric species with smooth cuticular armature by the throug hout the specimens examin ed , an d the species shows character combination: (1) small body up to about 160 µm in length; (2) presence of knob-like cephalic tentacles; (3) the clear discrepancy with the related congeners in the absence of dorsal and ventral adhesive tubes; (4) bifid combin atio n of several macro -characters, we determin e it a pedicles; (5) pyriform copulatory organ. Under scanning valid species. electron microscopy, numerous epidermal gland openings W e provide the description of the new species based on we re ob serv ed i n the n e w speci e s, cha r acteri stical l y fl anki n g the morphological characters and a discussion on the a bristle. Taxonomic accounts on the affinities, some brief taxonomic affinities, with illustrations and scanning remarks on the epidermal gland openings and the co- electron photomicrographs. occurrence with P . orientalis Lee and Chang, 2003 are also presented with detailed illustrations and scanning electron p hotomi c rogra phs. MA TERIALS AND METHODS Key words: Gastrotricha, Korea, Macrodasyida, new species, Materials were collected from the sublittoral sandy bottom Ptychostomella , SEM, Thaumastodermatidae, taxonomy containing fine to coarse shell fragments at about 6-7 m depth around Saeseom islet, just 20-30 meters off Seogwipo Harbor at the southern coast of Jeju Island the INTRODUCTION largest and southernmost island in South Korea. Samplings were taken by scooping the top sediments A total of 16 species have been recorded by the serial into a polyethylene vinyl bag or 700 mL volume plastic researches on the marine gastrotrich fauna from South bottles by SCUBA diving. The process of extracting Korea (Chang, Lee and Clausen, 1998a, b; Chang and Lee, gastrotrich specimens and preparation of whole mounts 2001; Lee and Chang, 2002, 2003, 2004, 2006, 2007), follows Lee and Chang (2003). Formalin-fixed specimens including two species belonging to the genus Ptychostomella were mounted in glycerin on H-S slide, and then observed (Thaumastodermatidae) , P . orientalis Lee and Chang, 2003 un de r a d i f feren tia l int erferenc e c o n trast m icro scop e ( Olym pu s and P . papillata Lee and Chang, 2003. BX-50 ) equ ipped with No marski o ptics. All drawings were Recently, during a faunistic study on the marine meiofauna carried out with the aid of a camera lucida. Measurements of Jeju Island, South Korea, we found a gastrotrich species were made using a digital camera for microscope (Cool belonging to the genus Ptychostomella with minute body SNAP 5.0M, Roper Scientific Co., USA) and a calibration size among sandy sediments containing lots of shell software QCapture Pro (ver. 5.0, Media Cybernetics Inc., USA ). * T o whom correspondence should be addressed. Materials for scanning elec tron microscopy were prefixed T el: +82-53-8506454; Fax: +82-53-8506459 with 2.5% glutaraldehyde in 0.1 M phosphate buffer (pH E-mail: cychang@daegu.ac.kr ANIMAL CELLS AND SYSTEMS Vo l. 13 No. 1 25 Ji Min Lee, Ui Wook Hw ang, and Cheon Y oung Chang 7.4) for 4-6 hours at 4, followed by rinsing with 0.1 M eyespot lacking; bearing paired knob-like tentacles phosphate buffer (pH 7.2-7.4) three times for 10 minutes dorsolaterally; dorsal cuticular armature smooth; numerous each. Specimens were postfixed in 2% cold osmium gland openings scattered on dorsal, dorsolateral and tetroxide in 0.1 M phosphate buffer for 2 hours, and left in ventrolateral surfaces, among which nearly half of the phosphate buffer overnight. After dehydration through a dorsal and dorsolateral ones flanking a bristle; adhesive graded series of ethanol (50-100% at 10% interval) for 30tubes: 3 TbA per side in a horizontal row; 5 TbVL per side, minutes each, the material was critical point dried using a including a small tube behind TbA; 4 slender Tb VL ev enly freeze-dryer, and coated with gold-palladium in a high spaced in intestinal region; 2 TbL per side, in the middle evaporator, and then examined using a scanning electron and at outer posterior edge of body, respectively; 5 TbP microscope (Hitachi S-4800) operated at 10kV. forming a pedicle, comprising 2 distal, 1 lateral and 2 T ype specimens are kept in the authors’ collection at themedial tubes; copulatory organ pyriform. specimen room of the Department of Biology, Daegu University (DB) and deposited in the National Institute of Description of the holotype: Body (Figs. 1, 2) minute, Lt Biological Resources (NIBR), Incheon, Korea.149 µ m long; semi-rectangular, with a short, bilobed T erminology mostly follows Ruppert (1991) and Clausen caudum; dorsal surface somewhat uneven with undulating (2000). Abbreviations used in the text are as follows: dorsolateral sides; bo th lateral si d es of body nearly parallel, Lt = total length, from anterior tip of head to posterior tip of with slight constriction in the middle of pharyngeal region. pedicles including adhesive tubes; U=percentage unit of Lt, Pharynx 36 µ m long (measured from ventral border of oral used for the location (U-) from anterior to posterior, or for opening to pharyngeo-intestinal junction); PhJIn located at the relative length (-U); PhJIn = junction between pharynx U33, with paired pharyngeal pores, opened ventrally at and intestine; TbA = anterior adhesive tubes; TbD = dorsal U32. Widths of oral opening/neck/PhJIn/trunk/caudal base adhesive tubes; TbL=lateral adhesive tubes; TbP=posterior33/23/24/29/23 µm at U06/U25/U33/U69/U93, respectively. adhesive tubes; TbV=ventral adhesive tubes; TbVL= Oral hood broad and a little swollen anteriorly, with ventrolateral adhesive tubes. slightly undulating border (Fig. 1A). Six to 8 long sensory hairs (ca. 10-15 µ m long) implanted along dorsal ma r gin of SYSTEMA TIC ACCOUNTS oral hood; more than 13 hairs (ranging 4-7 µ m long) along anterior edge of oral hood both dorsally and ventrally; a Family Thaumastodermatidae Remane, 1926 pair of cilia tufts consisting of 3 sensory hairs (ca. 15- Subfamily Thaumastodermatinae Ruppert, 197816 µ m long) situated on anterolateral part of oral hood at Genus Ptychostomella Remane, 1926U04; at least 11 pairs (ca. 9-14 µm long) of hairs located on Ptychostomella jejuensis new species subdorsal, dorsolateral and lateral sides along entire body (Fi g u re s1 -3 ) length posterior to knob-like tentacle (U10-U93); 4-6 pairs of sensory hairs aligned dorsolaterally per side, each pair Type specimens: Holotype (DBG1301) and 10 paratypes composed of a long (5-8 µ m) and a short (1-3 µ m) hair at (DBG1302-1111), mounted in glycerin on H-S slides, leg. U24-U81 (Fig. 3C). Eyespot lacking. Paired knob-like C. Y . Ch ang , J . M. L e e a nd S . H . K i m, 24 A p r i l 200 6. A n o the r tentacles (pestle organs) (Fig. 3A, arrow) small (ca. 3 µ m two paratypes (NIBRIV0000131 151, 0000131 159), mounteddiameter) and protruding dorsolaterally at U08. in glycerin, collection data same as in the holotype. Oral opening (Figs. 1B, 2B) (ca. 33 µ m in diameter) a little undulating ventrally, bearing numerous hairs (ca. 2-5 Additional material examined: Eight specimens with the µm long) along its posterior rim. same collection data are mounted on aluminum stub for Dorsal cuticular armature smooth, lacking embossed SEM observation. hemispherical elevations or papillae. Numerous epidermal glands irregularly scattered at dorsal, dorsolateral, and T ype locality: Saeseom islet, Seogwipo, Jeju Island, South ventrolateral surfaces, along nearly whole body length o o Korea (33 14'04''N, 126 33'56''E), in sublittoral sandy (U1 0 -U8 9 ); with generally circular shape, mixed in various sediments containing shell crumbles at about 6-7m depth. size (from 2 to 7 µ m in diameter). Numerous elliptical gland openings or ‘stomata’ (Figs. 1A, 3B-D) with cuticularized Etymology: The specific name jejuensis alludes to the type lips (from 1 to 3 µ m in diameter), some paired, but mostly locality of the present new species, Jeju Island, South scattered asymmetrically on dorsal and dorsolateral surfaces; Korea. 4-5 pairs of openings (Fig. 3E , F , arrows) sparsely distributed on ventrolateral side ranging from behind TbA to middle of Diagnosis: Small Ptychostomella with short, bilobed pharyngeal region (U23); about half of the gland openings caudum; body up to 164 µ m long; PhJIn at about U34; each flanking a short bristle (Fig. 3B, D, arrow), excluding 26 ANIMAL CELLS AND SYSTEMS Vol. 13 No. 1 Ptychostomella jejuensis n. sp. (Gastrotricha) from Korea Fig. 1. Ptychostomella jejuensis new species. A, habitus, dorsal; B, habitus, ventral. Scale bar=20 µm. CO, copulatory organ; E, egg; GO, gland opening; KT , k nob-l ik e tent ac le (pes tle or gan) ; PP , pharyngeal pore; SR , s emi nal rec ept ac le; T , tes ti s; T bA, anter ior adhes iv e tubes; T bL, later al adhesive tubes; TbP , posterior adhesive tubes; TbVL, ventrolateral adhesive tubes. ventrolateral openings. TbVL per side (Fig. 2B), foremost one rather short, ca. V entral cilia (Fig. 2B) covering mid-ventral surface, just 5 µ m long, situated a little behind TbA at U16; the others behind TbA to base of caudum. somewhat slender and long (ranging ca. 9-11 µ m long), Adhesive tubes: TbA 3 per side (Figs. 2B, 3A), evenly distributed a little more ventrally in intestinal region (at spaced and distributed in a nearly horizontal row behind U40, U54, U71 and U78, respectively), last 2 TbVL close oral opening at U13, composed of 1 short medial tube (ca. 6 to each other; 2 TbL (Fig. 1 A, B) per sid e, the former 9 µ m µ m long) and 2 lateral ones (ca. 9-10 µ m long) per side; 5 long, located a little ventrolaterally nearly in the middle of ANIMAL CELLS AND SYSTEMS Vo l. 13 No. 1 27 Ji Min Lee, Ui Wook Hw ang, and Cheon Y oung Chang The ordinary dorsal cuticular armature in the genus Ptychostomella has been known as ‘smooth’, lacking the usual three- to five-pronged cuticular sculptures which are typically shown among thaumstodermatid gastrotrichs and regarded as the important taxonomic characters. However, recently three species equipped with the embossed hemispherical elevations or papillae as the dorsal cuticular armature have been found: P . lepidota from Norway (Clausen, 2000), and P. orientalis and P. papillata from Korea (Lee and Chang, 2003). So, now the members of Ptychostomella are divided into two groups by the state of the cuticular armature. Among the eight species, sharing the smooth cuticular armatu re, the n ew sp eci es is c l o sely si mi la r to P . m e dit erran ea and P . tyrrhenica in having a small body length (less than 200 µ m), a pair of knob-like tentacles, 2 TbL, and absence of ‘foot-type’ TbV. However, P. jejuensis n. sp. is distinguished from P . mediterranea by the absence of TbD (against 6 TbD in P . mediterranea) and bifid pedicles (against trifid in P . mediterranea), and from P . tyrrhenica by 2 medial TbP per side between the bilobed caudum (against the absence of medial TbP in P . tyrrhenica ) and a pyriform copulatory organ (agai nst a bladder-like copulatory organ in P . tyrrhenica ). Moreover, the knob-like cephalic Fig. 2. Ptychostomella jejuensis new species, SEM micrographs. A, tentacles occur dorsolaterally in P . jejuensis n. sp., while it habitus, dorsal; B, habitus, ventral. Scale bars = 20 µm. is ev idently depicted as p rotru ding ventrolaterally ju st from the posterolateral corner of oral opening in the original lateral margin of body at U53, the latter 7 µ m long, at description of P . mediterranea ( se e Hummon et al., 1993, lateroposterior edge of body (U91); 5 TbP per side, eachFig. 9B, C). forming a pedicle, comprising 2 distal tubes (7 µ m long),Ptychostomella jejuensis n. sp. is also allied with P . flanked by 1 lateral (6 µm) and 2 medial ones (5-6 µ m).higginsi in sharing the presence of a pair of knob-like Reprod uctive sy stem: testis (Fig. 1B) single o n righ t side tentacles, 2 TbL, bifid pedicle and pyriform copulatory (in dorsal view), its tip at U36 not reaching PhJIn; vas organ; however, the new species differs from it by smaller deferens apparently not coiled but gently curved medially, size (up to 16 4 µ m vs. 240 µ m in total b ody length) as well ending at U87 toward posterior part of copulatory organ. as lower number and different arrangement of TbA, TbVL Copulatory organ (Fig. 1B) pyriform, located at U76-U93. and TbP . Furthermore, P. jejuensis was collected from the Seminal receptacle (Fig. 1B) oval (9 µ m × 8 µm), in front ofsublittoral bottom at 6m depth, while P . higginsi from deep copulatory organ at U68-U74, containing spermatozoa. Asea at about 160m depth. single suboval egg situated dorsally in mid-intestinal region,Although P. orientalis belongs to the other group with maximum size ca. 16 µ m ×40 µ m.the dorsal cuticular armature of embossed hemispheres, it is Occurred from the sandy sediments mixed with fine to somewhat similar to the new species in bearing 3 TbA and coarse shell fragments on sublittoral bottom about 6-7 m 2 TbL per side, and paired knob-like tentacles. However, depth, with Ptychostomella orientalis Lee and Chang and besides the dorsal cuticular armature, it is different from P. an unrecorded species of Platydasys .jejuensis by having more TbV(L) and TbP , and an oblong copulatory organ. Moreover, all of the epidermal gland T a x onom ic affinitie s: Ele ven sp eci es a r e c urrent ly reco gn iz edopenings of P. orientalis are simple, not flanking a bristle as in the genus Ptychostomella Remane, 1926: P . pectinatashown in the new species. Rem ane, 192 6, P . omm ato phora Rem a ne, 19 27, P . mediterranea Remane, 1927, P . h ela na Roszczak, 1939, P . brachycephalusRemarks: All of the specimens examined were fully (Lévi, 1954), P . tyrrhenica Hummon, T odaro and T ongiorgi, mature, and pre-mature individuals were not found. Body 1993, P . bergensis Clausen, 1996, P . lepidota Clausen, lengths of thirteen type specimens ranged from 125 µ m to 2000, P. orientalis Lee and Chang, 2003, P. papillata Lee 16 4 µ m ( m ea n 1 4 4 µ m , st and ard d e v iat io n 1 2), an d m a xi mu m and Chan g, 2 003 and P. higginsi Clausen, 2004. widths 26-35 µ m (20U-24U), measured in glycerin mount. 28 ANIMAL CELLS AND SYSTEMS Vol. 13 No. 1 Ptychostomella jejuensis n. sp. (Gastrotricha) from Korea Fig. 3. Ptychostomella jejuensis new species, SEM micrographs. A, head, ventral view, showing anterior adhesive tubes (TbA) and knob-like tentacle (arrow); B, cuticular openings of epidermal glands and sensory hairs near lateral adhesive tubes (TbL) on the posterol ateral edge o f trunk, dorsal view; C, a gland opening and paired sensory hairs on the dorsolateral side of trunk; D, a gland opening flanking a bristle (arrow) and a sensory hair on the lateral trunk region; E, gland openings near ventrolateral adhesive tube (TbVL) on the anterior phary ngeal region, ventral view; F , gland openings (arrows) in the middle of pharyngeal region, ventral view . Scale bars = 5 µ m (A, B, F), 3 µ m (C), 1 µ m (D, E). Those are the smallest members known in the genus appear identical to the strongly cuticularized lips or Ptychostomella so far. ‘stomata’, referred to in the description of T e t ran ch yr o d e r m a The arrangement and number of adhesive tubes wereweissi T odaro, 2002 (see T odaro, 2002, Fig. 2A, B, E). The r a t her c ons is te nt t h r o u ghout the sp ec im en s e xam i ned . A m ong similar cuticular openings have been already observed by total 21 specimen s ex amined, including SEM material, twoscanning electron microscopy in T. heterotentaculatum (see specimens were variable: one specimen had an additional Chang and Lee, 2001, Fig. 3G) and Ptychostomella lateral TbP and TbVL in the intestinal region (secondpapillata (se e Lee and Chang, 2003, Fig. 6B) from Korean TbVL consisting of two tubes as ‘fo o t-type’ in the left si d e , coasts, although they have not been described in detail. In asymmetrically); the other specimen possessed two the previous species, the openings were generally simple additional TbP laterally and medially. and arranged in two columns symmetrically, while nearly T he cut ic ula r op eni ngs o f ep ide r mal gla nds w e r e obs e r ved half of the openings on the dorsal and dorsolateral surfaces on the dorsal, dorsolateral and ventrolateral surfaces. They are flanked each by a bristle in the new species, showing ANIMAL CELLS AND SYSTEMS Vo l. 13 No. 1 29 Ji Min Lee, Ui Wook Hw ang, and Cheon Y oung Chang cuticular armature, seemingly as a reinforcement of the reproductive isolation or a character displacement between the two sympatric congeneric species. ACKNOWLEDGMENTS We are grateful to Dr. Sa Heung Kim of the INTHESEA KOREA Inc. for his help in collecting samples, and thankful to Mr. Byung- Chan Lee (Nano Practical Application Center , Daegu, Korea) for providing the facilities in which scanning electron microscopy was conducted. Authors also appreciate three reviewers for their critical comments that greatly improved the manuscript. This research was partly supported to CYC by Daegu University Research Grant, 2006. REFERENCES Chang CY , Lee JM, and Clausen C (1998a) Description of two new species thaumastodermatids (Gastrotricha, Macrodasyida) from Korea. Korean J Biol Sci 2: 315-321. Chang CY , Lee JM, and Clausen C (1998b) T wo new species of T hau masto d erma (Gastrotricha, Macrodasyida) from Korea. S a rsia 83: 329-336. Chang CY and Lee JM (2001) Two new T e tran chyr oderma gastrotrichs (Macrodasyida Thaumastodermatidae) from South Korea. Kor e an J B i o l Sci 5: 187-194. Clausen C (2000) Gastrotricha Macrodasyida from the Tromsø region, northern Norway. Sarsia 8 5 : 3 57- 384 . Fig. 4. A map showing the localities of Ptychostomella orientalis (▲ ) Clausen C (2004) Gastrotricha from the Faroe Bank. Sa rsi a 89: and P . jejuensis (●). 4 23- 45 8. Hummon WD, Todaro MA, and Tongiorgi P (1993) Italian marine Gastrotricha: II. One new genus and ten new species of Macrodasyida. Boll Zool 60: 109-127. somewhat irregular disposition. The presence of the cuticular openings on the ventrolateral side has been rarely Lee JM and Chang CY (2002) P s eudo st omel la gastrotrichs (Macrodasyida, Thaumastodermatidae) from South Korea, reported, that is, only mentioned in T. weissi and Platydasys with a brief review of the genus. Korean J Biol Sci 6: 207- ruber Swedmark, 1956 sensu Todaro, 2002 (Fig. 2F). In the 2 13. new species, the cuticular openings on the ventrolateral Le e JM an d Chang CY (2 003) T w o ne w ma r in e gastr o t ri c hs of t h e surface are also present but rare (only 4-5 openings on each genus Ptychostomella (Macrodasyida, Thaumastodermatidae) side), restricted to the anterior part of pharyngeal regionfrom South Korea. Zool Sci 20: 4 81- 48 9. behind the oral opening. In addition, they lack the bristle Lee JM and Chang CY (2004) Gastrotrichs of genus H a li chae tono tus (Chaetonotida: Chaetonotidae) from Korea. flanking the openings unlike those on dorsal and Korean J Syst Zool 20 (1 ): 5 5 - 6 2. dorsolateral surfaces. Lee JM and Chang CY (2006) Marine gastrotrichs of the genus Ptychostomella jejuensis n. sp. co-occurred with P. D i pl oda sy s (Macrodasyida: Thaumastodermatidae) from orientalis in the present type locality, Jeju Island (Fig. 4). K o r ea. Korean J Syst Zool 22(1): 109-115. This is the second record of the co-occurrence of Lee JM and Chang CY (2007) Two new marine gastrotrichs of the Ptychostomella congeners, next to the case of P. g e nus T e tranc hyr oderma (Macrodasyida: Thaumastodermatidae) brachycephalus with P. higginsi from Faroe Bank, the from South Korea. Zool Stud 4 6 ( 4 ) : 47 4-4 82. northeastern Atlantic (Clausen, 2004). The ratio of co- Ruppert EE (1991) Gastrotricha. In: Harrison FW and Ruppert EE (eds), Microscopic Anatomy of Invertebrates, IV: occurring individuals between the species from Korea was Aschelminthes, John Wiley & Sons, New York, pp 41-109. 21 (P . jejuensis ): 8 (P . orientalis). Ptychostomella orientalis Todaro MA (2002) An interesting new gastrotrich from littoral had been reported from four localities along the eastern meiobenthos (Long Beach Island, USA), with a key to species coast of South Korea (Lee and Chang, 2003). Comparing of T e t r anch y r o derma (Gastrotricha: Macrodasyida). J Mar with those of the populations from the eastern coast of Biol Assoc UK 82: 555-563. Korea, the individuals from Jeju Island show relatively [Received February 4, 2009; accepted February 28, 2009] larger embossed hemispherical elevations as the dorsal 30 ANIMAL CELLS AND SYSTEMS Vol. 13 No. 1
http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.pngAnimal Cells and SystemsTaylor & Francishttp://www.deepdyve.com/lp/taylor-francis/a-new-gastrotrich-species-of-the-genus-ptychostomella-macrodasyida-kE6sLrspFU
A new gastrotrich species of the genus ptychostomella (macrodasyida, thaumastodermatidae) from South Korea
A new gastrotrich species of the genus ptychostomella (macrodasyida, thaumastodermatidae) from South Korea
Abstract
Abstract A new marine gastrotrich species, Ptychostomella jejuensis n. sp. belonging to the family Thaumastodermatidae, is described on the basis of the specimens from subtidal sand bottom at about 6–7 m depth of Jeju Island, South Korea. Ptychostomella jejuensis n. sp. is distinguished from its congeneric species with smooth cuticular armature by the character combination: (1) small body up to about 160 μm in length; (2) presence of knob‐like cephalic tentacles; (3) absence...
Animal Cells and Systems 13: 25-30, 2009 A New Gastrotrich Species of the Genus Ptychostomella (Macrodasyida, Thaumastodermatidae) from South Korea 1 2, Ji Min Lee, Ui W ook Hwang , and Cheon Y oung Chang * Institute of Basic Science, Daegu University; Department of Biology, Teachers College, Kyungpook National University, Daegu 702-701, Kor ea; Department of Biological Science, College of Natural Sciences, Daegu University, Gyeongsan 712-714, Korea Ab s t ra ct : A new marine gastrotrich species, Ptychostomella crumbles from subtidal bottom at about 6-7 m depth. By the j e ju ensis n. sp. belonging to the family Thaumastodermatidae, detailed scannin g electronic microsco py , we confirmed that is described on the basis of the specimens from subtidal this species is characteristic in having the numerous sand bottom at about 6-7 m depth of Jeju Island, South cuticular gland openings mostly flanking a bristle on the Kor ea. Ptychostomella jejuensis n. sp. is distinguished from dorsal and dorsolateral surfaces. As the character is consistent its congeneric species with smooth cuticular armature by the throug hout the specimens examin ed , an d the species shows character combination: (1) small body up to about 160 µm in length; (2) presence of knob-like cephalic tentacles; (3) the clear discrepancy with the related congeners in the absence of dorsal and ventral adhesive tubes; (4) bifid combin atio n of several macro -characters, we determin e it a pedicles; (5) pyriform copulatory organ. Under scanning valid species. electron microscopy, numerous epidermal gland openings W e provide the description of the new species based on we re ob serv ed i n the n e w speci e s, cha r acteri stical l y fl anki n g the morphological characters and a discussion on the a bristle. Taxonomic accounts on the affinities, some brief taxonomic affinities, with illustrations and scanning remarks on the epidermal gland openings and the co- electron photomicrographs. occurrence with P . orientalis Lee and Chang, 2003 are also presented with detailed illustrations and scanning electron p hotomi c rogra phs. MA TERIALS AND METHODS Key words: Gastrotricha, Korea, Macrodasyida, new species, Materials were collected from the sublittoral sandy bottom Ptychostomella , SEM, Thaumastodermatidae, taxonomy containing fine to coarse shell fragments at about 6-7 m depth around Saeseom islet, just 20-30 meters off Seogwipo Harbor at the southern coast of Jeju Island the INTRODUCTION largest and southernmost island in South Korea. Samplings were taken by scooping the top sediments A total of 16 species have been recorded by the serial into a polyethylene vinyl bag or 700 mL volume plastic researches on the marine gastrotrich fauna from South bottles by SCUBA diving. The process of extracting Korea (Chang, Lee and Clausen, 1998a, b; Chang and Lee, gastrotrich specimens and preparation of whole mounts 2001; Lee and Chang, 2002, 2003, 2004, 2006, 2007), follows Lee and Chang (2003). Formalin-fixed specimens including two species belonging to the genus Ptychostomella were mounted in glycerin on H-S slide, and then observed (Thaumastodermatidae) , P . orientalis Lee and Chang, 2003 un de r a d i f feren tia l int erferenc e c o n trast m icro scop e ( Olym pu s and P . papillata Lee and Chang, 2003. BX-50 ) equ ipped with No marski o ptics. All drawings were Recently, during a faunistic study on the marine meiofauna carried out with the aid of a camera lucida. Measurements of Jeju Island, South Korea, we found a gastrotrich species were made using a digital camera for microscope (Cool belonging to the genus Ptychostomella with minute body SNAP 5.0M, Roper Scientific Co., USA) and a calibration size among sandy sediments containing lots of shell software QCapture Pro (ver. 5.0, Media Cybernetics Inc., USA ). * T o whom correspondence should be addressed. Materials for scanning elec tron microscopy were prefixed T el: +82-53-8506454; Fax: +82-53-8506459 with 2.5% glutaraldehyde in 0.1 M phosphate buffer (pH E-mail: cychang@daegu.ac.kr ANIMAL CELLS AND SYSTEMS Vo l. 13 No. 1 25 Ji Min Lee, Ui Wook Hw ang, and Cheon Y oung Chang 7.4) for 4-6 hours at 4, followed by rinsing with 0.1 M eyespot lacking; bearing paired knob-like tentacles phosphate buffer (pH 7.2-7.4) three times for 10 minutes dorsolaterally; dorsal cuticular armature smooth; numerous each. Specimens were postfixed in 2% cold osmium gland openings scattered on dorsal, dorsolateral and tetroxide in 0.1 M phosphate buffer for 2 hours, and left in ventrolateral surfaces, among which nearly half of the phosphate buffer overnight. After dehydration through a dorsal and dorsolateral ones flanking a bristle; adhesive graded series of ethanol (50-100% at 10% interval) for 30tubes: 3 TbA per side in a horizontal row; 5 TbVL per side, minutes each, the material was critical point dried using a including a small tube behind TbA; 4 slender Tb VL ev enly freeze-dryer, and coated with gold-palladium in a high spaced in intestinal region; 2 TbL per side, in the middle evaporator, and then examined using a scanning electron and at outer posterior edge of body, respectively; 5 TbP microscope (Hitachi S-4800) operated at 10kV. forming a pedicle, comprising 2 distal, 1 lateral and 2 T ype specimens are kept in the authors’ collection at themedial tubes; copulatory organ pyriform. specimen room of the Department of Biology, Daegu University (DB) and deposited in the National Institute of Description of the holotype: Body (Figs. 1, 2) minute, Lt Biological Resources (NIBR), Incheon, Korea.149 µ m long; semi-rectangular, with a short, bilobed T erminology mostly follows Ruppert (1991) and Clausen caudum; dorsal surface somewhat uneven with undulating (2000). Abbreviations used in the text are as follows: dorsolateral sides; bo th lateral si d es of body nearly parallel, Lt = total length, from anterior tip of head to posterior tip of with slight constriction in the middle of pharyngeal region. pedicles including adhesive tubes; U=percentage unit of Lt, Pharynx 36 µ m long (measured from ventral border of oral used for the location (U-) from anterior to posterior, or for opening to pharyngeo-intestinal junction); PhJIn located at the relative length (-U); PhJIn = junction between pharynx U33, with paired pharyngeal pores, opened ventrally at and intestine; TbA = anterior adhesive tubes; TbD = dorsal U32. Widths of oral opening/neck/PhJIn/trunk/caudal base adhesive tubes; TbL=lateral adhesive tubes; TbP=posterior33/23/24/29/23 µm at U06/U25/U33/U69/U93, respectively. adhesive tubes; TbV=ventral adhesive tubes; TbVL= Oral hood broad and a little swollen anteriorly, with ventrolateral adhesive tubes. slightly undulating border (Fig. 1A). Six to 8 long sensory hairs (ca. 10-15 µ m long) implanted along dorsal ma r gin of SYSTEMA TIC ACCOUNTS oral hood; more than 13 hairs (ranging 4-7 µ m long) along anterior edge of oral hood both dorsally and ventrally; a Family Thaumastodermatidae Remane, 1926 pair of cilia tufts consisting of 3 sensory hairs (ca. 15- Subfamily Thaumastodermatinae Ruppert, 197816 µ m long) situated on anterolateral part of oral hood at Genus Ptychostomella Remane, 1926U04; at least 11 pairs (ca. 9-14 µm long) of hairs located on Ptychostomella jejuensis new species subdorsal, dorsolateral and lateral sides along entire body (Fi g u re s1 -3 ) length posterior to knob-like tentacle (U10-U93); 4-6 pairs of sensory hairs aligned dorsolaterally per side, each pair Type specimens: Holotype (DBG1301) and 10 paratypes composed of a long (5-8 µ m) and a short (1-3 µ m) hair at (DBG1302-1111), mounted in glycerin on H-S slides, leg. U24-U81 (Fig. 3C). Eyespot lacking. Paired knob-like C. Y . Ch ang , J . M. L e e a nd S . H . K i m, 24 A p r i l 200 6. A n o the r tentacles (pestle organs) (Fig. 3A, arrow) small (ca. 3 µ m two paratypes (NIBRIV0000131 151, 0000131 159), mounteddiameter) and protruding dorsolaterally at U08. in glycerin, collection data same as in the holotype. Oral opening (Figs. 1B, 2B) (ca. 33 µ m in diameter) a little undulating ventrally, bearing numerous hairs (ca. 2-5 Additional material examined: Eight specimens with the µm long) along its posterior rim. same collection data are mounted on aluminum stub for Dorsal cuticular armature smooth, lacking embossed SEM observation. hemispherical elevations or papillae. Numerous epidermal glands irregularly scattered at dorsal, dorsolateral, and T ype locality: Saeseom islet, Seogwipo, Jeju Island, South ventrolateral surfaces, along nearly whole body length o o Korea (33 14'04''N, 126 33'56''E), in sublittoral sandy (U1 0 -U8 9 ); with generally circular shape, mixed in various sediments containing shell crumbles at about 6-7m depth. size (from 2 to 7 µ m in diameter). Numerous elliptical gland openings or ‘stomata’ (Figs. 1A, 3B-D) with cuticularized Etymology: The specific name jejuensis alludes to the type lips (from 1 to 3 µ m in diameter), some paired, but mostly locality of the present new species, Jeju Island, South scattered asymmetrically on dorsal and dorsolateral surfaces; Korea. 4-5 pairs of openings (Fig. 3E , F , arrows) sparsely distributed on ventrolateral side ranging from behind TbA to middle of Diagnosis: Small Ptychostomella with short, bilobed pharyngeal region (U23); about half of the gland openings caudum; body up to 164 µ m long; PhJIn at about U34; each flanking a short bristle (Fig. 3B, D, arrow), excluding 26 ANIMAL CELLS AND SYSTEMS Vol. 13 No. 1 Ptychostomella jejuensis n. sp. (Gastrotricha) from Korea Fig. 1. Ptychostomella jejuensis new species. A, habitus, dorsal; B, habitus, ventral. Scale bar=20 µm. CO, copulatory organ; E, egg; GO, gland opening; KT , k nob-l ik e tent ac le (pes tle or gan) ; PP , pharyngeal pore; SR , s emi nal rec ept ac le; T , tes ti s; T bA, anter ior adhes iv e tubes; T bL, later al adhesive tubes; TbP , posterior adhesive tubes; TbVL, ventrolateral adhesive tubes. ventrolateral openings. TbVL per side (Fig. 2B), foremost one rather short, ca. V entral cilia (Fig. 2B) covering mid-ventral surface, just 5 µ m long, situated a little behind TbA at U16; the others behind TbA to base of caudum. somewhat slender and long (ranging ca. 9-11 µ m long), Adhesive tubes: TbA 3 per side (Figs. 2B, 3A), evenly distributed a little more ventrally in intestinal region (at spaced and distributed in a nearly horizontal row behind U40, U54, U71 and U78, respectively), last 2 TbVL close oral opening at U13, composed of 1 short medial tube (ca. 6 to each other; 2 TbL (Fig. 1 A, B) per sid e, the former 9 µ m µ m long) and 2 lateral ones (ca. 9-10 µ m long) per side; 5 long, located a little ventrolaterally nearly in the middle of ANIMAL CELLS AND SYSTEMS Vo l. 13 No. 1 27 Ji Min Lee, Ui Wook Hw ang, and Cheon Y oung Chang The ordinary dorsal cuticular armature in the genus Ptychostomella has been known as ‘smooth’, lacking the usual three- to five-pronged cuticular sculptures which are typically shown among thaumstodermatid gastrotrichs and regarded as the important taxonomic characters. However, recently three species equipped with the embossed hemispherical elevations or papillae as the dorsal cuticular armature have been found: P . lepidota from Norway (Clausen, 2000), and P. orientalis and P. papillata from Korea (Lee and Chang, 2003). So, now the members of Ptychostomella are divided into two groups by the state of the cuticular armature. Among the eight species, sharing the smooth cuticular armatu re, the n ew sp eci es is c l o sely si mi la r to P . m e dit erran ea and P . tyrrhenica in having a small body length (less than 200 µ m), a pair of knob-like tentacles, 2 TbL, and absence of ‘foot-type’ TbV. However, P. jejuensis n. sp. is distinguished from P . mediterranea by the absence of TbD (against 6 TbD in P . mediterranea) and bifid pedicles (against trifid in P . mediterranea), and from P . tyrrhenica by 2 medial TbP per side between the bilobed caudum (against the absence of medial TbP in P . tyrrhenica ) and a pyriform copulatory organ (agai nst a bladder-like copulatory organ in P . tyrrhenica ). Moreover, the knob-like cephalic Fig. 2. Ptychostomella jejuensis new species, SEM micrographs. A, tentacles occur dorsolaterally in P . jejuensis n. sp., while it habitus, dorsal; B, habitus, ventral. Scale bars = 20 µm. is ev idently depicted as p rotru ding ventrolaterally ju st from the posterolateral corner of oral opening in the original lateral margin of body at U53, the latter 7 µ m long, at description of P . mediterranea ( se e Hummon et al., 1993, lateroposterior edge of body (U91); 5 TbP per side, eachFig. 9B, C). forming a pedicle, comprising 2 distal tubes (7 µ m long),Ptychostomella jejuensis n. sp. is also allied with P . flanked by 1 lateral (6 µm) and 2 medial ones (5-6 µ m).higginsi in sharing the presence of a pair of knob-like Reprod uctive sy stem: testis (Fig. 1B) single o n righ t side tentacles, 2 TbL, bifid pedicle and pyriform copulatory (in dorsal view), its tip at U36 not reaching PhJIn; vas organ; however, the new species differs from it by smaller deferens apparently not coiled but gently curved medially, size (up to 16 4 µ m vs. 240 µ m in total b ody length) as well ending at U87 toward posterior part of copulatory organ. as lower number and different arrangement of TbA, TbVL Copulatory organ (Fig. 1B) pyriform, located at U76-U93. and TbP . Furthermore, P. jejuensis was collected from the Seminal receptacle (Fig. 1B) oval (9 µ m × 8 µm), in front ofsublittoral bottom at 6m depth, while P . higginsi from deep copulatory organ at U68-U74, containing spermatozoa. Asea at about 160m depth. single suboval egg situated dorsally in mid-intestinal region,Although P. orientalis belongs to the other group with maximum size ca. 16 µ m ×40 µ m.the dorsal cuticular armature of embossed hemispheres, it is Occurred from the sandy sediments mixed with fine to somewhat similar to the new species in bearing 3 TbA and coarse shell fragments on sublittoral bottom about 6-7 m 2 TbL per side, and paired knob-like tentacles. However, depth, with Ptychostomella orientalis Lee and Chang and besides the dorsal cuticular armature, it is different from P. an unrecorded species of Platydasys .jejuensis by having more TbV(L) and TbP , and an oblong copulatory organ. Moreover, all of the epidermal gland T a x onom ic affinitie s: Ele ven sp eci es a r e c urrent ly reco gn iz edopenings of P. orientalis are simple, not flanking a bristle as in the genus Ptychostomella Remane, 1926: P . pectinatashown in the new species. Rem ane, 192 6, P . omm ato phora Rem a ne, 19 27, P . mediterranea Remane, 1927, P . h ela na Roszczak, 1939, P . brachycephalusRemarks: All of the specimens examined were fully (Lévi, 1954), P . tyrrhenica Hummon, T odaro and T ongiorgi, mature, and pre-mature individuals were not found. Body 1993, P . bergensis Clausen, 1996, P . lepidota Clausen, lengths of thirteen type specimens ranged from 125 µ m to 2000, P. orientalis Lee and Chang, 2003, P. papillata Lee 16 4 µ m ( m ea n 1 4 4 µ m , st and ard d e v iat io n 1 2), an d m a xi mu m and Chan g, 2 003 and P. higginsi Clausen, 2004. widths 26-35 µ m (20U-24U), measured in glycerin mount. 28 ANIMAL CELLS AND SYSTEMS Vol. 13 No. 1 Ptychostomella jejuensis n. sp. (Gastrotricha) from Korea Fig. 3. Ptychostomella jejuensis new species, SEM micrographs. A, head, ventral view, showing anterior adhesive tubes (TbA) and knob-like tentacle (arrow); B, cuticular openings of epidermal glands and sensory hairs near lateral adhesive tubes (TbL) on the posterol ateral edge o f trunk, dorsal view; C, a gland opening and paired sensory hairs on the dorsolateral side of trunk; D, a gland opening flanking a bristle (arrow) and a sensory hair on the lateral trunk region; E, gland openings near ventrolateral adhesive tube (TbVL) on the anterior phary ngeal region, ventral view; F , gland openings (arrows) in the middle of pharyngeal region, ventral view . Scale bars = 5 µ m (A, B, F), 3 µ m (C), 1 µ m (D, E). Those are the smallest members known in the genus appear identical to the strongly cuticularized lips or Ptychostomella so far. ‘stomata’, referred to in the description of T e t ran ch yr o d e r m a The arrangement and number of adhesive tubes wereweissi T odaro, 2002 (see T odaro, 2002, Fig. 2A, B, E). The r a t her c ons is te nt t h r o u ghout the sp ec im en s e xam i ned . A m ong similar cuticular openings have been already observed by total 21 specimen s ex amined, including SEM material, twoscanning electron microscopy in T. heterotentaculatum (see specimens were variable: one specimen had an additional Chang and Lee, 2001, Fig. 3G) and Ptychostomella lateral TbP and TbVL in the intestinal region (secondpapillata (se e Lee and Chang, 2003, Fig. 6B) from Korean TbVL consisting of two tubes as ‘fo o t-type’ in the left si d e , coasts, although they have not been described in detail. In asymmetrically); the other specimen possessed two the previous species, the openings were generally simple additional TbP laterally and medially. and arranged in two columns symmetrically, while nearly T he cut ic ula r op eni ngs o f ep ide r mal gla nds w e r e obs e r ved half of the openings on the dorsal and dorsolateral surfaces on the dorsal, dorsolateral and ventrolateral surfaces. They are flanked each by a bristle in the new species, showing ANIMAL CELLS AND SYSTEMS Vo l. 13 No. 1 29 Ji Min Lee, Ui Wook Hw ang, and Cheon Y oung Chang cuticular armature, seemingly as a reinforcement of the reproductive isolation or a character displacement between the two sympatric congeneric species. ACKNOWLEDGMENTS We are grateful to Dr. Sa Heung Kim of the INTHESEA KOREA Inc. for his help in collecting samples, and thankful to Mr. Byung- Chan Lee (Nano Practical Application Center , Daegu, Korea) for providing the facilities in which scanning electron microscopy was conducted. Authors also appreciate three reviewers for their critical comments that greatly improved the manuscript. This research was partly supported to CYC by Daegu University Research Grant, 2006. REFERENCES Chang CY , Lee JM, and Clausen C (1998a) Description of two new species thaumastodermatids (Gastrotricha, Macrodasyida) from Korea. Korean J Biol Sci 2: 315-321. Chang CY , Lee JM, and Clausen C (1998b) T wo new species of T hau masto d erma (Gastrotricha, Macrodasyida) from Korea. S a rsia 83: 329-336. Chang CY and Lee JM (2001) Two new T e tran chyr oderma gastrotrichs (Macrodasyida Thaumastodermatidae) from South Korea. Kor e an J B i o l Sci 5: 187-194. Clausen C (2000) Gastrotricha Macrodasyida from the Tromsø region, northern Norway. Sarsia 8 5 : 3 57- 384 . Fig. 4. A map showing the localities of Ptychostomella orientalis (▲ ) Clausen C (2004) Gastrotricha from the Faroe Bank. Sa rsi a 89: and P . jejuensis (●). 4 23- 45 8. Hummon WD, Todaro MA, and Tongiorgi P (1993) Italian marine Gastrotricha: II. One new genus and ten new species of Macrodasyida. Boll Zool 60: 109-127. somewhat irregular disposition. The presence of the cuticular openings on the ventrolateral side has been rarely Lee JM and Chang CY (2002) P s eudo st omel la gastrotrichs (Macrodasyida, Thaumastodermatidae) from South Korea, reported, that is, only mentioned in T. weissi and Platydasys with a brief review of the genus. Korean J Biol Sci 6: 207- ruber Swedmark, 1956 sensu Todaro, 2002 (Fig. 2F). In the 2 13. new species, the cuticular openings on the ventrolateral Le e JM an d Chang CY (2 003) T w o ne w ma r in e gastr o t ri c hs of t h e surface are also present but rare (only 4-5 openings on each genus Ptychostomella (Macrodasyida, Thaumastodermatidae) side), restricted to the anterior part of pharyngeal regionfrom South Korea. Zool Sci 20: 4 81- 48 9. behind the oral opening. In addition, they lack the bristle Lee JM and Chang CY (2004) Gastrotrichs of genus H a li chae tono tus (Chaetonotida: Chaetonotidae) from Korea. flanking the openings unlike those on dorsal and Korean J Syst Zool 20 (1 ): 5 5 - 6 2. dorsolateral surfaces. Lee JM and Chang CY (2006) Marine gastrotrichs of the genus Ptychostomella jejuensis n. sp. co-occurred with P. D i pl oda sy s (Macrodasyida: Thaumastodermatidae) from orientalis in the present type locality, Jeju Island (Fig. 4). K o r ea. Korean J Syst Zool 22(1): 109-115. This is the second record of the co-occurrence of Lee JM and Chang CY (2007) Two new marine gastrotrichs of the Ptychostomella congeners, next to the case of P. g e nus T e tranc hyr oderma (Macrodasyida: Thaumastodermatidae) brachycephalus with P. higginsi from Faroe Bank, the from South Korea. Zool Stud 4 6 ( 4 ) : 47 4-4 82. northeastern Atlantic (Clausen, 2004). The ratio of co- Ruppert EE (1991) Gastrotricha. In: Harrison FW and Ruppert EE (eds), Microscopic Anatomy of Invertebrates, IV: occurring individuals between the species from Korea was Aschelminthes, John Wiley & Sons, New York, pp 41-109. 21 (P . jejuensis ): 8 (P . orientalis). Ptychostomella orientalis Todaro MA (2002) An interesting new gastrotrich from littoral had been reported from four localities along the eastern meiobenthos (Long Beach Island, USA), with a key to species coast of South Korea (Lee and Chang, 2003). Comparing of T e t r anch y r o derma (Gastrotricha: Macrodasyida). J Mar with those of the populations from the eastern coast of Biol Assoc UK 82: 555-563. Korea, the individuals from Jeju Island show relatively [Received February 4, 2009; accepted February 28, 2009] larger embossed hemispherical elevations as the dorsal 30 ANIMAL CELLS AND SYSTEMS Vol. 13 No. 1
Journal
Animal Cells and Systems
– Taylor & Francis
Published: Jan 1, 2009
Keywords: Gastrotricha; Korea; Macrodasyida; new species; Ptychostomella; SEM; Thaumastodermatidae; taxonomy
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