BULLETIN OF MARINE SCrENCE. 62(1): 1-6. 1998 SPECIES OF PYURIDAE (ASCIDlACEA) FROM SOUTH VIETNAM Lin.da Cole and Maria Vorontsova ABSTRACT Four species of the family Pyuridae from SOUdl Viemam are listed and discussed, widl habitat and breeding nOles added. Thi is the second contribution to the ascidian fauna of Vietnam from the specimens that were collected by M. Vorontsova from Jline 1989-June 1991. Tunicates never before coUected from South Vietnam provided the opportunity to augment the descriptions of four previously described pecies of Pyuridae. The area tudied was Bing Cang Bay south to Cam Ranh Bay (Fig. I). Five species from the family Pyuridae were coUected: Microcosmus exasperatus Hellel~ 1878; Herdmania momus, 1816; Pyura curvigona Tokioka, 1950; Pyura shiinoi Tokioka, 1949 and Pyura camranica (Vorontsova and Cole, 1995). P. camranica was described by the authors previously, the other four species are discussed in this work. Breeding notes were only made on M. exasperatus and H. momus, the two most common species. Microcosmus exaspera.tus Heller, 1878 Figures 2A-E For earlier records, see Van Name. 1945. For synonyms, see KOll, 1985: 348: Monniot, 1989. fig. 2. pI. I. p. 479. ten-a tipiea: New South Wale Material £xamined.-AII from SOUdl China Sea, Cam Ranh Peninsula. 12/I1I-1990. (USNM 20115), from wharf on the middle of the west shore of peninsula, substrate: metal, dep. 0-4 111. IflII-1990, (USNM 20116), from bridge between peninsula and mainland. surface: metal. dep. 0- 4m. 4/IIJ-1990, (US M 20117). from bridge between peninsula and mainland, surface: metal. obrained larvae by anifieial fertilizaiion. In Soutb Vietnam, M. exasperatus was usually found in aggregations or cluster with other ascidians or attached to various other invertebrates. Only once was this species collected from a natmal substrate. M. exasperatus was found in large quantities among the fouling communities that were attached to the metallic sup- port or legs of the bridge that connects Cam Ranh Peninsula and the mainland of South Vietnam and in large quantities on the wharf located approximately 6 kIn. south of the bridge. On the bridge, M. exasperatus wa found inside thick colonies of Eudistoma sp. that were sometimes up to 6 cm thick. Only the four lobed bright orange iphon of M. exasperatus could be 'een protnlding from the tunic of the olive colored colonies of Eudistoma, the rest of the tunic of M. exasperatus is beige to light brown in color and thinly covered with algae and mud. Individuals were approximately 3 cm in length. In South Vietnam, the breeding season of this species starts around the middle of February and lasts until the middle of April. Mature eggs were approximately 350 tJ-m.Larvae were easily obtained by artificial fertilization. It takes 10-11 h for a larva to hatch after fertilization of an egg. Lal:-vae were small, usually 800 tJ-ffiin length with a trunk of 280 f-Lm. Upon hatching, definitive organs are not 2 BULLETIN OF MARl 10SCIENCE. VOL. 62. NO. I. 1998 12' .& PYllrlJo eurvioonlll v UIC;rOCQlllmUIIl eX88lHHIIltua • P)'urlll ."""(11 109- 10' 100" 2Q' Figure I. The vicinity of Nytha Trang. Vietmlm. Localities (symbols) show place specimens were collected. Map on right is an enlargemem of area Illost studied. yet developed; the larvae bas only a statocyte, the ocellus is absent. According to laboratory observation, the larvae can swim up to 24 h before settling on a ubstrate (Vorontsova, 1992). A typical specimen from Vietnam consists of a branchial lining that has sharply pointed siphonal armature (55 /-lm in length) in the upper third of its lining (Fig. 2E,F). which are approximately 250 /-lm in length and 75-250 I-Lffi wide. The lower part of the siphonallining contains threadJike filaments that are usually 500 fJ-m in length. The dorsal tubercle is quite large. The slit is V-shaped and pro- truding, with horns that spiral inward several times. There are eight wide folds on each side of the branchial sac, with 6-7 tigmata per mesh. The hepatic gland (liver), brain like with papiJIae (Fig. 2B), has two small lobes (Fig. 2A). Gonads are divided into three sections, with one section enclosed in the gut loop. B Figure 2. MicrocosIllU.\· ~xa.rperalu.I'. Left view of animal (A) showing gllt loop; (B) enlargement of hepatic gland showing structure of the gland. COL· A I) VOR NTSOVA: SOUTH VIETNAM T NI ATr,$ 3 Herdmania mOll1us (Savigny, 1816) Cylllilia /I/(J/lHI.~ Savigny. j 816. p. I·n. pI. I. fig. _. pI. 4. fig. I; Nerdllu/Ilia 1/lO/IlIIS Van arne. 1945. p. 341 Mal 'rial Exalllilled.-a. Vietnam. omh China Sea. ha Trang Bay, col. M. Voroms va: 17/1-1990. Sl. 4. Tam Island. coral reef al Ihe . side of island. 1 spec. 17/1-1990.51. 13, east side of M I Island. between branches of single coral "bushes," divided by sand spaces. dcp. 3-4 m. I spec. 16/11-1990, (USNM 20122), Sl. 15. north bank of the Bay on southern pari of Tre Island, on the upper and lower side, of dead flat corals. dep. 1-3 m, 9 spec. 23/11-19( O. (U M 20120). 51. 4. Tam Island. coral reef at the Ilonh side of island. 3 sp"c. 26fV-1990. (US M 20118). s. 6. Shang Lou. ollected during low tide (-2 lll). under flaI stoncs. 15 spec. b. Vietnam. soulh hina Sea. Cam Ranh. col. A. Gogolev and M. Vorontsova: 1111-1990, ( SNM 20119). bridge, in fouling community. 2 spec. 12/lII-1990. (USNM 20121). wharf. fouling comlllunity. dep. 0-4 m, 2 spec. Thjs pecie wa. one of the most abundant of the sp cies tudied in this area. 1 was found to be equally occurrent in natural habitats and artificial substrate. In natural habitat such a. large stone (up to 40 ern) or dead tubular Acropora colonies which seemed to be a preferred substrate for several ascidian pecies in the region, it was collected from five stations in Nha Trang Bay. In every tation, animal were found attached to the undersides of the ub trate. In Cam Ranh, H. mOl/'ltls was collected from the same artificial substrates at the exact ame place on the ubstrates tha M. exasperafu$ was found. In Cam Ranh, H. momus grow fairly large on artificial ubstrates, up to 9 cm in diam ter; whereas on natural substrates in Nha Trang Bay, this species never gets any larger than 3.5 cm. The tremendous growth on artificial ubstrat i probably due to the excellent water current conditions for ascidians bringing good upplies f oxygen and nutrition into Cam Ranh Bay. Cam Ranh Bay is shaUow and rich with phyto and zoo- plankton. Tide currents are strongest in tbe narrowest part of th bay where the bridge is located. The breeding season starts around the middle of December and lasts untiJ around the middle of April. There is a second shorter breeding season which takes place around the middle of July through mid August. Eggs ar'e large (approxi- mately 480 J.Lm) and orange. It rakes th larvae app1'OximateJy 14 h to hatch after the egg is fertilized. Larvae were found to be approximately 1400 J.l.min length with a trunk of 400 J.Lm, sen ory organs consists of an otoUth and ocellus with three len e . Siph ns opened 7 d after settlement. H. momllS i a welllcnown tropical species. The specimens collected w re round or oval shaped and attached by the ventral or ventro-lateral surface, siphons are terminal. Small specimens up to 4 cm) are light pink in color the larger ones are gray to brown. The mantle is pinkish red. The tunic of smaller pecimens is thin (2 nun or less) and almost transparenI and allows the mantle to be seen thus givi.ng the pinki h coloring in smaller individuals. A 'pecimens get larger the tunic becomes thicker up to 4 or 5 mm) and translucent and are often covered with other epibionts (algae, hydroide , colonial ascidians, etc.). An interesting thing to note is that the typica110ng spicu1es of this species, which are distributed in the tunic as we1l a in the ti sue resemble mantle mu culature in fre hly dissected material when observed under low magnification. In the branchial sac, there are eight folds on the left and eight on the right witll 6-7 stigmata per mesh on the fiat between folds. The stomach is narrow and elongated. The hepatic gland is large, elongated and unbranched, with numerou' tubules. The gonad' are lo- cated on both sides of the body and ar-e large and elongated. 4 BULLETIN OF MAIIINE S noNCE. VOL. 62. NO. I. 199M Figure 3. Pyura clIl1lig(ma. (Al entire animal .mached to coral; (B) left view of dissected animal showing gut loop: (C,D) Iwo differenl dorsal tubercles. Pyura curvigona Tokiaka, 1950 Figure 3 Tokioka. 1950: p. 147, fig. 22; pI. 10 figs. 4-6 967: p. 199-202, figs. 88---89 Palau lsI. Tokioka 'I/lel ishikawa. 1975. p. 339-340, figs. 37-40 (Hong Kong) Millar. 1975, p. 312-314. figs. 90-91 (Indonesia) Nishikawa, 1980. p. 101 (only listed) Kon and Goodbody, 1980. p. 539, pI. 3d (note, Kon. 1985) ishikawa, 1984, p. 136 (Truk Isl.). Kon, 1985, p. 296-299 (West. Auslrali<:t; Qucensland: Lizard) Material £xwllilled.-17/1V-1990 (4)-Solllh China Sea. Nlla Trang Bay, Trc lsI.. corol! rcef, under flat slone. del'. ] .Sm 16/11-1990 (US M 20123),15 spec.-Soulil China Sea, Nh •• Tnlllg Bay.