THEFIRSTZOEAL STAGEOF EUALUSSINENSIS (YU, 1931) (DECAPODA,CARIDEA, HIPPOL YTIDAE), WITHAKEYTOTHEKNOWNHIPPOL YTIDFIRSTZOEAE OFKOREAAND ADJACENTW ATERS
BY
HOI JEONG YANG 1,3/,HYUN SOOK KO 2/ andCHANG HYUN KIM 1/ 1/ Departmentof Biology,Pusan National University, Pusan 609-735, South Korea 2/ Departmentof LifeScience, Silla University, Pusan 617-736, South Korea
ABSTRACT
The rstzoeal stage of Eualussinensis (Yu,1931) is described and illustrated in detail. The presenceor absence of a posterolateralspine on abdominal somite 5 canbe used to separate the larvae of Eualus intotwo groups. The rstzoea of E. sinensis iseasily distinguished from that of E.leptognathus bythe absence of a rostrum,a pterygostomialspine, and anteroventral denticles onthe carapace, as well as by the rudiments of pereiopods. A keyto the known rstzoeae of 20 hippolytidspecies of Koreaand adjacent waters is provided.
RÉSUMÉ
Lepremier stade zoé de Eualussinensis (Yu,1931) est dé crit et illustréen dé tail. La pré sence oul’ absence de l’ épineposté rolaté rale du somite abdominal 5 peutê treutilisé e poursé parer leslarves de Eualus endeux groupes. La premiè re zoé de E. sinensis estfacilement distingué e de celle de E.leptognathus parl’ absence du rostre, de l’ é pinepté rygostomienne et des dentic- ulesanté roventraux sur la carapace, ainsi que par les pé ré iopodes rudimentaires. Une clé des premiersstades zoé s connusde 20 espè ces d’ Hippolytidae de Coré e etdes eaux voisines est fournie.
INTRODUCTION Eualussinensis (Yu,1931) inhabits small tidal poolsnear low water, and it has beenreported from Korea, southern Japan, and northern China (Hayashi &Miyake,1968; Kim, 1977). Nine species ofHippolytidae representing seven generaare knownto occur in Korean waters (Kim,1977). Of the ninespecies
3/ Currentaddress: Department of Life Science, Silla University, Pusan 617-736, South Korea.
© KoninklijkeBrill NV ,Leiden,2001 Crustaceana 74(1):1-9 2 H.J.YANG, H.S.KO &C.H.KIM recognized,the larval developmentof Latreutes planirostris (DeHaan, 1844) and Birulia kishinouyei (Yokoya,1930) has notyet beendescribed. For the genus Eualus,the complete larval developmentof Eualusleptognathus (Stimpson,1860) and E. sinensis has beendescribed by Y amashita &Hayashi(1984) and by Kurata (1968a),respectively. Kurata(1968a) gave a brief accountof the larval stages of E. sinensis underthe name Eualusgracilir ostris (Stimpson,1860). Beyond Koreaand adjacent waters, ninedescriptions of Eualus larvae basedon laboratory rearedzoeae as well as onplankton studies havebeen reported world-wide: Eualusfabricii (Krøyer, 1841) described by Haynes (1981) and Squires (1993); Eualussuckleyi (Stimpson,1864) described by Haynes (1981); Eualusgaimardii (H.Milne Edwards,1837) described by Lebour (1940), Pike &Williamson (1961), andSquires (1993); Eualusoccultus (Lebour,1936) described by Bourdillon- Casanova(1960), Lebour (1936) (as Spirontocarisocculta Lebour,1936), and Pike &Williamson (1961); Eualuspusiolus (Krøyer, 1841) described by Bull (1939) (as Spirontocarispusiola Krøyer, 1841) and Pike &Williamson (1961); Eualusherdmani (Walker,1898) described by Needler (1933) (as Spirontocaris herdmani Walker,1898); Eualusmacilentus (Krøyer, 1841) and Eualusbarbatus (Rathbun,1899) described by Ivanov (1971); Eualusdozei (A.Milne-Edwards, 1891)described by Albornoz& Wehrtmann(1997). Thepresent paperdescribes andillustrates in detail the rst zoeal stage of E. sinensis,comparesit with otherspecies of Eualus,andprovides a keyto the knownhippolytid rst zoeaeof Koreaand adjacent waters.
MATERIAL AND METHODS On24May 1998, an ovigerous female of Eualussinensis was collected from the oyster, Crassostrea gigas (Thunberg,1793), raft culture in Sangju,Korea (34±4300000N 127±5903000E).Tennewly hatched larvae wereremoved into glass bowlseach containing 33.3‰ ltered seawater. Theywere kept in a growth chamberat 20 ±Canddaily fedfreshly hatched Artemia nauplii.The remaining methodsfollow those usedby Y ang& Kim (1999).
RESULTS Noneof the rst larvae lived longerthan eight daysand vespecimens moulted successfully to the secondzoeal stage.