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Perspectives on Marine Environment Change in Hong Kong and Southern China, 1977-2001 (ed . B. Morton). Proceedings o f a n Internationa l Worksho p Reunio n Conference, Hon g Kon g 21-26 Octobe r 2001. Hong Kong : Hong Kon g University Press , 2003. DISTRIBUTIONS, DIETS AND REPRODUCTION O F HONG KONG SACOGLOSS A (MOLLUSCA : OPISTHOBRANCHIA) : A SUMMARY O F DATA, 1980-200 1 Kathe R . Jense n Asian Institute of Technology, P.O. Box 4 Klong Luang, Pathumthani 12120 , Thailand* ABSTRACT Sacoglossan opisthobranch s wer e first recorde d fro m Hon g Kon g i n 1985 . Of th e 1 3 species the n identified , fou r ha d been collected betwee n Decembe r 198 0 and Januar y 1981 and ten were collected in April 1983 . Four species and one genus were described as new. Additional species and ecological information have been collected subsequently , i.e., in April 1986 , 1989 , 199 5 and 1998 . Presently 2 2 species ar e known t o occur in Hong Kon g waters, seven have been described a s new, one remains undescribed, an d two are known only from photographs (on e still unidentified). Thi s paper summarize s information abou t the occurrence, diets and reproduction o f these species. INTRODUCTION Sacoglossan opisthobranch s compris e thre e majo r morphologica l groups : (1) , shelle d species (Oxynoacea); (2), unshelled specie s with lateral parapodia (Plakobranchoidea ) and (3), unshelled species with club-shaped cerata (Limapontioidea). Sacoglossans fee d suctorially on algal cell sap and have a specialized muscular pharynx with long, pointed radular teeth. Most sacoglossan s liv e in close association wit h their food algae . Diets and radular specializations have been described in a series of publications (Jensen 1981, 1983, 1991 , 1993a, b, c, 1996 , 1997a). The first sacoglossan s recorde d fro m Hon g Kong' s water s wer e collected a t 'th e shore opposite the Chinese University', that is, in Inner Tolo Harbour, and at Tsim Bei Present address : Zoologica l Museum , Universitetsparke n 15 , DK-210 0 Copenhage n 0 , Denmark. E-mail : krjensen@zmuc.ku.d k 348 K.R. JENSEN Tsui in Deep Bay. They were collected from Decembe r 198 0 to January 198 1 by J. S. Bleakney. In April 1983 , 1986, and 1989 , sacoglossans wer e collected intertidally an d from shallo w subtida l localitie s i n Tol o Harbour , Tol o Channel , Mir s Ba y an d Dee p Bay, s o that som e localities have been sample d a t 3-year intervals . In April 199 5 and 1998, collecting efforts wer e concentrated around the southeastern waters of Hong Kong, but trips to Deep Bay were also made. These data will be included in the present paper. Additional information abou t local sacoglossan anatomy and distribution has been published in several systematic accounts, using specimens collected between 198 0 and 1998 as well as from other locations (Jensen 1991 , 1992, 1993a, b, c, 1996, 1998, 1999, 2001). New records of Hong Kong sacoglossans have also been published. Furthermore, new synonymies have been proposed and it is therefore considere d appropriate to now summarize th e existin g knowledg e abou t th e sacoglossan s occurrin g i n Hon g Kon g waters. TAXONOMY AN D PROPOSED SYNONYMIE S The sacoglossan faun a o f Hong Kon g has been described in two papers (Jense n 1985 , 1990a). A few specie s not included i n these papers have been collected subsequently , however. These are Volvatella cf. viridis Hamatani, 1976 , Ercolania translucens Jensen, 1993, an d Elysia obtusa Baba , 1938 . A fe w specimen s o f a n unidentifie d Ercolania species, which is externally almos t identical to E. emarginata Jensen , 1985 , have been collected from Cape d'Aguilar. Thuridilla bayeri (Marcus, 1965) has been recorded only from a photograph with no locality given; an unidentified specie s of Elysia is also known only from a photograph. Volvatella cf. viridis Hamatani, 1976 Material examined: The following description is based on the one specimen of Volvatella cf. viridis, whic h wa s foun d i n Caulerpa sp . collected b y SCUB A diver s o n 22 Apri l 1989 at the southern en d of Chek Chau . Colour alive: Th e anima l wa s whit e except fo r th e mantle whic h wa s dar k gree n and...

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