Indian Journal of Geo-Marine Sciences Vol. 40 (4), August 2011, pp 487-490 Occurrence of opisthobranch mollusc Umbraculum umbraculum in Tuticorin coast, Southeast coast of India R Sankar*, P. Raja & A. Murugan Suganthi Devadason Marine Research Institute, 44-Beach Road, Tuticorin-628 001, Tamil Nadu, India *[E. mail: [email protected]] Received 4 June 2010; revised 19 November 2010 Live specimens of the opisthobranch mollusc, Umbraculum umbraculum were collected off Tuticorin, Southeast coast of India. Earlier literature mentions only the name of this species with photos of the shell without any description. This makes it difficult to characterize the species from another one Tylodina corticalis, which has similar shell shape. This is the first record of occurrence of live specimens along the Indian coast. The proximity of occurrence of the species near the Tuticorin Port area substantiates the possibility of its entry from some other place. [Keywords : Umbraculum umbraculum , Gulf of Mannar , invasive species, opisthobranch (mollusc), Tuticorin] Introduction The U. umbraculum has been recorded in Tylodinoidea, specialised superfamily of Eastern Mediterranean (Turkey, Antalya 9; opisthobranchs, are commonly called as umbrella Colombia 10 ; Syria, Lebanon, Israel, Cyprus, Ionian slugs 1. They have an external calcified shell and the Sea, Adriatic Sea, Aegean Sea, and Gulf of body of the animal is larger than the shell. Though İskenderun 11 ); Western Mediterranean (E. Spain, the species under the superfamily Tylodinoidea are Balearic Islands, France, W. Italy, Corsica, Sardinia, widespread in the tropical to warm temperate Indo- Sicily)12 ; Marmara Sea; Eastern Atlantic (Portugal, West Pacific Ocean 2,3 , individuals are exceptionally Spain, Madeira, The Azores, Canary Islands and 13 14 rare in tropical zone 2. They feed on sponges 4. Subba Selvagens Islands) ; Florida ; Chinese Seas, south 15 16 17 Rao 5 mentioned the occurrence of this species in eastern Tasmania ; New Zealand and Australia ; 18,19,20 21,20 22 Indian waters. No description was given and only the South Africa ; Mozambique ; Tanzania ; Gulf 23 24 25 photo of shell was presented. This is the first time of Aden ; Madagascar ; Mauritius ; Reunion Island (Indian Ocean) 26 ; North Sulawesi, Indonesia 27,28 ; that live specimens were collected along the Indian 29 30 coast, specifically from Gulf of Mannar area. Hawaii ; S. California to Panama and Cuba (Caribbean) to Brazil 31 . 3,6 The U. umbraculum has many synonyms . They are U. bertinia (F. P. Jousseaume, 1833); Material and Methods U. chinesis (Schumacher, 1817); U. mediterraneum Five live specimens of opisthobranch Umbraculum (J. B. Lamarck, 1819); U. ovale (P. P. Carpenter, umbraculum (Lightfoot, 1786) were collected at 1856); U. plicatulum (E. Von Martens, 1881); the depth of 8 m by lobster nets along the Tuticorin U. rushii (W. H. Dall, 1889); U. sinicum (J. F. coast; Gulf of Mannar (Lat. 8°44 ′39.37°N and Long. Gmelin, 1791); U. umbraculum (Lightfoot, 1786); 78°10 ′12.49 ′E), Southeast coast of India during U. indica (Lamarck, 1819); U. umbrella (Martyn) 2009 (Fig.1). The length and width of the shell and U. pulchrum (Lin Guangyu, 1981). All except were measured to the nearest mm. the last two are considered as synonyms of Depository U. umbraculum or U. mediterraneum depending : Suganthi Devadason Marine Research Institute (SDMRI) on whether they are from the Indo-West Pacific or the Atlantic 7. But, U. umbraculum is considered Systematics as the only living species under the genus Phylum : Mollusca Umbraculum 8. Class : Gastropoda 488 INDIAN J. MAR. SCI., VOL. 40, NO. 4, AUGUST 2011 Fig. 1—Map showing the location of samples Fig. 2 —Umbraculum umbraculum : a. whole animal; b. Gills & c. Shell Sub class : Opisthobranchia specimens, which covered the dorsum, were 86, 90, Superfamily : Tylodinoidea 92 and 95 mm long and 73, 73, 77 and 79 mm wide. Family : Umbraculidae The shells were encrusted with barnacles, sponges and micro algae and covered with a thin layer of Genus : Umbraculum Schumacher, 1817 periostracum. The shell, at the posterior left from the Species : umbraculum (Lightfoot, 1786) center, has backwardly curved, conically elevated apex called protoconch. The bright orange coloured Results circular body with large white pustules was circular Description: and larger than the top shell. The body doesn’t Only four specimens were in good shape. The elongate when the animal was crawling. shell of one specimen was broken and mangled. The mantle with serrated margins was observed The external, highly calcified, more or less below the shell and mantle. The large gills, which round, umbrella-like top shells (Fig. 2c) of the four appear like leaves (Fig. 2b) and located in the narrow SANKAR et al .: OCCURRENCE OF OPISTHOBRANCH MOLLUSC UMBRACULUM UMBRACULUM 489 mantle cavity, originate in the front and extend to the Acknowledgements right side of the body. The anal opening is located Authors thank Suganthi Devadason Marine near the posterior end of the gills and appears as small Research Institute for the facilities, Dr. Gary Copp rounded stick. A pair of large and distinct orange of Australia for confirming the identification of coloured rhinophores with longitudinal slit is located the species and Dr. Kathe Jensen of Denmark for the beneath the shell. The eyes are clearly visible and valuable suggestions. present at the base of the rhinophores. The mouth is located in the sole of the foot. The foot is large, References 1 Chen, M. H. and Chiu, Y. W., New record of Umbraculoidea tuberculate and the sole is smooth and flat. (Gastropoda: Opisthobranchia) from Taiwan, Journal of National Park , ROC, 15 (2005) 21-27. Discussion 2 Willan, R C, Order Notaspidea, in: Mollusca: The Southern The literature search for Indian records showed that Synthesis. Fauna of Australia , edited by P.L. Beesley, G.J.B. Ross & A. Wells, Volume 5, Part B. (CSIRO Publishing, there are no reports of the species U. umbraculum Melbourne) 1998, pp. 977-980. except the mention in the records of Zoological 3 Willan, R. C. & Burn, R., On the publicaton date, authorship, 5 Survey of India (ZSI) by Subba Rao in 2003. and type species of Umbraculum and Tylodina (Gastropoda: In addition, marine biodiversity database of India Opisthobranchia: Tylodinoidea): A rejoinder, The Nautilus , based in National Institute of Oceanography (NIO) 117 (2003) 23-29. also refers to Subba Rao 5 only and there is no 4 Willan, R. C., A review of diets in the Notaspidea (Mollusca: Opisthobranchia), Journal of the Malacological Society of morphological or anatomical description of this Australia , 6 (1984) 25-142. species except photos of the shell and a very brief 5 Subba Rao, N. V ., Indian seashells Polyplacophora and mention about shells. The brief detail mentioned Gastropoda. Records of the Zoological Survey of India ZSI, about the shell of this species earlier 5 was not clear Kolkata (Part 1) 2003, pp. 416. 6 Valdes, A., On the publication date, authorship, and and also coincides with that of Tylodina corticalis , type species of Umbraculum and Tylodina (Gastropoda: a similar species. However, the morphological Opisthobranchia: Tylodinoidea), The Nautilus , 115 (2001) features observed in the present observation clearly 29-34. distinguished U. umbraculum from T. corticalis . 7 Rudman B, Comment on Re: Umbraculum - how many species? by Erwin Koehler, in: Sea Slug Forum (Australian The U. umbraculum feeds on sponges 22 and has Museum, Sydney) http://www.seaslugforum.net/find/1922 been recorded along with Desmospongia, including (2000). 8 Willan R C; personal communication Tethya spp., Aaptos aaptos, Ancorina alata and 9 Swennen, C., On a collection of Opisthobranchia from 22 Plakina trilopha . It is to be noted that the sponge Turkey . Zoologische Mededelingen Leiden, 38 (1961) 41-75. fauna of India is dominated by the species 10 Marcus, Ev. and Marcus, Er., American opisthobranch mollusks, Stud. Trop. Oceanogr., 6 (1967) 1-256. of Desmospongia and out of 486 species described in India 32 , Gulf of Mannar and Palk Bay has the 11 Cevik, C. & Sarıhan, E., İskenderun Körfezi Mollusca 33 Faunası. Türk Sucul Ya şam Dergisi , 2 (2004) 93-97. highest diversity of 319 species . Demospongiae 12 Barash, A. & Danin, Z., Opisthobranchia (Mollusca) from like Hymedesmia mannarensis, H. stylophora, the Mediterranean waters of Israel, Israel. J. Zool., 20 (1971) Ectyodoryx lissostyla, Clathria frondifera, 151-200. Microciona rhopalophora, Axinella donnani, Halina 13 Cervera, J. L., Calado, G., Gavaia, C., Malaquias, M. A. E., Templado, J., Ballesteros, M., García-Gómez, J. C. & plicata, Plakina monolopha and Poecillastra schulzii Megina, C., An annotated and updated checklist of the 34 have already been reported from Gulf of Mannar . opisthobranchs (Mollusca: Gastropoda) from Spain and Portugal (including islands and archipelagos), Bol. Inst. Esp. 5 The mention about the shell of this species in 2003 Oceanog. , 20 (2006) 5-111. and the observation of five live specimens in the 14 Camp, D.K., Lyons, W.G. & Perkins, T. H., Checklists present study revealed the increased incidence of of selected shallow-water marine invertebrates of Florida, Florida Marine Research Institute Technical Report TR-3 this species along Tuticorin coast. Tuticorin port is (1998) 32. the second largest major port in Tamil Nadu and 15 Burn, R., A checklist and bibliography of the is known for its busy shipping activities. The specific Opisthobranchia (Mollusca: Gastropoda) of Victoria and the occurrence of this species along Tuticorin coast Bass Strait area, South-eastern Australia Museum Victoria indicate the possibility of its transportation from Science Reports, 10 (2006) 1-42. 16 Ericksen K H, Umbraculum umbraculum from New some other place through shipping activities, through Zealand, In: Sea Slug Forum , (Australian Museum, Sydney), natural dispersal mechanism is not ruled out. http://www.seaslugforum.net/find/18952 (2006). 490 INDIAN J. MAR. SCI., VOL. 40, NO. 4, AUGUST 2011 17 Klussman-Kolb, A., Dinapoli, A., Kuhn, K., Streit, B.