Museum Victoria Science Reports 10: 1–42 (2006) ISSN 1833-0290 http://www.museum.vic.gov.au/sciencereports/ A checklist and bibliography of the Opisthobranchia (Mollusca: Gastropoda) of Victoria and the Bass Strait area, south-eastern Australia ROBERT BURN Honorary Associate, Museum Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia Abstract Burn, R. 2006. A checklist and bibliography of the Opisthobranchia (Mollusca: Gastropoda) of Victoria and the Bass Strait area, south-eastern Australia. Museum Victoria Science Reports 10: 1–38. A checklist of the opisthobranch fauna (Mollusca: Gastropoda: Opisthobranchia) of Victoria and the Bass Strait area, south- eastern Australia comprises a total of 364 nominal species, divided as follows: Acteonida and Cephalaspidea 77 species, Rhodopemorpha 1 species, Sacoglossa 31 species, Anaspidea 10 species, Umbraculida 2 species, Pleurobranchida 6 species, Pteropoda 25 species, and Nudibranchia 212 species. One hundred and thirty eight species (38%) are assigned to genus only; these include both unidentified and unnamed species. Forty species (11%) are yet to be taken alive within the checklist area. The bibliography includes references for the original descriptions of all the genera and all the named species, together with all literature pertinent in some way to the opisthobranch fauna of Victoria, the Bass Strait area, and south- eastern Australia. Keywords Mollusca, Gastropoda, Opisthobranchia, Australia, Victoria, Bass Strait, checklist Introduction collected. For the Australian area, at least six such guides have been published within the past 20 years (Willan & Coleman, 1984; Coleman, 1989, 2001; Burn, 1989; Wells & Bryce, 1993; This checklist is a compilation of the 364 opisthobranch Marshall & Willan, 1999), each of which illustrates some mollusc species recorded from, or otherwise known to the species occurring within the Victoria and Bass Strait area. Most author as occurring in, Victoria and the Bass Strait area, south- species however are small to very small, often not easily seen in eastern Australia. Many entries are of unidentified and life and difficult to distinguish clearly from their food host, and unnamed species, even generic placement is in doubt in some problematic to photograph and draw. No guide is available to instances. Geographically, the checklist covers the help identify these small species. opisthobranch fauna of the area enclosed by a line in the west from the Victoria/South Australia border to the north-west Opisthobranchs are a very common component of the intertidal corner of Tasmania, a line in the east from the Victoria/New shorelines of Victoria and the Bass Strait area, both in numbers South Wales border to the north-east corner of Tasmania, the of species and number of specimens. The majority of species entire coastline of Victoria along the north, and the north are small to very small and are therefore easily overlooked or coastline of Tasmania along the south (roughly 37°30–41°S, not recognised. Nevertheless, by exploring the various habitats 140°–150°E). Bass Strait itself is generally less than 100 m on and around a rocky reef on the central Victorian coastline deep. However, the area delineated above includes slope waters (Wilsons Promontory to Cape Otway), it is possible for an up to 600 m deep in the west and 2000 m in the east, hence experienced person to observe 20-30, exceptionally more than inclusion of some few deep-water species in the checklist. 40, species on a single low tide. Repeated fortnightly observation and exploitation of all accessible habitats over two Zoogeographically, Victoria and the Bass Strait area lies within years at a single location (Point Danger, Torquay, 1980-1981, the southern Australian temperate region, and many R. Burn unpublished observations) resulted in a list of 95 opisthobranch species have wide distributions across southern species, at least 10% of which were new to science or Australia. At times, warmer-water incursions, more commonly previously unrecorded for Victoria. Over a longer period and from the east than from the west, bring warm-temperate species by more than one observer, the channel banks at San Remo, into the Bass Strait area, and on rarer occasions, tropical and Westernport produced a list exceeding 120 species, again with sub-tropical species to eastern Bass Strait. Cool-temperate both new and unrecorded species (Burn, 1990). In deeper species from south-eastern Tasmania are also sometimes waters, the Bass Strait Survey 1979-1984 showed that recorded from Victoria and the Bass Strait area. Further afield, opisthobranchs are common and diverse throughout the Strait, New Zealand too influences the Victorian and Bass Strait fauna some 140 live-taken species having been separated from benthic with about 20 species in common, not including the pteropods. samples. Five stations, sampled by epibenthic sled in depths of 55-130 m, averaged 21 species per station (Burn in Poore et al., Opisthobranchs are found from the intertidal to the deepest seas. 1985). However, large sampling gaps remain to be investigated: The species in this checklist have a depth range of 0-1760 m, little is known of the shallow water opisthobranch fauna of with the vast majority occurring in the top 30 m. Because of eastern Victoria (Wilsons Promontory to Cape Howe) or of the their beauty, opisthobranchs are favoured animals, especially of eastern and western sections of the north coast of Tasmania. the SCUBA-diving fraternity, and many regional guides are available to help identify species seen, photographed or 2 Robert Burn Some species in the checklist have yet to be found alive in species included in the inventory were: Ceratosoma Victoria and the Bass Strait area. These species are marked brevicaudatum, Hoplodoris nodulosa (as Staurodoris with an asterisk (*). This applies particularly to records of shell- pustulata), Dendrodoris nigra (as D. melaena) Doriopsilla bearing species (Cephalaspidea, Anaspidea, Thecosomata). No carneola (as Dendrodoris carneola), Paradoris dubia (as attempt has been made to assess the interstitial opisthobranchs Alloiodoris marmorata), Aphelodoris berghi (as Archidoris that may occur in the marine meiobenthos of south-eastern varia), and Armina sp. 1 (as Armina cygnea Bergh, 1876, a Australia. Species likely to occur include members of the small large species known from NSW, SA and WA, and possibly the order Acochlidioidea, as well as cephalaspideans (Philine, northern coastline of Australia). At this stage, the checklist of Philinoglossa) and aeolidoideans (Pseudovermis). Victorian and Bass Strait numbered 44 shell-bearing and eight shell-less or nudibranch species, totalling 52 species. The systematic classification followed in the checklist is Shortly after, the writer collected his first nudibranch, essentially that tabled in Mollusca: The Southern Synthesis Ceratosoma brevicaudatum, under stones among seagrass, San (Beesley et al., 1998). Papers published since 1995 (date of the Remo, Westernport, 13 March 1954. A burgeoning interest final acceptance of manuscripts for the above publication) and soon led to a single-minded concentration on nudibranchs and the closing date (30 September 2006) of the checklist present shelled opisthobranchs, and the rapid expansion of knowledge many changes, some major, some minor, some well supported, of the Victorian fauna. The next listing of Victorian marine some speculative. At the time of writing, the newest “Working molluscs (Macpherson & Gabriel, 1962) included 58 shelled Classification of Gastropoda” (Bouchet & Rocroi, 2005) and 62 nudibranch species, a total of 120 species. In a little summarizes recent phlyogenetic research, and speculates upon more than 10 years, the known opisthobranch fauna had more things to come. Reference to many of these changes is inserted than doubled (Burn, 1957a, 1957b, 1958, 1960b). By 1980, the at various points of the checklist. opisthobranch fauna known to the writer from Victoria and the Bass Strait area had more than doubled again to 250 species. History of discovery This number included many species described or recorded in papers published from 1963 to 1979 (Burn, see bibliography), “The history of discovery of opisthobranchs in Australia is best as well as many species awaiting description for want of considered separately for those with shells and those without. additional material and time to work up the descriptive text. Species with shells were included with other shelled molluscs by early collectors and so their discovery follows the path The last quarter century have seen the number increase further described elsewhere for other marine shells.” (Rudman, 1998: with the descriptions of new species (Rudman, 1982, 1983, 919). Shell-less species were too much of a problem for early 1986, 1987a, 1987b, 1990; Willan, 1988; Miller & Willan, collectors, so much so that they were almost totally ignored. 1986). Intensive intertidal and subtidal field work by the writer The history of discovery of opisthobranchs in Victoria and the and colleagues, and deeper water survey work in Bass Strait by Bass Strait area mirrors that for Australia. Museum Victoria, have revealed additional new records and new species. All species, named, unnamed, and unidentified, The very first shell-less opisthobranch reported from Victoria have an entry in the checklist, the total now standing at 363, of and the Bass Strait area was Pleurobranchaea maculata by which 152 are shell-bearing and 212 nudibranch species. And Quoy