Abstract
Two new species of the nudibranch genus Okenia Menke, 1830 (Goniodorididae) are described, one from eastern Australian waters and one from the western Indian Ocean. Okenia atkinsonorum sp. nov. is the third Australian species reported to feed on the bryozoan Pleurotoichus clathratus (Harmer, 1902) and is very similar in external shape and colour to the other two species, O. hallucigenia Rudman, 2004 and O. stellata Rudman, 2004. Okenia rhinorma sp. nov. is reported from Tanzania and the Red Sea. Its body shape and anatomy suggest it is related to the ascidian-feeding group in the genus characterised by O. aspersa (Alder & Hancock, 1845).
References
Alder, J. & Hancock, A. (1845) A monograph of the British nudibranchiate Mollusca: with figures of all the species. Pt. 1, fam. 1, pls. 4, 5, 26. Ray Society, London.
Baba, K. (1938) Opisthobranchia of Kii, Middle Japan. Journal of the Department of Agriculture, Kyushu Imperial University, 6, 1–19.
Camacho-Garcia, Y. & Gosliner, T.M. (2004) A new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from the Pacific Coast of Costa Rica. Proceedings of the California Academy of Sciences, 55, 431–438.
Cervera, J.L., Lopez-Gonzalez, P.J. & Garcia-Gomez, J.C. (1991) Taxonomic and geographical range data on two rare species of Okenia (Gastropoda: Nudibranchia: Doridacea) from the eastern Atlantic. The Veliger, 34, 56–66.
Gordon, D.P. & Rudman, W.B. (2006) Integripelta acanthus n. sp. (Bryozoa: Eurystomellidae) – a tropical prey species of Okenia hiroi (Nudibranchia) Zootaxa, 1229, 41–48.
Gosliner, T.M. (2004) Phylogenetic systematics of Okenia, Sakishimaia, Hopkinsiella and Hopkinsia (Nudibranchia: Goniodorididae) with descriptions of new species from the tropical Indo-Pacific. Proceedings of the California Academy of Sciences, 55, 125–161, 29 figs.
Gosliner, T.M. & Bertsch, H. (2004) Systematics of Okenia from the Pacific coast of North America (Nudibranchia: Goniodorididae) with descriptions of three new species. Proceedings of the California Academy of Sciences, 55, 414–430.
Hamatani, I. (2001) Two new species of Goniodorididae (Opisthobranchia; Nudibranchia) with a new genus from Kuroshima Island, Okinawa, Japan. Venus, 60, 151–156.
Harmer, S.F. (1902) On the morphology of the Cheilostomata. Quarterly Journal of microscopical Science, 46, 263–350.
Leuckart, F.S. (1828) Breves animalium quorundum maxima ex parte marinorum descriptiones, 24 pp, 1 pl. Heidelberg.
MacFarland, F.M. (1905) A preliminary account of the Dorididae of Monterey Bay, California. Proceedings of the Biological Society of Washington, 18, 35–54.
Montagu, G. (1815) Descriptions of several new or rare animals, principally marine, discovered on the south coast of Devonshire. Transactions of the Linnean Society of London, 11, 1–26, pls. 1–5. [for 1811].
Morse, M.P. (1972) Biology of Okenia ascidicola spec. nov. (Gastropoda: Nudibranchia). The Veliger, 15, 97–101.
Picton, B.E. & Morrow, C.C. (1994) A Field Guide to the Nudibranchs of the British Isles. Immel Publishing Ltd, London. 143pp.
Rudman, W.B. 1998 (Jan 13). Comment on Totally pink! by Bill Chambers. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find.cfm?id=72 (last accessed 22 October 2007).
Rudman, W.B. (1999) (Jan 29) Comment on Observations on Hopkinsia sp. by David Atkinson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find.cfm?id=522 (last accessed 22 October 2007).
Rudman, W.B. (2003a) (Feb 8) Comment on Hopkinsia from Sydney by Allan Saben. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find.cfm?id=8402 (last accessed 22 October 2007).
Rudman, W.B. (2003b) (Mar 4). Comment on Hopkinsia sp. laying eggs by Leanne Atkinson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find.cfm?id=9320 (last accessed 22 October 2007).
Rudman, W.B. (2004) Further species of the opisthobranch genus Okenia (Nudibranchia: Goniodorididae) from the Indo-West Pacific. Zootaxa, 695, 1–70.
Rudman, W.B. (2005a) (Jan 26) Comment on Re: Okenia cf. hiroi from New Zealand by Ian Skipworth. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find.cfm?id=13019 (last accessed 22 October 2007).
Rudman, W.B. (2005b) (May 9) Comment on Okenia hallucigenia from Bare Island, Sydney by R. Fea & J. Coombs. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find.cfm?id=13723 (last accessed 22 October 2007).
Skipworth, I. (2005) (Jan 25) Okenia hiroi? from New Zealand. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from: http://www.seaslugforum.net/find. cfm?id=12958 (last accessed 22 October 2007).
Thompson, T. & Brown, G.H. (1984) Biology of Opisthobranch Mollusks, vol. 2. Ray Society, London, UK, 229 pp, 41 pls.
Thompson, T.E. (1988) Molluscs: Benthic Opisthobranchs (Mollusca: Gastropoda). Synopses of the British Fauna (New Series). No. 8. 2nd Edition. E.J.Brill / W. Backhuys: Leiden. 356pp.
Valdés, Á. & Ortea, J. (1995) Revised taxonomy of some species of the genus Okenia Menke, 1830 (Mollusca: Nudibrancia) from the Atlantic Ocean, with the description of a new species. The Veliger, 38, 223–234.