ZOOTAXA 695 Further species of the opisthobranch genus Okenia (Nudibranchia: Goniodorididae) from the Indo-West Pacific W.B. RUDMAN Magnolia Press Auckland, New Zealand W.B. RUDMAN Further species of the opisthobranch genus Okenia (Nudibranchia: Goniodorididae) from the Indo-West Pacific (Zootaxa 695) 70 pp.; 30 cm. 25 October 2004 ISBN 1-877354-68-6 (Paperback) ISBN 1-877354-69-4 (Online edition) FIRST PUBLISHED IN 2004 BY Magnolia Press P.O. Box 41383 Auckland 1030 New Zealand e-mail: [email protected] http://www.mapress.com/zootaxa/ © 2004 Magnolia Press All rights reserved. No part of this publication may be reproduced, stored, transmitted or disseminated, in any form, or by any means, without prior written permission from the publisher, to whom all requests to reproduce copyright material should be directed in writing. This authorization does not extend to any other kind of copying, by any means, in any form, and for any purpose other than private research use. ISSN 1175-5326 (Print edition) ISSN 1175-5334 (Online edition) Zootaxa 695: 1–70 (2004) ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ ZOOTAXA 695 Copyright © 2004 Magnolia Press ISSN 1175-5334 (online edition) Further species of the opisthobranch genus Okenia (Nudibranchia: Goniodorididae) from the Indo-West Pacific W.B. RUDMAN The Australian Museum, 6 College St., Sydney, NSW 2010, Australia. E-mail: [email protected]. Table of Contents Abstract . 3 Introduction. 4 Materials and Methods . 5 Descriptions . 5 Okenia Menke, 1830. 5 Okenia echinata Baba, 1949. 6 Okenia purpurata sp. nov. 9 Okenia vena sp. nov.. 13 Okenia virginiae Gosliner, 2004. 16 Okenia mellita sp. nov. 19 Okenia barnardi Baba, 1937. 22 Okenia pellucida Burn, 1967 . 25 Okenia japonica Baba, 1949. 27 Okenia mija Burn, 1967 . 29 Okenia zoobotryon (Smallwood, 1910) . 32 Okenia stellata sp. nov.. 35 Okenia hallucigenia sp. nov.. 40 Okenia hiroi (Baba, 1938) . 42 Okenia pilosa (Bouchet and Ortea, 1983) . 46 Okenia plana Baba, 1960 . 49 Discussion. 53 Acknowledgements. 64 References. 64 Abstract Five new species of the nudibranch genus Okenia Menke, 1830 (Goniodorididae) are described from Australian waters and the anatomy of another ten species from Australia and the Indo-West Pacific are described. Okenia purpurata sp. nov. and O. vena sp. nov. are reported from northern New South Wales where they feed on the bryozoan Amathia tortuosa Tenison Woods, 1880. Okenia mellita sp. nov. is reported from New South Wales, and a pair of species, O. hallucigenia sp. nov. Accepted by D. Geiger: 12 Oct. 2004; published: 25 Oct. 2004 3 ZOOTAXA and O. stellata sp. nov. are reported from various locations in northern Australia where they both 695 feed on the bryozoan Pleurotoichus clathratus (Harmer, 1902). Okenia virginiae Gosliner, 2004 is reported for the first time from Australia as is the Atlantic species Okenia zoobotryon (Smallwood, 1910). Anatomical information for O. barnardi Baba, 1937, O. hiroi (Baba, 1938) and O. mija Burn, 1967 is provided for the first time, as is further information on O. plana Baba, 1960 and O. pilosa (Bouchet and Ortea, 1983) from Australia and Hong Kong. New observations on the bryo- zoan prey of various species is reported: O. mija feeding on Amathia wilsoni Kirkpatrick, 1888, O. zoobotryon on Zoobotryon verticillatum (delle Chiaje,1828), O. hiroi on an unnamed species of Integripelta Gordon, Mawatari & Kajihara, 2002, O. plana on Membranipora membranacea (Lin- naeus, 1767), Jellyella tuberculata (Bosc, 1802) and Cryptosula pallasiana (Moll, 1803). Okenia japonica Baba, 1949 and O. purpureolineata Gosliner, 2004 are reported feeding on the same uni- dentified species of Amathia Lamouroux, 1812. Key words: Mollusca, Goniodorididae, Okenia, new species, Australia, Indo-West Pacific Introduction In a recent revision of the Indo-West Pacific species of the goniodorid genera Okenia, Sak- ishimaia, Hopkinsiella and Hopkinsia, Gosliner (2004) proposed that they form a mono- phyletic clade and consequently synonymised all genera with the oldest name, Okenia. As Gosliner stated, our understanding of this group is still at a preliminary stage and we still have much to learn about the anatomy of many species of this group world wide. Thirteen species, including six new species are described by Gosliner from the Indo-West Pacific and a further 12 species, including five new species are described in this paper. There are at least six further species from the Indo-West Pacific we know little about, five from the eastern Pacific (Behrens 2004a, pers comm; Lance 1966; Millen et al. 1994) and at least 12 from the Atlantic (Cervera et a., 1991; Ortea & Espinosa 2000; Schmekel & Portmann 1982), giving us a group of over 40 species. Within this group there is a considerable vari- ation in external shape and radular morphology, but until we know more about the anat- omy and biology of individual species, it is difficult to interpret character variation within the group and analyse relationships. For example, the shape of the radular teeth changes very little within the family Goniodorididae, the radula of species of Trapania or Goniodoris, being indistinguishable from many species of Okenia, (see Rudman 1987), and yet in Okenia we find many species in which the radula has undergone considerable change in shape from the ‘typical’. Species such as Okenia nakamotoensis (Hamatani, 2001), O. kondoi (Hamatani, 2001), and O. stellata show little similarity to the teeth of ‘typical’ species such as O. echinata and O. virginiae (see Gosliner 2004; this paper). In some instances, such changes in form can be linked to functional changes. For example, it is not unreasonable to propose that a change in food could lead to alteration in the shape of the teeth. However within the Goniodorididae there are species of Trapania feeding on 4 © 2004 Magnolia Press RUDMAN entoprocts (Kamptozoa), species of Goniodoris feeding on ascidians, and species of Oke- ZOOTAXA nia feeding on both soft ctenostome bryozoans and hard calcareous cheilostome bryozo- 695 ans, all with very similarly shaped teeth. We also have in Okenia two pairs of species with the most modified teeth (O. nakamotoensis - O. kondoi and O. stellata – O. hallucigenia). The species within each pair feed on the same bryozoan, but in each case the teeth are quite different in shape and size. Clearly at this stage of our knowledge, any phylogenetic consideration of the group must be considered to be preliminary. In this paper the anatomy of 15 species is described, including five new species from Australian waters. Further information is provided for five species previously reviewed by Gosliner. Material and Methods All species were either seen by me alive or were accompanied by colour photographs of the living animals. Full dissections of the general anatomy, and in particular the alimentary canal and reproductive system, were conducted. The morphology of the radular teeth and the jaw elements was studied and photographed using a scanning electron microscope. Identification of bryozoan prey was made with the assistance of Dr D. P. Gordon, National Institute of Water & Atmospheric Research (NIWA), Wellington, New Zealand. All mate- rial used in this study, including samples of the bryozoan prey, is housed in the collections of the Australian Museum, Sydney. Descriptions Okenia Menke, 1830 Okenia Leuckart in Bronn, 1826: 329 (nomen nudum) Idalia Leuckart, 1828 (type species: Idalia elegans Leuckart, 1828 by original designation) not Huebner, 1819 (1820): 149 - Lepidoptera. Okenia Menke, 1830 (type species: Idalia elegans Leuckart, 1828 by monotypy) Idaliella Bergh, 1881 (type species: Idalia aspersa Alder & Hancock, 1845 by subsequent designa- tion by Iredale & O'Donoghue, 1923) Idalina Norman, 1890 (type species: Idalia elegans Leuckart, 1828 by original designation). Hopkinsia MacFarland, 1905 (type species: Hopkinsia rosacea MacFarland, 1905, by original des- ignation) Hopkinsella Baba, 1938 (type species: Hopkinsiella hiroi Baba, 1938, by original designation) Cargoa Vogel & Schultz, 1970 (type species: Cargoa cupella Vogel & Schultz, 1970, by original designation) Okenia Menke: Lemche, 1971, 265–266. Sakishimaia Hamatani, 2001 (type species: Sakishimaia kondoi Hamatani, 2001, by original desig- nation) INDO-WEST PACIFIC OKENIA © 2004 Magnolia Press 5 ZOOTAXA In general, species of Okenia are soft and elongate animals with a symmetrical arrange- 695 ment of dorso-lateral papillae around the edge of the body. In many cases the papillae arise from a small ridge, which represents the mantle edge, but in species without such a ridge, papillae arise directly from the body wall. There can also be a number of dorsal papillae, usually arranged in a symmetrical pattern. In some species there is a single papilla in the dorsal midline, anterior to the gills, while in other species there can be up to eight papillae arranged in a characteristic, species-specific pattern. The gills are usually simple or bipin- nate and although retractile, do not have the protection of a gill pocket. The internal anat- omy is very similar to that described for Trapania (see Rudman 1987), although the shape of the radular teeth exhibits much greater interspecific variation than in related genera. Okenia echinata Baba, 1949 (Figures 1, 2A, 9D, 25B, 26C, 28A) Okenia echinata Baba, 1949: 46, 138, Pl.15, fig 53; Rudman 2003a Okenia cf. oputia: Coleman 2001: 52 (misspelling of opuntia) Material: Callala Point, Jervis Bay, New South Wales, Australia: 4 October 1975, 3 spec- imens, 7–9 mm long, found together on rock, AM C103305; 6 October 1975, 1 specimen, 8 mm long, AM C103287. Long Reef, Sydney, New South Wales, Australia, 29 January 1975, 1 specimen, 10 mm long, on short brown seaweed, AM C99401. Red Rock, N of Woolgoolga, New South Wales, Australia, 8 November 1977, 1 specimen, AM C109881. Arrawarra rock platform, Woolgoolga, New South Wales, Australia, 3 December 1990, Photo only, AM C164553. Geographic Distribution: Japan (Baba 1949; Imamoto 2003; Kurihara 2003), eastern Australia (present study). External Morphology: Body low, elongate, with mantle edge forming distinct over- lap (Fig.