taxonID	type	description	language	source
89264239FFCE00032F8D1481F71AFDB1.taxon	materials_examined	Type species: Idalia elegans Leuckart, 1828 by monotypy For the detailed synonymy and diagnosis of the genus see Rudman (2004).	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCE00072F8D17BEF066FEC4.taxon	materials_examined	Material: The Pipeline, west side of Nelson Bay, Port Stephens, New South Wales, Australia, on Pleurotoichus clathratus, 11 m, 11 June 2005, 13 – 15 mm long alive, 1 specimen, 9 mm long preserved, AM C 445670 [Holotype], 5 specimens and radula SEM stub, AM C 445669 [Paratypes], coll: L & D. Atkinson. Bare Island, Botany Bay, Sydney, New South Wales, Australia. 6 – 15 m, 4 February 2005, 5 – 10 mm long alive [Photo only: Roxanne Fea].	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCE00072F8D17BEF066FEC4.taxon	etymology	Etymology: This species is named after Leanne & David Atkinson in recognition of the valuable observations they have made on opisthobranch biology in New South Wales and the many contributions they have made over many years to the Sea Slug Forum. Geographic distribution: This species is known only from New South Wales, Australia.	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCE00072F8D17BEF066FEC4.taxon	description	External morphology: Animal elongate, with relatively low profile (Figs 1 A, B, 4 C); mantle ridge absent but position indicated by presence of up to seven large mantle papillae on each side. Anterior-most papilla on each side sits just in front of adjacent rhinophore and points anteriorly; similar in size and shape to other papillae. Other lateral papillae on each side point outwards and somewhat upwards; length approximately one and one half times width of body, some with bluntly rounded, others with pointed tip. Papillae usually paired with those on opposite side of body, but not always. Usually two dorsal mantle papillae, in midline, one in front of gills, one behind. Gills, usually five, arranged in arc around anal papilla; sometimes two smaller posterior gills absent; each gill inserted separately. Gills simple, with broad rounded outside edge. Rhinophores long and tapering; club with up to 14 lamellae, occupies upper four-fifths of rhinophore. From above, head indistinguishable from foot; no oral tentacles; ventrally, distinct V-shaped groove differentiates anterior edge of foot from head (Fig. 2 A). Edge of foot extends out on each side some distance from body, anterior corners extended out into triangular processes. Colour: Animal bright pink (Fig. 1 A, B) except for tips of mantle processes, gills and rhinophores, which are a deeper, redder shade of same colour. Foregut anatomy: Anterior end of buccal bulb lined with cuticle, but no distinct thickened regions or areas with cuticular rodlets. Buccal bulb with relatively large buccal pump, ring of oral glands around mouth (Fig. 2 B). Radula formula 24 x 1.1.0.1.1. (AM C 445669). Innermost tooth with broad base and extremely long, twisted, rod-like blade with bluntly pointed tip and single flattened denticle (Fig 3). Outer teeth, much smaller, with broadly quadrangular shape, recurved hook-like tip sometimes with two or three remnant cusps. Reproductive system: Reproductive opening on right side of the body, below and just posterior to rhinophores (Fig. 2 C). Vaginal duct narrow, leading back to large spherical bursa copulatrix. Exogenous sperm sac small, elongate, opening separately into bursa copulatrix alongside openings to vaginal duct and narrow exogenous sperm duct. From ovotestis, spermoviduct expands into large ampullar region, usually distended with endogenous sperm. Inside female gland mass, spermoviduct divides into two short ducts; the oviduct, opening into fertilisation chamber; the sperm duct, opening into large recurved prostate gland. Vas deferens, short, narrow, running from prostate gland to muscular elongate penial bulb.	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCE00072F8D17BEF066FEC4.taxon	discussion	Remarks: Two species of pink Okenia have recently been described from Australian waters, O. stellata Rudman, 2004 and O. hallucigenia Rudman, 2004. Both species are found feeding on the bryozoan Pleurotoichus clathratus, sometimes together on the same colony. Both nudibranchs are almost identical in colour to the bryozoan. Okenia atkinsonorum is a third species, also of similar colour, found feeding on the same bryozoan. In fact the only records we have of this species are from colonies of Pleurotoichus. At present it is known only from central New South Wales, where its distribution overlaps with that of Okenia hallucigenia. The radular teeth of O. atkinsorum have some similarities to those of O. stellata in having a long elongate first lateral tooth but the teeth differ in shape and size. In O. stellata these teeth are simple rod-like structures, 800 microns in length, with a groove along one edge, while in O. atkinsonorum the teeth have a wide base, and taper to a tip which bears a subapical harpoon-like flange. Although more elongate than the teeth of most species of Okenia, they are only about 300 microns in length, so much shorter than those of O. stellata. In colour, O. atkinsonorum and O. hallucigenia are very similar, being a uniform pink except for the tips of the dorsal tentacles, papillae and rhinophores, which are a deeper reddish pink. Neither species have the red lines which form part of the colour pattern of O. stellata. In body shape, O. hallucigenia differs from the other two species in its elongate and high body profile and the distinct and separate oral veil. In shape, O. atkinsonorum is quite similar to O. hiroi (Baba, 1938) from the NW Pacific and O. rosacea (MacFarland, 1905) from the NE Pacific, but it has far fewer lateral processes, and differs in radular morphology and other anatomical features (Rudman 2004, Gosliner 2004). Recently photographs of a similar looking species have been published from northern New Zealand (Gordon & Rudman 2006, Rudman 2005 a, Skipworth 2005), but as it was found associated with an encrusting eurystomellid bryozoan, it is more likely to be related to O. hiroi than to O. atkinsonorum. In the two other species the number of lateral mantle papillae is constant, four pairs in O. hallucigenia and five pairs in O. stellata (Table 1). In Okenia atkinsonorum however, the number is variable and like Okenia hiroi and O. rosacea they are not always arranged in matching pairs. Of seven individuals, all about 14 mm in length, two had five papillae on each side, one had six and one had seven. Of those with unequal numbers on each side, two had seven and five, and one had six and five. All had a median papilla in front of the gills, but one animal lacked the median papilla behind the gills. Distribution Lateral Papillae Groove Radula Bryozoan papillae colour on sole tooth 1 food O. hallucigenia Tropical, subtrop. 4 pairs, pink, no v. small Pleurotoichus sp. Australia tapering tips darker tips denticulate Euthyrisellidae 30 µm In an earlier publication (Rudman 2004), O. stellata and O. hallucigenia were compared with a pair of species from the tropical Pacific (O. nakamotoensis (Hamatani, 2001), O. kondoi (Hamatani, 2001 )) which matched them in shape and colour and also fed on a similar euthyrisellid bryozoan, and a pair from the northern Pacific (O. rosacea, O. hiroi) which feed on similarly coloured eurystomellid bryozoans. In each pair the radular morphology is quite different, raising the question of whether the species are linked by food choice or radular morphology, or whether the radular differences indicate closely related species evolving to feed in a different way on the same food. We now have a case of three species, with distinctly different shaped radular teeth, feeding on the same bryozoan. Okenia atkinsonorum has been observed continuously by Leanne & David Atkinson in the Port Stephens region from the west side of Nelson Bay to Halifax Park, for over 15 years. They report that it is “ not seasonal, nor a casual visitor, almost always present in reasonable numbers and very specific to their food bryozoan ”.	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCE00072F8D17BEF066FEC4.taxon	diagnosis	Diagnosis: Okenia atkinsonorum can be distinguished from other pink species of Okenia feeding on the bryozoan Pleurotoichus clathratus by its shape, arrangement of lateral papillae and radular morphology.	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCE00072F8D17BEF066FEC4.taxon	biology_ecology	Biology: It has only been observed in association with its food, the bryozoan Pleurotoichus clathratus (Fig. 1 B). The pinkish egg ribbon is semicircular in cross-section, the flat surface being attached to the substrate. On a flat surface it is laid in a spiral of about two whorls and the whole ribbon is approximately 9 mm in diameter (Fig. 1 C), but on rough and branching surfaces the ribbon can be deposited in a less orderly manner, sometimes two or three ribbons being tangled together.	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCA000B2F8D13F4F1DAFE64.taxon	materials_examined	Material: Bongoyo Island, off Msasani Bay, Dar es Salaam, Tanzania. Coll: G. H. Brown, 7 November 1976. 11 mm long alive, AM C 443912 [Holotype]. Yatush slope, Eilat, Israel, Gulf of Eilat, Red Sea, 29 m, on sea grass and patch reef, 16 March 2005, 1 specimen approx 15 mm long alive, [Photo only: Binyamin Koretz, Shulamit Koretz].	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCA000B2F8D13F4F1DAFE64.taxon	etymology	Etymology: ‘ rhinorma’ is an invented word based on rhinophore and enormous to reflect the unusually large rhinophores in this species. Geographic distribution: Western Indian Ocean (Tanzania, Red Sea)	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCA000B2F8D13F4F1DAFE64.taxon	description	External morphology: Animal elongate and relatively high (Figs 1 D, 4 A, B), with mantle edge defined by ridge running between six large lateral papillae. Lateral papillae held out at right angles to edge of body; anteriormost pair point forward, relatively long, approximately equal to body width, tapering to a rounded point; second pair situated alongside rhinophores, of similar size and shape to anterior pair. Posterior pair of papillae situated just behind gills, half length of anterior papillae. Rhinophores relatively long, at least half the body length, held erect when fully extended, with lamellae on posterior side. Gills, long, six, held erect and arranged in arch around anus. Head region extends some distance forward of the mantle, anterior corners enlarged and rounded; ventrally, head and mouth are separate from anterior edge of foot (Fig. 5 A). Colour: Body opaque white with pattern of translucent regions, and orange and purple patches or spots (Fig. 1 D, 4 A, B). Size and proportion of orange and purple patching variable. Lateral papillae white with orange tips and subapical purple band. Rhinophores with translucent white base, white anterior spots, mottled purple pigmentation down each side, and orange tip. Gills translucent with brown and white pigmentation. Foregut anatomy: Buccal pump relatively large, non-pedunculate (Fig. 5 B). Radular formula 23 (+ 4) x 1.1.0.1.1. Inner teeth with wide base and long recurved pointed cusp; between five and seven large pointed denticles present at inside base of cusp (Fig. 6). Outer teeth only slightly smaller, with broad triangular base and long recurved, non-denticulate pointed cusp. Jaw plates or cuticular thickenings not found in SEM preparation. Reproductive system: Reproductive opening on the right side of body, below and slightly posterior to level of the rhinophores (Fig. 5 C). Vaginal duct elongate, leading back to large spherical bursa copulatrix. Exogenous sperm duct narrow, running from junction of vaginal duct and bursa copulatrix to fertilisation chamber within female gland mass. Small, rounded, exogenous sperm sac opening about one-third of the way along exogenous sperm duct. From ovotestis, spermoviduct expands into ampullar region, distended with endogenous sperm. Inside female gland mass, spermoviduct divides into two short ducts; the oviduct, opening into the fertilisation chamber; the sperm duct, opening into relatively short prostate gland. Vas deferens joins prostate gland to bulbous penial sac.	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCA000B2F8D13F4F1DAFE64.taxon	discussion	Remarks: There is some variability in colour between the holotype from Tanzania and an animal from the Red Sea. In the holotype the body is opaque white except for a pair of translucent bands on the head running forward from beneath the anterior lateral papilla on each side. There are some large orange patches on the head, some of which are irregularly edged in brownish purple. An orange band, mottled with purple and white, runs back between the rhinophores expanding to form large patch over much of the mantle, anterior to the gills. An orange band, irregularly bordered with purple, runs along each side of the body, beneath the mantle, to the tip of the posterior foot, which has brownish purple patches. The lateral papillae are white with an orange tip and subapical purple band. The rhinophores have a translucent whitish base, an orange-brown tip and the rest is mottled with patches of translucent purple, pigmented purple, and orange-brown, with two or three white spots down the anterior face. The gills are translucent with brown and white pigmentation. In the Red Sea specimen, the orange-brown bands described for the Tanzanian specimen are replaced with translucent colourless bands, except along the leading edge of the head, and the purple patches on the body are reduced to the anterior head and the posterior tip of the foot. Scattered over the body are small rounded orange spots. Small purple spots are also present on the lateral papillae, rhinophores and posterior tip of the foot. This species is similar in body shape to the ascidian-feeding species from the North Atlantic which has been identified as Okenia aspersa (Alder & Hancock, 1845), O. quadricornis (Montagu, 1815) and O. ascidicola Morse, 1972 (Cervera et al. 1991, Morse 1972, Picton & Morrow 1994, Thompson & Brown 1984, Thompson 1988, Valdés & Ortea 1995) but which may all be the same species. This, or these, species have a high profile and are very similar in external shape to ascidian-feeding species of the related genus Goniodoris, except for the absence of lateral mantle papillae in Goniodoris, and the presence of oral tentacles. The morphology of the radular teeth of O. aspersa, O. quadricornis and O. ascidicola as described in papers listed above, with the sole exception of Thompson & Brown, mention a large inner tooth with large denticles, and a slightly smaller non-denticulate outer tooth. This is very similar to the morphology described here for Okenia rhinorma and links this species to most other species of Okenia, where the outer teeth are small and reduced, usually six or more times smaller than the inner teeth. Although I have no information on the feeding habits of this new species, its general shape and radular morphology suggest it is probably an ascidian-feeding species as well.	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
89264239FFCA000B2F8D13F4F1DAFE64.taxon	diagnosis	Diagnosis: Okenia rhinorma can be distinguished by its colour pattern of orange and purple patches on a white background, its high body profile, long lateral papillae and very long rhinophores. It can also be distinguished by the morphology of the radular teeth with large pointed denticles on the inner tooth and outer teeth which are only slightly smaller than the inner teeth.	en	Rudman, William B. (2007): Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa 1657: 57-67, DOI: 10.5281/zenodo.179864
