taxonID	type	description	language	source
03B5F62B4710FF83E3A0FF10A6C89D9A.taxon	materials_examined	Material. Chag / 96 / 1 a, b: both 50 mm; inside Ile Boddam, Salomon Atoll; 8 February 1996; at 16 m depth. Chag / 96 / 74 a, b: 22 mm, 24 mm; Three Brothers, Great Chagos Bank; 29 February 1996; at 17 m depth. Description. The body was dark brown, appearing almost black, with bright orange spots and dots; these orange markings extended on to the ventral surface (® gure 2 a). Fine white edges were present on the parapodia, becoming less distinct and grey anteriorly. The body was slender, smooth and velvety. The left tail process was distinctly longer than the right, with orange spots in the larger specimens and without spots in the smaller. The head shield was trilobed anteriorly. In formaldehyde specimens retain much of their original colour: the black is reduced to a ® ne dusting and the orange internal organs are visible through the shell and the skin. Orange pigment spots remain distinct and are present on both shields, both parapodia and on the sole. The head is distinctly trilobed. The shells of two specimens (96 / 74) are clearly visible and these specimens have been transferred to 70 % alcohol. Geographic distribution. Western Indian Ocean: East Africa (Eliot, 1903 a), Madagascar (Marcus and Marcus, 1970), and Mauritius (Yonow and Hayward, 1991). In addition to this ® rst record from the Chagos we have a new record from the Maldives (coll. R. C. Anderson and S. G. Buttress, 1996). Remarks. This rarely recorded but distinctive species is similar only to C. castanea Yonow, 1994 from the Maldives (Yonow, 1994 a) which is chocolate brown with apricot spots and a four-lobed head (see also photograph in Debelius, 1996: 132).	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4711FF83E383FCE9A4029AAC.taxon	materials_examined	Material. Chag 96 / 54 a, b, c: 13 mm, 8 mm, 8 mm; inner reef of Petit Ile Mapou, Peros Banhos Atoll; 22 February 1996; at 14 m depth. Description. All three specimens of this minute species were jet black, with only a small area of cream anteriorly; head shield with three lobes anteriorly (® gure 2 b). The parapodia were held tightly against the body and did not meet mid-dorsally. The left posterior process was extended into an elongated ® lament, more than half of body length in largest specimen (apparently broken in one of the smaller specimens). Geographic distribution. Western Indian Ocean: from the Red Sea (Yonow, 1994 b), Zanzibar (Rudman, 1973) and the Maldives (Yonow, 1992, 1994 a). Remarks. This species is usually common where it occurs, on ® ne silty / sandy substrata. A similar species was noted from Western Australia (Wells and Bryce, 1993), which diOEers in being much larger, 20 mm, brownish and covered in irregular yellowish ¯ ecks with a concentration on the tip of the head shield. Chelidonura sandrana is either completely black or with petaloid orange and white patterns, and with or without cream anteriorly.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4711FF83E3BBF9DFA4C999FE.taxon	description	Elysia bayeri Marcus, 1965: 270, ® gures 5, 6; Carlson and HoOE, 1978: 91, ® gures 4, 5 b, 6 a, b. Thuridilla bayeri: Jensen, 1992: 273; Gosliner, 1995 (part): 1, ® gures 1 a, b, 2 a ± c.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4712FF81E3D5FA3DA4E59E1B.taxon	materials_examined	Material. Chag 96 / 31: 8 mm; outer reef of Ile de la Passe, Salomon Atoll; 14 February 1996; at 15 m depth. Description. A slender, brightly coloured species. Body brown with a series of coloured bands following parapodial margins. The margin was orange, the central band black and the inner band light blue. Orange band present laterally on head. The rhinophores were brown basally and white distally. The minute preserved specimen is green only on the parapodia, preserved as a network of ® ne speckles; the eyes are clearly visible. Geographic distribution. Indo-West Paci ® c: from Aldabra and South Africa (Gosliner, 1995) to Guam (Carlson and HoOE, 1978).	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4713FF81E379FE71A2499C00.taxon	description	Aplysia fasciata Poiret: Yonow, 1994 a: 104, ® gure 4 G.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4713FF81E379FE71A2499C00.taxon	materials_examined	Material. Chag 96 / 18: three specimens approximately 10 mm; outer reef of Ile de la Passe, Salomon Atoll; 12 February 1996; at 19 ± 20 m depth. Description. Body dark brown, with grey margins to parapodia and grey tips to rhinophores and oral tentacles (® gure 2 d). White stippling absent. Parapodia enlarged, upstanding and strongly undulated, originating separately anteriorly and meeting as a low rim on the tail. Rhinophores and oral tentacles large and erect. The three preserved specimens are well relaxed; the rolled rhinophores and oral tentacles are visible, with black pigment remaining within the tubes. The eyes are visible on all specimens and there is dark brown pigment variably remaining as a dusty covering along the edge of the foot and its sole on all specimens, in wrinkles	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B471CFF8EE3BBFBF1A7A499F1.taxon	materials_examined	Material. Chag 96 / 62: 65 mm; inner reef, Ile du Coin, Peros Banhos Atoll; 25 February 1996; at 22 m depth; coll. J. McGlade (radular preparation). Chag 96 / 63: 45 mm; inner reef, Ile Monpatre, Peros Banhos Atoll; 26 February 1996; at 5 m depth. Six individuals not collected: two together on sand, inner reef of Petite Ile de la Passe, Peros Banhos, 28 February 1996; at 19 m depth; three (only one photographed), Ile Fouquet, Peros Banhos, 4 March 1996, at 15 m depth; one photographed on inner reef wall, Ile Vache Marine, Peros Banhos Atoll; 4 March 1996; at 12 m depth. Description. Dorsum white with chocolate brown markings; in the smaller specimen stripes were visible but patches of brown were also present (® gure 4 a); in the larger specimen most of the dorsum was covered with one almost continuous chocolate brown patch (® gure 2 e). Foot with blue marginal and yellow submarginal bands; similar blue and yellow bands around rhinophore sheaths and bases of gill plumes. Rhinophores reddish brown with white tips. Gills tripinnate, white with reddish brown markings.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B471FFF8DE389F9C5A7EE99F1.taxon	materials_examined	Material. Chag 96 / 95: 14 mm; inner reef Ile Vache Marine, Peros Banhos Atoll; 4 March 1996; at 22 m depth.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4718FF8BE3DEFA72A4D39C2D.taxon	materials_examined	Material. Chag 96 / 36: preserved 103 23 2 mm; reacted with formaldehyde and covered in tiny globules; coll. A. JolliOEe in Salomon Atoll on 14 February 1996 on algae. Chag 96 / 84 a, b: 32 mm specimen from 23 m depth on sand (263 63 8 mm preserved, black-tipped rhinophores) and 21 mm specimen from 8 m depth on rubble (193 43 6 mm preserved, yellow rhinophores); south side of Nelson Island, Great Chagos Bank; third individual not collected; 3 March 1996. Chag 96 / 86: 143 133 3 mm high preserved, reacted with formaldehyde; Middle Brother, Great Chagos Bank; 2 March 1996; at 17 m depth. Description. The body was hard and nobbly, bright yellow with black lines and streaks: the longer, thicker lines tended to cross the dorsal surface almost perpendicular to the midline; the thinner, shorter streaks tended to lie at oblique angles to the midline (® gure 2 f). Rhinophores medium yellow with black tips, the latter indistinct or absent in some specimens. Geographic distribution. Indo-West Paci ® c: from Zanzibar (Eliot, 1904 b) to Queensland and New Caledonia (Yonow, 1994 a). In addition to this record from the Chagos, we have a new record from ReÂunion (colour slide by M. Parmentier; tips of rhinophores dark, perhaps green but not black). Remarks. The three species of yellow Notodoris were reviewed by Yonow (1994 a) based on a survey of the literature and on Paris and London museum specimens. Notodoris minor appears to be rare, and this record of ® ve animals from Chagos is unusual. Notodoris minor is normally very large, more than 100 mm in length, and the two juveniles present in this collection are the smallest specimens collected to date. Gosliner et al. (1996) record it as feeding on the yellow sponge Leucetta primigenia Haeckel, 1872, whereas the two larger specimens here were found on sandy substrata and the smallest in algae.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4719FF8BE36CFC42A56199F1.taxon	materials_examined	Material. Chag 96 / 90: 183 7 mm; Three Brothers, Great Chagos Bank; 2 March 1996; at 8 m depth. Description. The red dorsal surface was smooth but with numerous raised red ridges forming a pattern of reticulations, the resulting polygons of which were smaller marginally than medially (® gure 4 c). The raised ridges did not extend on to the mantle margin. The marginal depressions contained numerous black dots, whereas those medially contained few, with the exception of three roughly circular pits, one anterior to the rhinophores, one posterior to the rhinophores, and the third anterior to the gills. A pair of irregular light brown patches was present laterally, level with the second median dark pit. The rhinophore stalks and clubs were red, while the gills were light red with a light brown margin; tubercles were present around the rim of the gill pocket. The ventral surface was smooth, red with no markings either on the foot or hyponotum; the semi-circular head did not have oral tentacles and anterior foot margin was bilaminate without propodial tentacles. It was not possible to determine the radular formula: the long bristle-like teeth, measuring approximately 280 m m, were tangled and impossible to count. The serrations at the distal end are present only on one side of the tooth; they continue around the tip and appear to be hollow (® gure 6 C, D).	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B471AFF88E3B8FCA1A71A99F1.taxon	description	Halgerda tesselata Bergh: Rudman, 1978: 65, ® gures 4 c, d, 6; Carlson and HoOE, 1993: 16, ® gures 1 ± 3. Material. Chag 96 / 30 a, b: 15 mm, 25 mm; outer reef, Ile de la Passe, Salomon Atoll; 14 February 1996; at 8 m depth. Description. The body was orange-yellow, with a reticulate pattern of raised ridges on the dorsal surface forming incomplete triangular shapes (® gure 11 a). The areas between the ridges were dark brown with many small white spots. The foot was orange-yellow with a very dark brown, almost black, line on the metapodium. The long rhinophores had elongated tips; the clubs were dark brown, and the stalks were translucent cream with a thick dark brown line posteriorly. The orange rhinophore sheaths were short, and the gills were white, each with the rachis coloured dark brown externally. Geographic distribution. Indo-West Paci ® c: East Africa (Eliot, 1905) to Australia (Rudman, 1978), Micronesia (Bergh, 1880) and Guam (Carlson and HoOE, 1993). Remarks. Halgerda tesselata has brown marks in the junction between the foot and mantle and a median line on the top of the metapodium. These are absent in the preserved material from Chagos but present in two specimens from Kenya (Yonow, unpublished, 10 and 25 mm preserved lengths); two specimens from the Maldives (11 and 15 mm preserved lengths, coll. R. C. Anderson and S. G. Buttress, 1996) are completely faded except for a little dark speckling in the dorsal depressions.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B471BFF89E3DFFF50A5559903.taxon	materials_examined	Material. Chag 96 / 77 a, b: 29 mm (20 3 15 mm preserved, slightly curled; radula preparation), 12 mm (113 10 mm preserved, slightly curled); outer reef of Middle Brother, Great Chagos Bank; 1 March 1996; at 24 ± 25 m depth. Description. Body translucent white with series of raised yellow-orange ridges on the dorsum (® gure 11 b). These ridges were symmetrical, enclosing a double series of six depressions; these depressions each contained a longitudinal black streak, ¯ anked in the larger specimen by thin yellow streaks. The intersections of the ridges were marked by tubercles. Many black lines were present around the edge of the mantle, mostly radiating outwards to meet the mantle edge at right angles. Rhinophores long: lower two- ® fths of club translucent and central ® fth yellow anteriorly; distal two- ® fths of club dark brown; posterior dark brown line on translucent stalk. Rhinophore sheaths short, orange. Gills white, with dark brown lines externally. The preserved specimens have lost all traces of orange pigment but the black remains on the mantle, hyponotum, foot and rhinophores; the rhinophores are extended in both specimens. The radula was dissected out of the larger specimen, and there were no markings on the membranes; often species of Halgerda have a dark covering or pigmentation on the bulb. The formula is 44 ± 453 35.0.35. All the teeth are hook-shaped: the central # 14 on each side are as small and crowded as in H. iota Yonow, 1994. There are no bristles on the marginals, which are very reduced hooks (® gure 7). Geographic distribution. Indo-West Paci ® c. Remarks. Halgerda willeyi is usually very large, up to 90 mm (Yonow, 1990), and has white rhinophores and gills with black speckles distally and spots proximally. Large specimens diOEer in having yellow ridges surrounding depressions which contain mainly longitudinal black and yellow markings, and yellow lines and yellow tubercles around the margin in addition to the perpendicular black lines. The radula of the 100 m m	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4704FF97E359FD16A24899F1.taxon	materials_examined	Material. Chag 96 / 89: 15 mm; Three Brothers, Great Chagos Bank; 2 March 1996; 6 m; coll. F. Stewart. Description. The dorsal surface was covered with small raised tubercles (® gure 4 d). Centrally there were approximately 10 red-brown tubercles, partially surrounded by much smaller white pustules. Peripherally there were two concentric rows of circular daisy-like patterns, composed of a central fawn tubercle with a yellow rim surrounded by white tubercles. The mantle skirt was thin, covered in brown speckling. The rhinophores were mottled brown and white: stalk and lower 6 5 3 7 2 1 third of club translucent, middle third darker brown, and distal third and tips white. Six white gills. The single specimen is badly preserved. It is fairly soft in comparison to H. pustulata (H. nodulosa auctt., see discussion below). The dorsum is tuberculate and the spicules are not visible due to reaction of the mantle with formaldehyde. The mantle margin is very thin, unlike the thicker margin of H. pustulata. The six gills, of which the posteriormost are divided, are pale pink, and the dorsum retains a few patches of dense brown pigment spots. The rhinophore pockets appear to be tuberculate (but not distinctively so as in Carminodoris armata Baba, 1993). Ventrally, nothing is distinguishable except that the foot is tapered posteriorly and both the hyponotum and the foot have speckles of brown pigment spots. The radular formula is 183 # 39.0.39 and the sinuously hooked teeth are large, 110 m m in height. The teeth have a distinct ¯ ange on their bases and denticles on the outer sides of the cusps (® gures 6 E, 8). Geographic distribution. Central Indian Ocean (this record) to Central Paci ® c: Western Australia, Vietnam, the Philippines and the Marshall Islands (Gosliner and Behrens, 1998). Remarks. Externally, the dorsal pattern of daisies is distinctive, as is the deep brown speckling especially on the thin margin. The radula formula is di cult to compare as Gosliner and Behrens (1998) did not state the size of their dissected animal: they gave a radula formula of 263 65.0.65. However, tooth shape and size are almost identical: measurement of the height of a tooth in their SEM is just over 106 m m. Although the species is clearly recognized, the generic placement is fraught with di culties: in describing Hoplodoris novaezelandiae, Miller (1991) listed only two congeners: the type species H. desmoparypha Bergh and H. nodulosa (Angas), which he considered to include H. pustulata (Abraham). He considered the species described by Kay and Young (1969) as H. nodulosa as diOEerent from his de ® nition of H. nodulosa but failed to recognize that H. nodulosa and H. pustulata were distinctly diOEerent species, and that Kay and Young (1969) were in fact describing true H. nodulosa. Baba (1993) described two new species (belonging to the genus Carminodoris) comparing them to Hoplodoris nodulosa / Hoplodoris pustulata: he noted Kay and Young’ s (1969) specimen as being diOEerent from his, and additionall y noted that the original description of H. nodulosa by Angas (1864) was also diOEerent from his material. Jensen (1994) described Hoplodoris cf. pustulata and discussed the similarity between the original description of H. nodulosa and Kay and Young’ s specimen, both of which were diOEerent from hers. A search through the literature reveals that both Baba and Jensen were correct in their observations noting the similarities between Angas’ H. nodulosa and Kay and Young’ s specimens, and the diOEerences between these two and other descriptions and photographs of`H. nodulosa ’ (e. g. photographs in Bertsch and Johnson, 1981, Willan and Coleman, 1984 and Wells and Bryce, 1993). It appears that the epithet H. nodulosa (Angas) has been commonly used for a species which is in fact H. pustulata (Abraham) and that in synonymizing the two, Miller (1991), Thompson (1975) and Burn (1969) amongst others, were in error. Allan (1947, 1959) did, however, correctly identify her specimens as H. pustulata. Although the original description of H. nodulosa by Angas is brief, it can be recognized as having a bare patch without tubercles in the centre of the mantle, and was so recognized and described in detail by Kay and Young (1969). This appears to be the only true subsequent record of Hoplodoris nodulosa (Angas); Gosliner and Behrens (1998)	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4706FF95E3A3FD23A24899F1.taxon	materials_examined	Material. Chag 96 / 69: 253 8 mm; inner reef of Ile Diamant, Peros Banhos Atoll; 27 February 1996; at 6 m depth. Description. The body was roughly rectangular in shape, covered with numerous tiny pustules; the ground colour was cream with several yellow patches and streaks forming a ring around gill pocket and two lines running from the rhinophores to the gills. The mantle margin was deep yellow (® gure 4 e). Rhinophores sparsely lamellate, very long in comparison to body size; very dark brown but fading at the base. Six long gills, with pale grey rachides, brown pinnae and yellow pinnules. The oral tentacles and foot were white. The preserved specimen is soft and translucent pinkish white. The long stalks of the rhinophores retain an ochre hue, while the 18 ± 19 lamellae are speckled with black. The six gill rachides also retain black specks. The tubercles on the mantle skirt are spiculose; the spicules stick out of the sides and tops of most tubercles. The rhinophore pocket margins appear undulated. Ventrally the sole is smooth. The anterior edge is bilaminate and the upper one notched centrally; the short digitiform oral tentacles are visible behind the notched lamina (® gure 10 a). The radular formula is 30 (1 2 ± 3) 3 30.0.30 with a median thickening. The teeth are simply hooked with a small denticle on the cusp on all teeth and a groove or ¯ ange on the large broad base which forms a hump or peg on the top of the teeth (® gure 9 A ± C). There is a rapid increase in size in the ® rst dozen teeth, then a gradual increase to the last-buttwo or three. All the teeth have denticles and a ¯ ange, which might have been di cult to see without SEM; the very reduced outermost two or three teeth are still very di cult to distinguish unless greatly magni ® ed. The three outermost laterals have long bristles instead of denticles on the cusps. Geographic distribution. Western Indian Ocean; this is the ® fth record of this unusual species, also known from Sri Lanka (Kelaart, 1858; Farran, 1905), Madagascar (Gosliner and Behrens, 1998) and Tanzania (Eliot, 1906 b). Remarks. In his original description from Sri Lanka, Kelaart (1858) implied that he found it frequently in shallow water, and described the egg ribbon as`light green in two narrow tape-like convolutions’. However, we have only a single specimen, as did Farran; Eliot just had two specimens, as did Gosliner and Behrens (1998). Both Eliot and Farran gave identical radular formulae, 38 (1 2) 3 39.0.39, and descriptions of the teeth: 1 ± 10 were smaller with a small denticle on the top and a ridge or ¯ ange on the base. The outermost two or three teeth were very reduced, with a tuft of bristles at their tips. Gosliner and Behrens’ (1998) two specimens were 15 and 22 mm preserved, one of which had a radular formula of	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4700FF93E381FD09A5649BAD.taxon	materials_examined	Material. Chag 96 / 9: 14 mm; in cave on inner reef of Nelson Island, Great Chagos Bank; 3 March 1996; at 20 m depth. Description. A brightly coloured species with a deep yellow mantle covered with many pink-tipped, near-spherical tubercles; smaller and more numerous white ones were concentrated around the mantle margin. Rhinophores white and very long. Gills white. Geographic distribution. Indo-West Paci ® c: recorded only from Tanzania (Rudman, 1984) in the Indian Ocean and otherwise from New Caledonia (Risbec, 1928, 1953), Japan (Baba, 1949) and the Great Barrier Reef (Rudman, 1984). Remarks. This species is rarely recorded in the scienti ® c literature. It is easily recognized by its combination of bright orange mantle, pink-tipped rounded tubercles and extremely long white rhinophores. Until recently there has been only one named species of Cadlinella, but two species have recently been described from New Caledonia (Rudman, 1995) and Japan (Baba, 1996). A further two undescribed species have been photographed in the Red Sea (Debelius, 1996 as C. ornatissima) and Norfolk Island (South Paci ® c: Coleman, 1989: 44 as C. ornatissima). These diOEer signi ® cantly in external morphology and colour pattern from C. ornatissima, which is very constant, and from C. hirsuta Rudman, 1995 and C. subornatissima Baba, 1996. Cadlinella hirsuta is yellow with very long, tapering, white papillae; C. subornatissima is yellow centrally and white marginally with conical papillae. The Red Sea species is white with yellow reticulations and a narrow bright yellow margin, and the fusiform or digitiform tubercles are red to pink-red for their distal half. The South Paci ® c species is bright yellow like C. ornatissima but has tapering tubercles rather than round-ended cylindrical or spherical ones, suOEused with very pale pink. Perhaps more signi ® cantly, the rhinophores are bright yellow. (a) (b) (c) (d) (e) (f)	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4701FF93E38DFA43A24999F1.taxon	materials_examined	Material. Colour photograph of a single individual by M. Spalding: outer reef, Nelson Island, Great Chagos Bank; March 1996. Description. Photograph of dorsal surface clearly shows typical coloration of this species: a yellow-fawn dorsum, many violet ocellations with blue white rims, and four marginal bands. These comprise a thin white margin, a wider grey-fawn	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4702FF90E389FE86A5299D86.taxon	description	Chromodoris gleniei (Kelaart): Rudman, 1987: 391; Yonow, 1994 a: 115, ® gure 10 E. Material. Chag 96 / 73: 423 12 mm; Middle Brother, Great Chagos Bank; 29 February 1996; at 20 m depth. Description. The body was broadly oval. The mantle margin was white with a submarginal grey band, followed by a white band which contained faint yellow patches. The central area was orange-brown with an undulating dark border; this contained numerous irregular dark brown markings. Rhinophores and gills orange; gills with pale rachides. Foot translucent with an opaque white ventral margin. Geographic distribution. Western Indian Ocean: Tanzania (Rudman, 1987), the Maldives (Yonow, 1994 a) and Sri Lanka (Kelaart, 1858).	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4702FF91E338FCC3A24899F1.taxon	materials_examined	Material. Chag 96 / 16: 37 mm; inner reef between Ile du Sel and Ile Jacobin, Salomon Atoll; 12 February 1996; at 10 m depth. Chag 96 / 42: 22 mm; inner reef of Ile Diamant, Peros Banhos Atoll; 19 February 1996; at 5 m depth. Chag 96 / 51: 32 mm; inner reef of Grand Ile Mapou, Peros Banhos Atoll; 21 February 1996; at 4 m depth. Chag 96 / 52 a, b, c: live lengths not recorded; inner reef of Grand Ile Mapou, Peros Banhos Atoll; 21 February 1996; at 10 m depth; only three of nine individuals on patch of Halimeda algae collected. Chag 96 / 87: 40 mm; inner reef of Nelson Island, Great Chagos Bank; 3 March 1996; at 26 m depth (radular preparation). Description. Mantle wide, but not undulated, with a broad orange margin, the very edge of which was pale, and a thin submarginal white band (® gure 11 e, f). Dorsal surface blue and black striped: one black band enclosed the area and one black median stripe ran back from rhinophores to anterior margin of gill pocket; in some specimens a pair of black stripes (continuous or incomplete) extended from behind the rhinophores to the sides of the gill pocket; in a few specimens additional black streaks were also present; the number of black stripes thus varied from three to ® ve, with additional streaks. Rhinophores orange; gills orange with limited ® ne white speckling on edges of plumes. Foot with orange ventral margin and blue and black stripes laterally. The seven preserved specimens are very similar indeed, all retaining all the colours on the body and foot, with deeper orange gills and rhinophores. The radular formula of specimen 96 / 87 (40 mm alive) is 82 (1 3 ± 4) 3 62.0.62. The teeth are all denticulate on their outer sides (® gure 12 A, B). Geographic distribution. Western Indian Ocean: Chromodoris quadricolor has been recorded only from the Red Sea (Yonow, 1989) and Tanzania (Rudman, 1977, 1982 b), so this record represents a signi ® cant range extension. Remarks. The variations in these specimens are within the range of variations seen in the Red Sea specimens, where the species is extremely abundant. In addition	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B470CFF9EE396FE31A7AD9BCF.taxon	description	Chromodoris tennentana (Kelaart): Rudman, 1987: 364, ® gures 23, 32, 35, 36. Material. Chag 96 / 61: 18 3 4 mm; coral bommie east of Ile Poule, Peros Banhos Atoll; 25 February 1996; at 7 m depth. Description. Mantle with irregular purple margin and broad cream submarginal band which contained raised orange patches. Central area of notum brown with numerous black spots, each ocellated with white. Rhinophore clubs brown with white tips; stalks translucent. Gills grey and white. The preserved specimen is soft and well relaxed. It is translucent white and the dark gut is clearly visible through the body wall. The orange pigment spots around the mantle edge remain as patches and the mantle glands are extremely clear as evenly distributed groups around the edge, just in from the margin; they are absent in front of the rhinophores. Geographic distribution. Western Indian Ocean: recorded from Tanzania and Sri Lanka as C. cavae Eliot and C. vicina Eliot; this record from Chagos is a new locality. It is not uncommon in the Seychelles (photographs of several individuals and one specimen 83 5 mm alive; coll. P. Kemp, 1992). Remarks. Chromodoris tennentana is a large species, growing to more than 60 mm in length (preserved measurement, Eliot, 1904 a). The orange spots in the white submarginal band of our specimen are slightly raised; this had not been noted in previous descriptions.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B470CFF9FE368FB04A24899F1.taxon	materials_examined	Material. Chag 96 / 34: 34 mm; outer reef Ile Takamaka, Salomon Atoll; 15 February 1996; at 9 m depth (radular prep.). Chag 96 / 78 a, b: 25 mm, 18 mm; outer reef, Middle Brother, Great Chagos Bank; 1 March 1996; at 8 m depth. Chag 96 / 80: 20 mm; Three Brothers, Great Chagos Bank; 2 March 1996; at 5 m depth; coll. F. Stewart (no photographs). Description. Body soft and ¯ eshy with wide mantle. Ground colour cream with two large irregular chocolate brown patches: one encircled the rhinophores and the second included the gill pocket, the rim of which was white; these two patches were separated by a cream band across the mid-body, but joined by a thin isthmus of chocolate brown in two specimens (® gures 4 f, 13 b). Three to eight purple-black spots with white ocellations; fewest spots in smallest specimen, most in largest. Mantle edge pale purple; cream band with faint yellow patches encircling the notum (a) (b) (c) (d) (e) (f) submarginally. Rhinophores white with faint purple tips; gills white with light purple line down distal half of rachis and light purple tips to gill plumes. The preserved specimens are violet-purple in colour, dorsally and ventrally, with orange patches and spots on the dorsum and on top of the foot, coinciding with brown pigment and purple-black spots on the photographs. The gills and rhinophore s have the same dense purple hue as the body; the rim around the gill pocket is distinctly raised in each specimen. Ventrally, the anterior portion of the foot is bilaminate and both are notched medially. The head is visible with a puckered mouth and short digitate oral tentacles (® gure 10 b). When the radula was dissected	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B470EFF9DE3A4FB70A2069D1D.taxon	description	(® gure 13 c) Glossodoris cincta (Bergh): Rudman, 1986 a: 149, numerous ® gures; Yonow, 1994 a: 120, ® gure 10 H. Material. Chag 96 / 59: 27 mm; on rubble near bommie east of Ile Poule, inside Peros Banhos Atoll; 23 February 1996; at 7 m depth. Chag 96 / 82: 25 mm; Three Brothers, Great Chagos Bank; 3 March 1996; at 5 m depth. Chag 96 / 92 a, b: 37 mm, 35 mm; Victory Bank; 3 March 1996; at 8 m depth. Description. The body is solid and the mantle edge undulated, with a noticeably enlarged permanent fold mid-laterally on both sides. The mantle edge appeared dark green from a distance, but comprised an outer royal blue margin and an olive green submarginal band (® gure 13 c). The dorsal surface was pustular and mottled pinkish brown, speckled with white and yellow dots; there was a darker central ® eld extending from the rhinophores to the gills. The foot was dark pink, mottled with white-tipped pustules, with thin bright blue and olive green marginal bands. Rhinophores were dark brown speckled with white; white midline present anteriorly and (in one specimen) posteriorly. Gills pale brown, with ® ne dark edges. The preserved specimens are all well relaxed; they retain the red marbling on the dorsum and the blue and green margins on the mantle and foot. The colour pattern on the gills and rhinophores also remains. All specimens have stained their formaldehyde preservative yellow to yellowish brown. Geographic distribution. Indo-West Paci ® c: Red Sea (Yonow, 1989) and western Indian Ocean (Yonow and Hayward, 1991; Yonow, 1994 a) to Christmas Island (Indian Ocean), north Australia and the Philippines (Rudman, 1986 a). Remarks. This species is well known, occurring in several colour morphs: these specimens conform with the Red Sea and western Indian Ocean form which has a mottled red dorsum, an olive green submarginal and thin blue marginal line. In life the gills vibrated constantly in specimen 96 / 59, a feature also noted for the specimens from East Africa and the Philippines (Rudman, 1986 a), and typical of numerous species of Glossodoris. Specimen 96 / 92 was photographed in situ on a black sponge (cf. specimen from Maldives on purple sponge in Yonow, 1994 a: ® gure 10 H).	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B470FFF9DE39DFD7BA24899F1.taxon	materials_examined	Material. Chag 96 / 50: 26 mm; inner reef of Grand Ile Mapou, Peros Banhos Atoll; 21 February 1996; at 4 m depth. Chag 96 / 64: 13 mm; inner reef of Ile Monpatre, Peros Banhos Atoll; 26 February 1996; at 6 m depth. Description. The body was stout but soft and ¯ eshy; the mantle edge was very undulated, with a prominent mid-lateral fold on each side. The colour was semitranslucent, pale olive-fawn; the margin was marked with a ® ne, slightly broken orange-red rim; the foot had an extremely ® ne, continuous, orange-red rim (® gure 13 d). There was a broad opaque cream-to-white submargin to both the foot and the mantle. An indistinct yellow band was present between the white submargina l band of the mantle and the olive-fawn of the dorsum, most obvious on the larger specimen. An opaque creamy white band encircled the gills and a symmetrical double cross pattern was present on the dorsum; these two patterns were not complete in the smaller specimen. Rhinophores and gills orange-red. One preserved animal (96 / 50) is opaque pink: the very ® ne mantle frill is breaking up, but the mantle glands are visible as white spheres packed together in a wide continuous band, so much so that one part of the detached mantle looks like an egg ribbon. The smaller specimen (96 / 64) retains its ® ne crenulated mantle edge but there are no glands visible; the body colour is opaque cream and the dark gut is visible. Geographic distribution. Indo-West Paci ® c: this is the ® rst collection of this species since its original description from ReÂunion, Papua New Guinea and the Marshall Islands (Rudman, 1990); photographic records from the Seychelles (P. Kemp; also in Debelius, 1996) and Oman (Debelius, 1996) may be referred to this species. Remarks. Our specimens are identical in external morphology and colour to the type, but diOEer in two small details: in both specimens, the orange pigment on the mantle edge is slightly broken, present alternately as dark and faint dashes and spots, and there is a continuous very ® ne red line present around the edge of the foot.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4708FF9AE38DFF50A2289C61.taxon	description	(® gure 13 e) Hypselodoris maculosa (Pease): Rudman, 1986 b: 340, ® gure 1 I, J; Yonow, 1989: 302, pl. 21; Wells and Bryce, 1993: 114, ® gure 142. Hypselodoris decorata Risbec, 1928: 152, ® gure 43, pl. 7, ® gure 4; Rudman, 1984: 195, ® gure 57. Material. Chag 96 / 60: 11 mm; coral bommie east of Ile Poule, Peros Banhos Atoll; 23 February 1996; at 9 m depth. Description. Dorsal surface orange marginally and cream medially, with a complex pattern of pink and white spots, respectively, and ® ne white lines. Rhinophores large, white with an orange band approximately one-third from the tips. Gills white with orange tips and bases. Foot translucent white, but with numerous pink and white dots posteriorly, giving it the appearance of having a pink tail. Geographic distribution. Indo-West Paci ® c: recorded from the Red Sea (Yonow, 1989), East Africa and Christmas Island to South China and Tahiti in the Paci ® c (Risbec, 1928; Rudman, 1986 b); collected in the Seychelles (P. Kemp, 1992) and photographed in the Maldives (R. C. Anderson and S. G. Buttress, 1995). Remarks. This species has some variation in colour pattern, but is easily recognized by its distribution of red spots and wavy white lines on cream centrally, and white spots on red marginally. The rhinophores are characteristically long, banded with orange, although the orange bands may vary in number from one to three.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4708FF9BE398FCE9A2249FFF.taxon	description	(® gures 13 f, 14)	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4708FF9BE398FCE9A2249FFF.taxon	materials_examined	Material. Chag 96 / 58 a, b, c: 24 mm (15 mm preserved), 27 mm (17 mm preserved), 29 mm (20 mm preserved; radular preparation); underside of coral bommie, east of Ile Poule, inside Peros Banhos Atoll; 23 February 1996; at 7 m depth. Two other individuals at same location not collected. Description. Body smooth, robust and richly coloured: yellow with numerous black lines overlaid with purple (® gure 13 f). These purple and black lines covered the dorsal surface and sides of the foot, but did not include the mantle edge, which was plain yellow. Foot with pale purple marginal band. Rhinophores and gills brilliant orange-crimson. The radula had more than 70 rows of teeth with at least 65 teeth per row. The ® rst lateral is tricuspid while the rest are bi ® d but not denticulate (® gure 14). Geographic distribution. Western Indian Ocean: Tanzania (Eliot, 1904 a; Rudman, 1977) and Gulf of Aden (VayssieÁre, 1912) to Sri Lanka (Farran, 1905). Remarks. The three specimens are similar in colour pattern to the original description from Zanzibar (Eliot, 1904 a) and those redescribed from Tanzania (Rudman, 1977). Rudman’s specimens diOEered slightly in having orange and white gills instead of uniformly deep orange as in these specimens. The teeth of the Chagos specimen conform with those ® gured by Rudman (1977), except that the base is much larger, as ® gured by Farran (1905), especially in the outermost teeth. The specimens were found together on a spiculose sponge covered in small tubeworms on the underside of a coral bommie (sample collected but unidenti ® ed). 1	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4709FF9BE355FC88A24899F1.taxon	materials_examined	Material. Chag 96 / 7: 140 mm (60 mm pres. length); inner reef, Ile Boddam, Salomon Atoll; 10 February 1996; at 17 m depth. Description. Large, ¯ eshy, brown coloured (® gure 4 g). Dorsal surface with many large ¯ eshy compound tuberculate complexes, each of which had many folds and tubercles; central complexes larger than lateral ones. Central tubercle of each complex higher than ring of surrounding ones, each with orange pimple at apex, followed by series of folds to base. Lateral tubercles alternately brown and pale (almost cream). The tubercular complexes were densely packed with no bare mantle between them, giving each complex a polygonal outline. Mantle edge ® nely frilled. Underside of mantle brown, with numerous white spots surrounded by a black line (® gure 15). Rhinophores with long stalk and very angled club; lamellae brown, with white midline almost invisible distally and double basally. Gills brown with pale edging to plumes. Geographic distribution. Probably Indo-West Paci ® c: reliable records from India (Alder and Hancock, 1864), Zanzibar (Eliot, 1904 c), New Guinea (Quoy and Gaimard, 1832) and Japan (Hirano, 1992). Remarks. Taxonomically, this group of large warty dendrodorids is a di cult one, and Edmunds and Preece (1996) discussed this at length. Their specimen from the Pitcairn Islands (central Paci ® c) is diOEerent from ours and would be better assigned to D. carbunculosa Kelaart, which has warty nodules,`larger ones rising from a raised tubercular ringed base’. The original description of the foot and	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B470AFF99E34DFA63A74F99F1.taxon	materials_examined	Material. Chag 96 / 24 a, b: 24 mm, 18 mm; outer reef between Ile Boddam and Ile Poule, Salomon Atoll; 13 February 1996; at 10 m depth. Chag 96 / 27: 24 mm; coral bommie inside Salomon Atoll; 13 February 1996; at 12 m depth. (a) (b) (c) (d) (e) (f) Description. Ground colour pale blue. Raised median ridge with orange tubercles; orange tubercles almost continuous in smallest specimen; interrupted in two places by the joining of the two longitudinal black stripes in specimen 96 / 27. Two black stripes, one on either side of median ridge, with ® ve to seven rays extended to the mantle edge; additional black streaks between these rays. Rhinophores yellow. Geographic distribution. Indian Ocean: from Mauritius to Western Australia (Yonow, 1996).	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4734FFA6E3A9FEBAA6FB9B9F.taxon	materials_examined	Material. Chag 96 / 32: 12 mm; outer reef, Ile de la Passe, Salomon Atoll; 14 February 1996; at 15 m depth. Chag 96 / 43 a, b: 32 mm, 28 mm; inner reef, Ile Diamant, Peros Banhos Atoll; 19 February 1996; at 3 m depth. Chag 96 / 46: 16 mm; outer reef, Ile Diamant, Peros Banhos Atoll; 20 February 1996; depth not recorded; no photographs taken. Chag 96 / 53 a, b: 25 mm, 22 mm; inner reef, Ile Mapou, Peros Banhos Atoll; 21 February 1996; at 9 m depth; no photographs taken. Chag 96 / 67: 353 15 mm; coral bommie, east of Ile Poule, Peros Banhos Atoll; 25 February 1996; at 9 m depth; no photographs taken. Description. Ground colour pale granular blue. Three longitudinal black stripes, one on the midline interrupted by yellow tubercles; the two laterals were continuous but did not meet anteriorly between the rhinophores. Variable number of rounded, yellow tubercles arranged longitudinally; fewest in smallest specimen but otherwise no obvious correlation with size. Small black ¯ ecks peripherally. Rhinophores slightly deeper yellow than tubercles. Geographic distribution. Indo-West Paci ® c: Sri Lanka (Yonow, 1984 as P. alia), the Seychelles (Edmunds, 1972 as P. elegans) and South Africa (Gosliner, 1987 as P. varicosa) to Fiji (Brunckhorst, 1993). Remarks. Brunckhorst (1989, 1993) redescribed and illustrated this species; the majority of his material was from the Paci ® c, where it also appears to be relatively common.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4734FFA7E394FAF9A7759E7A.taxon	description	Phyllidia multituberculata Boettger: Yonow, 1996: 487, ® gures 2, 3, 4 B. Material. Chag 96 / 29: 27 mm; outer reef, Ile de la Passe, Salomon Atoll; 14 February 1996; at 22 m depth. Description. Bright orange, with seven white-edged black patches, three on each side and one anteriorly. Several black spots around periphery and two on midline. Dorsum with numerous orange tubercles, largest on midline and smallest near mantle edge. Rhinophores long, orange; anus on orange tubercle. Geographic distribution. Indian Ocean: Mauritius and the Seychelles (and one specimen from Indonesia; Yonow, 1996). Remarks. This species has been recently re-established (Yonow, 1996) and the Chagos specimen is virtually identical to the one illustrated in her ® gure 2 A from the Seychelles. This specimen from Salomon Atoll was found and photographed on a reddish orange sponge which had large osculae; on this substratum it appeared to be well camouāged.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4735FFA7E3BEFE99A7B29B29.taxon	materials_examined	Material. Chag 96 / 17: 8 mm; outer reef, Ile de la Passe, Salomon Atoll; 12 February 1996; at 20 m depth. Chag 96 / 33: 80 mm; outer reef, Ile de la Passe, Salomon Atoll; 14 February 1996; at 8 m depth. Chag 96 / 41 a, b: 55 mm, 30 mm; inner reef, Ile Boddam, Salomon Atoll; 18 February 1996; at 11 ± 13 m depth; smaller specimen coll. G. Heiss. Description. Body black, with three raised light blue-grey ridges which were topped with deep yellow tubercles. Numerous short peripheral tuberculate ridges perpendicular to margin. Digitiform rhinophores deep yellow. Sole of foot grey with broken black line medially in all specimens. Geographic distribution. Indo-West Paci ® c: from the Red Sea and South Africa to Hawaii (Yonow, 1996). Remarks. Previously collected from the Chagos by Gardiner and reported by Eliot (1910), Yonow (1996) noted that the specimen was collected at`Solomon Is., Indian Ocean’ but this was in error for Salomon Atoll, Chagos. There has been some controversy regarding the validity of this name for this species (Yonow, 1986; Brunckhorst, 1993; Yonow, 1996), in particular the apparent absence of a black line on the ® gure of the sole of the holotype of P. varicosa, long thought lost, and its presence in P. arabica Ehrenberg and all subsequent descriptions. The recent rediscovery of the holotype of P. varicosa in the MNHN (Paris; no registration number) and the con ® rmation that it does have a black line on the sole now resolves this issue (Willan et al., 1998).	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4735FFA7E369FBABA24899F1.taxon	materials_examined	Material. Chagos 96 / 14: 25 mm; inner reef between Ile Jacobin and Ile du Sel, Salomon Atoll; 12 February 1996; at 11 m depth. Chag 96 / 35: 18 mm; outer reef, Ile Takamaka, Salomon Atoll; 15 February 1996. Chag 96 / 39 e, j: 37 3 14 mm, 24 mm; Salomon Atoll, 13 ± 15 February 1996. Chag 96 / 68: 27 mm; outer reef, Ile Manoele, Peros Banhos Atoll; 27 February 1996; at 12 m depth. Additional material. Syntype: Pruvot-Fol (1957), Mauritius, 18 3 7 mm preserved (BMNH 1887.6. 7.1 0); Trou aux Biches, Mauritius, 18 mm preserved; Belle Mar Plage, Mauritius, 423 9 mm (BMNH acc. no. 2350, Yonow and Hayward, 1991). Description. Elongated in shape, with characteristically pointed tubercles. Four to six rings of tubercles with conūent bases medially (® gure 16 d). The black pattern	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4736FFA5E3BAFB37A54299F1.taxon	description	Phyllidia nigra Pease, 1868: 80, pl. 9, ® gure 5 (pre-occupied by P. nigra van Hasselt, 1824).	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4736FFA5E3BAFB37A54299F1.taxon	description	NOT Phyllidia mediocris Yonow and Hayward, 1991: 20, ® gures 11 C ± E, 13 A (as per Brunckhorst, 1993) (5 Phyllidiella striata, q. v. p. 866). Material. Chag 96 / 9: 20 mm; outer reef, Ile Anglais, Salomon Atoll; 11 February 1996; at 12 m depth. Chag 96 / 23: 17 mm; outer reef between Ile Boddam and Ile 1 mm 1 mm (a) (b) Poule, Salomon Atoll; 13 February 1996; at 10 m depth. Chag 96 / 39 a, b: 13 mm, 15 mm; Salomon Atoll; 13 ± 15 February 1996. Chag 96 / 48 a, b: 13 mm, 15 mm; outer reef, Ile Diamant, Peros Banhos Atoll; 20 February 1996; at 22 m depth. Chag 96 / 72 b: 163 6 mm; outer reef, Peros Banhos Atoll; 27 February 1996; coll. A. JolliOEe. Description. Body with three longitudinal raised but smooth pink ridges and four black lines; surrounding low pink ridges up to three in number, coalescing anteriorly and posteriorly. The median extended to just in front of the rhinophores, where it expanded slightly. Rhinophores black with pink sheaths. Ventrally, most of the specimens had a dusting of black along the top edge of the foot, and a black patch on the posterior end of the sole. The head and oral tentacles were also dusted with black (® gure 17 a). Geographic distribution. Indo-West Paci ® c: the Maldives and ReÂunion to Hawaii and Tahiti (Brunckhorst, 1993). Remarks. It appears that Phyllidiella rosans (Bergh, 1873 b) and Phyllidiella nigra (Pease, 1868) are not as tuberculate as their original descriptions indicated, and (with Phyllidiella soria Marcus and Marcus, 1970) are in fact one species originating from Tahiti. This species is characterized by the smooth pink ridges bearing a crest in larger specimens: three central longitudinal ones and up to three encompassing rings which converge anteriorly and posteriorly. Large specimens can be almost round in shape. The grey spots on the sole noted by Brunckhorst (1993) are concentrated submarginally, and there is frequently a black patch on the distal end of the sole. Brunckhorst (1993) had additional material from the Maldives and ReÂunion; certainly this species is extremely common in the Maldives (Yonow, unpublished). The specimens from Chagos range from 13 to 20 mm and are smaller than those from the Paci ® c, which are 18 ± 35 mm (Brunckhorst, 1993). It is noteworthy that despite many earlier collections in the Indian Ocean, this species was only recently recorded, despite being abundant when present.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4730FFA3E3BBFF50A24899F1.taxon	description	Phyllidia mediocris Yonow and Hayward, 1991: 20, ® gures 11 C ± E, 13 A (not P. rosans as per Brunckhorst, 1993). Material. Chag 96 / 2: 35 mm; inner reef, Ile Boddam, Salomon Atoll; 8 February 1996. Chag 96 / 5: 18 mm; outer reef, Ile Anglais, Salomon Atoll; 10 February 1996; at 20 m depth. Chag 96 / 8: 17 mm; outer reef, Ile Anglais, Salomon Atoll; 11 February 1996; at 8 m depth. Chag 96 / 13 and Chag 96 / 15: both 30 mm; inner reef between Ile Jacobin and Ile du Sel, Salomon Atoll; 12 February 1996; at 8 m and 12 m depth. Chag 96 / 21 and Chag 96 / 22: 26 mm and 21 mm; outer reef between Ile Boddam and Ile Poule, Salomon Atoll; 13 February 1996; at 15 m depth. Chag 96 / 28: 26 mm; coral bommie inside Salomon Atoll; 13 February 1996; at 14 m depth. Chag 96 / 38: 35 mm; coral bommie inside Ile Anglais, Salomon Atoll; 15 February 1996; at 12 m depth. Chag 96 / 39 d: 283 16 mm; Salomon Atoll; 13 ± 15 February 1996. Chag 96 / 49: 283 12 mm; outside reef, Ile Diamante, Peros Banhos Atoll; 20 February 1996. Chag 96 / 66: 293 8 mm; inner reef, Ile Monpatre, Peros Banhos Atoll; 25 February 1996; at 22 m depth. Additional material. Le Morne, Mauritius, 183 5.5 mm; Grand Baie, Mauritius, 143 5 mm and 153 5 mm; Trou aux Biches, Mauritius, 18 mm (BMNH acc. no. 2350, Yonow and Hayward, 1991). 1 mm Description. Dorsum very long and thin. Three central pink tuberculate ridges, which may be broken, met behind the rhinophores; the two laterals were bent outwards to the rhinophores (® gure 16 f). Single medial patch or ring of tubercles in front of the rhinophores; ring of tubercles behind the anus. First encompassing pink band may be a double row of tubercles; up to two more single rows of tubercles encircling mantle. Ventrally, the foot is pale and there is no black dusting on its top surface, although the gills are edged in black (® gure 17 b). Additional internal characters are the dusty black band on the oral tube and a very thick pharynx; other details are as described for the genus (Brunckhorst, 1993: 17). The swollen anus is black. Geographic distribution. Western Indian Ocean: Sri Lanka (Yonow, 1984), Mauritius (Bergh, 1889, Yonow and Hayward, 1991), Seychelles (Edmunds, 1972) and the Maldives (Eliot, 1906 a; R. C. Anderson, S. G. Buttress and N. Yonow, personal observations). Remarks. The epithet Phyllidiella striata Bergh is correctly recognized for this species for the ® rst time since Eliot (1904 a). The animal commonly called Phyllidiopsis striata is in fact Phyllidiopsis xishaensis (q. v. p. 870). Bergh’s ® gure (1889: pl. 84, ® gure 23) is identical to specimen 96 / 2 and both are reproduced here (® gures 16 f and 18 a, respectively). Eliot (1906 a) recognized the similarities between his single specimen from the Maldives and Bergh’s ® gure and stated clearly that the foot and gills were lighter than the dorsum (unlike Phyllidiopsis xishaensis in which there is a black line on the hyponotum beneath the gills). Eliot described three white lines on a blackish dorsum and white patches at each end. This is similar to Bergh’s ® gure and to approximately 25 specimens recently collected from the Maldives (Yonow, unpublished). At present, we consider the variation within the species to be restricted to continuous or broken tuberculate pink ridges and either a patch or ring anteriorly; the posterior ring appears to be a constant feature in all specimens examined. Small specimens can be confused with Phyllidiella rosans but diOEer in having tuberculate ridges which are often broken, and lacking the black pigmentation on the foot and oral tentacles. Additionally, Phyllidiella striata is long and thin, while Phyllidiella rosans is broadly oval. There are several other pink and black specimens in this collection which are vaguely similar but do not have the above combination of characters; these will be considered in a further work. Bergh’ s species is re-established, and assigned to Phyllidiella, in part due to the presence of distinct oral tentacles which, as Bergh states, are`shorte r and plumper than those of Phyllidia varicosa ’ (trans., 1889: 866): these are certainly not a characteristic of Phyllidiopsis, which he de ® ned as`brevissima a xa ’ (Bergh, 1875: 661; 1876: 380). The pharynx of this Chagos specimen was exactly as in Brunckhorst’s (1993) ® gure of Phyllidiella pustulosa, the type species of the genus: a long thickened tube with a dorsal split, which con ® rms this species as belonging to the genus Phyllidiella and not Phyllidiopsis. Of concern is the lack of glands on Bergh’s ® gure of the pharyngeal bulb (pl. 84, ® gure 24); however, these were very small and attached by extremely ® ne ducts in specimen 96 / 49; the arrangement of the digestive system was otherwise identical to that in Bergh’s ® gure.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4732FFA1E380FCDBA5629C35.taxon	description	NOT Phyllidia empelia Yonow, 1984: 223, ® gures 6, 7 B, 8 A, B (as per Brunckhorst, 1993) (5 Phyllidiella striata, q. v. p. 866).	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4732FFA1E380FCDBA5629C35.taxon	materials_examined	Material. Chag 96 / 3: 26 mm; Salomon Channel, Salomon Atoll; 9 February 1996; at 6 m depth (no photograph). Chag 96 / 11: 36 mm; outer reef, Ile Anglais, Salomon Atoll, 11 February 1996; at 15 m depth. Chag 96 / 19: 24 mm; outer reef, Ile de la Passe, Salomon Atoll; 12 February 1996; at 19 m depth. Chag 96 / 39 h: 333 13 mm; Salomon Atoll; 13 ± 15 February 1996. Description. All specimens have the classic hallmarks of P. zeylanica (® gure 19 a): the squared appearance of the anterior end of the animal, the curled-under edges of the mantle, the few, spaced lamellae on the long rhinophores, and the rather peculiar mouth-oral tentacle arrangement; these characters remain in the preserved specimens. The faintly tuberculate areas are pink and the smooth bands black. The long rhinophores are black, tapered and bent back slightly over the dorsum. Geographic distribution. Indian Ocean: East Africa to Christmas Island (Yonow, 1996). Remarks. Specimen 96 / 11 is almost identical to Edmunds’ ® gure (1972: ® gure 3 D); both are unusual in having broken longitudinal lines. Brunckhorst (1993: 56) assigned Edmunds’ specimen to Phyllidiella rosans but P. rosans bears smooth, usually continuous, pink ridges (q. v. p. 864). Furthermore, in Edmunds’ drawing of the ventral anterior end, the arrangement is the same as in the drawing of P. zeylanica (Yonow, 1996: ® gure 10 C); however, Edmunds did state that the oral tentacles were grey, not black. (a) (b) (c) (d)	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4733FFA1E3B4FC28A24899F1.taxon	materials_examined	Material. Chag 96 / 75: 383 16 mm; Three Brothers, Great Chagos Bank; 29 February 1996; at 20 m depth. Chag 96 / 81: live length not recorded; curled, approx. 25 mm preserved; Three Brothers, Great Chagos Bank; 2 March 1996; at 22 m depth. Description. Dorsal surface with numerous large complex tubercles and smaller simple ones. Colour mottled cream, brown and yellow in specimen 96 / 75 (® gure 19 b), red-brown in specimen 96 / 81. Mantle margin cream or yellow with black or dark green spots. Yellow anal papilla. Ventral surface of foot deep yellow with irregular brown spots around periphery. Rhinophores short, pale yellow with green tips. The preserved animals retain the three rows (not two as in Brunckhorst, 1993) of multicompound tubercles. Both specimens are uniformly very dark, a reddish black; the formaldehyde is tinted pink. Geographic distribution. Indo-West Paci ® c. Phyllidiopsis cardinalis is well known from the Paci ® c but has been rarely recorded from the Indian Ocean: Eliot (1904 c) recorded four specimens from Zanzibar; Gosliner and Behrens (1988) had one specimen from Aldabra, and Brunckhorst (1993) had two specimens from Western Australia and three from ReÂunion. N. Y. has photographs of one individual from	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B473CFFAEE3B4FEBDA7239AC5.taxon	materials_examined	Material. Chag 96 / 6: 14 mm; outer reef, Ile Anglais, Salomon Atoll; 10 February 1996; at 12 m depth. Chag 96 / 26: 18 mm; outer reef between Ile Boddam and Ile Poule, Salomon Atoll; 13 February 1996; at 8 m depth. Chag 96 / 47: 12 mm; outer reef, Ile Diamante, Peros Banhos Atoll; 20 February 1996; at 23 m depth. Description. Ground colour pale blue to white with four longitudinal black stripes, the inner two joining anteriorly between the rhinophores, the outer two joining anteriorly and posteriorly (® gure 19 c). Black stripes separated by three pale blue to white ridges: the median ridge is simple, the outer two are doubled. Numerous small black spots present peripherally on the margin. Rhinophores lamellate, pale ochre in colour. Ventrally, the sole and the hyponotum are pale grey, and there is a black line on the hyponotum beneath the gills. Geographic distribution. Indo-West Paci ® c: from the Maldives and Seychelles (Yonow, unpublished) to Indonesia (Bergh, 1889), China (Lin, 1983) and the Marshal l Islands (Brunckhorst, 1993). Remarks. This distinctive species is widely known as`Phyllidiopsis ’ striata; however, Phyllidiella striata (Bergh, 1889) is a species quite distinct from Phyllidiopsis xishaensis, and is also present in this collection from Chagos (see above). Phyllidiopsis xishaensis was ® rst described and illustrated by Bergh (1905: 181) but not recognized as a new species; he described a tiny specimen (9 mm) with`black behind the gills’ (trans.) from Siau Island (Indonesia) as Phyllidia varicosa Lamarck although`the foot sole is greyish white’ (trans.): P. varicosa has a black line on the sole. The ® gure of this specimen (Bergh, 1905: pl. 17, ® gure 8) is identical to the ® gure of a new species described by Lin (1983) as Phyllidia xishaensis. As Lin was describing an old preserved specimen (collected in 1958), the rhinophores, described as grey, had probably lost their ochre colour. The external pattern of this species is unmistakable (see Brunckhorst, 1993 and photographs in Wells and Bryce, 1993 and Coleman, 1989) and, since Phyllidiella striata and Phyllidia varicosa are misidenti ® cations, the ® rst available name is Phyllidiopsis xishaensis. This is the ® rst record for the Indian Ocean.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B473DFFAFE3B8FDBBA24899F1.taxon	description	Scyllaea pelagica Linnaeus: Thompson and Brown, 1981: 441, ® gures 3, 4. Material. Chag 96 / 55: four specimens approximately 18 mm; on ¯ oating Sargassum weed, inside Peros Banhos Atoll; 22 February 1996. Chag 96 / 56: 23 mm; collection details as above. No photographs. Description. The preserved specimens, although ¯ attened, appear identical to the photograph in Wells and Bryce (1993: 173; ® gure 223): the body is translucent and the organs within are opaque white; the brown radula and jaws are visible. The orange pigment spots remain on the preserved material. The two pairs of cerata with the gills on the mesial surface are squared in shape, irregularly lobed on their distal edges, and the dorsal ¯ ap posterior to the cerata is large and bears gills, ending bluntly at the short metapodium. In the smallest specimen (the only specimen without orange spots), the rows of teeth in the radula are clearly visible at 3 80 magni ® cation. When removed, examination provided a formula of 17 (1 3) 3 24 ± 25.1.25 ± 24 (® gure 18 b). There are no colour notes or photographs, but preserved body shape is identical to those illustrated by Baba (1949), Marcus and Marcus (1963) and Thompson and Brown (1981). Geographic distribution. Scyllaea pelagica is considered semi-planktonic, associated with the ¯ oating oceanic alga Sargassum. It has been recorded under numerous names from all areas of the world, including Antarctica, southern Britain and the western Atlantic (see Thompson and Brown, 1981). Remarks. Numerous species and varieties of Scyllaea have been described, all of which are found in Sargassum and analogous ¯ oating habitats. Odhner (1936) has synonymized the majority into ® ve species, distinguished by colour, shape and internal characteristics such as the radula, stomach plates and liver masses. Following Eliot’s (1906 b) example, Odhner’s (1936) primary distinctions between the species were in radula ribbon width, narrow (16 ± 17 lateral teeth) or broad (201 lateral teeth). This specimen, with 24 ± 25 laterals, clearly falls into the second group, which contains three species distinguished partly by colour and size. Scyllaea pelagica is the most common and the largest, characterized by blue patches or small spots and squared cerata. The other two species with a broad radula are S. marmorata Alder and Hancock, 1864 and S. viridis Alder and Hancock, 1864. The former, redescribed	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4738FFABE3BFFAC6A73D9FDB.taxon	materials_examined	Material. Photographs of single individual; approximatel y 10 ± 15 mm in length; outer reef, Ile de la Passe, Salomon Atoll; 12 February 1996. Description. Photographs depict an elongate body, transparent and opaque white. Cerata in six clusters, with the suggestion of faint orange bands near the distal ends. Oral tentacles long, opaque white with two translucent bands proximally and possibly orange distally. Rhinophores orange. Geographic distribution. Indo-West Paci ® c: Red Sea (Yonow, 2000) and South Africa to Hawaii (Gosliner and Willan, 1991). Remarks. The family Flabellinidae has been reviewed recently by Gosliner and Willan (1991).	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4739FFABE38EFBA3A42A99F1.taxon	materials_examined	Material. Chag 96 / 88: 25 mm; cave on inner reef, Nelson Island, Great Chagos Bank; 3 March 1996; at 23 m depth. Description. Ground colour deep orange-red. Rhinophores simple, long and tapering, deep orange-red. Digitiform cerata orange, with orange-red tips. Geographic distribution. Indo-West Paci ® c: South Africa and Red Sea to Hawaii (Yonow, 1994 a, 2000). Remarks. This species is normally found associated with dendrophyllid corals. The single specimen was found on the ¯ oor of a cave; it is possible that it was dislodged from corals on the cave roof by exhaust bubbles. Members of the genus tend to be medium-sized aeolids and have evolved to feed on corals. As a result, they lack the cnidosacs in the cerata, which have been replaced by enlarged gland cells. Three species are known: P. melanobrachia and P. minor Rudman are Indo- West Paci ® c in their distributions and P. lugubris (Bergh) (as P. sibogae Bergh auctt.) occurs throughout the Indo-Paci ® c.	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
03B5F62B4739FFABE38AFF33A74A9B2B.taxon	materials_examined	Material. Chag 96 / 4: 15 mm; Salomon Channel, Salomon Atoll; 9 February 1996; at 6 m depth. Chag 96 / 10: 20 mm; outer reef, Ile Anglais, Salomon Atoll; 11 February 1996; at 15 m depth. Chag 96 / 25: 25 mm; outer reef, between Ile Boddam and Ile Poule, Salomon Atoll; 13 February 1996; at 13 m depth. Chag 96 / 44: 22 mm; outer reef, Ile Diamante, Peros Banhos Atoll; 20 February 1996; at 15 m depth. Chag 96 / 57: length not recorded; inner reef, Ile du Coin, Peros Banhos Atoll; 22 February 1996; at 4 m depth, with two additional individuals (photographed). Description. Body very elongated and narrow. Dorsal coloration cream to brown, with bright blue median line. Many series of cerata, with more in the longer individuals. Cerata bulbous and longitudinally striated; coloration variable, from fawn with limited blue streaks to almost entirely blue or purple. Rhinophores fawn with white specks and purple tips or distal band. Oral tentacles long, white with three purple bands; opaque white to lime green area at base. Geographic distribution. Indo-West Paci ® c: Red Sea and South Africa to Hawaii (Yonow, 1994 a, 2000). Remarks. Rudman (1982 a) reported the presence of zooxanthellae, visible as brown speckling on the head, body and cerata. The morphological adaptations to these symbionts are seen in the well-spaced clusters of cerata, each cluster a large fan-shape; not only do the cerata not shade each other, but they do not shade the zooxanthellae in the body either. The presence of zooxanthellae partly explained why P. ianthina was rarely found on a food source. Subsequently, Willan (1989) published a short note on P. ianthina found feeding on the hydroids Halocordyle distincta (Goldfuss) and Ralpharia magni W ca Watson. The question still remains, however: from which species does the aeolid collect its zooxanthellae and how does it acquire them?	en	Yonow, Nathalie, Anderson, R. Charles, Buttress, Susan G. (2002): Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean. Journal of Natural History 36 (7): 831-882, DOI: 10.1080/00222930110039161, URL: http://dx.doi.org/10.1080/00222930110039161
