Hoplodoris estrelyado Gosliner and Behrens, 1998

Yonow, Nathalie, Anderson, R. Charles & Buttress, Susan G., 2002, Opisthobranch molluscs from the Chagos Archipelago, Central Indian Ocean, Journal of Natural History 36 (7), pp. 831-882 : 846-847

Hoplodoris estrelyado Gosliner and Behrens, 1998

(®gures 4d, 6E, 8)

Hoplodoris estrelyado Gosliner and Behrens, 1998: 280 , ®gures 1A, 2, 3.

Material. Chag96/89: 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 4d). 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 6E, 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)