Gelastreutes crosnieri Bruce, 1990

(Figs. 1, 2A–B)

Material examined. 1 female (pocl 4.6), Stn. Trawl 6, 26°23.044´N 126°47.724´E – 26°22.993´N 126°47.901´E, depth 64.0– 81.3 m, 10 Nov. 2009, NTOU M01139.

Additional material examined. 1 male (pocl 6.5), Palikulo Bay, West Mavéa Island, Vanuatu, “ SANTO 2006” Stn. AT14, 15°23.7/24’S 167°12.9/13.5’E, depth 102–120 m, 19 Sep 2006, MNHN-Na 17539.

Remarks. The single female collected during the “KUMEJIMA 2009” expedition differs somewhat from the New Caledonian female holotype (Bruce 1990), most notably in the dorsal carapace crest and the shape of the antennal scale. The dorsal carapace crest (Fig. 1 A–B) is much more pronounced than in the holotype and has only 5 teeth. The distal part of the rostrum (Fig. 1 A) is much shorter and has a terminal, dorsal tooth; the antennal scale is shorter and wider than in the holotype. In all other respects the Kumejima specimen closely resembles the holotype.

The specimen from Vanuatu shows a much greater resemblance to the holotype (Fig. 1 D), with both the dorsal and ventral lamina of the rostrum exhibiting the typical form for the species. A further pronounced difference between both specimens is the colour pattern (see below). However, a comparison of the mitochondrial barcoding gene COI (627 bp) between the Kumejima and Vanuatu specimens shows an identical sequence (GenBank accession nos. JN251749 and JN251750, respectively); suggesting that both forms are conspecific. The presently observed differences in morphology and colour patterns are clearly not related to sexual dimorphism, as the male specimen from Vanuatu resembles the female holotype more than the female collected in Kumejima. It is also not likely to be size-related, as both specimens are not overly dissimilar in carapace length.

The appendix masculina of the Vanuatu specimen (Fig. 1 E–F) is shorter than the appendix interna, and furnished with a series of serrulate setae along both its mesial and lateral margin.

Colour pattern. The specimen from Kumejima (Fig. 2A) has an overall purple to reddish background colour, with numerous darker maroon-red to deeper purple spots all over the carapace, abdomen and tail-fan. In contrast, the specimen from Vanuatu (Fig. 2B) has an overall salmon-pink colouration.

Distribution. Previously only known from a single specimen from New Caledonia, now also recorded from Vanuatu and the Ryukyu Islands.