Chandraniscus, George, 2004

George, Robert Y., 2004, Deep-sea asellote isopods (Crustacea, Eumalacostraca) of the north-west Atlantic: the family Haploniscidae, Journal of Natural History 38 (3), pp. 337-373 : 342-343

Chandraniscus n. gen.

(figure 4)

Type species: Chandraniscus eastwardae n. gen., n. sp.

Diagnosis. Haploniscidae with pereonites 5–7 free, without any trace of middorsal or lateral fusion. Antenna 2 lacking a spinous dorsal process on peduncular article 2. Uropod uniramous, composed of a single segment.

Etymology. This new genus is named in honour of my wife Mrs Chandra George (a biologist) who spent several hours inking the author’s original pencil drawings of the new species described in this paper.

Remarks. Lincoln (1985a), while describing haploniscid isopods from off New Zealand, added five new species to the genus Haploniscus Richardson, 1908 and brought the total number of known species in this genus to 52. Nevertheless, he pointed out that lack of any single diagnostic character in this genus makes ‘a simple and unambiguous definition of the genus impossible’. He also expressed the view that the genus Haploniscus has ‘thus become a depository for all forms lacking a distinctive morphology and further work will undoubtedly reveal the heterogeneity of this genus’. The new genus Chandraniscus, established in this paper, accommodates all those species previously attributed to Haploniscus that exhibit no fusion in pereonites 5–7.

The type species of the genus, Haploniscus biscuspis (Sars, 1877), shows pronounced sexual dimorphism with males showing fusion of pereonites 6 and 7 with the pleotelson, but females showing fusion of only pereonite 7 with the pleotelson. Such sexual dimorphism is lacking in another species, H. angustus Lincoln, 1985 b, which displays similar morphology in both sexes, with only pereonite 7 fused with pleotelson. In this paper all the known species of Haploniscus showing different patterns of fusion in the pereonites are retained in the genus and all other species with distinct free pereonites without any fusion are transferred to the new genus Chandraniscus.

Therefore, all five species of Haploniscus described by Lincoln (1985a) from off New Zealand, H. tangaroae, H. silus, H. miccus, H. piestus and H. saphos, are now accommodated in the new genus Chandraniscus because of the free, non-fused, nature of pereonites 5–7. However, all eight species of Haploniscus (five new species and three known species) reported by Lincoln (1985 b) from the north-east Atlantic show different patterns of fusion of pereonites 5–7 and are now considered genuine species of the genus Haploniscus.

Menzies (1962) added 20 new species to the genus Haploniscus from both the south and north Atlantic. Lincoln (1985a) assigned six of these 20 species to a new genus, Chauliodoniscus, which includes those species that have the lateral extremities of some anterior pereonites produced at the anterolateral angles. Haploniscus excisus Richardson, 1908 from the north-west Atlantic off New England has free pereonites 5–7 and, therefore, it is accommodated in the new genus Chandraniscus. Five new species of Chandraniscus are described below from the north-west Atlantic in this study.