Andamancalliax Sakai, 2011: 494–495.— Sakai, 2018: 738.

Type species. Calliax andamanica Sakai, 2002, by original designation and monotypy.

Diagnosis. Maxilliped 3 ischium and merus narrow, more than twice as long as wide at their articulation; ischium with strong proximal lobe on lower margin, wider proximally than distally. Major cheliped broad, minor cheliped narrower, with long fingers. Male pleopod 1 article 1 with distal long setae, article 2 blade like; without appendix interna. Male pleopod 2 appendix interna digitiform; appendix masculina a lobe fused to appendix interna attached midway on endopod margin. Telson widest anteriorly, more or less semicircular.

Remarks. Andamancalliax was erected for a single species, sharing with species of Calliaxina similar pereopod 3, pleopod 3, telson, uropod, and male and female pleopods 2. We have assumed that Sakai’s (2002) figure 2B, labelled as from a female, is of the simple male pleopod 1; Sakai (2002) reported it absent but later (Sakai, 2005b, 2011) said it was present, uniramous and with an emarginate tip. It would appear to be a juvenile form. Sakai’s (2011) generic diagnosis contains nothing that would distinguish the new genus from any other eucalliacid—in fact it is wrong in stating that the male pleopod 2 lacks an appendix interna—it is clearly figured in Sakai’s (2002) mislabelled figure 2A. He provided no justification for the new genus; his key separated Andamancalliax with emarginate distal male pleopod 1 article from Eucalliaxiopsis where this article was said to incurve distally but the male pleopod 1 of members of the latter varies markedly. Calliax andamanica has a more acute rostrum than most species of Calliaxina but among its members the rostrum ranges from almost non-existent to sharply triangular (in C. sakaii, for example). However, A. andamanica has a narrow maxilliped 3 with a proximal lobe (similar to that in Paraglypturus spp. and Pseudocalliax tooradin) and asymmetrical chelipeds, quite unlike other eucalliacids and the genus is justified. A new species of this genus possesses a small exopod on maxilliped 3, not reported for A. andamanica (Poore, in press).