Eucalliax Manning and Felder, 1991

Poore, Gary C. B., Dworschak, Peter C., Robles, Rafael, Mantelatto, Fernando L. & Felder, Darryl L., 2019, A new classification of Callianassidae and related families (Crustacea: Decapoda: Axiidea) derived from a molecular phylogeny with morphological support, Memoirs of Museum Victoria (Mem. Mus. Vic.) 78, pp. 73-146 : 127

Eucalliax Manning and Felder, 1991

Eucalliax Manning and Felder, 1991: 781–783 (partim).— Ngoc-Ho, 2003: 489–490 (partim).— Sakai, 2011: 502–503 (partim).— Hyžný and Hudáčková, 2012: 12–14 (partim).— Sakai, 2017a: 1122 (partim).— Sakai, 2018: 742.

Type species. Callianassa quadracuta Biffar, 1970 , by original designation.

Diagnosis. Anterior dorsal carapace with median ridge posterior to rostrum and submedian pair of oblique ridges. Maxilliped 3 ischium and merus less than twice as long as wide at their articulation. Male major cheliped with palm about twice as long as carpus, 1.5 times as long as wide; minor chela slightly smaller, with elongate fingers; major cheliped carpus upper margin with 2 distal sharp spines in both sexes. Male pleopod 1 article 1 with distal long setae; article 2 blade like, with bifid apex, sometimes obscure; without appendix interna. Male pleopod 2 appendix interna minute; appendix masculina

4 times as long as wide, attached near apex of endopod reaching, or exceeding tip of endopod. Uropodal endopod triangular, anterior margin strongly convex, posterior margin straight. Telson convex-sided, widest near midpoint, posterior margin slightly excavate; with transverse crest.

Remarks. The most obvious characters distinguishing the only species, Eucalliax quadracuta , from other eucalliacids is the triangular uropodal endopod and the male pleopod 2 with its appendix masculina well exceeding the endopod.Re-examination by us ( PCD) showed the presence of a minute appendix interna (fig. 19w); Sakai’s figure (1999a; fig. 30c) is misleading.

Eucalliax was differentiated initially from Calliax simply “in having the chelipeds equal and similar”, the two genera being placed in the same new subfamily ( Manning and Felder, 1991). The genus was treated as a synonym of Calliax by Sakai (1999a, 2005b) without justification but revived later ( Sakai, 2011). Sakai (2017a) differentiated Eucalliax from Eucalliaxiopsis Sakai, 2011 on differences in male pleopods 1 and 2 but not from other genera.