Calliaxina, Nguyen Ngoc-Ho, 2003

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 : 126-127

Calliaxina Ngoc-Ho, 2003

Calliaxina Ngoc-Ho, 2003: 493–494 .— Sakai, 2011: 497–498.—

Hyžný, 2012: 55–56.— Sakai and Türkay, 2014: 191.— Ngoc-Ho, 2014:

549.— Poore and Dworschak, 2017: 120 (partim).— Sakai,2018: 739–741. Calliax .— Sakai, 2005b: 196 (partim, not Calliax de Saint

Laurent, 1973). Calliamina Sakai and Türkay, 2014: 190 (misspelling).

Type species. Calliax punica de Saint Laurent and Manning, 1982 , by original designation.

Diagnosis. Cardiac sulci present. Pleomere 1 with pair of sternal plates anterior to pleopods 1. Maxilliped 3 ischium and merus broad, less than twice as long as wide at their articulation. Both chelipeds with palms as long as wide in both sexes, minor slightly smaller if at all. Male pleopod 1 article 1 with distal long setae; article 2 blade-like with bifid apex (sometimes obscure), or article 2 much shorter, digitiform (sometimes fused); with appendix interna (present at least as hooks on endopod). 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, curving to broad convex apex.

Remarks. Calliaxina differs from Eucalliaxiopsis in having a tapering telson without a transverse ridge, and at least a vestige of an appendix interna on pleopod 1 of the male. All species have an exopod on maxilliped 3, sometimes vestigial, whereas only one species of Eucalliaxiopsis does.

Calliaxina was erected by Ngoc-Ho (2003) for three species previously included by Sakai (1999a) in Paraglypturus Türkay and Sakai, 1995 and later (Sakai, 2005) in Calliax . Ngoc-Ho (2003) tabulated differences between these genera but did not include Eucalliax Manning and Felder, 1991 , which she diagnosed separately in her table. Her diagnosis relied importantly on the presence of an exopod on maxilliped 3, equal and similar chelipeds, appendix interna on pleopods 1 and 2 of the male. Some of her key features are difficult to quantify, notably the shape of the front and anterolateral projections of the carapace, and length of the appendix interna on pleopods 3–5. Sakai (2005) synonymised Calliaxina with Calliax without discussing any morphological similarities or differences. Later, Sakai (2011) revived Calliaxina which he had earlier synonymised in new sense (sensu nov.) by including other species with similar maxillipeds 3 and with one or two cardiac sulci, although some lack maxillipedal 3 exopods. At the same time, he erected a monotypic genus Eucalliaxiopsis Sakai, 2011 , relying on the possession of unique male pleopods (see below).

As already explained, Robles et al. (in press) divided the species allocated by Sakai (2011) to Calliaxina and Eucalliaxiopsis into two groups. Their molecular analysis grouped C. bulimba , C. kensleyi , C. novaebritanniae and C. sakaii into a one clade, and C. aequimana , C. inaequimana , C. panglaoensis , C. jonesi and three others into a second clade. The morphological treatment includes C. punica , type species of Calliaxina in the first and C. cearaensis , type species of Eucalliaxiopsis in the second. These two names are applied to these clades.