Eucalliaxiopsis Sakai, 2011

Poore, Gary, 2021, Indo-West Pacific and Australian species of Eucalliacidae with descriptions of four new species (Crustacea: Axiidea), Memoirs of Museum Victoria 80, pp. 1-41 : 16

Eucalliaxiopsis Sakai, 2011

Eucalliaxiopsis Sakai, 2011: 503–504 .— Poore et al., 2019: 127–

128 (synonymy).

Remarks. Eucalliaxiopsis differs from Calliaxina in having a strong ridge across the telson, lacking an exopod on maxilliped 3 (with one exception), the appendix masculina overlapping the endopod of pleopod 2, and in the major cheliped of the male usually being more robust, the palm longer and wider, than that of the female. In Calliaxina , the telsonic ridge is absent or obsolete, maxilliped 3 always possesses an exopod, the appendix masculina does not reach the apex of the endopod of pleopod 2, and chelipeds of males and females are not differentiated from each other nor scarcely from the minor chelipeds. In as much as can be deduced from published illustrations, the lower margin of the merus of the chelipeds is smooth or with small tubercles at its midpoint in Eucalliaxiopsis , whereas this margin bears small proximal truncate teeth in Calliaxina . The post-rostral dorsal area of some species of Eucalliaxiopsis ( E. aequimana , E. madagassa ) has a broad median longitudinal ridge, seen also in Eucalliax quadracuta ( Biffar, 1970) .

Eucalliaxiopsis includes seven species from the Indo-West Pacific, of which three are newly described here, plus three species from the Western Atlantic: E. cearaensis ( Rodrigues and Manning, 1992) from Brazil, E. jonesi from the Bahamas and E. mcilhennyi from Florida, USA. The species identified as E. HWI from Hawaii by Robles et al. (2020), which is genetically quite separate from six other species, was not available for study.

Eucalliaxiopsis panglaoensis , E. dworschaki and E. paradoxa , the last two being new species described here, differ from the others. All possess a transverse telson ridge beset with a row of short spiniform setae, a distally excavate uropodal endopod, a cheliped carpus with two distal spines on the upper margin, two mesiodistal lobes near the apex of the lower lateral margin plus a submarginal distal ridge on the mesial face. The carpus is similar to that of Eucalliax quadracuta , sole member of its genus. The first two of this group were found to be sister taxa by Robles et al. (2020) but the others were not monophyletic.

Calliaxiopsis Sakai and Türkay, 2014 , was synonymised with Calliaxina by Poore and Dworschak (2017). Bakercalliax Sakai, 2018 , Heardcalliax Sakai, 2018 , and Manningcalliax Sakai, 2018 , were all differentiated from Eucalliax , Calliaxina and from each other largely on the basis of the male pleopod 1 but also on the relative sizes of the appendices interna and masculina of pleopod 2. All were synonymised with Eucalliaxiopsis by Poore et al. (2019), who argued that similar forms of the male pleopod 1 are found in Eucalliaxiopsis and Calliaxina and that some of the forms used as generic characters by Sakai (2018) are characteristic of juveniles.