Caviallianassa, Poore & Dworschak & Robles & Mantelatto & Felder, 2019

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 : 92

Caviallianassa gen. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:9819F120-10C6-

496D-80E2-BDDAD3FBAE07

Type species. Cheramus cavifrons Komai and Fujiwara, 2012 , by present designation.

Diagnosis. Rostrum obsolete or obtusely triangular, flat, not reaching cornea. Pleomere 1 tergite undivided or with weak transverse ridge. Antennular peduncle articles 2 and 3 with single lateral row of 6–10 well-spaced long setae along lower margin. Maxilliped 3 merus wider at ischium-merus suture than long; dactylus ovate, with dense brush of long setae over most of upper-distal margin, few setae along lower margin. Male major cheliped merus with 1–3 oblique similar short proximal spines on lower margin, beaded beyond; propodus distal margin unornamented, oblique, or with small lateral tooth. Minor cheliped two-thirds width of major cheliped, both flattened. Pereopod 3 propodus rectangular, lower margin deeply convex, leading to broadly rounded free proximal lobe. Uropodal endopod ovoid, usually longer than wide, anterior margin straight or slightly convex, posterodistal margin evenly convex, with facial spiniform setae on rib. Uropodal exopod posterodistal margin with row of 6–8 long blade-like setae proximal to long setae on distal margin. Telson about as wide as long, tapering from anterolateral lobe; anterolateral lobe obsolete, undefined.

Etymology. An alliteration of the name of the type species and Callianassa , type genus of the family.

Remarks. A group of two, possibly three, undescribed species from Papua New Guinea and French Polynesia was revealed by our molecular treatment (Robles et al., in press). Morphological examination revealed these to be similar to Cheramus cavifrons , of which only the female is known. The chelipeds are similarly compact in all species and have a row of tubercles on the lower margin of the merus beyond a proximal tooth or series of small short spines. Komai and Fujiwara (2012) did not illustrate the unusual setation of the dactylus of maxilliped 3 but its proportions are otherwise similar to the undescribed species, nor did they illustrate the spiniform setae on the face of the uropodal endopod; both features are generally overlooked.

Caviallianassa shares with two genera related on genetic and molecular evidence (Robles et al., in press) a maxilliped 3 dactylus with a dense brush of long setae over most of the upper-distal margin and few setae along the lower margin. Caviallianassa differs from the first, Rudisullianassa , in having the antennular peduncle about as long as or a little longer than the antennal peduncle (vs exceeded by all or most of the antennal peduncular article 5) and having a small spine on the merus of the major cheliped (vs smooth). Males and females of Caviallianassa are known but only females with male gonopores of Rudisullianassa are known. Caviallianassa differs from Fragillianassa in having a wider minor cheliped, lacking a prominent hook on the merus of the major cheliped and having facial setae on the uropodal endopod.