Callichirus Stimpson, 1866

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 : 109

Callichirus Stimpson, 1866

Callichirus Stimpson, 1866: 47 .—de Saint Laurent and Le Loeuff, 1979: 55–56.— Manning and Felder, 1991: 775–776.— Sakai,2011: 418 (abbreviated synonymy).

Callianassa (Callichirus) .— Borradaile, 1903: 546–547.—De Man, 1928: 28, 96 (partim).

Type species. Callianassa major Say, 1818 , by original designation and monotypy.

Diagnosis. Anterior branchiostegal lobe sclerotised, well produced anteriorly beyond junction with oblique branchiostegal ridge with which it articulates by means of a virtual condyle. Rostrum obsolete or obtusely triangular, flat, not reaching cornea. Pleomere 1 tergite divided into 2 sections by unsclerified band; tergite weakly sclerotised, if so only posteriorly; pleura oblique thin rods independent of tergite dorsally, separated by extensive flexible region; sternite a thin transverse plate. Pleomeres 3–5 with symmetrical pattern of deep curved transverse and longitudinal grooves plus paired tufts of dense setae, pleomere 6 with pair of deep longitudinal grooves on wide swollen anterior section, defined by lateral concavity. Antennular peduncle length longer than antennal peduncle. Maxilliped 3 ischium and merus less than twice as long as wide at their articulation; crista dentata absent (or few proximal spines only); propodus about as wide as long, free distal margin clearly oblique or free distal margin transverse or nearly so. Male major cheliped merus with denticulate blade, more prominent over proximal half of lower margin or with prominent proximal denticulate blade-like tooth on lower margin; major cheliped carpus much longer than palm, especially in male. Male minor cheliped much narrower than major, carpus longer than palm, fingers shorter than palm. Pereopod 3 propodus subpentagonal, with strong broadly rounded proximal lobe on lower margin, lower margin straight-concave. Pereopod 4 subchelate. Male pleopod 1 consisting of 2 articles, article 2 longer than wide, with or without slight apical notch. Male pleopod 2 appendix interna absent or reduced to obsolete distomesial lobe. Pleopods 3–5 appendices internae barely emerging from endopod margin. Uropodal endopod strap-like, posterior margin concave. Telson thickened, with constriction on anterior region, with posterolateral swellings, posterior margin with medial notch at end of longitudinal groove.

Remarks. Species of Callichirus are recognised by the symmetrical pattern of deep curved transverse and longitudinal grooves plus paired tufts of dense setae on pleomeres 3–5, deep longitudinal grooves on the wide anterior section of pleomere 6, the long antennular peduncle, the strap-like curved uropodal endopods and the thickened telson, with a proximal constriction. Callichirus kraussi is here removed to its own genus, Kraussillichirus , on genetic evidence (Robles et al., in press) and uropodal endopods more typical of the family. Species of Callichirus may be functional hermaphrodites with some or all females having male gonopores ( Souza et al., 2017, 2018)