Fragillianassa, 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 : 94

Fragillianassa gen. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:CFA11DDC-A9C5-

4ACC-AC90-E2C6A5456E82

Type species. Callianassa fragilis Biffar, 1970 , by present designation.

Diagnosis. Rostrum obsolete or obtusely triangular, flat, not reaching cornea. Pleomere 1 tergite undivided or with weak transverse step. Antennular peduncle length about 2.5–3 times the width of both eyestalks. Antennal scaphocerite reduced to small floating disc. 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 prominent truncate hook armed with serrations along lower margin, excavate laterally at base; propodus distal margin with deep notch at base of fixed finger. Pereopod 3 propodus rectangular, lower margin deeply convex, leading to broadly rounded free proximal lobe. Male pleopod 2 absent. Uropodal endopod ovoid, usually longer than wide, anterior margin straight or slightly convex, posterodistal margin evenly convex. Uropodal exopod posterodistal margin with row of 6–8 long blade-like setae proximal to long setae on distal margin. Telson truncate, or slightly convex between posterolateral angles, or slightly concave, sometimes with medial spine.

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

Remarks. Fragillianassa , with two species recognised so far, is most similar to Necallianassa and Neotrypaea , with which it shares a similar eyestalk, antennule and maxilliped 3 merus. Fragillianassa differs from both in having an extremely reduced scaphocerite, a dense brush of long setae over most of the upper-distal margin of the dactylus of maxilliped 3 and an ovoid uropodal endopod longer than wide, more symmetrical than in the other two. Fragillianassa differs from Necallianassa most obviously in lacking spines on the sides of the telson and on the anterior margin of the uropodal endopod, and it differs from Neotrypaea in lacking a transverse facial row of setae on the uropodal endopod.