Gustavus, Ahyong, Shane T. & Ng, Peter K. L., 2009

Ahyong, Shane T. & Ng, Peter K. L., 2009, Aphanodactylidae, a new family of thoracotreme crabs (Crustacea: Brachyura) symbiotic with polychaete worms, Zootaxa 2289, pp. 33-47 : 40

Gustavus n. gen.

Type species. Gustavus mecognathus n. sp., by present designation.

Diagnosis. Carapace wide, ovate to subpentagonal, males 1.4 times wider than long, females 1.8 times wider than long; lateral margins cristate but not continuous to external orbital end; surface finely pubescent, especially towards anterior half. Front narrow, deflexed medially, prominently triangular in frontal view; medially emarginate in dorsal view. Orbit transverse, normal; orbital margins entire, unarmed; infraorbital margin mesially terminating in rounded angle; supraorbital margin demarcated from antennular fossa by acute tooth; infraorbital and supraorbital margins not continuing laterally beyond orbit proper. Eyes short, mobile, fully occupying orbit. Antennules articulating obliquely. Epistome short, medially sunken. Maxilliped 3 covering buccal cavern; ischium slender, triangular, markedly longer than merus, inner distal angle produced mesially to form rounded lobe; merus rounded-subquadrate. Thoracic sternites 1 and 2 completely fused, broadly rounded anteriorly; sternites 2/3 demarcated by shallow groove; sternites 3/4 fused, laterally unarmed; sternites 4–8 demarcated by narrow grooves, those demarcating sternites 4–7 medially incomplete; without longitudinal groove. Cheliped merus and carpus unarmed, covered with short, fine, black-brown setae and some longer plumose setae on merus and carpus. P2–5 similar in shape, P3 longest; meri 3 or more times as long as high, slightly longer than carpus and propodus combined; covered with short, fine, black setae, especially on carpus and propodus, and longer plumose setae on merus to coxa. P5 markedly shorter than preceding leg, dorsal to others. P4 and 5 ischia and meri with prominent spines of flexor margins. P2–5 with short spines on distoflexor angle of propodi opposing dactyli; dactyli very short, claw-like. Male abdomen broad, linguiform, somites 4–6 fused; widest at somite 3; thoracic sternite 8 exposed when abdomen closed. Female abdomen with telson and all somites freely articulating, widest at somite 4. Vulva large, ovate, almost as wide as sternite 6. G1 simple, slender, strongly bent mesially at distal quarter. G2 small, about ¼ length of G1, slender, apex blunt.

Etymology. Named for Gustav Paulay, who collected the type material of G. mecognathus . Gender masculine.

Included species. Monotypic.