Genus Crocydocinus n. gen.

Type species. Crocydocinus ewok n. sp., by present designation, gender masculine.

Diagnosis. Carapace pyriform. Carapace region well-defined. Pseudorostral spines short, bifid. Carapace, legs covered in thick layer of setae. Antennae almost as long or longer than pseudorostral spines. Pre-orbital spine roundish to sharp; hiatus between supraorbital eave and post-orbital lobe wide, U-shaped; post-orbital lobe terminally blunt. Basal antennal article longer than broad, outer margin slightly curved to straight margin. Third maxilliped with ischium subquadrate; anterolateral margin of merus weakly produced. Cheliped with margins of merus, carpus, propodus, and palm of chelae carinate. Ambulatory legs slender and cylindrical, merus, carpus and propodus smooth, not carinate, covered with setae, smooth when denuded; P2 longest. Male thoracic sternites 3 and 4 fused without median sutures; lateral margins of sternites 3 and 4 slightly constricted, surface concave. Male pleon triangular, all somites and telson free. Adult female pleon rounded, with all somites and telson free (Fig. 16A, B). G1 with single distal angle; G2 shorter than G1, with distal tip rounded (Fig. 18 A–F).

Etymology. The new genus is named after the characteristic thick layer of setae covering the entire carapace and legs of the crab—“ crocydo ” meaning downy fibers on woollen cloth in Latin, which is originally a Greek word, “ krokydos ”. It is used in arbitrary combination with the Latin word “ carcinus ” from the Greek word “ karkinus ” for crab. Gender masculine.

Remarks. This new genus is morphologically similar to Tunepugettia Ng, Komai & Sato, 2017, in general carapace form and having relatively wide male thoracic sternites 3 and 4 with slightly constricted lateral margins and a concave surface. Crocydocinus n. gen., however, differs from Tunepugettia in having the carapace regions more clearly defined, often with granules on each region (Figs. 13, 14) (versus carapace regions defined by strongly swollen regions and usually with no or few granules in Tunepugettia; Fig. 11A, D); the pseudorostral spines are short and straight, cylindrical and diverging to form a distinct V-shaped structure (Figs. 13, 14) (versus pseudorostral spines short, straight, slightly dorso-ventrally flattened with the outer margin slightly curved in Tunepugettia; Fig. 11A, D); the postorbital lobe is slender with a rounded distal margin (Fig. 17) (versus cup-like postorbital lobe with the side slightly flatten in Tunepugettia; Fig. 11C, F); the basal antennal article has a relatively straight to slightly convex outer margin with distal angle distinct (Figs. 15, 16) (versus outer margin of basal antennal article prominently convex with distal angle less pronounced in Tunepugettia; Fig. 11B, E); the telson of the male pleon is generally more dome shaped (Figs. 15A, D, 16C) (versus the telson of the male pleon is more triangular in Tunepugettia; Fig. 11B, E); and the ambulatory legs are smooth with the merus, carpus and propodus not carinate (Figs. 13, 14) (versus ambulatory legs with margins of merus, carpus and propodus directly carinate in Tunepugettia; Fig. 11A, D).

The G1s of all the species of Tunepugettia end in a bilobed tip (Figs. 12; Ng et al. 2017: fig. 7); while in almost all species of Crocydocinus n. gen., the G1 distal tip is simple (Figs. 18, 19 E–H); the exception being C. decipata (Williams & Eldredge, 1994) (Fig. 19 A–D). In the form of the basal antennal article and non-carinate ambulatory legs, however, C. decipata should be transferred to Crocydocinus n. gen.

With the description of four new species from Papua New Guinea, Philippines, and Vanuatu, and the transfer of four species to Crocydocinus n. gen.: C. beauchampi (Alcock & Anderson, 1894) comb. nov., C. brevirostris (Doflein, 1904) comb. nov., C. crosnieri (Griffin & Tranter, 1986) comb. nov., and C. decipata (Williams & Eldredge, 1994) comb. nov., there are eight species in this new genus.