Rayapinus, Rahayu & Ng, 2014

Rahayu, Dwi Listyo & Ng, Peter K. L., 2014, New genera and new species of Hexapodidae (Crustacea, Brachyura) from the Indo-West Pacific and east Atlantic, Raffles Bulletin of Zoology 62, pp. 396-483 : 459

Rayapinus , new genus

Diagnosis. Carapace broader than long; surface almost smooth with sparse tubercles on margin or distinctly granulated; regions indistinct, with shallow U-shaped depression medially. Anterolateral margin arcuate; pterygostomial region with row of long and short, broken or entire, oblique striae and scattered tubercles. Eye short, stout, slightly movable, cornea subglobular. Third maxilliped broad, without gap when closed; ischium narrow slightly longer than merus, mesial margin rounded; carpus, propodus and dactylus cylindrical; dactylus longer than propodus; exopod moderately wide. Chelipeds unequal, P2–P4 short, stout; propodus and dactylus very short; propodus rounded, dactylus shorter than propodus; dactylus of P2 and P4 slightly curved. Thoracic sternites 1 and 2 fused; sternite 3 separated from sternite 4 by tuberculate ridge laterally, median area appearing fused; sternites 4–7 well developed, separated from each other by distinct suture; sternite 8 exposed, triangular, as long as male abdominal somite 1. Sternoabdominal cavity reaches middle of thoracic sternite 4. Male thoracic sternal groove short. Male abdomen narrow, somites 1, 2 and 6 free, somites 3–5 fused; telson rounded. G1 stout, bent subdistally, apice not concealed under abdomen. Female abdomen relatively narrow, somites 1–6 fused, telson almost as long as somite 6.

Etymology. Named in honor of Ray Manning. The name Rayapinus is derived from his first name, Ray, with “- pinus ”, the suffix of the allied genus Hexapinus . Gender masculine.

Remarks. This genus is remarkable for its short and stout P2–P4 with the propodus and dactylus especially short, and the characteristic G1 shape that has wide apices with row of spines. The extension of the male thoracic sternal groove is similar to that of Hexapinus but the shapes of their third maxillipeds and male abdomens are different. In Hexapinus , the ischium of the third maxilliped is strongly dilated mesially ( Fig. 13C ) and the male abdominal somite 6 is slightly shorter than somites 3–5 ( Fig. 21C ). In Rayapinus , the ischium of the third maxilliped is not dilated mesially ( Fig. 53E ) and the male abdominal somite 6 is much shorter than somites 3–5 ( Fig. 53F ).

Species included. Rayapinus maenosonoi , new species (type species by present designation).

Figures

Fig. 13. Hexapinus latipes (De Haan, 1835). A, B, E, G, female (10.2 × 7.6 mm) (NSMT-Cr 5694); C, holotype female (10.6 × 6.4 mm) (RMNH 31783d; D, F, female (30.4 × 17.5 mm) (KPM NH 6331). A, overall view of carapace; B, thoracic sternites 1–5, showing thoracic sternal groove and sternoabdominal cavity; C–E, left third maxilliped; F, G, female abdomen and telson. Scale bars: A, B, D–G = 1.0 mm; C not to scale.

Fig. 21. Hexapinus simplex, new species. A, B, F, holotype male (7.8 × 5.0 mm) (MZB); C, paratype female (6.9 × 4.5 mm) (ZRC 2013.1689); D, paratype female (4.5 × 2.8 mm) (ZRC 2013.1689); E, paratype male (5.4 × 3.4 mm) (ZRC 2013.1689); G, male (12.7 × 7.5 mm)(ZRC 2012.1016). A, B, G1; C, D, female abdomen and telson; E–G, male abdomen and telson. Scale bars = 1.0 mm.

Fig. 53. Rayapinus maenosonoi, new species. A–K, holotype male (6.6 × 4.9 mm) (RUMF-ZC-2115); L, paratype female (4.3 × 3.1 mm) (ZRC 2012.1034). A, carapace; B, anterior view of carapace; C, thoracic sternites 1–5, showing sternoabdominal cavity and thoracic sternal groove; D, thoracic sternites 1–5, showing thoracic sternal groove and telson; E, left third maxilliped; F, male abdomen and telson, G, major chela; H, minor chela; I, left P4; J, K, G1; L, female abdomen and telson. Setae on chelae not drawn. Scale bars = 1.0 mm.