Megaesthesius westralia Davie, 2013

Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), Zootaxa 4209 (1), pp. 1-182 : 91-92

Megaesthesius westralia Davie, 2013

( Figs. 19 M–R; 34C; 82J–M)

Megaesthesius sagedae —Poore et al. 2008: 46. Not Megaesthesius sagedae Rathbun, 1909 .

Megaesthesius westralia Davie, 2013: 470 , figs. 1, 2, 3A‒E [type locality: Western Australia].

Type material. Holotype male (3.4 × 3.8 mm) ( NMV J54597 ), Australia, Western Australia, off Ningaloo, Southern Surveyor, stn SS10-2005, 22°04.00’S, 113°48.40'E, Sherman sled, 101-106 m, 10.12.2005.

Diagnosis. Carapace ( Fig. 19 M; Davie 2013: fig. 1A, B) subquadrate, 1.1 wider than long; front bilobed, with deep median cleft; dorsal surface with low, spherical tubercles. Lateral margins straight, parallel to each other, each with 4 teeth (last as large tubercle) separated by deep notches. Long orbits, eye peduncle elongated ( Fig. 19 O); Davie 2013: fig. 2A, B), immobile, cornea reduced, non-pigmented. Antennule greatly enlarged ( Fig. 19 N, O; Davie 2013: fig. 1), particularly in males. Third maxillipeds ( Fig. 34 C; Davie 2013: fig. 2C) nearly fill buccal cavern when closed; merus subtriangular, outer margin with small teeth; ischium subquadrate, outer margin with small teeth, about same size as merus; outer margins of merus, ischium with small spines. Chelipeds unknown. Proportionally short ambulatory legs ( Fig. 19 Q, R; Davie 2013: fig. 2D, E), dorsal, ventral margins of meri of P4 with minute teeth. Fused thoracic sternites 1, 2 ( Fig. 19 P; Davie 2013: fig. 1B, C) broadly triangular, proportionally broad, short. Male pleon ( Fig. 19 P; Davie 2013: fig. 3E) with lateral margins of somite 6, fused somites 3–5 nearly straight; postero-lateral regions slightly swollen; telson proportionally short. G1 ( Fig. 82 J–L; Davie 2013: fig. 3A– C) slender, distal segment straight, with spinules, apex slanted. G2 ( Fig. 82 M; Davie 2013: fig. 3D) nearly as long as G1, straight; slender, distal segment long, curved, as long as basal segment, directed inward. Female unknown.

Remarks. This species is known only from one male specimen without chelipeds. It is apparently closest to M. yokoyai , but can be separated by a suite of carapace, ambulatory legs, male pleon, and G1 characters (see key to species of Megaesthesius ).

Distribution. Known only from Western Australia. Depth: 101- 106 m.