Bioacoustics of Thalassograpsus harpax

Redescription. Carapace subquadrate ( Figs. 16 a, 18a), about 1.2 times as broad as long, maximum breadth between second anterolateral teeth; posterior surface smooth, small granules sparsely over posterior surface; anterior half of carapace moderately elevated; curved frontal ridges slightly elevated, granular. Front 2-lobed, lobes wide, slightly convex, separated by wide, deep median notch; frontal edge clearly longer than posterior edge of carapace. Inner orbital margins curved downward, completely separated from frontal lobes; elevated ridge extends obliquely from inner orbital margin towards frontal ridge; infraorbital margin with 3 interrupted lobes, median, lateral lobs granular; upper orbital margin is divided to 2 unequal lobes with hardly distinguishable fissure; margin of inner small lob smooth; margin of outer long lob obviously granular. Anterolateral margin with 3 teeth, first two of same size, large; last one smaller than formers; tip of teeth in large males quite blunt, white, in small specimens spiniform. Third maxillipeds ( Fig. 16 d) with narrow gap between them, narrower in middle part; ischium smooth, about 3/ 2 as long as merus, narrowing proximally, inner margin elevated, long setae along inner margin; merus slightly broader than long, with prominently elevated margins, anterior margin nearly 2-lobed, inner lobe rounded, outer lobe nearly straight. Stridulating strip of males ( Fig. 16 c) with 4 parts: first one linear, regularly crenulated; second linear, massive, moderately rounded on anterior end, narrowing backwardly, reaching to anterior angle of first anterolateral tooth; third prominently rounded in anterior end, backwardly linear, reaching to anterior angle of second anterolateral tooth; fourth as large rounded tubercle. Stridulating strip of females linear, continuous, regularly crenulated, reaching to middle of first anterolateral tooth. Chelipeds of males ( Fig. 16 b) large, usually subequal, smooth. Manus large, massive, as board as long; outer surface smooth, short row of small granulates longitudinally on other surface of unmovable finger; inner surface with patch of dense setae. Fingers slender, large gap between them, tips of fingers spooned, white-coloured; immovable finger curved upward distally, cutting edge without tooth; movable finger with large blunt tooth on middle point (in one of cheliped, left or right), variable amount of small teeth towards distal end. Walking legs slender, flattened; merus with small distal spine on outer surface, fourth walking legs ( Fig. 16 e) with small distal spine on distal edge of carpus, dactylus with 4–6 distal spines on anterior surface, 1 or 2 median spines on posterior surface. G1 ( Fig. 16 f) straight over most of its length, relatively stout, approximately diagonal in cross section, gently curved in the proximal part, distal part very slightly swollen, tip brown, narrow, directed outward, with distal margin concave, surrounded by long setae; genital opening distal ( Fig. 16 g).