Bioacoustics of Venitus dentipes

Redescription. Carapace ( Fig. 4 a) moderately wider than long (CB/CL = 1.6–1.7), slightly convex; large granules scattered on entire posterior surface except in narrow median, frontal regions, granules on branchial regions high, longitudinal row of 6–8 high granules on epibranchial region, granules on median regions low, round. Regions well defined; furrows wide, moderately deep, normally beset with dense setae. Frontal region remarkably deflexed downward, smooth; front very narrow, about 0.06–0.07 times as wide as carapace, strongly constricted medially; anterior edge remarkably concave, bi-lobed, frontal furrow markedly deep. Lateral margin of carapace ( Fig. 4 a) with 3 distinct teeth (including exorbital tooth); first nearly subquadrate, with posterior margin smooth, curved forward; second triangular, with smooth margin, higher than first, greatest width of carapace between second lateral teeth; third very small, directed forwards; posterolateral margin nearly straight, slightly converging posteriorly, with small granules, beset with long setae; posterior margin with very small granules. Eyestalks narrow ( Fig. 4 a), long, but not reaching to exorbital angle; upper orbital margin fairly convex, regularly granular, granules large, high, pointed, directed laterally; lower orbital margin ( Fig. 4 b) with round granules on inner third, 5–6 long tubercles on outer portion of margin forming stridulating ridge. Third maxillipeds leaving small gap between; ischium slightly more than twice the length of merus, inner margin of ischium, merus with long setae, outer margins with short setae, outer margin of ischium completely straight, outer margin of merus sharply sloping distally; outer surface of ischium, merus smooth, elliptical row of long setae proximally on outer surface of ischium. Chelipeds nearly equal, sometimes subequal, remarkably long in large specimens ( Fig. 4 f). Merus ( Fig. 4 e) long; inner upper margin with distinct stridulating ridge, large granules along it, larger distally, with scarce setae; inner lower margin with small granules, continuous with lower surface; upper margin with small granules on proximal portion, with scarce setae. Carpus smooth on outer surface, inner upper margin with denticles, distally larger, small granules along inner portion of these denticles. Palm long ( Figs. 4 c, d, f), about 1.8–2.3 times as long as high in proximal portion; outer surface smooth ( Figs. 4 c, f) without longitudinal ridge; inner surface ( Fig. 4 d) smooth, patch of dense setae on upper portion, parallel to upper margin; lower margin nearly smooth; upper margin with large granules on proximal portion, smaller distally. Fingers remarkably curved inward distally, movable finger with upper margin smooth, long setae densely along inner surface of upper margin, continuous on upper, outer surface, cutting edge with subproximal differentiated tooth, small teeth distally; immovable finger narrow, with relatively large teeth on cutting edge, long setae along inner surface. Cheliped of females small; outer surface of palm smooth, longitudinal ridge short, extending from base of immovable finger to proximal half; upper margin with small granules, with long setae; lower margin smooth, with relatively short setae; fingers distinctly long, slightly less than 1.5 length of palm; cutting edge faintly tuberculate, chitinous distal margin long, more than half of length of finger, long setae on inner surface of fingers. Walking legs moderately long; second, third longest, with margins of segments more granular than those of first, fourth. Merus long, that of third leg about 4 times as long as wide; merus of first, second, third walking legs with subdistal tooth on anterior margin, 3–4 large denticles distally on posterior margin, merus of females with large denticles on anterior margin. Carpus of first walking leg, with longitudinal ridge, that of second, third with two ridges of long granules on anterior margin, carpus of third with one distinct large denticle distally on posterior margin. Propodus of second with small denticles on anterior, posterior margins; propodus of third with small denticles on anterior margin, large, spine-shaped denticles on posterior margin; dense setae on upper portion of anterior surface of carpus, propodus of third. Posteromedian margin of epistome nearly straight, short longitudinal ridge on anterior part of buccal cavity. Male abdomen ( Fig. 5 d) with segments 3, 4 of same length, slightly shorter than segment 5; segments 5, 6 nearly of same length, with lateral margins nearly straight; lateral margins of segment 6 with small depression at one third distal portion; telson very slightly longer than segment 6, lateral margins strongly converging distally, apically rounded. Female abdomen ( Fig. 5 e) with large telson, slightly longer than segment 6, distinctly wider than half length of segment 6. Male G1 ( Fig. 5 a) moderately stout, slightly curved outward medially; distal half relatively narrowing, with apical chitinous process ( Figs. 5 b, c) remarkably long, narrow, curved outward at about 45°; distal opening ( Fig. 5 b) large, distinct, subdistal on dorsal portion of apical process; long feather-shaped setae densely set along lateral margin, long setae around apical process. Female gonopore ( Fig. 5 f) on outer wall of depression, directed mesially, anterior margin distinctly rounded, elevated, outer margin slightly convex; operculum small, directed laterally.