Macrobrachium indicum, Jayachandran & Joseph, Jayachandran & Joseph, 1986

Mary, Ajina S., Jayachandran, K. V., Landge, Asha T., Gladston, Y. & Pavan-Kumar, A., 2019, Establishment of taxonomic status of Macrobrachium indicum Jayachandran & Joseph (Decapoda: Palaemonidae) through molecular characterization with a note on related species, Zootaxa 4652 (1), pp. 174-182 : 175-177

Morphological data .

Materials examined: 10 male specimens (53.9 to 10.4 mm in size), six non-berried females

(45.0 to 62.0 mm in size), one berried female of size 45.3mm collected from the Neyyar river (Latitude: 8°39’06” N, Longitude: 77°09’23” E) during April 2015 to November 2017.

Measurements (mm): Total length 104.0, carapace length 47.0,cephalo-thoracic length 28.0, length of rostrum 20.0, length of telson 11.0, length of podomeres of larger second pereiopod—ischium 27.0,merus 30.0, carpus 58.0,propodus 67.0, palm 44.0, fixed finger 26.0, movable finger (curved) 22.0, smaller second pereiopod—ischium 13.0,merus 21.0, carpus 34.0,propodus 42.0, palm 26.0, fixed finger 11.0, movable finger (not curved) 11.0.

Taxonomic account: Rostrum moderately long, reaching as far as or slightly beyond the antennular peduncle, convex proximally, distal end slightly upturned; upper margin with 9 to 12 teeth, of which 3 teeth post-orbital, gap between the dorsal teeth progressively increases slightly from proximal to distal part; ventral margin with 3 or 4 teeth (fig. 2A & 2B). Setae present in between teeth of both dorsal and ventral margins.

Carapace smooth, both antennal and hepatic spines present (characteristics of the genus).

Telson basally broad, narrowing distally, about 1.5 times longer than that of the sixth abdominal segment; dorsal surface with two pairs of spines, proximal pair beyond midway, distal pair near to tip of telson; distal end bears two pairs of spines, outer pair immovable, inner pair longer and movable and reaches beyond tip. Several plumose setae present in between the inner pair of spines.

First pair of chelate legs slender, reaching beyond the antennal scale with chela. Second chelate legs unequal in shape and size, either left or right leg larger; larger leg with ischium flattened and smaller than of merus and as long as or longer than fixed finger; merus cylindrical smaller than palm; carpus long, almost double the length of ischium, longer than palm; palm elongate and flattened; fingers much shorter than palm, slender, movable finger arched and shorter than fixed finger, 5 to 6 denticles on cutting edges, proximal denticles are larger than the distal ones; fixed finger with its tip curved so that a wide gap exists when fingers closed (more prominent in fully mature males); all podomeres covered with very closely set of spinules, larger on lower surface; velvet and stiff setae present in ischium, merus and dorsal part of the carpus (fig 2C). Smaller second pereiopod with ischium flat and about the half or less than half length of carpus; merus cylindrical, about half length of chela; carpus cylindrical, and longer than the merus, palm; palm more than double length of fingers; fingers with minute denticles at the cutting edges; palm and fingers covered with velvet setae.

The non-chelate legs are typical in structure and covered with setae; total length slightly increasing from 1 st to 3 rd.

Pleopods are typical in structure.

Second pereiopods of female equal sized and much smaller than that of the male.

Comparison of morphological characters of M. indicum , M. australae , M. ustulatum are given table1.