Stelomon tharnlod, Yeo & Naiyanetr, 2000

Yeo, D. C. J. & Naiyanetr, P., 2000, A new genus of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand, with a description of a new species, Journal of Natural History 34 (8), pp. 1625-1637 : 1634-1636

Stelomon tharnlod sp. nov.

(®gures 6, 7)

Material examined

HOLOTYPE: male (38.5 Ö 29.1 mm) ( ZRC 1998.1146 ), Tritrung waterfall, Tharn Lod, Si Sawat District , Kanchanaburi Province, Thailand, coll. P. Naiyanetr, 8 September 1996.

PARATYPE: male (c. 39.5 Ö 29.9 mmÐ broken carapace) ( ZRC 1998.114 7), same data as holotype .

Diagnosis

Third maxilliped exopod with well-developed ¯agellum, slightly longer than merus width. Male abdomen narrowly triangular; telson triangular, with distinctively concave lateral margins, tip rounded. G1 terminal segment relatively long, c. 0.6 times length of subterminal segment, stout, c. 3.4 times longer than broad, twisted along longitudinal axis, with groove for G2 clearly visible from ventral view, with distinct swelling on median part of inner margin, narrowed distal part straight, with distinct subdistal notch on outer margin, tip rounded, with more or less dorsal distal opening. G2 distal segment c. 0.7 times length of basal segment.

Remarks

Stelomon tharnlod sp. nov. is distinguished from S. kanchanaburiens e by the distal part of its G1 terminal segment being upright (versus distally hooked) (®gures 2B±H, 7B±E). As in S. pruinosum ( Alcock, 1909) , the ¯agellum of the third maxilliped exopod of S. tharnlod also diOEers slightly from that of S. kanchanaburiens e in being slightly longer than the merus (versus ¯agellum not exceeding merus width) (®gures 2A, 7A). Stelomon tharnlod is similar to S. pruinosum in having a straight and upright G1 terminal segment but, as mentioned earlier, can be separated from it by the narrower shape of its male abdomen (see earlier). In addition, S. tharnlod can be further diOEerentiated from S. pruinosum by the presence of a distinct subdistal notch on its G1 terminal segment outer margin (versus lacking a distinct subdistal notch on the outer margin) as well as its G1 distal opening being dorsal in position (versus ventrally positioned distal opening) (®gures 5B±E, 7B±E).

Etymology

The species is named after its type locality, Tharn Lod in Kanchanabur i Province, Thailand. The name is used as noun in apposition .