Badistemon Yeo & Ng, 2007

Mitra, Santanu, Monica, Thingbaijiam & Waikhom, Mema Devi, 2020, A new species of freshwater crab of the genus Badistemon Yeo & Ng, 2007 (Decapoda: Brachyura: Potamidae: Potamiscinae) from Manipur State, India with the reassignment of Potamiscus pealianus (Wood-mason, 1871), Zootaxa 4838 (4), pp. 475-490 : 489

Key to the species of Badistemon Yeo & Ng, 2007

1. Suture between male thoracic sternites s3/s4 is prominent; sixth pleonal somite ca. 2.5 times wider than median length; telson elongated, distal end narrowing; G1 subterminal segment distal part relatively broad, slightly narrower than basal width, terminal segment relatively shorter, ca. 0.32 times than combined length of subterminal segment and flexible joint ( Fig. 6 A–C, 8 A–C; Yeo & Ng, 2007: fig. 4. a–e)........................................ B. turgidulum ( Alcock, 1909) ( Myanmar)

- Male thoracic suture between s3/s4 is not prominent, represent as a small depression in lateral margin of sternites; sixth pleonal somite note more than ca. 2 times wider than median length; telson elongated, distal end narrowing; G1 subterminal segment distal part neck-like, abruptly narrower than basal width, terminal segment relatively long, more than ca. 0.40 times than combined length of subterminal segment and flexible joint........................................................ 2

2. Cervical groove prominent, regions distinct ( Fig. 7A ), male telson as long as broad ( Fig. 7C ), G1 terminal segment sub-cylindrical, tip truncated ( Fig. 8 D–F; Wood–Mason, 1871: pl. 14, fig.7)..... B. pealianus comb. nov. (Assam & Mizoram, India)

- Cervical groove superficial, regions not distinct ( Fig. 2A ), male telson broader than long ( Fig. 2 C ), G1 terminal segment conical, tip pointed ( Fig. 4 A–D, 5A, B)............................................ B. fulvum sp. nov. (Manipur, India)

Figures

FIGURE 2. Badistemon fulvum n.sp., holotype male (ZSI-C7543/2) (cw 48.7 mm × cl 39.5 mm): A. dorsal habitus; B. frontal view of cephalothorax; C. male thoracic sternum and pleon.

FIGURE 4. Badistemon fulvum n. sp., holotype male (ZSI-C7543/2) (cw 48.7 mm × cl 39.5 mm):A. ventral view of left G1; B, dorsal view of left G1; C, ventral view of terminal segment of left G1; D, dorsal view of terminal segment of left G1; E, dorsal view of left G2. Scale bar=1 mm.

FIGURE 6. Badistemon turgidulum (Alcock, 1909), lectotype male (ZSI-C6952/2) (cw 28.7 mm × cl 23.5 mm):A. dorsal view of carapace; B. frontal view of cephalothorax; C. male thoracic sternum and pleon.

FIGURE 7. Badistemon pealianus (Wood-Mason, 1871), comb. nov. holotype male (ZSI-C 6958/3) (cw 41.6 mm × cl 35.2 mm): A. dorsal view of carapace; B. frontal view of cephalothorax; C. male thoracic sternum and pleon.

FIGURE 8. Badistemon turgidulum (Alcock, 1909), lectotype male (ZSI-C6952/2) (cw 28.7 mm × cl 23.5 mm):A. dorsal view of left G1, B. ventral view of left G1, C. dorsal view right G2; Badistemon pealianus (Wood-Mason, 1871) comb. nov., holotype male (ZSI-C 6958/3) (cw 41.6 mm × cl 35.2 mm): D. dorsal view of left G1, E. ventral view of left G1, F. dorsal view of right G2. Scale bar=1 mm.