Gurumon, Pati, 2022

Pati, Sameer K., 2022, Gurumon gurumayum, a new genus and new species of freshwater crab (Decapoda: Brachyura: Potamidae) from Arunachal Pradesh, northeastern India, European Journal of Taxonomy 847, pp. 28-45 : 30

Genus Gurumon gen. nov.

urn:lsid:zoobank.org:act:BCA0A03D-DC25-440D-B62E-51F2D7AA753C

Figs 1–4

Type species

Gurumon gurumayum sp. nov., by present designation; gender neuter.

Diagnosis

Small adult size (adult CW <15 mm). Carapace transversely ovate; dorsal surface generally smooth, glabrous, conspicuously arched; epigastric cristae low, visible as 2 broad protuberances; postorbital cristae indiscernible; external orbital angle indistinct, low; epibranchial tooth very low; cervical grooves barely visible ( Figs 1A–B , 2A, E, H , 3A ). Epistome posterior margin with well-developed, triangular medial tooth ( Fig. 1B ). Antennules short, folded in longitudinally broad fossae; antennae vestigial ( Fig. 1B ). Mandibular palp 3 segmented; terminal segment simple, undivided ( Fig. 2B ). First, second maxillipeds each with short flagellum on exopod; third maxilliped exopod relatively stout, tapered, reaching beyond anterolateral angle of ischium, completely lacking flagellum ( Figs 1B–C , 3B ). Chelipeds smooth, glabrous ( Figs 1A, C , 2A, E, H ). Ambulatory legs glabrous, slender; merus (P2–P5) elongated ( Figs 1A, C , 2A, E, H ). Male s2/s3 deep, reaching lateral margins; s3/s4 indiscernible; s7/s8 lacking transverse ridge ( Figs 1C , 2C–D , 3C ). Male pleon broad, with distinctly broader pleonal somite 6 ( Figs 1C , 3C–D ). Male telson tongue-shaped, with concave lateral margins ( Figs 1C , 3C–D ). G1 stout, long; flexible zone small; terminal segment stout, cylindrical, long, ca 0.6 × combined length of flexible zone and subterminal segment, curved outwards, dorsal flap absent; subterminal segment stout ( Figs 2C , 3E , 4A–B ). G2 longer than G1; distal segment long, ca 0.4 × as long as basal segment ( Figs 2C , 3F , 4C ). Vulvae on S6 located apart from each other (VD/SW = ca 0.25), open mesially, subovate, large ( Fig. 2G ).

Etymology

The genus is named in the honour of Dr Shantabala Devi Gurumayum for her extensive work in aquatic biology, in arbitrary combination with the genus name Potamon Savigny, 1816 . The gender of the generic name is neuter.

Figures

Fig. 1. Gurumon gurumayum gen. et sp. nov., holotype (ZSI-WRC C.2170), ♂ (CW 10.9 × CL 8.8 mm). A. Entire animal, dorsal view. B. Cephalothorax, frontal view. C. Entire animal, ventral view. Scale bars: A, C = 5 mm; B = 2 mm.

Fig. 2. Gurumon gurumayum gen. et sp. nov. A–D. Paratype (ZSI-WRC C.2171), ♂ (CW 13.3 × CL 9.9 mm). E–G. Paratype (ZSI-WRC C.2171), ♀ (CW 12.7 × CL 10.0 mm). C. Paratype (ZSI-WRC C.2172), ♀ (CW 12.6 × CL 9.5 mm). A, E, H. Entire animal, dorsal view. B. Mandibular palp, dorsal view. C. Thoracic sternites with G1 and G2 in situ. D. Posterior thoracic sternites (s5–s8). F. Pleonal somites 3–6 and telson. G. Thoracic sternites showing vulvae. Scale bars: A, E, H = 5 mm; C–D, F–G = 2 mm; B = 0.5 mm.

Fig. 3. Gurumon gurumayum gen. et sp. nov., holotype (ZSI-WRC C.2170), ♂ (CW 10.9 × CL 8.8 mm). A. Cephalothorax, dorsal view. B. Third maxilliped (left). C. Thoracic sternites (s1–s7), pleonal somites 3–6 and telson. D. Pleon and telson. E. G1 (left), dorsal view. F. G2 (left). Scale bars: A, C–D = 2 mm; B, E–F = 1 mm.

Fig. 4. Gurumon gurumayum gen. et sp. nov., holotype (ZSI-WRC C.2170), ♂ (CW 10.9 × CL 8.8 mm). A. G1 (left), dorsal view. B. G1 (left), ventral view. C. G2 (left). Scale bars = 1 mm.