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| Gurumon gurumayum Pati, 2022 |
ABSTRACT
A new genus and new species of potamid crab, Gurumon gurumayum gen. et sp. nov., are described from the Arunachal Pradesh State of northeastern India. Gurumon gen. nov. has affinities with Abormon Mitra, Pati & Ng, 2021, Pararanguna Dai & Chen, 1985, and some species of Potamiscus Alcock, 1909, but the new genus can easily be differentiated from them mainly by its low external orbital angle, the relatively stouter exopod of the third maxilliped, and the relatively broader male pleonal somite 6. Their male first gonopods are also different from each other. Counting Gurumon gurumayum gen. et sp. nov., India is currently known for ten genera and 24 species of potamiscine freshwater crabs, and Arunachal Pradesh for eight genera and 11 species of these crabs. The current nomenclatural problems with Potamiscus are also discussed.
Keywords: taxonomy, Crustacea, Potamiscinae, nomenclature, Potamiscus
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| Gurumon gurumayum gen. et sp. nov., paratype (ZSI-WRC C.2171), ♂ (CW 13.3 × CL 9.9 mm), colour in life. |
Taxonomy
Phylum Arthropoda von Siebold, 1848
Subphylum Crustacea Brünnich, 1772
Class Malacostraca Latreille, 1802
Order Decapoda Latreille, 1802
Infraorder Brachyura Latreille, 1802
Superfamily Potamoidea Ortmann, 1896
Family Potamidae Ortmann, 1896
Subfamily Potamiscinae Bott, 1970 (sensu Yeo & Ng 2004)
Genus Gurumon gen. nov.
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.
Gurumon gurumayum sp. nov.
Etymology: The species epithet is the family name of Dr Shantabala Devi Gurumayum, an Indian zoologist who kindly collected and provided the crab specimens for the present study. The species name is treated here as a Latin noun in apposition.
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| Map showing India, China and distribution of the species of Gurumon gen. nov., Abormon Mitra, Pati & Ng, 2021, Pararanguna Dai & Chen, 1985, and Potamiscus Alcock, 1909. |
Sameer K. Pati. 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(1), 28–45. DOI: 10.5852/ejt.2022.847.1979
