taxonID	type	description	language	source
F74A2513FFF5F104FDEA2AABFE4305C6.taxon	description	urn: lsid: zoobank. org: act: BCA 0 A 03 D-DC 25 - 440 D-B 62 E- 51 F 2 D 7 AA 753 C Figs 1 – 4	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFF5F104FDEA2AABFE4305C6.taxon	type_taxon	Type species Gurumon gurumayum sp. nov., by present designation; gender neuter.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFF5F104FDEA2AABFE4305C6.taxon	diagnosis	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 1 A – B, 2 A, E, H, 3 A). Epistome posterior margin with well-developed, triangular medial tooth (Fig. 1 B). Antennules short, folded in longitudinally broad fossae; antennae vestigial (Fig. 1 B). Mandibular palp 3 segmented; terminal segment simple, undivided (Fig. 2 B). 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 1 B – C, 3 B). Chelipeds smooth, glabrous (Figs 1 A, C, 2 A, E, H). Ambulatory legs glabrous, slender; merus (P 2 – P 5) elongated (Figs 1 A, C, 2 A, E, H). Male s 2 / s 3 deep, reaching lateral margins; s 3 / s 4 indiscernible; s 7 / s 8 lacking transverse ridge (Figs 1 C, 2 C – D, 3 C). Male pleon broad, with distinctly broader pleonal somite 6 (Figs 1 C, 3 C – D). Male telson tongue-shaped, with concave lateral margins (Figs 1 C, 3 C – D). G 1 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 2 C, 3 E, 4 A – B). G 2 longer than G 1; distal segment long, ca 0.4 × as long as basal segment (Figs 2 C, 3 F, 4 C). Vulvae on S 6 located apart from each other (VD / SW = ca 0.25), open mesially, subovate, large (Fig. 2 G).	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFF5F104FDEA2AABFE4305C6.taxon	etymology	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.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFF2F103FD982859FE7F0082.taxon	materials_examined	Material examined Holotype INDIA – Arunachal Pradesh State • ♂, CW 10.2 mm, CL 8.5 mm; Upper Siang District: Tulung Village, near Tutting, Abor Hills; 29.006 ° N, 94.897 ° E; alt. 1240 m; 5 Nov. 2019; S. Mitra leg.; ZSIK C. 8610 / 2. Paratype INDIA – Arunachal Pradesh State • 1 ♀, CW 14.5 mm, CL 11.8 mm; same collection data as for holotype; ZSIK C. 8612 / 2.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFF2F103FD9F2BC6FD3A0642.taxon	materials_examined	Material examined Holotype INDIA – Arunachal Pradesh State • ♂, CW 12.9 mm, CL 10.5 mm; Upper Siang District: Dambung Stream, approximately 1.7 km from Hawa Camp, Mouling National Park, Abor Hills; 28.686 ° N, 94.969 ° E; alt. 406 m; 28 Oct. 2017; G. Maheswaran et al. leg.; ZSI-WRC C. 1941. Paratype INDIA – Arunachal Pradesh State • 1 ♀, CW 14.5 mm, CL 11.5 mm; Upper Siang District: Ramsing Guest House, Mouling National Park, Abor Hills; 28.656 ° N, 94.976 ° E; alt. 601 m; 26 Oct. 2017; G. Maheswaran et al. leg.; ZSI-WRC C. 1942.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFF2F103FE4D2D87FA82074C.taxon	materials_examined	Material examined Paratype CHINA – Yunnan Province • 1 ♂, CW 14.0 mm, CL 11.9 mm; Fengqing County: Dashan Village, Xueshan Town; [24.466 ° N, 99.780 ° E]; 1 Feb. 2004; Yang Zheng Bing leg.; ZRC 2013.0559.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFF2F103FD912C75FC5304D3.taxon	materials_examined	Material examined Holotype CHINA – Yunnan Province • ♂; Xi Yi Village, Baoshan; [24.928 ° N, 99.323 ° E]; 13 Oct. 1981; A. Y. Dai and G. X. Chen leg.; IZCAS CB 05191. Paratypes CHINA – Yunnan Province • 1 ♀; same collection data as for holotype; IZCAS CB 05191 • 1 ♂, CW 21.8 mm, CL 17.3 mm; same collection data as for holotype; ZRC 2020.0085 • 1 ♀, CW 20.2 mm, CL 16.6 mm; same collection data as for holotype; ZRC 2020.0085.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFF2F10CFDA32E11FC7604EA.taxon	materials_examined	Material examined Lectotype INDIA – Assam State • ♂, CW 33.0 mm, CL 25.0 mm; Cachar District: Nemotha; [25.029 ° N, 92.948 ° E]; J. Wood-Mason leg.; ZSIK 6602 - 3 / 9.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFF2F10CFDA32E11FC7604EA.taxon	discussion	Remarks Gurumon gen. nov. certainely belongs to Potamiscinae (sensu Yeo & Ng 2004) because the transverse ridge on s 7 / s 8 is absent (Fig. 2 C – D). The medial portion of the s 8, however, is conspicuously narrow so that the longitudinal medial groove is indiscernible (Fig. 2 C – D). The indistinct, low external orbital angle (Figs 1 A, 2 A, E, H, 3 A), the relatively stouter exopod of the third maxilliped (Figs 1 C, 3 B), and the relatively broader male pleonal somite 6 (proximal width ca 3 × the medial length) (Figs 1 C, 3 C – D) are characteristic to Gurumon gen. nov. by which it can be distinguished from the morphologically related Potamiscus loshingensis, Potamiscus rongjingensis, Abormon, and Pararanguna. The external orbital angle is distinct and triangular, the exopod of the third maxilliped is relatively slenderer, and the male pleonal somite 6 is relatively narrower (proximal width ca 2.0 – 2.5 × the medial length) in Potamiscus loshingensis, Potamiscus rongjingensis, Abormon, and Pararanguna (see Wu 1934: fig. 1; Dai et al. 1990: pl. 1 fig. 2, fig. 2 (1, 8); Dai 1999: pl. 25 fig. 1, fig. 200 (1 – 2); Naruse et al. 2018: figs 20 a, 21; Mitra et al. 2021: figs 2 a – b, e, 6 a – b, e). In carapace morphology, Gurumon gen. nov. most resembles Abormon in that both genera have a transversely ovate carapace, the low epigastric cristae, the indiscernible postorbital cristae, a very low epibranchial tooth, barely visible cervical grooves, the deep s 2 / s 3, a broad male pleon, and a tongueshaped male telson with the lateral margins concave (Figs 1 A – C, 2 A, C, E, H, 3 A, C – D; see Mitra et al. 2021: figs 1 a – c, 2 a, d – e, 4 a, 5 a – c, 6 a, d – e, 8 a). In addition to the character states of the external orbital angle, third maxilliped exopod and male pleonal somite 6, Gurumon gen. nov. can be separated from Abormon by the relatively small flexible zone of the G 1 (Figs 3 E, 4 A) (vs G 1 flexible zone relatively large; see Mitra et al. 2021: figs 3 a – b, 7 a – b), the cylindrical G 1 terminal segment with the dorsal flap absent (Figs 3 E, 4 A – B) (vs G 1 terminal segment conical with the dorsal flap distinct but low; see Mitra et al. 2021: figs 3 a – c, 7 a – c), and the mesially open, subovate and relatively large vulvae (Fig. 2 G) (vs vulvae anteriorly open, transversely ovate and relatively small; see Mitra et al. 2021: figs 4 c, 8 c). Although both genera are known from the mountains of the Arunachal Pradesh State (Fig. 5), Gurumon gen. nov. seems to be restricted to the elevated areas (2473 – 2513 m altitude), while Abormon dwells at relatively lower altitude (406 – 1240 m) (Mitra et al. 2021). In G 1 structure, Gurumon gen. nov. is quite similar to Potamiscus loshingensis and P. rongjingensis because all possess a stout G 1 with the terminal segment being cylindrical, relatively long (ca 0.5 – 0.6 × the combined length of the flexible zone and the subterminal segment) and lacking a dorsal flap (Figs 3 E, 4 A – B; see Wu 1934: fig. 1; Dai et al. 1990: fig. 2 (5); Dai 1999: figs 103 (5 – 6), 105 (4 – 5 )). Despite their similar G 1 s, Gurumon gen. nov. differs from Potamiscus loshingensis and P. rongjingensis by the relatively small flexible zone of the G 1 (Figs 3 E, 4 A) (vs G 1 flexible zone relatively large; see Dai et al. 1990: fig. 2 (5); Dai 1999: fig. 103 (5 – 6 )), and the relatively less stout G 1 terminal segment (Figs 3 E, 4 A, B) (vs G 1 terminal segment relatively stouter; see Wu 1934: fig. 1; Dai et al. 1990: fig. 2 (5); Dai 1999: figs 103 (5 – 6), 105 (4 – 5 )). Other features of carapace, including those of the external orbital angle, third maxilliped exopod and male pleonal somite 6, however, confirm their separation. For instance, the epigastric cristae are low in Gurumon gen. nov. (Figs 1 A, 2 A, E, H, 3 A) (vs epigastric cristae well-developed in Potamiscus loshingensis and P. rongjingensis; see Wu 1934: fig. 1; Dai et al. 1990: pl. 1 fig. 2); the postorbital cristae are indiscernible in Gurumon gen. nov. (Figs 1 A, 2 A, E, H, 3 A) (vs postorbital cristae relatively distinct in Potamiscus loshingensis and P. rongjingensis; see Wu 1934: fig. 1; Dai et al. 1990: pl. 1 fig. 2); the external orbital angle is indistinct, low in Gurumon gen. nov. (Figs 1 A, 2 A, E, H, 3 A) (vs external orbital angle distinct, triangular in Potamiscus loshingensis and P. rongjingensis; see Wu 1934: fig. 1; Dai et al. 1990: pl. 1 fig. 2); the epibranchial tooth is very low in Gurumon gen. nov. (Figs 1 A, 2 A, E, H, 3 A) (vs epibranchial tooth relatively distinct in Potamiscus loshingensis and P. rongjingensis; see Wu 1934: fig. 1; Dai et al. 1990: pl. 1 fig. 2); the exopod of the third maxilliped is relatively stouter in Gurumon gen. nov. (Figs 1 C, 3 B) (vs third maxilliped exopod relatively slenderer in Potamiscus loshingensis and P. rongjingensis; see Wu 1934: fig. 1; Dai et al. 1990: fig. 2 (1 )); and the male pleon is relatively stouter, with the pleonal somite 6 broad, proximal width ca 3 × the medial length in Gurumon gen. nov. (Figs 1 C, 3 C – D) (vs male pleon relatively slenderer, with the pleonal somite 6 narrow, proximal width ca 2.0 – 2.1 × the medial length in Potamiscus loshingensis and P. rongjingensis; see Wu 1934: fig. 1; Dai et al. 1990: fig. 2 (8 )). While the structure of the vulvae is not known in Potamiscus rongjingensis, P. loshingensis possesses the transversely ovate vulvae, which are close to each other (VD / SW = ca 0.1) (see Dai 1999: fig. 103 (9 )) against the subovate and relatively widely located vulvae (VD / SW = ca 0.25) of Gurumon gen. nov. (Fig. 2 G). Gurumon gen. nov. is found in the Arunachal Pradesh State of northeastern India, while Potamiscus loshingensis and P. rongjingensis are known only from Guangxi and / or Sichuan provinces of China (Wu 1934; Dai et al. 1990; Dai 1999) (Fig. 5). The disjunct geographical distributions with several mountain barriers further corroborate their separation. Gurumon gen. nov. need not to be confused with Potamiscus s. str. (represented by the type species) because the new genus possesses the following characters in contrast to those of Potamiscus s. str.: the low epigastric cristae (Figs 1 A, 2 A, E, H, 3 A) (vs epigastric cristae well-developed; see Yeo & Ng 2007: fig. 11 a); the indiscernible postorbital cristae (Figs 1 A, 2 A, E, H, 3 A) (vs postorbital cristae distinct, reaching each epibranchial tooth; see Yeo & Ng 2007: fig. 11 a); the indistinct, low external orbital angle (Figs 1 A, 2 A, E, H, 3 A) (vs external orbital angle distinct, triangular; see Yeo & Ng 2007: fig. 11 a); the very low epibranchial tooth (Figs 1 A, 2 A, E, H, 3 A) (vs epibranchial tooth distinct; see Yeo & Ng 2007: fig. 11 a); the relatively stouter exopod of the third maxilliped (Figs 1 C, 3 B) (vs third maxilliped exopod relatively slenderer; see Alcock 1910: pl. III fig. 10 b); the relatively stouter male pleon, with a relatively broad pleonal somite 6, proximal width ca 3 × the medial length (Figs 1 C, 3 C – D) (vs male pleon relatively slenderer, with a relatively narrow pleonal somite 6, proximal width ca 2.5 × the medial length; see Bott 1970: pl. 46 fig. 26); the tongue-shaped male telson, with the lateral margins concave (Figs 1 C, 3 C – D) (vs male telson triangular, with the straight lateral margins; see Bott 1970: pl. 46 fig. 26); and the relatively stouter and longer G 1 (tip reaching up to s 4 / s 5 in situ), with a cylindrical, less strongly curved and long terminal segment, measuring ca 0.6 × the combined length of the flexible zone and the subterminal segment (Figs 2 C, 3 E, 4 A – B) (vs G 1 relatively slenderer and shorter (tip reaching slightly beyond s 5 / s 6 up to the proximal third of s 5 in situ), with a conical, strongly bent and short terminal segment, ca 0.2 × the combined length of the flexible zone and the subterminal segment; see Bott 1970: pl. 38 fig. 28; unpublished data). Moreover, Potamiscus s. str. was originated from the hills of lower Assam (Alcock 1909), which is some 460 km away from the known range of Gurumon gen. nov. (Fig. 5). As mentioned earlier, Gurumon gen. nov. is immediately distinguished from Pararanguna by the shapes of external orbital angle, third maxilliped exopod and male pleonal somite 6. The additional differences include the very low epibranchial tooth (Figs 1 A, 2 A, E, H, 3 A), the distinctly concave lateral margins of the male telson (Figs 1 C, 3 C – D), the relatively small flexible zone of the G 1 (Figs 3 E, 4 A), and the cylindrical G 1 terminal segment that lacks a dorsal flap (Figs 3 E, 4 A – B) in Gurumon gen. nov. against the distinct epibranchial tooth (see Dai 1999: pl. 25 fig. 1; Naruse et al. 2018: fig. 20 a), the almost straight lateral margins of the male telson (see Dai 1999: fig. 200 (2); Naruse et al. 2018: fig. 21), the relatively large flexible zone of the G 1 (see Dai 1999: fig. 200 (5); Naruse et al. 2018: fig. 22 b), and the conical G 1 terminal segment with a distinct dorsal flap (see Dai 1999: fig. 200 (4 – 5); Naruse et al. 2018: fig. 22 a – b) in Pararanguna. Pararanguna is known only from the Yunnan Province of southwestern China (Dai 1999; Naruse et al. 2018) (Fig. 5). The elevated mountains with deep valleys between Yunnan and Arunachal Pradesh justify the separation of Gurumon gen. nov. from Pararanguna.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFF2F10CFDA32E11FC7604EA.taxon	distribution	Geographical distribution Gurumon gen. nov. is currently known only from the Mehao Wildlife Sanctuary in the Lower Dibang Valley District of Arunachal Pradesh State, northeastern India (Fig. 5).	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFFDF108FDC82E2EFE9200F2.taxon	description	urn: lsid: zoobank. org: act: 766 FC 0 A 2 - 3 E 63 - 4089 - 9949 - CD 72800 E 492 F Figs 1 – 4, 6	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFFDF108FDC82E2EFE9200F2.taxon	diagnosis	Diagnosis As for new genus.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFFDF108FDC82E2EFE9200F2.taxon	etymology	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.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFFDF108FDC82E2EFE9200F2.taxon	materials_examined	Material examined Holotype INDIA – Arunachal Pradesh State • ♂, adult, CW 10.9 mm, CL 8.8 mm, CH 4.7 mm, FW 3.9 mm; Lower Dibang Valley District: Mayodia, Mehao Wildlife Sanctuary; 28.233 ° N, 95.909 ° E; alt. 2473 m; 17 Oct. 2015; S. D. Gurumayum leg.; ZSI-WRC C. 2170. Paratypes INDIA – Arunachal Pradesh State • 1 ♂, adult, CW 13.3 mm, CL 9.9 mm, CH 5.6 mm, FW 4.6 mm; same collection data as for holotype; ZSI-WRC C. 2171 • 1 ♀, adult, CW 12.7 mm, CL 10.0 mm, CH 5.9 mm, FW 4.4 mm; same collection data as for preceding; ZSI-WRC C. 2171 • 1 ♀, adult, CW 13.1 mm, CL 9.9 mm, CH 5.6 mm, FW 4.2 mm; same collection data as for preceding; ZSI-WRC C. 2172 • 1 ♀, adult, CW 12.6 mm, CL 9.5 mm, CH 5.7 mm, FW 4.0 mm; same collection data as for preceding; ZSI- WRC C. 2172. Additional material INDIA – Arunachal Pradesh State • 3 ♂♂, 4 ♀♀; Lower Dibang Valley District: near Mayodia Inspection Bungalow, Mehao Wildlife Sanctuary; 28.235 ° N, 95.917 ° E; alt. 2513 m; 5 Sep. 2016; S. D. Gurumayum leg.; ZSI-WRC C. 2173.	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFFDF108FDC82E2EFE9200F2.taxon	description	Description of male holotype Carapace transversely ovate, broader than long (CW / CL = 1.2), low (CH / CW = 0.4); dorsal surface generally smooth, glabrous, conspicuously arched; anterolateral surface gently inflated in frontal view; anterolateral margins almost straight, subcristate, shorter than posterolateral margins; posterolateral margins converging posteriorly, almost straight medially; front broad (FW / CW = 0.3), strongly deflexed anteriorly, almost rectangular, anterior margin smooth, cristate, gently concave medially in dorsal view; epigastric cristae low, visible as 2 broad, rugose protuberances; postorbital cristae indiscernible; external orbital angle indistinct, low; epibranchial tooth very low, with very small cleft; postorbital region gently concave; branchial regions inflated; cervical grooves very shallow, narrow; mesogastric groove moderately deep, narrow, long, bifurcated posteriorly; H-shaped groove distinct; subhepatic region smooth, glabrous; suborbital region smooth, glabrous; pterygostomial region generally smooth, glabrous; supraorbital margin cristate, smooth, straight; suborbital margin cristate with low granules, almost straight on mesial half, curved upwards on lateral half, continuous with supraorbital margin; frontal medial triangle incomplete, with dorsal margin only, lateral margins indiscernible (Figs 1 A – C, 3 A). Epistome posterior margin with well-developed, narrowly triangular medial tooth and gently sinuous lateral margins (Fig. 1 B). Eyes occupying most of orbital space; eyestalk short, stout; cornea moderately large, pigmented (Fig. 1 B). Antennules short, folded in longitudinally broad fossae; antennae vestigial (Fig. 1 B). Mandibular palp 3 segmented; terminal segment simple, undivided. First, second maxillipeds each with short flagellum on exopod. Third maxillipeds cover most of buccal cavity when closed; ischium subrectangular, longer than broad, with deep, oblique medial groove; merus subpentagonal, broader than long, sunken; exopod stout, tapered, reaching beyond anterolateral angle of ischium, completely lacking flagellum (Figs 1 B – C, 3 B). Chelipeds smooth, glabrous, unequal, right chela larger (Fig. 1 A, C). Major chela with 5 low, blunt teeth on each finger, distinct gape when fingers closed; dactylus gently curved, moderately stout, shorter than palm, smooth; palm longer than high, smooth; carpus smooth, gently inflated, with low, blunt inner distal tooth; merus smooth, lacking subterminal spine (Fig. 1 A, C). Ambulatory legs generally smooth, glabrous, slender, short, P 3 longest; merus (P 2 – P 5) elongated, lacking subdistal spine; dactylus (P 2 – P 5) gently recurved, slightly longer than propodus, with distinct, sharp chitinous spines on margins (Fig. 1 A, C). Thoracic sternites punctate, glabrous; s 1 and s 2 completely fused; s 2 / s 3 prominent, deep, narrow, gently sinuous, reaching lateral margins; s 3 / s 4 indiscernible; s 4 / s 5, s 5 / s 6, s 6 / s 7 shallow, narrow, indiscernible towards sternopleonal cavity; s 7 / s 8 shallow, narrow, medially interrupted by longitudinal groove of s 7, lacking transverse ridge; s 8 completely covered by pleon, narrowed medially, longitudinal medial groove indiscernible (Figs 1 C, 3 C). Pleonal locking mechanism with prominent tubercle on submedial part of s 5. Sternopleonal cavity deep, long, reaching to imaginary line joining submedial part of cheliped coxae (Figs 1 C, 3 C). Pleon broad, triangular; pleonal somites 1 – 2 almost rectangular, narrower than pleonal somite 3; pleonal somite 3 subrectangular, broadest; pleonal somites 4 – 5 trapezoidal; pleonal somite 6 trapezoidal, distinctly broader than long (proximal width ca 3 × medial length), slightly longer than preceding pleonal somites, shorter than telson, with convex lateral margins (Figs 1 C, 3 C – D). Telson tongueshaped, broader than long (proximal width ca 1.5 × medial length), with concave lateral margins, apex broad, rounded (Figs 1 C, 3 C – D). G 1 stout, long, tip reaching up to s 4 / s 5 in situ; flexible zone small; terminal segment stout, cylindrical, long, ca 0.6 × combined length of flexible zone and subterminal segment, curved outwards at angle of about 30 ° from longitudinal axis, distal half gently upcurved, tip broad, blunt, dorsal flap absent; subterminal segment almost straight, stout, broad at base, relatively narrow distally, outer margin sinuous, inner margin almost straight; groove for G 2 median (Figs 3 E, 4 A – B). G 2 slightly longer than G 1, ca 1.1 × as long as G 1; distal segment gently curved, cylindrical, long, ca 0.4 × as long as basal segment, with blunt tip; basal segment stout at proximal third, appearing narrowly ovate (Figs 3 F, 4 C).	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFFDF108FDC82E2EFE9200F2.taxon	discussion	Remarks The male paratype (ZSI-WRC C. 2171) of Gurumon gurumayum sp. nov. is an adult and slightly larger in size than the male holotype. The male paratype shares most of the morphological features with the holotype except for its relatively broader carapace, CW / CL = 1.3 (Fig. 2 A) (vs carapace relatively less broad, CW / CL = 1.2 in the holotype; Figs 1 A, 3 A) and the straight s 2 / s 3 (Fig. 2 C) (vs s 2 / s 3 gently sinuous in the holotype; Figs 1 C, 3 C). The female paratypes (ZSI-WRC C. 2171, 2172) of Gurumon gurumayum sp. nov. are adults and slightly larger than the male holotype. All the female paratypes possess most of the non-sexual character states as those in the male holotype. Their carapace, however, is relatively broader, CW / CL = 1.3 (Fig. 2 E, H) like that of the male paratype. All the female paratypes have subequal chelipeds (Fig. 2 E, H) unlike the unequal chelipeds of the holotype and paratype males (Figs 1 A, C, 2 A). The pleonal somites and telson of the female paratypes are ovate in shape, which cover the thoracic sternum except for lateral edges when closed (Fig. 2 F). Their pleonal somite 1 is the shortest; pleonal somites 2 – 5 are progressively longer; and pleonal somite 6 is the longest, much broader than long, subequal in length to the telson, with the convex lateral margins (Fig. 2 F). The telson in the female paratypes is broadly triangular, much broader than long, with convex lateral margins and narrow apex (Fig. 2 F). The vulvae in female paratypes are located apart from each other (VD / SW = ca 0.25) on s 6, each opens mesially, subovate, large, occupying three-quarters the length of s 6, touching but not pushing s 5 / s 6 anteriorly, and covered by soft membranous operculum (Fig. 2 G).	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFFDF108FDC82E2EFE9200F2.taxon	description	Colour in life The cephalothorax is dark purple; the chelipeds are generally reddish brown with dark purplish-brown upper surface; and the ambulatory legs are light brown with dark purple blotches (Fig. 6).	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
F74A2513FFFDF108FDC82E2EFE9200F2.taxon	biology_ecology	Ecological notes Gurumon gurumayum sp. nov. was found among the moss-covered stones in the shallow (ca 10 cm deep) and slow-flowing brooks of the subalpine forests of Mayodia during September and October. Located within the Mehao Wildlife Sanctuary, Mayodia is situated in the Mayu hills of the Lower Dibang Valley District of Arunachal Pradesh, which is about 56 km from the district headquarters at Roing. The new species is known to dwell at 2473 – 2513 m altitude and seems restricted to the high mountains. These crabs are very unlikely to be found during the winter season (Nov. – Feb.) as Mayodia experiences snowfall. Their activities, however, resume during the summer (Mar. – Jun.) (S. D. Gurumayum, personal communication). Geographical distribution Gurumon gurumayum sp. nov. is currently known only from two adjacent localities of the Mehao Wildlife Sanctuary in the Lower Dibang Valley District of Arunachal Pradesh State, northeastern India (Fig. 5).	en	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: 28-45, DOI: https://doi.org/10.5852/ejt.2022.847.1979, URL: http://dx.doi.org/10.5852/ejt.2022.847.1979
