taxonID	type	description	language	source
523F87990946FFAEFF49FC32452AFD44.taxon	description	urn: lsid: zoobank. org: act: 64 A 6 FDF 7 - 2362 - 4 D 69 - AAB 4 - DAB 6 BC 1 E 0755	en	Dang, Phan Doan, Tien, Tran Van, Tu, Do Van (2025): Tayninhon nuibaden, a new genus and new species of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Ba Den Mountain, Southeast Vietnam. Zootaxa 5693 (2): 291-300, DOI: 10.11646/zootaxa.5693.2.10, URL: https://doi.org/10.11646/zootaxa.5693.2.10
523F87990946FFAEFF49FC32452AFD44.taxon	type_taxon	Type species. Tayninhon nuibaden gen. nov., sp. nov., by present designation.	en	Dang, Phan Doan, Tien, Tran Van, Tu, Do Van (2025): Tayninhon nuibaden, a new genus and new species of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Ba Den Mountain, Southeast Vietnam. Zootaxa 5693 (2): 291-300, DOI: 10.11646/zootaxa.5693.2.10, URL: https://doi.org/10.11646/zootaxa.5693.2.10
523F87990946FFAEFF49FC32452AFD44.taxon	diagnosis	Diagnosis. Carapace medium in size (13.7 – 26.5 mm, n = 12), subquadrate, dorsal surface relatively flat, rugae and striae on branchial and metabranchial regions; external orbital angle broadly triangular; epigastric and postorbital cristae low, rounded, distinctly separated by short groove; epistome with posterior margin acutely triangular at median, each lateral margin with two concavities; epibranchial tooth low with shallow notch; concavity between frontal margins broad, shallow; anterolateral margin weakly serrated; H-shaped grove well developed (Fig. 1 A – D). Exopod of third maxillipeds reaching beyond upper edge of ischium with well-developed flagellum (Fig. 1 E). Fingers of adult male major chela with almost no gap when closed (Fig. 2 A); ambulatory legs not elongated, third pair longest, first pair shortest; ratio of length to width of fourth merus less than 4 (Fig. 1 A, B). Sternopleonal cavity reaching to imaginary line connecting anterior edges of cheliped coxae (Figs. 2 C, 3 A). Thoracic sternum relatively wide; sternites 3 and 4 completely fused, separated by shallow oblique grooves; sternite 8 not visible when pleon closed (Figs. 1 B, 2 C). Telson triangular, relatively narrow, lateral margins concave (Fig. 2 D). G 1 subterminal segment relatively broad; G 1 terminal article slender, hook shape, with dorsal fold extending at basal part of terminal article, curved inwards (Figs. 3 A, 4 A – D). G 2 slightly shorter than G 1, distal article shorter than basal article. Vulvae oblique in position, proximal margin of each just touching suture with sternite 5 (Fig. 4 E, F).	en	Dang, Phan Doan, Tien, Tran Van, Tu, Do Van (2025): Tayninhon nuibaden, a new genus and new species of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Ba Den Mountain, Southeast Vietnam. Zootaxa 5693 (2): 291-300, DOI: 10.11646/zootaxa.5693.2.10, URL: https://doi.org/10.11646/zootaxa.5693.2.10
523F87990946FFAEFF49FC32452AFD44.taxon	etymology	Etymology. The genus is named after the location, the province of Tay Ninh, in combination with the genus name Potamon. The gender is neuter.	en	Dang, Phan Doan, Tien, Tran Van, Tu, Do Van (2025): Tayninhon nuibaden, a new genus and new species of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Ba Den Mountain, Southeast Vietnam. Zootaxa 5693 (2): 291-300, DOI: 10.11646/zootaxa.5693.2.10, URL: https://doi.org/10.11646/zootaxa.5693.2.10
523F87990946FFAEFF49FC32452AFD44.taxon	discussion	Remarks. Tayninhon gen. nov. is morphologically closest to Demanietta Bott, 1966, in the shape of the carapace and the presence of a dorsal flap on the terminal segment of the first gonopod but is easily distinguished by the following characteristics: (1) the carapace size is smaller, the largest specimen is 26.5 mm in width (versus CW 27.7 – 62.8 mm of Demanietta see Rathbun 1904, 1905; Naiyanetr 1986; Yeo et al. 1999; Ng 2018; Shi et al. 2020; Lheknim et al. 2023; Tan et al. 2024); (2) sternopleonal cavity reaches to imaginary line connecting anterior edges of cheliped coxae (Figs. 1 B, 2 C) (versus sternopleonal cavity reaches to imaginary line connecting median points of cheliped coxae in Demanietta; see Yeo et al. 1999: fig. 1 F; Lheknim et al. 2023: fig. 4 C); and (3) G 1 terminal article is bent and curving inwards with dorsal fold present only along the proximal part (Figs. 3 A, 4 A – D) (versus G 1 terminal article bent and curving outwards with dorsal fold extending across the middle part in Demanietta; see Tan et al. 2024: fig. 4 D). According to Yeo et al. (1999), almost all species of Demanietta were collected from fast-flowing mountain streams, waterfalls and cascades. However, the habitats of the new genus are more terrestrial. The holotype specimen was collected in an area without water, this individual appeared after heavy rain, crawling on large rocks. Tayninhon gen. nov. resembles Thaiphusa somewhat in the form of the G 1, but the new genus can be distinguished by the following characters: (1) the carapace is relatively flat and all regions are well defined (Fig. 1 A) (versus the carapace is distinctly swollen and all regions are smooth in Thaiphusa; e. g., see Ng & Naiyanetr 1993: fig. 22); (2) the anterolateral margins are serrated and cristae (Fig. 1 A) (versus the anterolateral margins are almost smooth and cristae very low; e. g., see Ng & Naiyanetr 1993: fig. 22); (3) the epigastric cristae are distinctly separated from the postorbital cristae (Fig. 1 A) (versus epigastric cristae are not distinctly separated from postorbital cristae; e. g., see Ng & Naiyanetr 1993: fig. 22); and (4) the terminal segment is about 0.4 times the length of the subterminal article with the dorsal fold prominent only along the proximal part of the terminal article (Figs. 3 A, 4 A – D) (versus terminal article is about 0.63 times length of subterminal article; and with the dorsal fold extends to the median part of terminal article; e. g., see Ng & Naiyanetr 1993: fig. 56).	en	Dang, Phan Doan, Tien, Tran Van, Tu, Do Van (2025): Tayninhon nuibaden, a new genus and new species of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Ba Den Mountain, Southeast Vietnam. Zootaxa 5693 (2): 291-300, DOI: 10.11646/zootaxa.5693.2.10, URL: https://doi.org/10.11646/zootaxa.5693.2.10
523F87990945FFABFF49FD3745B8F993.taxon	description	(Figures 1 – 5)	en	Dang, Phan Doan, Tien, Tran Van, Tu, Do Van (2025): Tayninhon nuibaden, a new genus and new species of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Ba Den Mountain, Southeast Vietnam. Zootaxa 5693 (2): 291-300, DOI: 10.11646/zootaxa.5693.2.10, URL: https://doi.org/10.11646/zootaxa.5693.2.10
523F87990945FFABFF49FD3745B8F993.taxon	materials_examined	Material examined. Holotype: male (29.2 × 25.0 mm) (IB-FC-TBx 01) Vietnam, Tay Ninh Province, Tay Ninh City, Thanh Tan Commune, Ba Den Mountain, N 11 ° 23 ’ 01.7 ” E 106 ° 09 ’ 44.7 ”, coll. Phan DD & Tran VT, August 2020. Paratypes: 1 male (20.5 × 15.2 mm), 2 females (26.5 × 20.5 mm, 15.2 × 11.8 mm) (IB-FC-TBx 02), same data as holotype. Others: 1 male (23.0 × 18.2 mm) (VNM 00070944), 1 male (13.7 × 11.1 mm) (VNM 00070945), 1 male (18.6 × 14.5 mm) (VRTC-SB-AE 10011), 1 male (14.8 × 11.9 mm) (VRTC-SB-AE 10012), 1 female (15.5 × 12.7 mm) (VNM 00070946), 1 female (15.5 × 12.7 mm) (VNM 00070947), 1 female (16.2 × 12.7 mm) (VRTC-SB-AE 10013), 1 female (15.9 × 12.7 mm) (VRTC-SB-AE 10014), Vietnam, Tay Ninh Province, Tay Ninh City, Thanh Tan Commune, Ba Den Mountain, N 11 ° 23 ’ 00.5 ” E 106 ° 10 ’ 52.4 ”, coll. Phan DD & Tran VT, 30 January 2024.	en	Dang, Phan Doan, Tien, Tran Van, Tu, Do Van (2025): Tayninhon nuibaden, a new genus and new species of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Ba Den Mountain, Southeast Vietnam. Zootaxa 5693 (2): 291-300, DOI: 10.11646/zootaxa.5693.2.10, URL: https://doi.org/10.11646/zootaxa.5693.2.10
523F87990945FFABFF49FD3745B8F993.taxon	description	Description. Carapace subquadrate, about 1.3 times broader than long; female slightly larger than male; dorsal surface relatively low, not inflated, regions well defined (Fig. 1 A, B). Frontal region almost smooth; lateral parts of anterolateral and branchial regions weakly rugose; mesogastric, urogastric, cardiac and intestinal regions very weakly rugose; orbital regions weakly rugose; suborbital and pterygostomial regions uneven, rugose covered by small granules (Fig. 1 A). Epigastric cristae low, not sharp, rugose, separated by broad, shallow Y-shaped furrow, separated from postorbital cristae by short, shallow groove; postorbital cristae low, not sharp, almost straight, confluent with epibranchial tooth, breaking up into rugae and granules before epibranchial tooth (Fig. 1 A). Cervical grooves distinct; H-shaped median gastric groove developed (Fig. 1 A). Frontal margin divided into two broad, medium lobes, separated by broad concavity; margin of each lobe gently convex, confluent with supraorbital margin (Fig. 1 A, C, D). External orbital angle broadly triangular, with outer margin longer than inner margin, demarcated from rest of anterolateral margin by small, shallow notch, lined with distinct granules; epibranchial tooth distinct, low, broadly triangular (Fig. 1 A, C, D). Anterolateral margins convex, cristate, lined with distinct granules (Fig. 1 A). Posterolateral margin almost straight, strongly convergent posteriorly (Fig. 1 A). Orbits subovate; eye filling most of orbital space; ocular peduncle long; cornea normal (Fig. 1 A, C, D). Supra- and infraorbital margins gently sinuous, lined with small but distinct granules (Fig. 1 C, D). Suborbital margin concave, complete, lined with small granules (Fig. 1 C, D). Posterior margin of epistome acutely triangular at median, each lateral margin with 2 concavities (Fig. 1 C, D). Third maxilliped ischium subrectangular, about 1.6 times longer than wide, with distinct median oblique groove; merus subquadrate, about 0.7 times as long as wide, outer surface concave, anteroexternal angle nearly round, not expanded; exopod slender, with prominent anterointernal margin tooth, reaching beyond upper edge of ischium, to approximately two-fifth lengths of length of merus, flagellum distinct, shorter than width of merus (Fig. 1 E). Cheliped slightly asymmetrical, relatively stout without significant difference between males and females (Fig. 2 A, B). Anterior margin of basis-ischium almost smooth; inner margins of merus granulated (Fig. 2 A, B). Outer surface of carpus rugose, inner distal angle with distinct sharp tooth. Outer surfaces of chelae rugose; chela palm in large males approximately 2.4 times as long as broad; major chela stouter, longer than minor chela (Fig. 2 A, B). Major chela with fingers stout, gently curved, shorter than palm, outer surface smooth; cutting edges of both fingers with different sized teeth and denticles, almost no gap when fingers closed, tips not crossing (Fig. 2 A, B). Minor chela with fingers slender, shorter than major chela, fingers tips relatively straight, almost no gap when closed (Fig. 2 A, B). Ambulatory legs not elongated; third pair longest, first pair shortest (Fig. 1 A, B). Outer surface of merus slightly rugose, dorsal margin weakly serrated, length to width ratio of fourth merus 3.6; carpus slightly rugose, outer surface with submedian crista on first to third legs, absent on the fourth leg; propodus subrectangular, length to width ratio of fourth propodus 2.5; dactylus gently curved, margins with short, sharp corneous spines on both inner, outer and upper margins (Fig. 1 A, B). Thoracic sternum relatively wide, surface smooth with lateral margins slightly setose (Figs. 1 B, 2 C). Sternites 1 and 2 completely fused to form broad triangular plate, lateral margin distinctly convex, separated from sternite 3 by complete suture; sternites 3 and 4 completely fused, without suture; sternite 8 not visible when pleon closed. Sternopleonal cavity reaching to imaginary line connecting anterior edges of cheliped coxae (Fig. 2 C). Male pleon narrowly triangular; telson triangular, relatively narrow, lateral margins concave, width to length ratio 1.2; proximal margin of telson slightly wider than the distal margin of somite 6; somite 6 subrectangular, width to length ratio 2.6 (Fig. 2 D). Male pleonal locking tubercle just below median part of sternite 5 (Fig. 3 A). Female pleon ovate, covering most of thoracic sternum. Vulvae ovate; low vulvar cover on extend oblique edge of vulva, occupied mostly in sternite 6 with the proximal margin appressed against the suture with sternite 5 (Fig. 3 B). G 1 slender, sinuous, reaching to median part of sternite 5, with terminal and subterminal articles clearly demarcated; subterminal article relatively broad, 2.9 times longer than broad, neck-like at distal part, 2.2 times as long as the terminal article; terminal article relatively long, hook shape, bent at about 10 ° along longitudinal axis, with fold extending at basal part of terminal article, distal part curved inwards, tip sharp, about 0.4 times length of subterminal article (Figs. 3 A, 4 A – D). G 2 slightly shorter than G 1, distal article short, about 0.74 times length of basal article (Figs. 3 A, 4 E, F). Live colouration. The dorsal surface is golden brown. Ambulatory legs are orange and the colour is brighter on the dactyli (Fig. 5).	en	Dang, Phan Doan, Tien, Tran Van, Tu, Do Van (2025): Tayninhon nuibaden, a new genus and new species of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Ba Den Mountain, Southeast Vietnam. Zootaxa 5693 (2): 291-300, DOI: 10.11646/zootaxa.5693.2.10, URL: https://doi.org/10.11646/zootaxa.5693.2.10
523F87990945FFABFF49FD3745B8F993.taxon	etymology	Etymology. The new species is named after the type locality, “ Núi Bà Đen ”. The name is used as a noun in apposition. Habitat. These crabs have been observed in rock crevices and fissures within areas that have slow flowing water. Burrowing behaviour was not observed, and the crabs are also not arboreal. The species has been recorded at an elevation of approximately 400 m, and there have been no observations at higher elevations even though the mountain reaches 986 m. This could be due to the steep terrain in the upper part of the mountain, which causes water sources to become scarce during the dry season, while in the rainy season, the water flow becomes too strong, making the upper terrain habitat unsuitable for this crab species. The species was observed both during the day and at night, with more individuals recorded at night, possibly due to the nocturnal activity patterns typical of freshwater crabs. The best time for observation and specimen collection is at the beginning of the rainy season, around August, when environmental conditions may be more favourable for their appearance. This area is characterised by large piles of rocks and is completely devoid of soil. The local flora consists of vines and rock- dwelling plants with secondary roots (Fig. 6 A – D).	en	Dang, Phan Doan, Tien, Tran Van, Tu, Do Van (2025): Tayninhon nuibaden, a new genus and new species of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Ba Den Mountain, Southeast Vietnam. Zootaxa 5693 (2): 291-300, DOI: 10.11646/zootaxa.5693.2.10, URL: https://doi.org/10.11646/zootaxa.5693.2.10
523F87990945FFABFF49FD3745B8F993.taxon	discussion	Remarks. Based on field surveys conducted in January 2024, this new genus and new species appears to be restricted to a single locality with ongoing habitat degradation. Ba Den Mountain may be the only remaining habitat for this species. This mountain is also home to some endemic species found only in this region. Recently, scientists have described a new species of gecko, Cyrtodactylus thuongae Phung, Van Schingen, Ziegler & Nguyen, 2014, and lizard, Scincella badenensis Nguyen, Nguyen, Nguyen & Murphy, 2019, from this area, highlighting its conservation importance (Nguyen et al. 2019; Phung et al. 2019). Ba Den Mountain harbours not only biological uniqueness but also holds historical and cultural significance in southern Vietnam. The blooming of tourist activities following the construction of infrastructure on the mountain’s summit, intensive agriculture in the surrounding foothills and climate change may threaten the survival of this species. Based on the criterial by IUCN Standards and Petitions Committee (2024), this species can be assessed at least as Vulnerable (VU) under IUCN Criterion B — Geographic Range, specifically: (1) B 1. Extent of Occurrence (EOO) — the area of Bà Đen Mountain is approximately 24 km ², which is well below the threshold of 100,000 km ²; (2) B 2 ab — the population is severely fragmented or known from only a single location; and there is a continuing decline, observed or inferred, in: (i) extent of occurrence; (ii) area of occupancy; (iii) area, extent and / or quality of habitat (Cumberlidge et al. 2009; IUCN Standards and Petitions Committee 2024). A targeted conservation program should be developed for this newly described species, incorporating habitat protection measures and further field surveys to assess its population status and ecological requirements. Such efforts will also benefit the broader biodiversity of this unique montane ecosystem in southeastern Vietnam.	en	Dang, Phan Doan, Tien, Tran Van, Tu, Do Van (2025): Tayninhon nuibaden, a new genus and new species of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Ba Den Mountain, Southeast Vietnam. Zootaxa 5693 (2): 291-300, DOI: 10.11646/zootaxa.5693.2.10, URL: https://doi.org/10.11646/zootaxa.5693.2.10
