Revision of two species of Sinopotamon Bott, 1967 (Crustacea, Brachyura, Potamidae) endemic to China: a new combination and a new synonym Author Wang, Ruxiao https://orcid.org/0000-0002-1626-1366 Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Rd, Nanjing 210023, China Author Pan, Da https://orcid.org/0000-0001-5445-6423 Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Rd, Nanjing 210023, China Author Chen, Hui Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Rd, Nanjing 210023, China Author Zhu, Binqing Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment, Nanjing 210042, China & Research Station for Ecological Environment of Wuyi Mountains / Biodiversity Comprehensive Observation Station for Wuyi Mountains / State Environmental Protection Key Laboratory on Biosafety, Nanping, 353000, China Author Sun, Hongying https://orcid.org/0000-0003-2311-1814 Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, 1 Wenyuan Rd, Nanjing 210023, China text ZooKeys 2022 2022-07-14 1112 179 197 http://dx.doi.org/10.3897/zookeys.1112.85278 journal article http://dx.doi.org/10.3897/zookeys.1112.85278 1313-2970-1112-179 2308C47E483A460AB1561A4D8DE50C28 E7867FA0C61D57738EC6CC81942D16BD Huananpotamon koatenense (Rathbun, 1904) comb. nov. Figs 4 , 5 , 6 , 7A , 8A Patamon (Potamon) koatenensis Rathbun, 1904: 308-309, pl. 13, fig. 3. Sinopotamon koatenense (Rathbun, 1904): Ng et al. 2008 : 166. Type material. Potamon (P.) koatenensis , holotype , 1 female, 18.4 x 23.4 mm, MNHN-IU-2014-23011 (citation: http://coldb.mnhn.fr/catalognumber/mnhn/iu/2014-23011), 1200 m a.s.l., Koaten, Western Fujian Province, China, coll. Armand David, October 1873. Other material. 1 male 15.8 x 19.2 mm , NNU 16C-211220HK1, 27°42.40'N , 117°41.47'E , 890 m a.s.l. , Guwangkeng , Tongmu Village , Wuyishan National Park , Fujian Province , China , coll. Hui Chen , Ruxiao Wang , Yunlong Sun & Hongying Sun , 20 December 2021 . 2 females , 19.7 x 25.4 mm , NNU 16C-211220 HK 2; 14.9 x 18.8 mm , NNU 16C-211220 HK 3, same collection data as above . 2 females , 17.0 x 21.6 mm , NNU 16C-211220HK4; 14.3 x 17.6 mm , NNU 16C-211220 HK 5, 27°45.77'N , 117°41.23'E , 854 m a.s.l. , Qiaoxia , Tongmu Village , Wuyishan National Park , Fujian Province , China, coll. Hui Chen , Ruxiao Wang , Yunlong Sun & Hongying Sun , 17 December 2021 . 1 female , 13.6 x 16.8 mm , NNU 16C-211220HK6, 27°46.15'N , 117°41.28'E , 893 m a.s.l. , Jiangdun , Tongmu Village , Wuyishan National Park , Fujian Province , China , coll. Hui Chen , Ruxiao Wang , Yunlong Sun & Hongying Sun , 18 December 2021 . Comparative material. Huananpotamon angulatum (Dai, Chen, Song, Fan, Lin & Zeng, 1979), male, 14.3 x 18.9 mm , NNU 11B-21413HA1, Jianou, Fujian, 1 April 2021 ; Huananpotamon lichuanense Dai, Zhou & Peng, 1995, male, 12.0 x 14.4 mm , NNU 11B-21320HL1, Lichuan, Jiangxi, 20 March 2021 ; Huananpotamon lini Cheng & Li, 2008, male, 16.5 x 18.8 mm , NNU 11B-211225HL1, Songxi, Fujian, 25 December 2021 ; Huananpotamon yiyangense Dai, Zhou & Peng, 1995, male, 13.7 x 16.3 mm , NNU 11B-21415HY1, Yiyang, Jiangxi, 15 April 2021 . Diagnosis. Carapace broader than long, dorsal surface slightly convex, finely pitted (Figs 4A , 6A, D ); frontal margin distinctively bilobed, separated medially by shallow concavity (Figs 4A , 6A, D ); epigastric cristae prominent, separated medially by distinct Y-shaped furrow (Figs 4A , 6A, D ); postorbital cristae distinct, slightly rugose, confluent with epibranchial teeth (Figs 4A , 6A, D ); anterolateral region convex, with rugose (Figs 4A, C , 6A, D ). Third maxilliped exopod with flagellum (Figs 4A , 6A ). G1 slender; tip part of terminal segment expanded, inner-distal angle prominent, outer-distal angle elongated, dagger-shaped (Figs 5B, G , 8A ). G2 slender, terminal segment long (Fig. 5D ). Vulvae without operculum, not reaching suture of sternites 5/6 anteriorly, closely spaced from one another, opening inwards (Fig. 6B ). Figure 4. Huananpotamon koatenense , male, 15.8 x 19.2 mm NNU 16C-211220HK1 A dorsal view B ventral view C frontal view D ventral view showing sterno-pleonal cavity with right G1 in situ. Scale bars: 1.0 cm. Description. Carapace broader than long, regions distinct, dorsal surface gently convex, finely pitted (Figs 4A , 6A, D ). Frontal margin distinctively bilobed, divided into two broad lobes, separated by shallow concavity, margin of each lobe gently convex (Figs 4A , 6A, D ). Epigastric cristae prominent, separated medially by distinct Y-shaped furrow extending to frontal region (Figs 4A , 6A, D ); postorbital cristae distinct, slightly rugose, confluent with epibranchial teeth (Figs 4A , 6A, D ). Cervical grooves distinct, deep (Figs 4A , 6A, D ); H-shaped groove shallow but distinct (Figs 4A , 6A, D ); anterolateral region convex with weak rugae; posterolateral surface smooth, with oblique striae; posterolateral margins converging posteriorly (Figs 4A , 6A, D ). External orbital angle distinct, sharp, triangular, outer margin longer in length to inner margin, outer margin lined with small granules (Figs 4A , 6A, D ). Epibranchial tooth granular, clearly demarcated from external orbital tooth by small gap (Figs 4A , 6A, D ). Anterolateral margin convex, lined with 15-18 granules (Figs 4A, C , 6A, D ). Orbits ovate, large; supraorbital, infraorbital margins cristate, lined with numerous inconspicuous granules (Fig. 4C ). Epistome posterior margin with median lobe broadly triangular, lateral margins almost straight (Fig. 4C ). Figure 5. Huananpotamon koatenense , male, 15.8 x 19.2 mm, NNU 16C-211220HK1 A left third maxilliped B left G1 (dorsal view) C left G1 (ventral view) D left G2 E male right cheliped F male left cheliped G left G1 terminal segment (lateral view). Scale bars: 1.0 mm. Ischium of third maxillipeds trapezoidal, length ~ 1.3 x width, with distinct median oblique groove; merus subquadrate, length ~ 0.8 x width (Figs 5A , 6B, E ); exopod slender, reaching proximal one-third of merus length, with flagellum (Fig. 5A ). Chelipeds slightly asymmetrical (Figs 4A , 6A, D ). Merus margins crenulated (Fig. 4A ). Carpus surface wrinkled with sharp spine on inner margin, spinule at base (Fig. 4A ). Major cheliped palm length ~ 1.4 x height, surface rugose; fingers of major cheliped slightly curved, outer surface with rows of pits; dactylus 1.1 x as long as palm length. Occlusal margin of both fingers lined with 11-15 irregular small teeth, forming small gape when fingers closed (Fig. 5E, F ). Figure 6. Female specimens compared in this study: Huananpotamon koatenense , 19.7 x 25.4 mm, NNU 16C-211220HK2 A dorsal view B thoracic sternum and vulvae C pleon. H. koatenense , holotype, 18.4 x 23.4 mm, MNHN-IU-2014-23011 D dorsal view E thoracic sternum and vulvae F pleon. Scale bars: 1.0 cm. Ambulatory legs slender, surfaces and margins with scattered short setae (Figs 4A , 6A, D ); second ambulatory leg longest, merus ~ 1.5 x as long as dactylus (Figs 4A , 6A, D ). Thoracic sternum surface generally smooth, weakly pitted (Figs 4B, D , 6B, E ); sternites 1, 2 fused, forming triangular structure, separated from sternite 3 by conspicuous suture; sternites 3, 4 completely fused without obvious median suture (Figs 4B , 6B, E ). Male sterno-pleonal cavity reaching to imaginary line connecting median part of cheliped coxae (Fig. 4B, D ). Male pleonal locking tubercle on median part of sternite 5 (Fig. 4D ). Male pleon triangular, surface smooth (Fig. 4B, D ); somites 3-6 gradually decreasing in width; somite 6 width ~ 2.0 x length; telson broad triangular, width ~ 1.6 x length, apex rounded (Fig. 4B ). Female pleon ovate; somite 6 width ~ 3.4 x length; telson semicircular, width ~ 2.9 x length (Fig. 6C, F ). G1 slender, bent dorsal-ward at proximal one-thirds (Fig. 5B, C ); tip well exceeding pleonal locking tubercle in situ, reaching suture between thoracic sternites 4, 5 (Fig. 4D ); subterminal segment length ~ 2.1 x length of terminal segment; distal part of subterminal segment almost straight; terminal segment slender, inner margin slightly concave, outer margin straight, distally expanded, inner-distal angle high, rounded, outer-distal angle elongated, dagger-shaped (Fig. 5B, C, G ); groove for G2 running mid-line of ventral surface (Fig. 5B ). G2 slender, longer than G1, subterminal segment length ~ 1.7 x length of terminal segment (Fig. 5D ). Female vulvae on thoracic sternite 6, elongate-ovate, without distinct operculum, closely spaced from one another, opening inwards (Fig. 6B ). Live coloration. Generally dark brown to purplish brown. The immovable finger of the chelipeds and surrounding areas are pale yellow (Fig. 7A ). Figure 7. Huananpotamon koatenense A color in life B natural habitat. Photographs by Hongying Sun, 20 December 2021, Tongmu Village, Wuyishan National Park, Fujian Province, China. Distribution and habitat. Tongmu Village, Wuyishan National Park, Fujian Province, China. This species lives in moist mud burrows under rocks near the small hillstream, ca 900 m a.s.l. (Fig. 7B ). Bottapotamon engelhardti (Bott, 1967) was found to be sympatric with H. koatenense and appears to occupy the shallower parts of the streams and hides under rocks. Remarks. Thanks to digitalization of the specimen, we are able to examine the photographs of the holotype of S. koatenense provided by MNHN (http://coldb.mnhn.fr/catalognumber/mnhn/iu/2014-23011). Potamon (P.) koatenensis can be distinguished from Sinopotamon by several characters: small sized (versus large sized in Sinopotamon ; cf. Bott 1967 ; Dai 1999 ), external orbital angle acutely triangular (Fig. 6D ) (versus external orbital angle broadly triangular in Sinopotamon ; cf. Bott 1967 ; Dai 1999 ), maxilliped 3 ischium relatively broad (Fig. 6E ) (versus maxilliped 3 ischium relatively narrow in Sinopotamon ; cf. Bott 1967 ; Dai 1999 ; fig. 139(1)), ambulatory legs slender (Fig. 6D, E ) (versus ambulatory legs stout in Sinopotamon ; cf. Bott 1967 ; Dai 1999 ), male sterno-pleonal cavity relatively narrow (Fig. 6E ) (versus male sterno-pleonal cavity relatively broad in Sinopotamon ; cf. Bott 1967 ; Dai 1999 ), female pleon broadly ovate (Fig. 6F ) (versus female pleon ovate in Sinopotamon ; cf. Bott 1967 ; Dai 1999 ), vulvae relatively small and narrow (Fig. 6E ) (versus vulvae relatively large and wide in Sinopotamon ; cf. Bott 1967 ; Dai 1999 ). In contrast, the holotype of S. koatenense conforms well to the genus diagnosis for Huananpotamon : small sized (cf. Dai and Ng 1994 ; Dai 1999 ), postorbital region narrow (Fig. 6A, D ; cf. Dai and Ng 1994 ; Dai 1999 : pl. 7, fig. 7), external orbital angle acutely triangular (Fig. 6A, D ; cf. Dai and Ng 1994 ; Dai 1999 : pl. 7, fig. 7), maxilliped 3 ischium relatively broad (Fig. 6A, D ; cf. Dai and Ng 1994 : fig. 1; Dai 1999 : fig. 66(1)), ambulatory legs slender (Fig. 6A, B, D, E ; cf. Dai and Ng 1994 ; Dai 1999 : pl. 7, fig. 7), male sterno-pleonal cavity relatively narrow (Fig. 6B, E ; cf. Dai and Ng 1994 : fig. 1; Dai 1999 : fig. 66(8)), female pleon broadly ovate (Fig. 6C, F ; cf. Dai and Ng 1994 : fig. 1; Dai 1999 : fig. 66(7)), vulvae small, ovate, not reaching the sutures of sternites 5/6 (Fig. 6B, E ; cf. Dai and Ng 1994 : fig. 1; Dai 1999 : fig. 66(8)). Figure 8. The ventral view of G1 A Huananpotamon koatenense , 15.8 x 19.2 mm, NNU 16C-211220HK1 B Huananpotamon angulatum , male, 14.3 x 18.9 mm, NNU 11B-21413HA1 C Huananpotamon lichuanense , male, 12.0 x 14.4 mm, NNU 11B-21320HL1 D Huananpotamon lini , male, 16.5 x 18.8 mm, NNU 11B-211225HL1 E Huananpotamon yiyangense , male, 13.7 x 16.3 mm, NNU 11B-21415HY1. Scale bars: 1.0 mm. Huananpotamon koatenense is close to four other Huananpotamon species, H. angulatum (Dai, Chen, Song, Fan, Lin & Zeng, 1979), H. lichuanense Dai, Zhou & Peng, 1995, H. lini Cheng & Li, and H. yiyangense Dai, Zhou & Peng, 1995 in having slender G1 terminal segment, and elongated outer-distal angle of G1 terminal segment (Fig. 8 ). However, the G1 terminal segment of H. koatenense can be distinguished from its congeners by the following characters: inner margin of G1 terminal segment slightly concave (Fig. 8A ) (versus inner margin of terminal segment relatively straight in H. lichuanense and H. lini ; cf. Dai et al. 1995 : fig. 3; Cheng et al. 2008 : fig. 1; Fig. 8C, D ), G1 terminal segment with inner-distal angle relatively higher, globular in shape (Fig. 8A ) (versus terminal segment with inner-distal angle relatively lower, somewhat blunt in H. angulatum , H. lichuanense , and H. yiyangense ; cf. Dai and Ng 1994 : fig. 1; Dai et al. 1995 : figs 1, 3; Fig. 8B-C, E ), G1 terminal segment with outer-distal angle relatively short (Fig. 8A ) (versus terminal segment outer-distal angle relatively elongated in H. angulatum , H. lichuanense , and H. yiyangense ; cf. Dai and Ng 1994 : fig. 1; Dai et al. 1995 : figs 1, 3; Fig. 8B-C, E ). Other differences existing in the external orbital teeth, epibranchial teeth, and vulva are listed in Table 2 . In this study, only one male specimen was collected, so we did not have enough specimens to analyze intraspecific variations and this matter may require further investigation. Table 2. Morphological differences among Huananpotamon koatenense , and the other four species of Huananpotamon , H. chongrenense , H. lini , H. medium , H. obtusum , and H. ruijinense .

Character	External orbital tooth	Epibranchial tooth	Cleft between external orbital and epibranchial teeth	Vulva
H. koatenense	Sharp (Fig. 4A )	Granular (Fig. 4A )	Shallow (Fig. 4A )	Ovate (Fig. 6B )
H. angulatum (cf. Dai & Ng, 1994: fig. 1)	Sharp	Granular	Shallow	Ovate
H. lichuanense (cf. Dai et al., 1995 : fig. 3)	Acutely sharp	Granular	Shallow	Widely ovate
H. lini (cf. Cheng et al., 2008 : fig. 1)	Acutely sharp	Rounded	Deep, U-shaped	Widely ovate
H. yiyangense (cf. Dai et al., 1995 : fig. 1)	Acutely sharp	Rounded	Shallow	Ovate