Huananpotamon koatenense (Rathbun, 1904) Wang & Pan & Chen & Zhu & Sun, 2022

Wang, Ruxiao, Pan, Da, Chen, Hui, Zhu, Binqing & Sun, Hongying, 2022, Revision of two species of Sinopotamon Bott, 1967 (Crustacea, Brachyura, Potamidae) endemic to China: a new combination and a new synonym, ZooKeys 1112, pp. 179-197 : 179

publication ID	https://dx.doi.org/10.3897/zookeys.1112.85278
publication LSID	lsid:zoobank.org:pub:2308C47E-483A-460A-B156-1A4D8DE50C28
persistent identifier	https://treatment.plazi.org/id/CB6DC1E5-0706-5F8E-9E4B-907940E3BFE5
treatment provided by	ZooKeys by Pensoft
scientific name	Huananpotamon koatenense (Rathbun, 1904)
status	comb. nov.

Treatment

Huananpotamon koatenense (Rathbun, 1904) View in CoL comb. nov.

Figs 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7A View Figure 7 , 8A View Figure 8

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 × 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 × 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 GoogleMaps . 2 females, 19.7 × 25.4 mm, NNU 16C-211220 HK 2; 14.9 × 18.8 mm, NNU 16C-211220 HK 3, same collection data as above GoogleMaps . 2 females, 17.0 × 21.6 mm, NNU 16C-211220HK4; 14.3 × 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 GoogleMaps . 1 female, 13.6 × 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 GoogleMaps .

Comparative material.

Huananpotamon angulatum (Dai, Chen, Song, Fan, Lin & Zeng, 1979), male, 14.3 × 18.9 mm, NNU 11B-21413HA1, Jianou, Fujian, 1 April 2021; Huananpotamon lichuanense Dai, Zhou & Peng, 1995, male, 12.0 × 14.4 mm, NNU 11B-21320HL1, Lichuan, Jiangxi, 20 March 2021; Huananpotamon lini Cheng & Li, 2008, male, 16.5 × 18.8 mm, NNU 11B-211225HL1, Songxi, Fujian, 25 December 2021; Huananpotamon yiyangense Dai, Zhou & Peng, 1995, male, 13.7 × 16.3 mm, NNU 11B-21415HY1, Yiyang, Jiangxi, 15 April 2021.

Diagnosis.

Carapace broader than long, dorsal surface slightly convex, finely pitted (Figs 4A View Figure 4 , 6A, D View Figure 6 ); frontal margin distinctively bilobed, separated medially by shallow concavity (Figs 4A View Figure 4 , 6A, D View Figure 6 ); epigastric cristae prominent, separated medially by distinct Y-shaped furrow (Figs 4A View Figure 4 , 6A, D View Figure 6 ); postorbital cristae distinct, slightly rugose, confluent with epibranchial teeth (Figs 4A View Figure 4 , 6A, D View Figure 6 ); anterolateral region convex, with rugose (Figs 4A, C View Figure 4 , 6A, D View Figure 6 ). Third maxilliped exopod with flagellum (Figs 4A View Figure 4 , 6A View Figure 6 ). G1 slender; tip part of terminal segment expanded, inner-distal angle prominent, outer-distal angle elongated, dagger-shaped (Figs 5B, G View Figure 5 , 8A View Figure 8 ). G2 slender, terminal segment long (Fig. 5D View Figure 5 ). Vulvae without operculum, not reaching suture of sternites 5/6 anteriorly, closely spaced from one another, opening inwards (Fig. 6B View Figure 6 ).

Description.

Carapace broader than long, regions distinct, dorsal surface gently convex, finely pitted (Figs 4A View Figure 4 , 6A, D View Figure 6 ). Frontal margin distinctively bilobed, divided into two broad lobes, separated by shallow concavity, margin of each lobe gently convex (Figs 4A View Figure 4 , 6A, D View Figure 6 ). Epigastric cristae prominent, separated medially by distinct Y-shaped furrow extending to frontal region (Figs 4A View Figure 4 , 6A, D View Figure 6 ); postorbital cristae distinct, slightly rugose, confluent with epibranchial teeth (Figs 4A View Figure 4 , 6A, D View Figure 6 ). Cervical grooves distinct, deep (Figs 4A View Figure 4 , 6A, D View Figure 6 ); H-shaped groove shallow but distinct (Figs 4A View Figure 4 , 6A, D View Figure 6 ); anterolateral region convex with weak rugae; posterolateral surface smooth, with oblique striae; posterolateral margins converging posteriorly (Figs 4A View Figure 4 , 6A, D View Figure 6 ). External orbital angle distinct, sharp, triangular, outer margin longer in length to inner margin, outer margin lined with small granules (Figs 4A View Figure 4 , 6A, D View Figure 6 ). Epibranchial tooth granular, clearly demarcated from external orbital tooth by small gap (Figs 4A View Figure 4 , 6A, D View Figure 6 ). Anterolateral margin convex, lined with 15-18 granules (Figs 4A, C View Figure 4 , 6A, D View Figure 6 ). Orbits ovate, large; supraorbital, infraorbital margins cristate, lined with numerous inconspicuous granules (Fig. 4C View Figure 4 ). Epistome posterior margin with median lobe broadly triangular, lateral margins almost straight (Fig. 4C View Figure 4 ).

Ischium of third maxillipeds trapezoidal, length ~ 1.3 × width, with distinct median oblique groove; merus subquadrate, length ~ 0.8 × width (Figs 5A View Figure 5 , 6B, E View Figure 6 ); exopod slender, reaching proximal one-third of merus length, with flagellum (Fig. 5A View Figure 5 ).

Chelipeds slightly asymmetrical (Figs 4A View Figure 4 , 6A, D View Figure 6 ). Merus margins crenulated (Fig. 4A View Figure 4 ). Carpus surface wrinkled with sharp spine on inner margin, spinule at base (Fig. 4A View Figure 4 ). Major cheliped palm length ~ 1.4 × height, surface rugose; fingers of major cheliped slightly curved, outer surface with rows of pits; dactylus 1.1 × 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 View Figure 5 ).

Ambulatory legs slender, surfaces and margins with scattered short setae (Figs 4A View Figure 4 , 6A, D View Figure 6 ); second ambulatory leg longest, merus ~ 1.5 × as long as dactylus (Figs 4A View Figure 4 , 6A, D View Figure 6 ).

Thoracic sternum surface generally smooth, weakly pitted (Figs 4B, D View Figure 4 , 6B, E View Figure 6 ); 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 View Figure 4 , 6B, E View Figure 6 ). Male sterno-pleonal cavity reaching to imaginary line connecting median part of cheliped coxae (Fig. 4B, D View Figure 4 ). Male pleonal locking tubercle on median part of sternite 5 (Fig. 4D View Figure 4 ).

Male pleon triangular, surface smooth (Fig. 4B, D View Figure 4 ); somites 3-6 gradually decreasing in width; somite 6 width ~ 2.0 × length; telson broad triangular, width ~ 1.6 × length, apex rounded (Fig. 4B View Figure 4 ). Female pleon ovate; somite 6 width ~ 3.4 × length; telson semicircular, width ~ 2.9 × length (Fig. 6C, F View Figure 6 ).

G1 slender, bent dorsal-ward at proximal one-thirds (Fig. 5B, C View Figure 5 ); tip well exceeding pleonal locking tubercle in situ, reaching suture between thoracic sternites 4, 5 (Fig. 4D View Figure 4 ); subterminal segment length ~ 2.1 × 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 View Figure 5 ); groove for G2 running mid-line of ventral surface (Fig. 5B View Figure 5 ). G2 slender, longer than G1, subterminal segment length ~ 1.7 × length of terminal segment (Fig. 5D View Figure 5 ). Female vulvae on thoracic sternite 6, elongate-ovate, without distinct operculum, closely spaced from one another, opening inwards (Fig. 6B View Figure 6 ).

Live coloration.

Generally dark brown to purplish brown. The immovable finger of the chelipeds and surrounding areas are pale yellow (Fig. 7A View Figure 7 ).

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 View Figure 7 ). 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 View Figure 6 ) (versus external orbital angle broadly triangular in Sinopotamon ; cf. Bott 1967; Dai 1999), maxilliped 3 ischium relatively broad (Fig. 6E View Figure 6 ) (versus maxilliped 3 ischium relatively narrow in Sinopotamon ; cf. Bott 1967; Dai 1999; fig. 139(1)), ambulatory legs slender (Fig. 6D, E View Figure 6 ) (versus ambulatory legs stout in Sinopotamon ; cf. Bott 1967; Dai 1999), male sterno-pleonal cavity relatively narrow (Fig. 6E View Figure 6 ) (versus male sterno-pleonal cavity relatively broad in Sinopotamon ; cf. Bott 1967; Dai 1999), female pleon broadly ovate (Fig. 6F View Figure 6 ) (versus female pleon ovate in Sinopotamon ; cf. Bott 1967; Dai 1999), vulvae relatively small and narrow (Fig. 6E View Figure 6 ) (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 View Figure 6 ; cf. Dai and Ng 1994; Dai 1999: pl. 7, fig. 7), external orbital angle acutely triangular (Fig. 6A, D View Figure 6 ; cf. Dai and Ng 1994; Dai 1999: pl. 7, fig. 7), maxilliped 3 ischium relatively broad (Fig. 6A, D View Figure 6 ; cf. Dai and Ng 1994: fig. 1; Dai 1999: fig. 66(1)), ambulatory legs slender (Fig. 6A, B, D, E View Figure 6 ; cf. Dai and Ng 1994; Dai 1999: pl. 7, fig. 7), male sterno-pleonal cavity relatively narrow (Fig. 6B, E View Figure 6 ; cf. Dai and Ng 1994: fig. 1; Dai 1999: fig. 66(8)), female pleon broadly ovate (Fig. 6C, F View Figure 6 ; 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 View Figure 6 ; cf. Dai and Ng 1994: fig. 1; Dai 1999: fig. 66(8)).

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 View Figure 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 View Figure 8 ) (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 View Figure 8 ), G1 terminal segment with inner-distal angle relatively higher, globular in shape (Fig. 8A View Figure 8 ) (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 View Figure 8 ), G1 terminal segment with outer-distal angle relatively short (Fig. 8A View Figure 8 ) (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 View Figure 8 ). Other differences existing in the external orbital teeth, epibranchial teeth, and vulva are listed in Table 2 View 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.