Songpotamon malipoense gen. et 2023, sp. nov.
Creators: name: Shi, Boyang
name: Pan, Da
name: Sun, Hongying
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Decapoda
Potamidae
Songpotamon
Songpotamon malipoense

description: Songpotamon malipoense gen. et sp. nov.  
Figs 7, 8, 9D-F, 10C, D  
Type material.  
  Holotype.  China • ♂, 21.7 × 16.8 mm; Yunnan Province, Wenshan Prefecture, Malipo County, Tiechang Township; 23.20°N, 104.83°E; altitude 864 m asl.; 24 Oct. 2020; Boyang Shi, Ruxiao Wang, and Hongying Sun leg.; GenBank: OR469052; NNU-167444-01.   
  Paratype.  China • ♂, 22.1 × 17.8 mm; same collection data as for holotype; GenBank: OR469053; NNU-167444-02 • ♂, 20.3 × 16.2 mm; same collection data as for holotype; NNU-167444-03 • ♂, 19.6 × 15.7 mm; same collection data as for holotype; NNU-167444-04 • ♀, 20.7 × 16.7 mm; same collection data as for holotype; NNU-167444-05 • ♀, 20.5 × 15.4 mm; same collection data as for holotype; NNU-167444-06 • ♀, 18.6 × 14.3 mm; same collection data as for holotype; NNU-167444-07.   
Diagnosis.  
 Medium sized (adult carapace width 19-22 mm, n = 7). Carapace broader than long, ovate; dorsal surface convex, smooth, pitted, regions not clear; branchial regions swollen, smooth (Fig. 7A). Postorbital and epigastric cristae inconspicuous, not confluent, separated by shallow groove (Fig. 7A); epigastric cristae weakly developed, oblique, separated by deep inverted Y-shaped groove; postorbital cristae low, weakly rugose (Fig. 7A). External orbital angle bluntly triangular, outer margin convex, separated from anterolateral margin of carapace by shallow cleft (Fig. 7A). Anterolateral margin of carapace convex, cristate, granular; posterolateral margin straight, with multiple weakly oblique striae (Fig. 7A). Orbits large; sub-orbital regions smooth; sub-hepatic and pterygostomial regions with small, rounded granules (Fig. 7B, C). Antennular fossae semi-circular; median lobe of epistome posterior margin broadly triangular (Fig. 7B). Exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Fig. 8C). Thoracic sternites 3/4 in male fused except for relatively shallow, incomplete groove demarcating suture (Figs 7C, 8E, G). Vulvae transversely ovate, closely located to each other, touching suture of thoracic sternites 5/6, opened inwards (Fig. 8H). Male pleon narrowly triangular; somite 6 relatively narrow, width ~ 2.5 × as length (Fig. 8E). G1 slender, reaching beyond pleonal locking tubercle up to suture between thoracic sternites 4/5 in situ (Figs 8G, 9D, E, 10C, D); subterminal segment relatively slender, gently sinuous, inner margin almost straight; terminal segment short, slender, subconical, relatively less strongly bent at ~ 30° outwards, ~ 0.4 × length of subterminal segment, with distinct groove for G2 on ventral side, tip subtruncate, recurved upwards (Figs 9D, E, 10C, D). G2 longer than G1; terminal segment relatively short; subterminal segment ~ 5 × length of terminal segment (Fig. 9F).   
Description.  
 Medium sized (adult carapace width 19-22 mm, n = 7). Carapace broader than long, ovate; dorsal surface convex transversely, longitudinally, smooth, pitted, regions not clear; branchial region swollen, smooth (Fig. 7A). Postorbital and epigastric cristae inconspicuous, not confluent, separated by shallow groove; epigastric cristae weakly developed, oblique, separated by deep inverted Y-shaped groove; postorbital cristae low, weakly rugose, reaching epibranchial tooth (Fig. 7A). Cervical groove distinct, shallow (Fig. 7A). External orbital angle bluntly triangular, outer margin convex, with shallow cleft demarcating it from epibranchial tooth; epibranchial tooth weakly developed (Fig. 7A). Anterolateral margin of carapace convex, cristate, granular; posterolateral margin straight, with multiple weakly oblique striae, converging towards posterior carapace margin (Fig. 7A). Orbits large; supraorbital and infraorbital margins smooth; sub-orbital regions smooth, sub-hepatic and pterygostomial regions with small, rounded granules (Fig. 7B, C). Antennular fossae semi-circular in anterior view; median lobe of epistome posterior margin broadly triangular (Fig. 7B). Third maxilliped with subrectangular ischium; exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Fig. 8C).   
Chelipeds unequal (Figs 7A, C, 8A, B). Merus trigonal in cross section; margins crenulated (Fig. 7A, C). Carpus with bluntly stout spine at inner-distal angle (Fig. 7A, C). Major cheliped palm length ~ 1.2 × as height (Fig. 8A). Occlusal margin of fingers with rounded, blunt teeth; distinct gape when closed (Fig. 8A).   
Ambulatory legs not elongated, slender dactyli (Figs 7A, C, 8D); second pair longest, last pair shortest (Fig. 7A, C). Outer surface of merus slightly rugose, dorsal margin weakly serrated, without subdistal tooth, length ~ 3.5 × as width (Fig. 8D).   
Male thoracic sternum generally smooth, weakly pitted; sternites 1/2 fused forming triangular structure (Figs 7C, 8E, G); sternites 2/3 demarcated by horizontal groove; sternites 3/4 fused except for relatively shallow, incomplete groove demarcating suture (Figs 7C, 8E, G); median longitudinal suture of sternites 7/8 deep (Fig. 8E, G). Vulvae transversely ovate, closely located to each other, touching suture of thoracic sternites 5/6, opened inwards, posteromesial margin with low raised rim (Fig. 8H).  
Male pleon narrowly triangular; telson relatively broad, lateral margins slightly convex, width ~ 1.3 × as length (Figs 7C, 8E); somite 6 broadly rectangular, width ~ 2.5 × as length; suture between somites 6/7 sinuous; somites 3-5 trapezoidal, gradually decreasing in width; somite 2 trapezoidal, reaching to bases of coxae of fourth ambulatory legs; thoracic sternite 8 not visible when pleon closed (Figs 7C, 8E). Female pleon ovate, covering most of thoracic sternum (Fig. 8F).   
 G1 slender, reaching beyond pleonal locking tubercle up to suture between thoracic sternites 4/5 in situ, with terminal and subterminal segments clearly demarcated (Figs 8G, 9D, E, 10C, D); subterminal segment relatively slender, gently sinuous, distal part prominently narrow, inner margin almost straight (Figs 9D, E, 10C, D); terminal segment short, slender, subconical, relatively less strongly bent at ~ 30° outwards, ~ 0.4 × length of subterminal segment, outer margin convex, inner margin convex, with distinct groove for G2 on ventral side, tip subtruncate, recurved upwards (Figs 9D, E, 10C, D). G2 longer than G1, terminal segment relatively short; subterminal segment ~ 5 × length of terminal segment (Fig. 9F).   
Etymology.  
The species is named after Malipo County, the type locality of the new species in the Yunnan Province of China.  
Colour in life.  
The dorsal surface of the carapace is dark brown, with brighter chelae; the ventral surface is paler.  
Habitat.  
 Songpotamon malipoense gen. et sp. nov. is usually found hiding under rocks in small hill streams. Some large specimens have nevertheless been collected from deep mud burrows at the bank of hill streams, suggesting a semi-terrestrial lifestyle.   
Remarks.  
 The new species superficially resembles S. dixuense comb. nov. in overall carapace physiognomy, especially in possessing the granular anterolateral margin of the carapace and the relatively slender G1. Songpotamon malipoense gen. et sp. nov., however, can immediately be distinguished from S. dixuense comb. nov. by the following characters: 1) carapace dorsal surface glabrous, with dense pits (Fig. 7A) (vs with few short setae and scattered pits); 2) inverted Y-shaped groove between the epigastric cristae relatively deep (Fig. 7A) (vs relatively shallow); 3) chela generally smooth on the outer surface (Fig. 8A) (vs relatively rugose); 4) pterygostomial regions with prominent rounded granules (Fig. 7B) (vs relatively smooth); 5) antennular fossae rectangular in anterior view (Fig. 7B) (vs slit-like); 6) median tooth on the epistome posterior margin broadly triangular (Fig. 7B) (vs narrowly triangular); 7) male pleonal somite 6 relatively narrower (vs relatively broader); and 8) G1 with an almost straight inner margin of the subterminal segment (Fig. 9D, E, 10C, D) (vs with a gently concave inner margin) (cf. Naruse et al. 2018: figs 24A, B, 25B, 26A, C). Biogeographically, these two species are also isolated due to their occurrence in different drainages, with the new species in the Yuanjiang-Red River Basin and S. dixuense comb. nov. in the Pearl River Basin (Fig. 1). Songpotamon malipoense gen. et sp. nov. need not be confused with S. funingense gen. et sp. nov. (see Remarks for the latter new species).   
Geographic distribution.  
 Songpotamon malipoense gen. et sp. nov. is known from Malipo County, southern Wenshan Prefecture, Yunnan Province, southwest China.
description: Published as part of Shi, Boyang, Pan, Da & Sun, Hongying, 2023, A taxonomic revision of the freshwater crab genus Parvuspotamon Dai & Bo, 1994 (Decapoda, Brachyura, Potamidae), with descriptions of a new genus and two new species, pp. 13-38 in ZooKeys 1183 on page 13, DOI: 10.3897/zookeys.1183.109948