Songpotamon malipoense gen. et, 2023

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, ZooKeys 1183, pp. 13-38 : 13

publication ID	https://dx.doi.org/10.3897/zookeys.1183.109948
publication LSID	lsid:zoobank.org:pub:DA6935B9-D9E1-4B0B-8686-7B661CB9140E
DOI	https://doi.org/10.5281/zenodo.10170914
persistent identifier	https://treatment.plazi.org/id/6D3DB24F-9039-4DDB-A1C7-F0F46443826C
taxon LSID	lsid:zoobank.org:act:6D3DB24F-9039-4DDB-A1C7-F0F46443826C
treatment provided by	ZooKeys by Pensoft
scientific name	Songpotamon malipoense gen. et
status	sp. nov.

Treatment

Songpotamon malipoense gen. et sp. nov.

Figs 7 View Figure 7 , 8 View Figure 8 , 9D-F View Figure 9 , 10C, D View Figure 10

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 View Figure 7 ). Postorbital and epigastric cristae inconspicuous, not confluent, separated by shallow groove (Fig. 7A View Figure 7 ); epigastric cristae weakly developed, oblique, separated by deep inverted Y-shaped groove; postorbital cristae low, weakly rugose (Fig. 7A View Figure 7 ). External orbital angle bluntly triangular, outer margin convex, separated from anterolateral margin of carapace by shallow cleft (Fig. 7A View Figure 7 ). Anterolateral margin of carapace convex, cristate, granular; posterolateral margin straight, with multiple weakly oblique striae (Fig. 7A View Figure 7 ). Orbits large; sub-orbital regions smooth; sub-hepatic and pterygostomial regions with small, rounded granules (Fig. 7B, C View Figure 7 ). Antennular fossae semi-circular; median lobe of epistome posterior margin broadly triangular (Fig. 7B View Figure 7 ). Exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Fig. 8C View Figure 8 ). Thoracic sternites 3/4 in male fused except for relatively shallow, incomplete groove demarcating suture (Figs 7C View Figure 7 , 8E, G View Figure 8 ). Vulvae transversely ovate, closely located to each other, touching suture of thoracic sternites 5/6, opened inwards (Fig. 8H View Figure 8 ). Male pleon narrowly triangular; somite 6 relatively narrow, width ~ 2.5 × as length (Fig. 8E View Figure 8 ). G1 slender, reaching beyond pleonal locking tubercle up to suture between thoracic sternites 4/5 in situ (Figs 8G View Figure 8 , 9D, E View Figure 9 , 10C, D View Figure 10 ); 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 View Figure 9 , 10C, D View Figure 10 ). G2 longer than G1; terminal segment relatively short; subterminal segment ~ 5 × length of terminal segment (Fig. 9F View Figure 9 ).

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 View Figure 7 ). 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 View Figure 7 ). Cervical groove distinct, shallow (Fig. 7A View Figure 7 ). External orbital angle bluntly triangular, outer margin convex, with shallow cleft demarcating it from epibranchial tooth; epibranchial tooth weakly developed (Fig. 7A View Figure 7 ). Anterolateral margin of carapace convex, cristate, granular; posterolateral margin straight, with multiple weakly oblique striae, converging towards posterior carapace margin (Fig. 7A View Figure 7 ). Orbits large; supraorbital and infraorbital margins smooth; sub-orbital regions smooth, sub-hepatic and pterygostomial regions with small, rounded granules (Fig. 7B, C View Figure 7 ). Antennular fossae semi-circular in anterior view; median lobe of epistome posterior margin broadly triangular (Fig. 7B View Figure 7 ). Third maxilliped with subrectangular ischium; exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Fig. 8C View Figure 8 ).

Chelipeds unequal (Figs 7A, C View Figure 7 , 8A, B View Figure 8 ). Merus trigonal in cross section; margins crenulated (Fig. 7A, C View Figure 7 ). Carpus with bluntly stout spine at inner-distal angle (Fig. 7A, C View Figure 7 ). Major cheliped palm length ~ 1.2 × as height (Fig. 8A View Figure 8 ). Occlusal margin of fingers with rounded, blunt teeth; distinct gape when closed (Fig. 8A View Figure 8 ).

Ambulatory legs not elongated, slender dactyli (Figs 7A, C View Figure 7 , 8D View Figure 8 ); second pair longest, last pair shortest (Fig. 7A, C View Figure 7 ). Outer surface of merus slightly rugose, dorsal margin weakly serrated, without subdistal tooth, length ~ 3.5 × as width (Fig. 8D View Figure 8 ).

Male thoracic sternum generally smooth, weakly pitted; sternites 1/2 fused forming triangular structure (Figs 7C View Figure 7 , 8E, G View Figure 8 ); sternites 2/3 demarcated by horizontal groove; sternites 3/4 fused except for relatively shallow, incomplete groove demarcating suture (Figs 7C View Figure 7 , 8E, G View Figure 8 ); median longitudinal suture of sternites 7/8 deep (Fig. 8E, G View Figure 8 ). 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 View Figure 8 ).

Male pleon narrowly triangular; telson relatively broad, lateral margins slightly convex, width ~ 1.3 × as length (Figs 7C View Figure 7 , 8E View Figure 8 ); 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 View Figure 7 , 8E View Figure 8 ). Female pleon ovate, covering most of thoracic sternum (Fig. 8F View Figure 8 ).

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 View Figure 8 , 9D, E View Figure 9 , 10C, D View Figure 10 ); subterminal segment relatively slender, gently sinuous, distal part prominently narrow, inner margin almost straight (Figs 9D, E View Figure 9 , 10C, D View Figure 10 ); 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 View Figure 9 , 10C, D View Figure 10 ). G2 longer than G1, terminal segment relatively short; subterminal segment ~ 5 × length of terminal segment (Fig. 9F View Figure 9 ).

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 View Figure 7 ) (vs with few short setae and scattered pits); 2) inverted Y-shaped groove between the epigastric cristae relatively deep (Fig. 7A View Figure 7 ) (vs relatively shallow); 3) chela generally smooth on the outer surface (Fig. 8A View Figure 8 ) (vs relatively rugose); 4) pterygostomial regions with prominent rounded granules (Fig. 7B View Figure 7 ) (vs relatively smooth); 5) antennular fossae rectangular in anterior view (Fig. 7B View Figure 7 ) (vs slit-like); 6) median tooth on the epistome posterior margin broadly triangular (Fig. 7B View Figure 7 ) (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 View Figure 9 , 10C, D View Figure 10 ) (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 View Figure 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).