Songpotamon malipoense Shi, Pan & Sun 2023

Songpotamon malipoense Shi, Pan & Sun, 2023 Figs 11, 12, 13, 14 Songpotamon malipoense Shi, Pan & Sun, 2023: 29–32, figs 8, 9 D – F, 10 C – D. Material examined. • 5 males (16.5 × 13.1, 17.0 × 13.8, 18.8 × 14.7, 18.9 × 14.7, 21.0 × 16.2 mm), 7 females (15.0 × 12.3, 15.3 × 12.4, 17.0 × 13.8, 17.8 × 14.3, 18.1 × 14.5, 18.9 × 14.7, 19.0 × 15.5 mm) (IB - FC-SMx 01), a small stream in Khau Vai, Khau Vai Commune, Meo Vac County, Ha Giang Province, Vietnam, 23°4'55.3920"N, 105°29'34.4639"E, 22 Mar 2024, Do et al. leg. • 2 males (21.8 × 16.3 mm; 19.4 × 15.3 mm), 1 female (18.8 × 14.6 mm) (ZRC 2024.0321), same data as above. Description. None (see Shi et al. 2023 for full description). Distribution. This species has only been found in karst landscapes between Vietnam and China, namely, Malipo County, Wenshan Prefecture, Yunnan Province, southwest China, and Khau Vai Commune, Meo Vac District, Ha Giang Province, northern Vietnam. Ecology. This species was found in mud burrows on the banks of small hill streams (Fig. 11 B). Field observations agree well with Shi et al. ’ s (2023) account of their material from Yunnan province, China; the present specimens collected from Ha Giang province, Vietnam, also exhibit a semi-terrestrial lifestyle. Colouration. The dorsal surface of the carapace is dark brown, brighter on the ventral surface, and orange on the chelae (Fig. 11 A; cf. Shi et al. 2023: fig. 7 A). Remarks. The examined specimens agree well with Songpotamon malipoense (see Shi et al. 2023). The specimens collected from Vietnam, like those from China are characterized by the following traits: relatively small adult carapace size (15.3–21 mm, n = 14); carapace broader than long, ovate; dorsal surface convex, smooth, pitted, regions not well defined; branchial regions swollen, smooth (Fig. 12 A; cf. Shi et al. 2023: fig. 7 A); 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 (Fig. 12 A; cf. Shi et al. 2023: fig. 7 A); external orbital tooth bluntly triangular, outer margin convex, separated from anterolateral margin of carapace by shallow cleft (Fig. 12 A; cf. Shi et al. 2023: fig. 7 A); anterolateral margin of carapace convex, cristate, granular; posterolateral margin straight, with multiple weakly oblique striae (Fig. 12 A; cf. Shi et al. 2023: fig. 7 A); orbits large; suborbital regions smooth sub-hepatic and pterygostomial regions with small, rounded granules (Fig. 12 B; cf. Shi et al. 2023: fig. 7 B); median lobe of epistome posterior margin broadly triangular (Fig. 12 C; cf. Shi et al. 2023: fig. 7 B); exopod of third maxilliped without flagellum (Fig. 12 D; cf. Shi et al. 2023: fig. 8 C); chelipeds unequal in males (Fig. 12 A; cf. Shi et al. 2023: fig. 7 A); thoracic sternites 3, 4 in male fused except for relatively shallow, incomplete groove demarcating suture (Fig. 13 A; cf. Shi et al. 2023: fig. 7 C); male pleon narrowly triangular; somite 6 relatively narrow, width to length ratio 2.0 (Fig. 13 A; cf. Shi et al. 2023: fig. 8 E); G 1 slender, reaching beyond pleonal locking tubercle up to suture between thoracic sternites 4 and 5 (Fig. 13 B; cf. Shi et al. 2023: fig. 8 G); subterminal article relatively slender, gently sinuous, inner margin almost straight; terminal article short, slender, subconical, relatively less strongly bent at about 30 ° angle outwards, about 0.4 times length of subterminal article, with distinct groove for G 2 on ventral side, tip subtruncate, recurved upwards (Fig. 14; cf. Shi et al. 2023: fig. 9 D, E); G 2 longer than G 1; terminal article relatively short; subterminal article about 3.0 times length of terminal article (Fig. 14; cf. Shi et al. 2023: fig. 9 D); female pleon ovate, covering most of thoracic sternum (Fig. 13 C; cf. Shi et al. 2023: fig. 8 F); vulvae transversely ovate, closely located to each other, touching suture of thoracic sternites 5 and 6, opened inwards (Fig. 13 D; cf. Shi et al. 2023: fig. 8 H). Geographically, the Chinese and Vietnamese populations are separated by about 70 km (Fig. 15) of lowlands. The area where the Vietnamese specimens were collected is part of a larger karst landscape known as the Dong Van Karst Plateau, which itself is a contiguous extension of the South China karst belt (Yunnan karst plateau) (Tran et al. 2022) where the type locality of S. malipoense Shi, Pan & Sun, 2023, is located.