Parvuspotamon Dai & Bo, 1994

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.10170924
persistent identifier	https://treatment.plazi.org/id/96446683-2328-5EB8-92B2-CB81DD77C366
treatment provided by	ZooKeys by Pensoft
scientific name	Parvuspotamon Dai & Bo, 1994
status

Treatment

Genus Parvuspotamon Dai & Bo, 1994 View in CoL

Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Type species.

Parvuspotamon yuxiense Dai & Bo, 1994, by original designation.

Diagnosis.

Medium sized (adult carapace width 16-26 mm, n = 15). Carapace broader than long, ovate; dorsal surface convex, smooth, regions not clear; branchial regions swollen, smooth (Figs 2A View Figure 2 , 4A View Figure 4 ). Epigastric cristae weakly developed, oblique, separated from each other by deep inverted Y-shaped groove; postorbital cristae low, indistinct, confluent with epigastric cristae (Figs 2A View Figure 2 , 4A View Figure 4 ). External orbital angle bluntly triangular, outer margin and anterolateral margin of carapace confluent (Figs 2A View Figure 2 , 4A View Figure 4 ). Anterolateral margin of carapace entire convex, smooth; posterolateral margins of carapace gently converging, smooth (Figs 2A View Figure 2 , 4A View Figure 4 ). Epibranchial tooth indistinct (Figs 2A View Figure 2 , 4A View Figure 4 ). Sub-orbital, sub-hepatic and pterygostomial regions smooth (Figs 2B, C View Figure 2 , 4B, C View Figure 4 ). Antennular fossae slit-like in anterior view; median lobe of epistome posterior margin narrowly triangular (Figs 2B View Figure 2 , 4B View Figure 4 ). Exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Fig. 3G View Figure 3 ). Thoracic sternites 3/4 in male completely fused (Figs 2C View Figure 2 , 3C, E View Figure 3 , 4C View Figure 4 ). Vulvae transversely ovate, widely located from each other, touching suture of sternites 5/6 (Fig. 3F View Figure 3 ). Male pleon broadly triangular (Figs 2C View Figure 2 , 3C View Figure 3 , 4C View Figure 4 ). G1 slender, reaching pleonal locking tubercle in situ (Figs 3E, H, I View Figure 3 , 4D, E View Figure 4 ); subterminal segment stout, slightly sinuous (Figs 3H, I View Figure 3 , 4D, E View Figure 4 ); terminal segment slender, relatively long, subconical, strongly sinuous, bent inwards, inner margin strongly concave, ~ 0.6 × length of subterminal segment, without groove for G2 on ventral side, tip rounded, dorsal flap absent (Figs 3H, I View Figure 3 , 4D-G View Figure 4 ). G2 longer than G1; terminal segment relatively long; subterminal segment ~ 1.5 × length of terminal segment (Fig. 3J View Figure 3 ).

Remarks.

Parvuspotamon was previously known by two species, P. yuxiense (type species) and P. dixuense . The latter species was recently described by Naruse et al. (2018) based on the characters in the carapace and G1 terminal segment. Based on morphological and molecular data, P. dixuense , however, is transferred to Songpotamon gen. nov. since it possesses the generic characters of the new genus (see Remarks for the new genus). The present revision thus restricts Parvuspotamon only to the type species, i.e., P. yuxiense .

The morphological similarities between Parvuspotamon and Songpotamon gen. nov. notwithstanding, Parvuspotamon can easily be distinguished from Songpotamon gen. nov. by the characters in the carapace, vulvae and G1 (see Remarks for Songpotamon gen. nov.). Parvuspotamon is immediately distinguished from most of the remaining Chinese potamid genera by the combination of its medium body size (adult carapace width 16-26 mm), the strongly sinuous G1 terminal segment, and the absence of a flagellum on the exopod of the third maxilliped ( Dai and Bo 1994; Dai 1999).

Geographic distribution.

Parvuspotamon is known only from Yunnan Province of southwest China.