Songpotamon, Shi & Pan & Sun, 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.10170926
persistent identifier	https://treatment.plazi.org/id/8CCC83D0-C234-4C34-AB6B-A3580AF601CD
taxon LSID	lsid:zoobank.org:act:8CCC83D0-C234-4C34-AB6B-A3580AF601CD
treatment provided by	ZooKeys by Pensoft
scientific name	Songpotamon
status	gen. nov.

Treatment

Genus Songpotamon gen. nov.

Figs 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8 , 9 View Figure 9 , 10 View Figure 10

Type species.

Songpotamon funingense sp. nov., by present designation.

Species included.

Songpotamon dixuense (Naruse, Chia & Zhou, 2018), comb. nov., Songpotamon funingense gen. et sp. nov., and Songpotamon malipoense gen. et sp. nov.

Diagnosis.

Medium sized (adult carapace width 19-27 mm, n = 16). Carapace broader than long, ovate; dorsal surface convex, generally smooth, pitted, regions not clear; branchial regions swollen (Figs 5A View Figure 5 , 7A View Figure 7 ). Postorbital and epigastric cristae not confluent, separated by shallow groove (Figs 5A View Figure 5 , 7A View Figure 7 ). External orbital angle bluntly triangular, outer margin separated from anterolateral margin of carapace by shallow cleft (Figs 5A View Figure 5 , 7A View Figure 7 ). Anterolateral margin of carapace convex (Figs 5A View Figure 5 , 7A View Figure 7 ). Orbits large; supraorbital and infraorbital margins smooth (Figs 5B View Figure 5 , 7B View Figure 7 ). Exopod of third maxilliped reaching beyond anterolateral corner of ischium, without flagellum (Figs 6C View Figure 6 , 8C View Figure 8 ). Thoracic sternites 3/4 in male fused except for incomplete groove demarcating suture (Figs 5C View Figure 5 , 6E, G View Figure 6 , 7C View Figure 7 , 8E, G View Figure 8 ). Vulvae transversely ovate, relatively closely located to each other, touching suture of sternites 5/6 (Figs 6H View Figure 6 , 8H View Figure 8 ). Male pleon narrowly triangular (Figs 5C View Figure 5 , 6E View Figure 6 , 7C View Figure 7 , 8E View Figure 8 ). G1 slender, almost reaching or reaching beyond pleonal locking tubercle in situ (Figs 6G View Figure 6 , 8G View Figure 8 , 9A, B, D, E View Figure 9 , 10A-D View Figure 10 ); terminal segment slender, subconical, bent outwards, relatively short, ~ 0.4 × length of subterminal segment, with distinct groove for G2 on ventral side, tip subtruncate, gently recurved upwards, dorsal flap absent (Figs 9A, B, D, E View Figure 9 , 10A-D View Figure 10 ). G2 longer than G1; terminal segment relatively short; subterminal segment ~ 5 × length of terminal segment (Fig. 9C, F View Figure 9 ).

Etymology.

The genus is named after the late Prof. Daxiang Song, a senior academician in the Chinese Academy of Sciences, in the honour of his immense contributions to Chinese invertebrate systematics; in arbitrary combination with the genus name Potamon Savigny, 1816. Gender of genus neuter.

Remarks.

Songpotamon gen. nov. is established for S. dixuense comb. nov. and two new species, S. funingense sp. nov. and S. malipoense sp. nov. Songpotamon dixuense comb. nov. was previously in Parvuspotamon , but here transferred to Songpotamon gen. nov. because it possesses the key generic characters of the new genus, which includes, the medium body size (adult carapace width 19-27 mm), the third maxilliped exopod lacking a flagellum, the external orbital angle being bluntly triangular, the slender G1 shape, and the terminal segment being subconical and with a groove for G2 on the ventral side (cf. Naruse et al. 2018: figs 24-27).

Songpotamon gen. nov. can easily be distinguished from Parvuspotamon by the following characters: 1) carapace dorsal surface with scattered pits (Figs 5A View Figure 5 , 7A View Figure 7 ; cf. Naruse et al. 2018: fig. 25A) (vs smooth; Figs 2A View Figure 2 , 4A View Figure 4 ); 2) outer margin of the external orbital angle separated from the anterolateral margin of the carapace by the shallow cleft (Figs 5A View Figure 5 , 7A View Figure 7 ; cf. Naruse et al. 2018: fig. 25A) (vs confluent with each other; Figs 2A View Figure 2 , 4A View Figure 4 ); 3) vulvae relatively close located to each other (Figs 6H View Figure 6 , 8H View Figure 8 ; cf. Naruse et al. 2018: fig. 27) (vs relatively widely located from each other; Fig. 3F View Figure 3 ); 4) G1 terminal segment relatively shorter, ~ 0.4 × the length of the subterminal segment, with a truncated tip (Figs 9A, B, D, E View Figure 9 , 10A-D View Figure 10 ; cf. Naruse et al. 2018: fig. 26A-D) (vs relatively longer, ~ 0.6 × the length of the subterminal segment, with a rounded tip; Figs 3H, I View Figure 3 , 4D-G View Figure 4 ); 5) G1 terminal segment bent outwards but with the tip gently recurved upwards, the inner margin being straight to gently curved (Figs 9A, B, D, E View Figure 9 , 10A-D View Figure 10 ; cf. Naruse et al. 2018: fig. 26 A-D) (vs bent inwards, with the inner margin being strongly concave; Figs 3H, I View Figure 3 , 4D-G View Figure 4 ); and 6) groove for G2 on the G1 terminal segment clearly visible in the ventral view (Figs 9 B, E View Figure 9 , 10B, D View Figure 10 ; cf. Naruse et al. 2018: fig. 26A, B) (vs not visible; Figs 3I View Figure 3 , 4E, G View Figure 4 ).

Furthermore, Songpotamon gen. nov. is most likely to be confused with Chinapotamon Dai & Naiyanetr, 1994, as both the genera have a very similar carapace physiognomy, and their G1 terminal segment is subconical, with the groove for G2 visible in the ventral view. The new genus, Songpotamon gen. nov., is nevertheless distinguished from Chinapotamon by the following characters: 1) carapace relatively high (Figs 5B View Figure 5 , 7B View Figure 7 ) (vs relatively low); 2) ambulatory legs relatively stout (Figs 5A, C View Figure 5 , 6D View Figure 6 , 7A, C View Figure 7 , 8D View Figure 8 ) (vs relatively slender); 3) anterolateral margin of the carapace being less convex (Figs 5A View Figure 5 , 7A View Figure 7 ) (vs strongly convex); 4) third maxilliped exopod without flagellum (Figs 6C View Figure 6 , 8C View Figure 8 ) (vs with well-developed flagellum); 5) thoracic sternites 3/4 with incomplete but distinct groove demarcating suture (Figs 5C View Figure 5 , 6E, G View Figure 6 , 7C View Figure 7 , 8E, G View Figure 8 ) (vs groove demarcating suture absent); and 6) G1 terminal segment gently curved outwards (Figs 9A, B, D, E View Figure 9 , 10A-D View Figure 10 ) (vs strongly bent outwards) (cf. Dai 1999: figs 42-47; Ng 2017: figs 2-4, 6-8; Zou et al. 2018: figs 2-6).