Erimetopus, RATHBUN, 1894

Cumberlidge, Neil & Daniels, Savel R., 2022, A new multilocus phylogeny reveals overlooked diversity in African freshwater crabs (Brachyura: Potamoidea): a major revision with new higher taxa and genera, Zoological Journal of the Linnean Society 194 (4), pp. 1268-1311 : 1290

GENUS ERIMETOPUS RATHBUN, 1894

( FIGS 1B 2 , 4A–C, 9A; TABLES 1–3 )

Erimetopus Rathbun, 1894: 26 ; 1900: 285; 1905: 270, pl. 19, fig. 8; 1921: 433–434, pl. 33, fig. 15; Lenz, 1912: 9; Colosi, 1920: 27; Balss, 1936: 195; 1957: 164; Chace, 1942: 225; Capart, 1954: 846, fig. 43; Cumberlidge, 1998: 196; 2008: 72, 77, tab. 1; 2011: 79, 82–83 tabs 6.1, 6.3; Ng et al., 2008: 171.

Potamon (Acanthothelphusa) Ortmann, 1903: 300 .

Potamonautes (Erimetopus) Bott, 1955: 224–225 , fig. 7a–b, pl. III, fig. 1a–c; 1955: 225–226, fig. 8a–b, pl. III, fig. 2a–c.

Diagnosis: Anterolateral margin denticulated between exorbital, epibranchial teeth. Cheliped carpus inner margin with two large subequal pointed teeth; cheliped carpus outer margin with two or three teeth; anterolateral margin of carapace behind epibranchial tooth with several small teeth; carpi, propodi of P2–5 with spines on their margins; margins of meri of P2–5 either smooth or sparsley setose; G1 TA slim tapering, not widened by raised lobes ( Fig. 4A–C ).

Type species: Erimetopus brazzae A. Milne-Edwards, 1886 , by original designation.

Species included: Erimetopus brazzae (A. Milne- Edwards, 1886) and Erimetopus vandenbrandeni ( Balss, 1936) .

Distribution: Erimetopus brazzae and E.vandenbrandeni are endemic to the Lower and Middle CongoRiverBasinintheRepublicoftheCongoandtheD.R. Congo (Cumberlidge, 1999; Cumberlidge & Reed, 2004; Fig. 9A ).

Remarks: Erimetopus is revised and redescribed here. Erimetopus accommodates two species of unusual freshwater crabs from the Lower Congo Basin in Central Africa ( Cumberlidge & Reed, 2004). Bott (1955) established Potamonautes (Erimetopus) with Erimetopus spinosus Rathbun, 1894 as the type species for two species, Potamonautes (Erimetopus) brazzae brazzae and Potamonautes (Erimetopus) brazzae frontospinulosa . Cumberlidge & Reed (2004) recognized Erimetopus as a valid genus with two species, E. brazzae and E. vandenbrandeni . The phylogenies of Daniels et al. (2015: fig. 2), Daniels & Klaus (2018: fig 1) and Wood et al. (2019: Fig. 1 ) all recovered E. brazzae as a welldefined lineage sister to Longipotamonautes ballayi . The lineage represented by Longipotamonautes ( Bott, 1955) is sister to the branch for Occidensonautes ecorssei from West Africa ( Fig. 1B 2 ).

Figures

Figure 1. A, maximum clade credibility tree of the Afrotropical freshwater crab fauna based on four DNA loci with support values (posterior probabilities and bootstrap values of the ML analyses) with a geological timescale below the tree topology. Posterior probabilities> 0.95 pP (*above branch) and bootstrap values> 75% (* below branch) were regarded as statistically supported and are shown on the tree topology. Clade A, Liberonautinae, clade B, Potamonautinae, clade B1, Maritimonautini, clade B2, Erimetopini, clade B3, Potamonautini. B, detail of the maximum clade credibility tree of the Afrotropical freshwater crab fauna showing Clade B3 Potamonautini with the species included in the five genera within the tribe: Arcopotamonautes (B3[1]), Lirrangopotamonautes (B3[2]), Platythelphusa (B3[3]), Potamonautes s.s. (B3[4]) and Rotundopotamonautes (B3[5]).

Figure 4. Gonopods 1 and 2 of the four genera in Erimetopini. A–C, Erimetopus vandenbrandeni; D–F, Longipotamonautes ballayi; G–I, Nesonautes margaritarius; J–L, Occidensonautes ecorssei. Scale bar: A–L = 2.0 mm.

Figure 9. Maps showing the distributional ranges of the four genera of Erimetopini (A) Erimetopus, (B) Longipotamonautes, (C) Nesonautes and (D) Occidensonautes.

Figure 2. Liberonautinae. Gonopods 1 and 2 of Liberonautes latidactylus, NMU9.V.2005B (CW 72, CL 47.2, CH 20.5, FW 19.3 mm) Guinea, West Africa. A, left G1 ventral view; (B) left G1 dorsal view; (C) left G2 ventral view. Scale bar: A, B = 2.8 mm, C = 1.8 mm.