POTAMONAUTINAE BOTT, 1970

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 : 1283-1284

SUBFAMILY POTAMONAUTINAE BOTT, 1970

( FIGS 1B , 4 , 6 , 8A; TABLES 1–3)

Diagnosis: Potamonautinae are recognized by the lack of an intermediate tooth between the exorbital and epibranchial teeth on the anterolateral margin of the carapace, by the elongated G2 TA, 0.9 × the G2 SA length ( Fig. 4C, F, I ) and by the exopod of the third maxilliped that has a flagellum that is subequal in length to the exopod ( Figs 4A–I , 5A–E ).

Type genus: Potamonautes MacLeay, 1838 , by monotypy, gender masculine.

Etymology: Potamonautinae is derived from the family level name Potamonautidae Bott, 1970 and this subfamily is assigned here to the Potamonautidae .

Tr i b e s i n c l u d e d: E r i m e t o p i n i t r i b e n o v., Maritimonautini tribe nov. and Potamonautini ( Bott, 1970) stat. nov.

Genera included: Arcopotamonautes ( Bott, 1955) stat. nov., Erimetopus Rathbun, 1894 , Lirrangopotamonautes ( Bott, 1955) stat. nov., Longipotamonautes ( Bott, 1955) stat. nov., Maritimonautes gen. nov., Nesonautes gen. nov., Occidensonautes gen. nov., Platythelphusa A. Milne- Edwards, 1887, Potamonautes MacLeay, 1838 s.s. and Rotundopotamonautes ( Bott, 1955) stat. nov.

Distribution: Potamonautinae is found throughout sub-Saharan Africa in the following regions and countries: West Africa (from Senegal to Nigeria), São Tomé Island, Central Africa ( Cameroon, Central African Republic, Gabon, Equatorial Guinea, Republic of the Congo and the D.R. Congo), eastern and northern Africa ( Tanzania, Kenya, South Sudan, Sudan, Egypt, Somalia) and southern Africa ( Angola, Malawi, Mozambique, Zambia, Zimbabwe, Botswana, Namibia, South Africa, Eswatini, Lesotho) ( Fig. 8A ).

Remarks: Potamonautinae is a monophyletic assemblage ( Fig. 1B ) with three main lineages, the Maritimonautini for Maritimonautes ( Fig. 1B 1 ), the Congowestini ( Fig. 1B 2 ) for Erimetopus , Longipotamonautes , Nesonautes and Occidensonautes and the Potamonautini ( Fig. 1B 3 ) for Arcopotamonautes , Lirrangopotamonautes , Platythelphusa , Potamonautes s. s. and Rotundopotamonautes . The relationships in the updated phylogeny ( Fig. 1B ) agree with those of Daniels & Klaus (2018) and Wood et al. (2019) each of which recovered a well-supported clade ( Fig. 1B , the Potamonautinae ) with the three lineages that are recognized here as three tribes ( Fig. 1B1 , B 2 , B3). Divergence within the Potamonautinae took place 23.41 Mya during the Oligocene-Miocene when the earliest clade (the Maritimonautini ; Fig. 1B1 ) branched off. This was followed by the Erimetopini ( Fig. 1B 2 ), which diverged 22.03 Mya, and by the Potamonautini ( Fig. 1B 3 ), which diverged 21.10 Mya.

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 3. Gonopods 1 and 2 of four genera in Liberonautinae. A–C, Buea asylos (Cumberlidge et al., 2019: fig. 7a, d; 8a); D–F, Potamonemus mambilorum (Cumberlidge et al., 2019: fig. 7b, e; 8b); G–I, Sudanonautes floweri; J–L, Louisea balssi (Mvogo Ndongo et al., 2018: fig. 5a–c, © Magnolia Press, reproduced with permission from the copyright holder). A, D, G, J, left G1 ventral view; B, E, H, K, left G1 dorsal view; C, F, I, L, left G2 ventral view. Scale bar: A, B, D, E, G, H, J, K = 2.0 mm, C, F, I, L = 1.8 mm.

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 5. Gonopods 1 and 2 of one genus in Maritimonautini and three genera in Potamonautini. A–C, Maritimonautes obesus; D–F, Arcopotamonautes suprasulcatus; G–I, Lirrangopotamonautes dybowskii; J–L, Platythelphusa armata. Scale bar: A, B, G–L = 2.0 mm, C, F = 1.8 mm; D, E = 5.0 mm; L = 6.7 mm.

Figure 6. Gonopods 1 and 2 of two genera in Potamonautini. A–C, Potamonautes anchetiae (CAW 450A), Angola. A, D, left G1 ventral view. D–F, Rotundopotamonautes loveni, Kenya, B, E, left G1 dorsal view; C, F, left G2 ventral view. Scale bar: A, B, D, E = 2.0 mm, C, F = 1.8 mm.

Figure 8. Maps showing the distributional ranges of (A) Potamonautinae, (B) Maritimonautini, (C) Erimetopini and (D) Potamonautini.

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.