Arcopotamonautes, (BOTT, 1955)

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 : 1293-1294

GENUS ARCOPOTAMONAUTES ( BOTT, 1955) STAT. NOV.

( FIGS 1B 3 [1], 5D–F, 10A; TABLES 1–3 )

Zoobank registration: urn:lsid:zoobank.org:act:187310FB-E397-49F6-A482-254C75929C62 .

Telphusa Hilgendorf, 1898: 8–9 , fig. 5, 5a–d.

Potamon De Man, 1898: 438 ; Chace, 1942: 222.

Potamon (Potamonautes) Rathbun, 1905: 172 ; 1933: 256; 1935: 26; Colosi, 1924: 4.

Potamonautes Balss, 1929: 348 ; Barnard, 1935: 484; Cumberlidge, 1997: 581–582; 1998: 204; 2004: 418–423, figs 1–8, 17–25, 30; 2008: 72, 77, tab. 1; 2011: 79, 82–83, tabs 6.1, 6.3; Reed & Cumberlidge, 2006a: 34–37, figs 113–123, 167–168, 184, pl. XII; Ng et al., 2008: 171.

Potamonautes (Arcopotamonautes) Bott, 1955: 270– 272 , pl. XVII, figs 1a–d, 40 (for Telphusa suprasulcata, Hilgenforf, 1898 ; not Potamon (Potamonautes) alluaudi Bouvier, 1921 , Telphusa bipartite Hilgendorf, 1898 ).

Potamonautes (Gerdalopotamonautes) Bott, 1955 : pl. 13, figs 3a–d, 34, 82 (for Potamonautes (Gerdalopotamonautes) gerdalensis Bott, 1955 ).

Potamonautes (Platypotamonautes) Bott, 1955: 229 , pl. IV, figs la–d, 12, 66 (for Potamon (Potamonautes) platynotus Cunnington, 1907 ; not Po. margaritarius (= Nesonautes margaritarius ), Po. ecorssei (= Occidensonautes ecorssei ), Po. pilosus (= Rotundopotamonautes pilosus ) and Po. neumanni (= Rotundopotamonautes neumanni ).

Diagnosis: Postfrontal crest distinct, traversing entire carapace between epibranchial teeth; epibranchial tooth reduced to small granule; posterior carapace sulci deep, distinct; G1 TA distinctly widened in midsection (dorsal fold higher than ventral fold), tip curved upward; except for A. suprasulcatus whose G1 TA is a long, slim, curving and tapered and not widened in midsection.

Type species: Telphusa suprasulcata Hilgendorf, 1898 , by original designation.

Species included: Arcopotamonautes amosae ( Cumberlidge, Johnson, Clark & Genner, 2021) comb. nov., Arcopotamonautes bellarussus ( Daniels et al., 2014) comb. nov., Arcopotamonautes caputanatis (Cumberlidge, Clark & Fastiggi, 2019) comb. nov., Arcopotamonautes gerdalensis ( Bott, 1955) comb. nov., Arcopotamonautes infravallatus ( Hilgendorf, 1898) comb. nov., Arcopotamonautes johnstoni (Miers, 1885) comb. nov., Arcopotamonautes loveridgei (Rathbun, 1933) comb. nov.

Arcopotamonautes montivagus ( Chace, 1953) comb. nov., Arcopotamonautes orbitospinus (Cunnington, 1907) comb. nov., Arcopotamonautes platycentron (Hilgendorf, 1897) comb. nov.

Arcopotamonautes platynotus (Cunnington, 1907) comb. nov., Arcopotamonautes raybouldi ( Cumberlidge & Vannini, 2004) comb. nov., Arcopotamonautes suprasulcatus ( Hilgendorf, 1898) comb. nov., Arcopotamonautes unisulcatus ( Rathbun, 1921) comb. nov. and Arcopotamonautes xiphoidus (Reed & Cumberlidge, 2006) comb. nov.

Distribution: Arcopotamonautes species are found in the southern and central parts of the Rift Valley around Lake Malawi and Lake Tanganyika ( Malawi, Tanzania and Zambia) ( Fig. 10A ). Eight species, A. unisulcatus , A. xiphoidus , A. gerdalensis , A. infravallatus , A. johnstoni , A. loveridgei , A. platycentron and A. raybouldi , have a distribution in Tanzania ( Reed & Cumberlidge, 2006a), with the range of A. platycentron and A. raybouldi extending just across the border into southern Kenya ( Cumberlidge & Vannini, 2004; Reed & Cumberlidge, 2006a). One species, A. amosae , is found in the basins of rivers draining into Lake Tanganyika in Tanzania and also in Lake Kivu, in Nord-Kuvi Province in the D.R. Congo (Cumberlidge et al., 2021). Three species, A. montivagus , A. suprasulcatus and A. loveridgei , are found in southern Tanzania (Iringa, Mbeya and Ruvuma provinces) and in Malawi (Northern Region) ( Chace, 1953; Reed & Cumberlidge, 2006a) and one species A. caputanatis is found in Zambia (Northern Province) ( Cumberlidge et al., 2019). Four species in this genus are found in large lakes such as A. platycentron (Lake Chala) ( Reed & Cumberlidge, 2006a), A. amosae (Lake Kivu) (Cumberlidge et al., 2021), A. platynotus (Lake Tanganyika) ( Reed & Cumberlidge, 2006a) and A. orbitospinus (Lake Malawi) (Cumberlidge et al., 2021).

Remarks: The subgenus Potamonautes (Arcopotamonautes) Bott, 1955 is given generic status and revised. Arcopotamonautes is recognized here to accommodate 14 species from the African Rift Valley. Bott (1955) established P. ( Arcopotamonautes ) for P. (A.) suprasulcatus suprasulcatus , P. (A.) s. alluaudi and P. (A.) bipartitus . Arcopotamonautes includes Telphusa suprasulcata Hilgendorf, 1898 , the type species of P. ( Arcopotamonautes ) as well as P. (Gerdalopotamonautes) gerdalensis Bott, 1955 , the type species of P. (Gerdalopotamonautes) Bott, 1955. The latter subgenus becomes a junior synonym of Aropotamonautes under the rule of priority because Telphusa suprasulcata Hilgendorf, 1898 , is the senior name. Similarly, Arcopotamonautes also includes Potamon (Potamonautes) platynotus Cunnington, 1907 , which is the type species of the subgenus P. (Platypotamonautes) Bott, 1955. The latter subgenus becomes a junior synonym of Aropotamonautes under the rule of priority because Telphusa suprasulcata Hilgendorf, 1898 is the senior name.

DNA data are available for six of these species: A. gerdalensis , A. montivagus , A. orbitospinus (as Po. lirrangensis in Fig. 1B 3 [2]), A. platynotus , A. raybouldi and A. suprasulcatus . These species group together in a well-supported lineage within the large clade for the Potamonautini ( Daniels et al., 2015, fig. 2; Daniels & Klaus, 2018: fig 1; Wood et al., 2019: fig 1; Fig. 1B 3 ). In the absence of DNA data, the other eight species assigned here to this genus ( A. amosae , A. caputanatis , A. infravallatus , A. johnstoni , A. loveridgei , A. platycentron , A. suprasulcatus and A. unisulcatus ) are included based on shared morphological characters that conform to the generic diagnosis.

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 10. Maps showing the distributional ranges of the five genera of Potamonautini. (A) Arcopotamonautes, (B) Lirrangopotamonautes, (C) Platythelphusa, (D) Potamonautes s.s. and (E) Rotundopotamonautes.