POTAMONAUTIDAE 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 : 1279-1281

FAMILY POTAMONAUTIDAE BOTT, 1970

( FIGS 1–10 ; TABLES 1–3 )

Rediagnosis: Potamonautidae taxa are recognized by a mandibular palp with two articles comprising either a small ledge at their junction, or a simple terminal article completely lacking a lobe.

Subfamilies included: Liberonautinae subfam. nov. and Potamonautinae .

Genera included: Arcopotamonautes ( Bott, 1955) stat. nov., Buea Cumberlidge, Mvogo Ndongo, Clark & Daniels, 2019 , Erimetopus Rathbun, 1894 , Liberonautes Bott, 1955 , Lirrangopotamonautes ( Bott, 1955) stat. nov., Longipotamonautes ( Bott, 1955) stat. nov., Louisea Cumberlidge, 1994 , Maritimonautes gen. nov., Nesonautes gen. nov., Occidensonautes gen. nov., Platythelphusa A. Milne-Edwards, 1887 , Potamonautes MacLeay, 1838 s.s., Potamonemus Cumberlidge & Clark, 1992 , Rotundopotamonautes ( Bott, 1955) stat. nov. and Sudanonautes Bott, 1955 .

Distribution: Taxa of this family are found throughout sub-Saharan Africa (Cumberlidge, 1999; Fig. 6B ).

Remarks: The revised Potamonautidae includes the majority of species found on the African continent except for seven species in three genera of Deckeniidae and a species of Potamon (Potamidae) found in North Africa. Potamonautidae is divided here ( Tables 2–3 ; Figs 7A–C ) into Liberonautinae and Potamonautinae . The differences between these two subfamilies reflect phylogenetic divergence within the clade for Potamonautidae c. 30.14 Mya during the Eocene-Oligocene that gave rise to two lineages, each of which includes groups of morphologically distinct genera ( Daniels et al., 2006, 2015; Fig. 1 ).

KEY TO THE GENERA OF POTAMONAUTIDAE

1 No intermediate tooth on anterolateral margin between exorbital and epibranchial teeth ..................... 6

1’ Intermediate tooth on anterolateral margin between exorbital and epibranchial teeth ........................... 2

2 G1 TA directed inwards ................................................................................ .............................. Liberonautes

2’ G1 TA either straight or directed outwards ................................................................. ................................ 3

3 Third maxilliped exopod with long flagellum ................................................................. ........ Sudanonautes

3’ Third maxilliped exopod lacking flagellum ................................................................................................... 4

4 G2 TA long and flagellum-like ............................................................................................................ Louisea

4’ G2 TA short stub, lacking flagellum ............................................................................................................. 5

5 G1 TA elongate (TA/SA 0.86) .................................................................................................................. Buea

5’ G1TA medium length (TA/SA 0.63) ......................................................................................... Potamonemus

6 G1 TA short or medium length (0.25–0.30 × as long as G1 SA) ............................................................. ..... 7

6’ G1 TA long (0.40–0.45 × as long as G1 SA) ................................................................................. Nesonautes

7 G1 TA slim, tapering to pointed tip .............................................................................................................. 8

7’ G1 TA hose-like, ending in broad tip .............................................................................. Longipotamonautes

8 Endemic to West Africa ......................................................................................................... Occidensonautes

8’ Not found in West Africa ............................................................................................................................... 9

9 Outer margins of S4 raised and thickened .......................................................................... Maritimonautes

9’ Outer margins of S4 low, not raised ............................................................................................................ 10

10 Cheliped carpus outer margin with two or three small teeth ...................................................... Erimetopus

10’ Cheliped carpus outer margin smooth, lacking teeth ................................................................................ 11

11 Third maxilliped ischium with vertical sulcus............................................................................................. 12

11’ Third maxilliped ischium smooth, lacking vertical sulcus ........................................................................ 13

12 G1 TA with only slightly raised dorsal fold ....................................................................... Potamonautes s.s.

12’ G1 TA with distinctly raised dorsal fold .......................................................................... Arcopotamonautes

13 Thoracic sternal sulcus S3/4 completely traversing sternum ................................................................... 14

13’ Thoracic sternal sulcus S3/4 completely traversing sternum .................................. Rotundopotamonautes

14 G1 SA slim (SA base 0.25 × SA length) .................................................................... Lirrangopotamonautes

14’ G1 SA broad (SA base 0.5 × SA length) ................................................................................. Platythelphusa

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 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.

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 7. Maps showing the distributional range of (A) Potamonautidae, (B) Liberonautinae.

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

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

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.