Potamonautes perlatus (H. Milne-Edwards) Balss, 1936

Phiri, Ethel E. & Daniels, Savel R., 2014, Disentangling the divergence and cladogenesis in the freshwater crab species (Potamonautidae: Potamonautes perlatus sensu lato) in the Cape Fold Mountains, South Africa, with the description of two novel cryptic lineages, Zoological Journal of the Linnean Society 170 (2), pp. 310-332 : 322-323

POTAMONAUTES PERLATUS SENSU STRICTO (CLADE 2, FIG. 2 )

Historically, this species was thought to have a wide geographical distribution ranging from the Democratic Republic of the Congo (formerly Zaire), into Namibia (formerly South-West Africa), and South Africa. The precise geographical provenance of the holotype (deposited in the Museum of Natural History, Paris, accession: B 4360) is unknown. It is clear that the name P. perlatus was historically applied to a number of distinct poorly defined species. In the present study, following the genetic evidence, we restrict the use of the name of P. perlatus to all the specimens in the western flowing drainages of the Western Cape Province of South Africa (clade 2, Fig. 2 ).

Material examined

Holotype / neotype: The holotype is dry and could not be sent for comparison. However, because of the uncertainty of the geographical provenance of the holotype, we designated a specimen from the western flowing drainages (housed at the SAM, Iziko Museums of Cape Town ) as a neotype: Krieddouwkrans, SAM A45755 (1 ♂), 32°21′60″S, 18°57′00″E, collected on 10.ix.1994 by M. Somers. Morphological measurements of the neotype: carapace length (CL) = 41.4 mm; carapace width at the widest point ( CWW) = 60.5 mm, carapace width at posterior margin ( CWP) = 19.0 mm, frontal width (FW) = 41.0 mm, distance between postfrontal crest and anterior margin ( PFCD) = 5.3 mm, carapace height ( CH) = 28.4 mm, major cheliped propodus length ( MCPL) = 55.0 mm, major cheliped propodus height ( MCPH) = 23.8 mm, pereopod 2 merus length (P2 ML) = 24.3 mm, pereopod 2 merus width (P2 MW) = 8.8 mm, pereopod 5 merus length (P5 ML) = 22.2 mm, and pereopod 5 merus width (P5 MW) = 7.7 mm.

Additional material examined: Jonkershoek (Stellenbosch, Eerste River drainage system), SAM A41142 (1 ♂, 1 ♀), 33°57′60″S, 18°57′60″E, collected on 25.iii.1994 by M. van der Merwe and L. Hoenson; Jonkershoek (Stellenbosch, Lang River , Eerste River drainage system), SAM A41215 (5 ♂, 1 ♀), 33°57′59.76″S, 18°57′59.76″E, collected on 17.xi.1994 by J. Hulley; Tokai (Cape Peninsula), SAM A41137 (3 ♂, 9 ♀), 34°03′60″S, 18°25′60″E, collected on 29.v.1992 by B. Stewart and L. Hoenson; and Paarl Rock (Paarl, Berg River drainage system), SAM A41306 (1 ♂, 1 ♀), 31°43′60″S, 18°55′60″E, collected on 05.ix.1994 by J. Hulley and L. Hoenson. The following are all from the Olifants River drainage system: Boontjieskloof (Cedarberg), SAM A44980 (1 ♀), no GPS coordinate, collected on 14.iv.1996 by S. R. Daniels and J. Leaner, Cederberg (Cape), SAM A41166 (2 ♀), 32°25′60″S, 19°04′60″E, collected on 12.xii.1972, no collector’s name; Doringbos (near Clanwilliam), SAM A41191 (1 ♂), 33°14′60″S, 19°19′60″E, collected on 20.ii.1970 by B. F. Kensley; Keurbos ( Rondegat River ), SAM A41305 (1 ♀) and SAM A41186 (1 ♂, 2 ♀), no GPS coordinate, collected on 08.xii.1994 and 10.ix.1994 (respectively) by M. Somers; Krieddouwkrans, SAM A41187 (5 ♂), 32°21′60″S, 18°57′0″E, collected on 10.ix.1994 by M. Somers; Olifants River (above Clanwilliam Dam, Olifants River drainage system), SAM A41216 (2 ♂, 2 ♀), 32°12′59.76″S, 18°54′60″E, collected on 25.xi.1994 by M. Somers .

Description and diagnosis: The carapace margin is smooth, ending in a reduced epibrachial tooth at the anterolateral margins of the carapace. The species has a carapace depth ( CH /CL) of 0.69 mm and a posterior margin width ( CWP /CL) of 0.46 mm. The postfrontal crest is complete with a groove in the middle. The sternites, maxillipeds, and mandibular palp are characteristic of Potamonautes ( Cumberlidge & Tavares, 2006) . Males are heterochelous with the right cheliped being larger than the left and the dactylus of the right cheliped slightly arched. Females have equal size chelipeds. The cheliped teeth have sharp unequal serrations. The pereopods are long and broad; pereopod two is the longest. The abdomen is triangular and widest at segment 3 and narrowest at the telson. The posterior view of the terminal segment of gonopod 1 points away from the midline and its terminal point curves left and slightly upward ( Fig. 6A ) and the margins of the subterminal of gonopod 1 have numerous setae ( Fig. 6A, B ). The terminal segment of gonopod 2 (posterior view) is slanted away from the midline ( Fig. 6C ). The subterminal segment of gonopod 2 is approximately two thirds of the length of gonopod 1.

Distribution: Potamonautes perlatus s.s. is restricted to western flowing drainages in the Western Cape, South Africa, occurring from the Olifants River in the Cederberg Mountains, to the Cape Peninsula, Eerste River, and Berg River. Based on the current data, it is not clear whether this species occurs in sympatry with Potamonautes barbarai sp. nov., which also occurs in the Berg River drainage system in LaMotte Forest. In the Olifants River, P. perlatus is restricted to all the localities above Bulshoek dam. Potamonautes granularis Daniels, Stewart, & Coke, 1998 , occurs below the Bulshoek dam wall where the two species occur in sympatry.

Remarks: There are no visible differences in the diagnostic morphological characters between this species and the two novel lineages described below. In particular, no differences were found amongst the gonopods of the three lineages ( Fig. 6A–I ).

Etymology: Potamonautes perlatus s.s. was previously regarded as a widespread species. With the use of genetic evidence, we restrict the name to specimens of P. perlatus occurring in western flowing drainages.

Conservation: The conservation status of P. perlatus s.s. is Least Concern ( Cumberlidge, 2013). However, the distribution of the species ( P. perlatus s.s.) has now been narrowed with the description of two novel lineages within the species complex. According to Cumberlidge (2013), current and future threats to P. perlatus s.l. in its presumed distribution range are habitat loss and degradation. Therefore, we consider the species to be Data Deficient.

POTAMONAUTES BARBARAI SP. NOV.

Figures

Figure 2. A maximum likelihood (ML) phylogram of the combined mtDNA sequences for the phylogenetic reconstruction of Potamonautes perlatus s.l. The ML node support is shown by bootstrap values above each branch (only values above 75% are shown). The values below the branches are bootstrap values for maximum parsimony (MP)/posterior probabilities for Bayesian inference (BI; the * indicates no support). The numbers next to each taxon name represent the individual specimens; no numbering is given to taxa for which the entire population occurs on one branch.

Figure 6. A–C, Potamonautes perlatus s.s. male neotype (SAM A45755): A, left gonopod 1, anterior view; B, left gonopod 1 posterior view; C, left gonopod 2 posterior view. D–F, Potamonautes barbarai sp. nov. male holotype (SAM A41061): D, left gonopod 1, anterior view; E, left gonopod 1 posterior view; F, left gonopod 2 posterior view; and G–I, Potamonautes barnardi sp. nov. male holotype (SAM A41013): G, left gonopod 1, anterior view; H, left gonopod 1 posterior view; I, left gonopod 2 posterior view. Scale bars = 1.0 mm.