Potamonemus mambilorum Cumberlidge & Clark, 1992

Ndongo, Pierre A. Mvogo, Rintelen, Thomas von & Cumberlidge, Neil, 2021, A new species of the freshwater crab genus Potamonemus Cumberlidge & Clark, 1992 (Crustacea, Potamonautidae) endemic to the forested highlands of southwestern Cameroon, Central Africa, ZooKeys 1017, pp. 127-141 : 127

Potamonemus mambilorum Cumberlidge & Clark, 1992 Figures 1b , 2b , 3b , 4b , 5c, d, i , 6d-f , 7b, f

Material examined.

6 adult ♂ (CW 29.05 mm, CL 21.17 mm, CH 12.10 mm, FW 8.85 mm; CW 29.56 mm, CL 21.35 mm, CH 12.34 mm, FW 9.12 mm; CW 29.16 mm, CL 20.70 mm, CH 12.00 mm, FW 9.12 mm; CW 28.93 mm, CL 20.69 mm, CH 11.85 mm, FW 9.94 mm; CW 26.74 mm, CL 19.62 mm, CH 11.32 mm, FW 9.63 mm; CW 26.74 mm, CL 19.62 mm, CH 11.32 mm, FW 9.63 mm) . 2 adult ♀ (CW 27.06 mm, CL 19.76 mm, CH 12.45 mm, FW 8.34 mm; CW 26.68 mm, CL 19.06 mm, CH 11.03 mm, FW 7.72 mm); Cameroon, Littoral region, Mount Nlonako Ecological Reserve (4.891820, 9.984830), 900 m a.s.l., 26 May 2018, coll. P.A. Mvogo Ndongo (ZMB Crust. 32428) . 1 adult ♂ (CW 28.00 mm, CL 19.10 mm, CH 11.37 mm, FW 8.56 mm) ; 1 adult ♀ (CW 28.36 mm, CL 20.00 mm, CH 10.27 mm, FW 7.79 mm; Southwest Region, Mount Manengouba Ecological Reserve, small stream around the mountain (ZMB Crust. 30326) (5.034920, 9.836150), 1,958 m asl, 14 March 2017, coll. P.A. Mvogo Ndongo.

Remarks.

The distributional range of P. mambilorum is extended in this work by the discovery of populations in Mount Nlonako Ecological Reserve in the littoral region of Cameroon. Potamonemus mambilorum was previously known from seven localities in the forested highlands and lowlands of southwestern Cameroon (extent of occurrence (EOO) 43,291 km2). The conservation status of this species was assessed as Least Concern ( Cumberlidge 2008a), but this was before the threats to the freshwater ecosystems of this part of Africa were brought to light. The conservation status of P. sachsi was assessed as Vulnerable, B1ab(iii)+2ab(iii), based on its distributional range that includes the Bamenda highlands in southwest Cameroon and the neighboring Obudu plateau in southeast Nigeria, which is continuous with the Bamenda highlands (EOO 24,219 km2) and perceived threats ( Cumberlidge 2008b). The areas where P. mambilorum and P. sachsi occur are now known to be at risk from a number of anthropogenic threats, including deforestation, together with intensive and encroaching agricultural practices and firewood collection, as well as release of pollutants such as agrochemicals potentially affecting the eggs, hatchling-carrying female crabs, and other aquatic organisms.

Figures

Figure 1. Species of Potamonemus from southwestern Cameroon, whole animal, dorsal view a largest adult male (CW 29 mm) of P. mambilorum from Mount Nlonako (ZMB Crust. 32428) b adult male (CW 28 mm) of P. mambilorum from small stream on Mount Manengouba (ZMB Crust. 30326) c adult male (CW 31 mm) of P. man sp. nov. from Bakossi National Park (ZMB Crust. 30328) d adult male, holotype (CW 25 mm) of P. man sp. nov. from Man Lake, Mount Manengouba (ZMB Crust. 30320). Scale bars: 15 mm (a), 16 mm (b), 17 mm (c), 16 mm (d).

Figure 2. Species of Potamonemus from southwestern Cameroon, dorsal view a largest adult male (CW 29 mm) of P. mambilorum from Mount Nlonako (ZMB Crust. 32428) b adult male (CW 28 mm) of P. mambilorum from small stream on Mount Manengouba (ZMB Crust. 30326) c adult male (CW 31 mm) of P. man sp. nov. from Bakossi National Park (ZMB Crust. 30328) d adult male, holotype (CW 25 mm) of P. man sp. nov. from Man Lake, Mount Manengouba (ZMB Crust. 30320). Scale bars: 13 mm (a), 13 mm (b), 14 mm (c), 11 mm (d).

Figure 3. Species of Potamonemus from southwestern Cameroon, ventral view a largest adult male (CW 29 mm) of P. mambilorum from Mount Nlonako (ZMB Crust. 32428) b adult male, holotype (CW 28 mm) of P. mambilorum from small stream on Mount Manengouba (ZMB Crust. 30326) c adult male (CW 31 mm) of P. man sp. nov. from Bakossi National Park (ZMB Crust. 30328) d adult male, holotype (CW 25 mm) of P. man sp. nov. from Man Lake, Mount Manengouba (ZMB Crust. 30320). Scale bars: 16 mm (a), 17 mm (b), 16 mm (c), 17 mm (d).

Figure 4. Species of Potamonemus from southwestern Cameroon, frontal view a largest adult male (CW 29 mm) of P. mambilorum from Mount Nlonako (ZMB Crust. 32428) b adult male, holotype (CW 28 mm) of P. mambilorum from small stream on Mount Manengouba (ZMB Crust. 30326) c adult male (CW 31 mm) of P. man sp. nov. from Bakossi National Park (ZMB Crust. 30328) d adult male, holotype (CW 25 mm) of P. man sp. nov. from Man Lake, Mount Manengouba (ZMB Crust. 30320). Scale bars: 13 mm (a), 12 mm (b), 14 mm (c), 11 mm (d).

Figure 5. Frontal view of the right and left chelae of adult males of species of Potamonemus from southwestern Cameroon a, b largest adult male (CW 29 mm) of P. mambilorum from Mount Nlonako (ZMB Crust. 32428) c, d adult male (CW 28 mm) of P. mambilorum from small stream on Mount Manengouba (ZMB Crust. 30326) e, f largest adult male, holotype (CW 31 mm) of P. man sp. nov. from Bakossi National Park (ZMB Crust. 30328) g, h adult male, holotype (CW 25 mm) of P. man sp. nov. from Man Lake, Mount Manengouba (ZMB Crust. 30320). Dorsal view of the right cheliped carpus of adult males of species of Potamonemus i, largest adult male (CW 29 mm) of P. mambilorum from Mount Nlonako (ZMB Crust. 32428) j adult male (CW 28 mm) of P. mambilorum from small stream on Mount Manengouba (ZMB Crust. 30326) k adult male (CW 31 mm) of P. man sp. nov. from Bakossi National Park (ZMB Crust. 30328) l adult male, holotype (CW 25 mm) of P. man sp. nov. from Man Lake, Mount Manengouba (ZMB Crust. 30320). Scale bars: 5 mm (a, c, g), 2.5 mm (b, d, f, h), 5 mm (i, j, k, l).

Figure 6. Dorsal view of left G 1 (a, d, g, j) and ventral view of left G 1 (c, f, i, l) of adult males of species of Potamonemus from southwestern Cameroon. a, c largest adult male (CW 29 mm) of P. mambilorum from Mount Nlonako (ZMB Crust. 32428) d, f adult male (CW 28 mm) of P. mambilorum from small stream on Mount Manengouba (ZMB Crust. 30326) g, i adult male (CW 31 mm) of P. man sp. nov. from Bakossi National Park (ZMB Crust. 30328) j, l adult male, holotype (CW 25 mm) of P. man sp. nov. from Man Lake, Mount Manengouba (ZMB Crust. 30320). Ventral view of G 2 of adult males of species of Potamonemus from southwestern Cameroon b largest adult male (CW 29 mm) of P. mambilorum from Mount Nlonako (ZMB Crust. 32428) e adult male (CW 28 mm) of P. mambilorum from small stream on Mount Manengouba (ZMB Crust. 30326) h adult male (CW 31 mm) of P. man sp. nov. from Bakossi National Park (ZMB Crust. 30328) k adult male, holotype (CW 25 mm) of P. man sp. nov. from Man Lake, Mount Manengouba (ZMB Crust. 30320). Scale bars: 2 mm (a-k).

Figure 7. Frontal view of the left third maxilliped of adult males of species of Potamonemus from southwestern Cameroon a largest adult male (CW 29 mm) of P. mambilorum from Mount Nlonako (ZMB Crust. 32428) b adult male (CW 28 mm) of P. mambilorum from small stream on Mount Manengouba (ZMB Crust. 30326) c adult male (CW 31 mm) of P. man sp. nov. from Bakossi National Park (ZMB Crust. 30328) d adult male, holotype (CW 25 mm) of P. man sp. nov. from Man Lake, Mount Manengouba (ZMB Crust. 30320). Frontal view of the left mandible of adult males of species of Potamonemus from southwestern Cameroon e largest adult male (CW 29 mm) of P. mambilorum from Mount Nlonako (ZMB Crust. 32428) f adult male (CW 28 mm) of P. mambilorum from small stream on Mount Manengouba (ZMB Crust. 30326) g adult male (CW 31 mm) of P. man sp. nov. from Bakossi National Park (ZMB Crust. 30328) h adult male, holotype (CW 25 mm) of P. man sp. nov. from Man Lake, Mount Manengouba (ZMB Crust. 30320). Scale bars: 5 mm (a-d), 2 mm (e-h).