Sudanonautes nkam, Mvogo Ndongo & Clark & Rintelen & Cumberlidge, 2024

Mvogo Ndongo, Pierre A., Clark, Paul F., Rintelen, Thomas Von & Cumberlidge, Neil, 2024, Validation of four species of Sudanonautes (Decapoda: Potamonautidae), from Cameroon, Central Africa, Zootaxa 5492 (1), pp. 140-144 : 143

Sudanonautes nkam sp. nov.

Sudanonautes nkam Mvogo Ndongo, Clark, von Rintelen & Cumberlidge, 2024: 11 , Figs. 1D, 2D, 3D, 4B, 5P—T, 6J—L.

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Type Material. Holotype: Cameroon, Nkam River, draining lowland moist forest, Parc des Princes, Yabassi City , Littoral Region of Cameroon, adult ♂ ( CW 41.6 , CL 27.9, CH 19.4, FW 10.2 mm), coll. P.A. Mvogo Ndongo, 30 August 2015 ( ZMB Crust. 33110) . Paratypes: Nkam River , Banya, Yabassi City, Littoral Region, adult ♂ ( CW 34.7 , CL 24.0, CH 16.8, FW 11.2 mm), 2 adult ♀ (CWs 39.0, 37.7, CLs 27.8, 26.8, CHs 19.5, 19.0, FWs 10.8, 9.8), coll. P.A. Mvogo Ndongo, 02 September 2015 ( ZMB Crust. 33111) .

Description. Carapace ovoid, high, arched ( CH /FW 1.63, N = 8), wide (CW/FW 3.81, N = 8), smooth. Front deflexed, anterior margin highly concave medially. Carapace surface smooth, cervical, urogastric, cardiac, branchial grooves distinct. Exorbital tooth small, low, distinct; intermediate tooth small, triangular; epibranchial tooth small. Postfrontal crest distinct yellow colour, complete, lateral ends curving backward, not meeting either epibranchial tooth or carapace lateral margin; mid-groove on postfrontal crest short, forked. Carapace branchiostegite divided into 3 parts by longitudinal, vertical, sutures; longitudinal suture dividing smooth suborbital, subhepatic regions from pterygostomial region, beginning at respiratory opening, curving backward; vertical suture short, granular, dividing suborbital from subhepatic regions beginning at base of intermediate tooth, then curving sharply down to meet longitudinal suture; pterygostomial region with field of large granules medially, otherwise smooth. S2/3, completely traversing sternum, deep; S3/4 incomplete, reduced to 2 short side notches.

Proximal superior margin of palp TA with large rounded accessory lobe ca. ½ length of TA. Third maxillipeds filling entire buccal cavern except for transversely oval efferent respiratory openings visible at superior lateral corners; exopod with well-developed slender flagellum; ischium with distinct vertical sulcus.

Chelipeds of adult male unequal, right (major) cheliped longer than left cheliped. Fingers slim, elongated; movable finger (dactylus) of major chela straight, with three large teeth, two proximally, one at mid-point; fixed finger with three large teeth proximally. Minor cheliped with occluding margins of both fingers lined by small teeth; cheliped carpus distal, proximal teeth both pointed, distal larger than proximal. Inferior cheliped merus margins lined by small sharp teeth, inner margin with large distal meral tooth. Walking legs (pereiopods P2–5) moderately slender, posterior margins of propodi serrated with small blunt teeth, dactyli tapering, each bearing rows of downward-pointing large sharp spines.

Male pleon plus telson broadly triangular with straight inward-tapering margins.

G1TA proximal two-thirds straight, distal third bent outward, distinctly widened in mid-section by raised dorsal lobe; G1TA long (G1TA length slightly shorter than G1SA length; margins lined by long, dense setae. G2 shorter than G1, reaching only to G1TA-G1SA junction. G2TA extremely short, only one-fifteenth as long as G2SA, G2SA widest at base, then tapering sharply inward, forming long, thin, pointed, upright process supporting short G2TA, with rounded collar at G2TA-G2SA junction.

Etymology. The species name refers to the Nkam River near Yabassi in Southwest Cameroon where it was collected. The name “nkam ” is used as a Latin noun in nominative singular.

Remarks. For detailed figures, photographs, coloration, distribution and more distinguishing characters of S. nkam see Mvogo Ndongo et al. (2024).