Sudanonautes koudougou, Cumberlidge & Mvogo Ndongo & Clark, 2021

Cumberlidge, Neil, Mvogo Ndongo, Pierre A. & Clark, Paul F., 2021, Disentangling the Sudanonautes granulatus (Balss, 1929) species complex (Potamoidea: Potamonautidae), with the description of two new freshwater crabs from Nigeria and Côte d’Ivoire, West Africa, Zootaxa 4948 (2), pp. 201-220 : 207-208

Sudanonautes koudougou n. sp.

( Figs. 3A–D , 5E, F, I , 7A–C , 8 )

Sudanonautes granulatus, Cumberlidge, 1993a: 806–807 , 812 (in part), figs. 1a, b, 2a–d, 3a–c, 4a, b.

Holotype. NBL CRUS.D.35246, adult male ( CW 58.1 , CL 38.73, CH 18.2, FW 15.11 mm; lower margin of propodus of right chela = 61.6 mm), Côte d’Ivoire, Koudougou , 10 km southwest of Bouafl (6.957348 N, - 5.763060 W), Dec. 1980.

Diagnosis. Carapace surface, anterolateral margins, suborbital margins, postfrontal crest, all completely smooth. Carapace distinctly wide (~4 × FW, CW/FW 3.9), elongated (CL/FW 2.6). Exorbital tooth blunt, low, intermediate tooth reduced to granule, epibranchial tooth almost undetectable; postfrontal crest mid-part distinct, ends faint towards anterolateral margins; vertical sulcus on branchiostegite running from intermediate tooth to longitudinal sulcus ( Fig. 4C ). Mandibular palp with 2 articles, terminal article simple, article junction with fringe of long setae but lacking lobe or ledge ( Fig. 3C ); third maxilliped exopod with flagellum, ischium smooth, with only faint vertical sulcus ( Fig. 3B ). Thoracic sternal suture S3/4 reduced to 2 small notches at sides of sternum, outer margins of S4 flat, not raised. Chelipeds: moveable finger (dactylus) of right chela narrow, strongly arched enclosing wide, ovoid space when closed and tips touching; palm of propodus swollen ( Fig. 5E, F, I ); propodus of right chela lower margin elongated, longer than CW ( Figs. 3A , 5E, F, I ). Gonopods: mesial, lateral margins of G1 SS fringed by long setae; G1 TA only slightly widened in mid-section, with distinct longitudinal sulcus running length of TA ( Fig. 7A, B ); G2 TA extremely short (TA/SS 0.1 ( Fig. 7C ).

Description. Male holotype. Carapace. Cephalothorax ovoid, carapace distinctly wide (~4 × FW, CW/FW 3.9), elongate (CL/FW 2.6), medium height ( CH /FW 1.2). Anterior margin of front straight, curving under; carapace posterior margin width about one third CW ( Figs. 3A , 4C ). Surface of carapace smooth with no deep grooves; postfrontal crest mid-part distinct, ends faint towards anterolateral margins; midgroove broad, shallow. Exorbital tooth blunt, low, intermediate tooth reduced to granule, epibranchial tooth almost undetectable.Anterolateral margin of carapace entirely smooth, lacking teeth or granules ( Fig. 3A ). Longitudinal sulcus on branchiostegite beginning at respiratory opening, curving backwards, dividing suborbital, subhepatic regions from pterygostomial region; vertical sulcus on branchiostegite in line with intermediate tooth; vertical sulcus meeting longitudinal sulcus, dividing suborbital from subhepatic region ( Fig. 4C ).

Thoracic sternum. Sternal suture S1/2, short, faint, S2/3 horizontal, completely traversing sternum; S3/4 reduced to 2 small notches at sides of sternum, outer margins of S4 flat, not raised. Third maxillipeds filling entire oral field, except for transversely oval efferent respiratory openings, exopod with long flagellum, ischium smooth, with faint vertical sulcus ( Fig. 3B ). Mandibular palp with 2 articles, terminal article simple, article junction with fringe of long setae, but lacking either anterior lobe or ledge ( Fig. 3C ). First five pleomeres of male (A1–5) broad, short, tapering inward, distal pleomere (A6) long, narrow, telson triangular, distal tip rounded ( Fig. 3D ).

Pereiopods. Major (right) chela propodus longer, higher than left chela ( Figs. 3A , 5C, D ); moveable finger (dactylus) of right chela narrow, strongly arched enclosing wide, ovoid space when closed and tips touching; palm of propodus swollen ( Fig. 5E, F, I ); lower margin of propodus of right chela longer than CW ( Fig. 5E, F, I ); movable, fixed fingers of right chela each lined by series of small pointed teeth. Left chela showing less enlargement, but dactylus narrow, slightly arched, enclosing long space, lined by small teeth (5F). Cheliped merus lower margins both with rows of small round teeth, distal tooth larger, pointed ( Fig. 5I ); cheliped carpus inner margin distal tooth small, pointed, proximal tooth smaller, pointed ( Fig. 5I ). P2–5 neither elongated nor shortened, P4 longest leg, P5 shortest leg; dactyli P2–5 tapering to point, each bearing rows of downward-pointing corneous spines ( Fig. 3A ).

Gonopods. G1 TA long (TA/SS 0.76), basal half straight in line with G1 SS longitudinal axis, midpoint curved outward at 63° to G1 SS longitudinal axis, distal third tapering to pointed tip; TA midsection only slightly widened ( Fig. 7A, B ); longitudinal sulcus of TA visible on ventral side for proximal two-thirds of TA, sulcus continuing to tip, but visible only if gonopod turned to superior view. G1 SS broad (ratio of width of basal margin / distal margin = 4); G1 SS ventral side with slim flap folded inward, distally almost meeting outer margin, angled diagonally downwards, leaving heavily setose ventral side of G1 SS exposed ( Fig. 7A ). G2 shorter than G1 (G2 only reaching G1 TA-SS junction). G2 TA extremely short (G2 TA/SS 0.14), tip rounded ( Fig. 7C ); G2 SS widest at base, tapering sharply inward about one-third along length, with last two-thirds forming long, thin, tapering, upright process supporting short TA ( Fig. 7C ).

Size. Large species, size at maturity ca. CW 58 mm.

Type locality. Côte d’Ivoire, Koudougou, 10 km southwest of Bouaflé (6.957348 N, - 5.763060 W) in the Marahoué Region in the Sassandra-Marahoué District .

Etymology. The new species is named for the town of Koudougou in central Côte d’Ivoire, where it was collected. The species epithet is used as a noun in apposition.

Habitat. The Marahoué Region where Koudougou is situated lies in the middle of the Eburneo Freshwater Ecoregion 514 ( Thieme et al. 2005; Abell et al. 2008). This area is bounded by the basins of the Comoé, Bandama, and Sassandra Rivers that flow south into the Atlantic Ocean. The vegetation in this ecoregion reflects the amount of rain received, with dry Sudan savanna woodland in the plateau in the northern part of this ecoregion that records the lowest annual rainfall. South of this the vegetation is a forest-savanna mosaic that receives more annual rainfall, to the south of which is Guinean rain forest that gets the highest annual rainfall. Sudanonautes koudougou n. sp. was collected in the southern part of this ecoregion in the Guinean rain forest zone where much of the forest vegetation has now been converted to other uses.

Distribution. This species is known only from the Marahoué Region in central Côte d’Ivoire.

Remarks. The holotype (NBL CRUS.D.35246) was originally identified as S. granulatus s.l. by Cumberlidge (1993a: figs. 1a, b, 2a–d, 3a–c, 4a, b) and was therefore part of the material included in that earlier redescription. The figures of this specimen by Cumberlidge (1993a) have been reorganized, relabeled, and used in the present work to illustrate the holotype of S. koudougou n. sp. ( Figs. 3A–D , 5E, F, I , 7A–C ). Cumberlidge (1993a) attributed differences between the paralectotype of S. granulatus s.s. from Togo and S. koudougou n. sp. from Côte d’Ivoire to be the result of geographical variation within S. granulatus s.l. There are a number of morphological differences in characters of the carapace, cheliped, thoracic sternum, and G1 between the paralectotype of S. granulata s.s. and the holotype of S. koudougou n. sp. that support the recognition of these 2 specimens as separate species that are also distinct from all other species of Sudanonautes .

Comparisons. In addition to S. koudougou n. sp., Côte d’Ivoire is home to 5 other species of freshwater crabs in 3 genera ( Cumberlidge 1999): Liberonautes latidactylus (de Man, 1903) , L. chaperi (A. Milne-Edwards, 1886) , L. nimba Cumberlidge, 1999 , Potamonautes ecorssei ( Marchand, 1902) , and S. aubryi ( Cumberlidge 1999) . Species of Sudanonautes and Liberonautes can be distinguished from Potamonautes by the presence of an intermediate tooth between the exorbital and epibranchial teeth on the anterolateral margin (vs the lack of an intermediate tooth in all Potamonautes species) ( Cumberlidge 1999: 128–129). Species of Sudanonautes can be distinguished from Liberonautes by the angle of the G1 TA: it is directed outwards in Sudanonautes species ( Cumberlidge 1999: figs. 38A–E, 39A–E) and inwards in Liberonautes species ( Cumberlidge 1999: figs. 28A–D, 29A–D). Sudanonautes koudougou n. sp. can be distinguished from S. aubryi by the position of the postfrontal crest which (although faint) is aligned to meet the epibranchial teeth in S. koudougou n. sp. ( Fig. 4C ) (vs a postfrontal crest whose lateral ends meet the anterolateral margins behind the epibranchial teeth in S. aubryi ; Cumberlidge 1999: fig. 30A).

Figures

FIGURE 3. Sudanonautes koudougou n. sp. holotype from Koudougou, Côte d’Ivoire (NBL CRUS.D.35256). A. whole animal, dorsal view; B. left third maxilliped, frontal view; C. left mandible, external view; D. pleon, ventral view. Scale bars: A = 23.2 mm, B, C= 4 mm, D = 7 mm. Figures A–D are based on those originally published in Cumberlidge (1993a) and are reproduced here with the permission of Oxford University Press, the copyright owner of the Journal of Crustacean Biology.

FIGURE 4. Carapace frontal view. A. Sudanonautes granulatus (Balss, 1929) s.s. paralectotype from Bismarckburg, Togo (MNB Crust.8977); B. S. umaji n. sp. holotype from Umaji, Nigeria (NMU 9.IV.1983); C. S. koudougou n. sp. holotype from Koudougou, Côte d’Ivoire (NBL CRUS.D.35256). Scale bars: A = 3.7 mm, B = 4.5 mm, C = 9.1 mm. Figure C was originally published in Cumberlidge (1993a) and is reproduced here with the permission of Oxford University Press, the copyright owner of the Journal of Crustacean Biology.

FIGURE 5. Sudanonautes granulatus (Balss, 1929) s.s. paralectotype from Bismarckburg, Togo (MNB Crust.8977). A. right chela, external view; B. left chela, external view. Sudanonautes umaji n. sp. holotype from Umaji, Nigeria (NMU 9.IV.1983). C. right chela, external view; D. left chela, external view. Sudanonautes koudougou n. sp. holotype from Koudougou, Côte d’Ivoire (NBL CRUS.D.35256). E. right chela, external view; F. left chela, external view. Right cheliped carpus and merus superior view of G. S. granulatus (Balss, 1929) s.s. (MNB Crust.8977); H. S. umaji n. sp. (NMU 9.IV.1983); I. S. koudougou n. sp. (NBL CRUS.D.35256). Scale bars: A, B = 6.2 mm, C, D = 8 mm, E, F= 3 mm, G–I = 4.9 mm. Figures E, F, and I are based on those originally published in Cumberlidge (1993a) and are reproduced here with the permission of Oxford University Press, the copyright owner of the Journal of Crustacean Biology.

FIGURE 7. Sudanonautes koudougou n. sp. holotype from Koudougou, Côte d’Ivoire (NBL CRUS.D.35256). A. right G1 ventral view; B. right G1 dorsal view; C. right G2 ventral view. Sudanonautes granulatus s.s. (Balss, 1929) (MNB Crust.8977). D. left mandible, external view; E. left third maxilliped, external view. Sudanonautes umaji n. sp. holotype from Umaji, Nigeria (NMU 9.IV.1983). F. left mandible, external view. Scale bars: A, B, 2.9 mm, C = 2.5 mm, D, F = 5 mm. Figures A–C are based on those originally published in Cumberlidge (1993a) and are reproduced here with the permission of Oxford University Press, the copyright owner of the Journal of Crustacean Biology.

FIGURE 8. Map showing the geographic distribution of Sudanonautes koudougou n. sp. (yellow square), S. granulatus s.s. (Balss, 1929) (red circles), S. umaji n. sp. (blue circles), and S. tiko (black pentagons). Scale bar = 500 km. See text for exact localities.