Auchenoglanis senegali, Retzer, 2010

Retzer, Michael E., 2010, Taxonomy of Auchenoglanis Günther 1865 (Siluriformes: Auchenoglanididae), Zootaxa 2655 (1), pp. 25-51 : 47-49

Auchenoglanis senegali , new species

( Figs. 8a , 9 , 10 ; Table 3)

Holotype: MRAC P–79002.211, 153.0 mm SL, Senegal, Saint-Louis, Gorom River, Camp Djoudj , 16°22'N – 16°16'W, K.U.L. Expedition, 28 December, 1978.

Paratypes: MRAC P–79002.212-214, 3, 148.0–166.0 mm SL, same locality data as holotype ; INHS 102910 (ex. MRAC P–79002.215, 1, 166.0 mm SL, same locality data as holotype; MRAC P–73005.2814, 1, 114.0 mm SL, Lake Guiers , Mbane , Saint-Louis, Senegal, 16°17'N – 15°48'W; MRAC P–80001.0099, 1, 203 mm SL, same locality data as holotype; MRAC P–81003.0381, 1, 147 mm SL, Gambia River, Ba-Foula-Bé, Tambacounda, Gambia, 13°01'N – 13°14'W.

Diagnosis: Auchenoglanis senegali can be distinguished from all other Auchenoglanis except A. sacchii (the pigmentation of A. sacchii is only vaguely known from its original description) by the presence of three horizontal series of dark spots on the body and intense dark spots on the fins, and tear-shaped premaxillary tooth patches ( Fig. 2d ). Other species of Auchenoglanis lack these rows of dark spots on the body and dark spots on the fins ( Figs. 8a , 10 ), and have oblong-oval, round, square, or triangular-shaped tooth patches.

Auchenoglanis senegali can be distinguished from A. sacchii by having a shorter pectoral-spine length relative to the head length (PcSL to HL ratio less than 0.54 in A. senegali versus 0.61 in A. sacchii ) and by having a longer preorbital-head length relative to the interorbital distance (PrOL to IOD ratio greater than 1.5 in A. senegali versus 1.3 in A. sacchii ). The new species can be further distinguished from A. tanganicanus by having a shorter preorbital-head length relative to the interorbital distance (PrOL to IOD ratio less than 1.8 in A. senegali versus greater than 1.9 in A. tanganicanus ) and by having a deeper minimum caudal-peduncle height relative to interpelvic distance (MnCPH to IPvD ratio greater than 0.8 in A. senegali versus less than 0.8 in A. tanganicanus ). Auchenoglanis senegali can be further distinguished from A. wittei and A. biscutatus by having a shorter maxillary-barbel length relative to the head length (MxBL to HL ratio in A. senegali less than 0.48 versus greater than 0.49 in A. wittei and A. biscutatus ) and by having a shorter maxllary barbel relative to the preorbital-head length (MxBL to PrOL ratio less than 0.9 in A. senegali versus greater than 0.9 in A. wittei and A. biscutatus ). The new species can be further distinguished from A. biscutatus by having a longer preorbital-head length relative to the interorbital distance (PrOL to IOD ratio greater than 1.5 in A. senegali versus less than 1.4 in A. biscutatus ).

Adults of A. senegali can be distinguished from adults in other species of Auchenoglanis except A. biscutatus , by the anterior edge of the adipose fin that rises steeply and reaches its maximum height at a point approximately one half of the length of the adipose fin versus having the anterior edge of the adipose fin that rises gradually to its maximum height at the posterior end of the fin, well behind the mid-point of the adipose fin. The origin of the adipose fin is before the anal-fin origin in A. senegali , versus over it in A. sacchii . Auchenoglanis senegali can be distinguished from all other Auchenoglanis except A. sacchii (the pigmentation of A. sacchii is only vaguely known from its original description) by its light grey-brown barbels versus black or dark brown, of A. acuticeps , A. wittei , A. tanganicanus , and A. biscutatus and white mandibular barbels of A. tchadiensis and dark maxillary barbels of A. occidentalis .

Description: Morphometrics are presented in Table 3. The fin ray counts are as follows: dorsal fin II,7 (8); pectoral fin I,8 (4), I,9 (4); pelvic fin i,5 (8). The head is large with the dorsal edge in the lateral profile rising moderately from the tip of the snout to the to the dorsal-fin origin; the ventral edge is straight from the tip of the snout to the lower posterior margin of the opercle. Body depth is greatest at the dorsal-fin origin. The dorsal-lateral profile descends less steeply from the dorsal-fin origin to the caudal peduncle with a noticable rise and descent under the adipose fin. The minimum caudal-peduncle height is at the posterior edge of the base of the adipose fin. The ventral-lateral profile from the rear of the head to the anal fin is flat and slightly concave under the caudal peduncle. In adults the leading lateral edges of the nuchal plates are straight. The leading lateral edges converge to form a blunt point at the anterior end of the first nuchal plate and that plate does not form a notch in the rear edge of the supraoccipital.

The middle rays of the dorsal fin extend beyond the spine and the last rays but the anterior rays are longer. The dorsal spine is stout and nonserrated on the posterior edge. The distal edge of the pectoral fin is straight. The pectoral spine is very stout and serrated on the posterior edge. The distal edge of the pelvic fin is straight with the second branched ray being the longest ray. The rays of the anal fin are much longer than the base, and the second or third branched ray of the anal fin is longest. The distal edge of the caudal fin is emarginate.

The pectoral fin is placed approximately on the anterior one-third of the body well ahead of the dorsal-fin origin. The pelvic fin is placed behind the dorsal-fin origin. The anal fin is placed approximately on the posterior one third of the body.

The length of the maxillary barbel is shorter than the external mandibular barbel. The length of the internal mandibular barbel is shorter than the other barbels. The maxillary and external mandibular barbels are slender, but the internal mandibular barbel is thicker particularly at the base. The lower lip is thin.

The mouth is subterminal and narrow relative to the head width. The premaxillary tooth patches are tearshaped.

The color is based on examination of specimens preserved in alcohol. The adult body is white to light brown on the sides of the body; the ventral portion is white. Occasionally the upper one half of the body is slightly darker than the lower half. Large specimens have three horizontal series of dark spots on the body and intense dark spots on the fins although spots may be less intense and more diffuse on some specimens. The barbels are light grey or brown although the mandibular barbels may be less dark than the maxillary barbels. The sides and top of the head are brown and without spots. The lower side of the head is white including the lower lip.

Range: Auchenoglanis senegali is known only from the Senegal and Gambia River basins of west Africa ( Fig. 9 ).

Etymology: Named for the country of Senegal, where the type locality is located.

Figures

FIGURE 2. Diagrams of the five types of premaxillary tooth patches of Auchenoglanis. a) oblong-oval, b) round, c) square, d) tear, and e) triangle. The arrow indicates the direction of the anterior end of the patches.

FIGURE 8. Spot patterns of the caudal and anal fins of a) A. senegali (MRAC P–79002.211) and b) A. biscutatus (ZMB 16556).

FIGURE 9. Collection localities of Auchenoglanis senegali (black circles) and A. occidentalis (black squares). The triangle denotes the type locality of A. senegali. Symbols may represent multiple collections.

FIGURE 10. The holotype of Auchenoglanis senegali n. sp. MRAC P–79002.211, 153.0 mm SL.