Synodontis ouemeensis, Musschoot & Lalèyè, 2008

Musschoot, Tobias & Lalèyè, Philippe, 2008, Designation of a neotype for Synodontis schall (Bloch and Schneider, 1801) and description of two new species of Synodontis (Siluriformes: Mochokidae), Journal of Natural History 42 (17 - 18), pp. 1303-1331 : 1309-1315

Synodontis ouemeensis sp. nov.

( Table 5, Figure 7 )

Holotype

MRAC 97-007 -P-0012: Avagbodji ( Benin), Oueme River, Coll. P. Vandewalle, collected 07/02/ 1997, 108 mm SL.

Paratypes

MRAC 97-007 -P-0013-0014: Avagbodji ( Benin), Oueme River, Coll. P. Vandewalle, collected 07/02/1997, 85- 93 mm SL .

Differential diagnosis

Gill opening not extending ventrally beyond the level of the insertion of the pectoral fin spine (vs. gill opening extending ventrally beyond the level of the insertion of the pectoral fin spine: S. dekimpei , S. batensoda and S. membranaceus ); maxillary barbel without ramifications or tubercles (vs. ramifications or tubercles present: S. resupinata , S. clarias and S. annectens ); dorsal spine not serrated or very finely serrated anteriorly, except for some larger distal serrations (vs. spine entirely and clearly serrated anteriorly: S. serrata , S. batesii and S. albolineata ); humeral process without posteriorly directed spines (vs. spines present: S. omias and S. budgetti ); maxillary barbels longer than head (vs. shorter than head: S. sorex , S. vermiculata , S. haugi , S. gobroni , S. violacea , S. thysi , S. guttata , S. xiphias , S. courteti and S. voltae ); skin more or less villose, especially in front of the flanks (vs. skin non-villose: S. caudovittata , S. ocellifer , S. arnoulti , S. marmorata , S. punctifer , S. victoriae , S. euptera , S. ansorgii , S. koensis , S. velifer , S. filamentosa , S. bastiani , S. eburneensis , S. obesus , S. robbianus , S. waterloti , S. tourei , S. macrophthalma , S. tessmanni , S. frontosa , S. khartoumensis , S. gambiensis , S. melanoptera and S. comoensis ); maxillary barbel with a very small and indistinct membrane, or membrane absent (vs. very clear or even large membrane present: S. steindachneri , S. nigrita and S. rebeli ); 18–36 mandibulary teeth (vs. 40–90 mandibulary teeth: S. afrofischeri and S. polyodon ); adipose fin base length at least 2.4 times the distance between dorsal and adipose fin (vs. maximum 1.5 times this distance: S. ruandae ). Pectoral girdle width 1 68.3–87.5% HL; specimens between 95 and 125mm SL have OD 17.6–25.9% HL and IOD 28.4–36.2% HL; East African specimens with PGW.85.0% HL have OD 22.1– 26.0% HL and IOD 37.6–38.5% HL or 88.8–91.5% SNL (vs. PGW minimum 85% HL, OD 22.3–26.2% HL, IOD 33.3–39.2% HL or 77.1–89.1% SNL: S. macrops ; only known from type specimens between 95 and 125mm SL); premaxillary toothplate width 6.3–9.9% SL or 21.6–32.7% HL; and predorsal length 35.7– 42.7% SL, snout length 42.0–48.6% HL or 49.0–65.0% PGW and orbit diameter 42.9–63.9% SNL (vs. premaxillary toothplate width 3.9–8.0% SL or 12.9–24.3% HL for specimens from 31 to 319 mm SL, and 4.0–8.0% SL or 12.9–24.3% HL for specimens between 39 and 213 mm SL: S. schall ; or predorsal length 35.4–36.6% SL, snout length 47.3–50.5% HL or 60.9–67.2% PGW and orbit diameter 39.0– 44.7% SNL: S. levequei ); orbit diameter 6.6–8.2% SL (20.5–26.8% HL), caudal peduncle height 8.9–10.9% SL (26.5–38.0% HL), prepectoral length 23.4–28.2% SL (76.1–89.0% HL), pectoral girdle width 23.2–28.2% SL (78.0–87.5% HL), distance between humeral process and occipito-nuchal shield 9.7–13.1% SL (30.3–45.5% HL) (vs. orbit diameter 5.5–6.8% SL (19.4–21.0% HL), caudal peduncle height 10.4–11.1% SL (32.4–41.5% HL), prepectoral length 21.6–23.3% SL (69.6–82.8% HL), pectoral girdle width 22.0–25.1% SL (68.3–83.0% HL), distance between humeral process and occipito-nuchal shield 11.8–14.6% SL (41.6–46.1% HL): S. kogonensis ).

Description (based on three types and 15 additional specimens)

Predorsal profile straight to slightly convex; head triangular when viewed dorsally, rather pointed than rounded; maxillary barbels with a very small membrane, hardly visible, or membrane absent; gill opening from level of ventral margin of eye down to level of pectoral spine base; occipito-nuchal shield terminating posteriorly with two pointed processes on each side of the dorsal fin; maxillary barbels reaching or almost reaching posterior tip of humeral process, unbranched; external mandibular barbels with filaments, usually reaching base of pectoral spine, sometimes longer; internal mandibular barbels with short filaments, tuberculate, reaching beyond a vertical from anterior margin of eye; anterior nostrils tubular with lateral flap, posterior nostrils with flap along anterior margin; eye superolateral; orbit with free margin; mouth inferior; teeth unicuspid; 24–36 mandibular teeth; ridge of humeral process variably developed, most obvious at anterior base of process, upper margin of process a little concave, lower margin straight or weakly convex; proximal part of lateral line positioned above mid-lateral line, at about 1/3 from dorsal fin base; dorsal spine very finely serrated anteriorly with some larger serrations distally, and clearly serrated posteriorly; dorsal fin spine usually slightly curved backwards; adipose fin well developed with a convex margin, except for the posterior margin which is most often more or less straight, not rounded; caudal fin deeply forked, upper lobe just a little longer than lower; anterior side of pectoral spine with very fine serrations proximally, larger serrations distally, directed outwards, posteriorly with less but marked serrations along its entire side, which are directed towards the body; pelvic fins inserted between dorsal and adipose fin or at adipose fin origin, posterior margin more or less rounded, almost or clearly reaching anal fin base; anal fin at least reaching a vertical through the posterior margin of adipose fin, usually longer; urogenital pore and vent positioned at the level of the adipose fin origin.

Dorsal fin I7; anal fin 11–13; pectoral fin I8–10; pelvic fin 7

Colouration (preserved specimens)

No bars or spots, except for a supra-humeral spot; body brownish or greyish dorsally and on the flanks, with pale whitish-yellowish or grey venter; barbels entirely pale whitish-yellowish, sometimes pale grey; pectoral fin, especially the first soft rays, pelvic and anal fins dark greyish or brownish to black; paired fins sometimes with a pale base; dorsal fin usually a little lighter than paired fins and anal fin, or equally dark; adipose fin same colour as body, with a very thin dark outer margin, especially in pale specimens; lobes of caudal fin with a dark submarginal band, sometimes very obvious in smaller specimens, and often a darker interstegal membrane and paler rays between upper and lower dark band. No large differences were observed between populations or specimens of different sizes.

Distribution

Known from the Ogun ( Nigeria), Oueme ( Benin) and Mono ( Togo) basins.

Etymology

Named for the Oueme River ( Benin), along which the type locality is situated .

Additional specimens

Togo: MNHN 1981-927 : Atchinedji ( Togo), Coll. Leveque, 104 mm SL; MNHN 1981-928 : Tetetou ( Togo), Coll. Leveque, 149 mm SL; MNHN 1982-995 : Kpessi ( Togo), Coll. Paugy, 55 mm SL; MNHN 2002-0783 : Atchinedji ( Togo), Coll. Benech, 107 mm SL . Benin: MRAC A06-049 -P-0001-0005: Agonlin Lowé (Adjohoun), Oueme River ( Benin), Coll. P. Laleye, 101–111 mm SL (two specimens); MNHN 1981-924 : Atchakpa ( Benin), Coll. Leveque, 157 mm SL; MNHN 1981-925 : Beterou ( Benin), Coll. Leveque, 107 mm SL; MNHN 1981-926 : Zagnanado ( Benin), Coll. Leveque, 100 mm SL; MNHN 1982-993 : Atchakpa ( Benin), Coll. Paugy, 151 mm SL . Nigeria: BMNH 1909.3.3.23-24: Aro, Ogun River ( Nigeria), 42–44 mm SL; BMNH 1953.4.28.5-6: Ogun River ( Nigeria), Coll. E. Trewavas, 89 mm SL (only one specimen); BMNH 1956.9.6.15: Ikorodu, Lagos lagoon ( Nigeria), 39 mm SL; BMNH 1959.8.18.57: Adboyi Creek , Lagos ( Nigeria), 76 mm SL .

Figures

Figure 7. Holotype of Synodontis ouemeensis MRAC 97-007-P-0012, Avagbodji (Benin), Oueme River, Coll. P. Vandewalle, 108 mm SL.