Microsynodontis notatus , Ng, Heok Hee, 2004
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Microsynodontis batesii (non Boulenger) Pellegrin, 1909: 66; 1915: 503.
Type material: Holotype: MRACAbout MRAC 80 51 P 839, male, 41.0 mm SL: Gabon: Ezanga River, about midway between Lake Ezanga and Ogooué mainstream; T. R. Roberts, 10 September 1978.
Paratypes: MRACAbout MRAC 73 2 P 1906–1910 (5), 3 females: 26.9 –31.0 mm SL; 2 males: 33.3 –40.0 mm SL; Gabon: Lake Onangue, Mountsomanie; D. F. E. Thys van den Audenaerde, 28 August 1981. MRACAbout MRAC 80 51 P 17 (1), female: 53.6 mm SL; Gabon: Ogooué River, mainstream at Lambaréné; T. R. Roberts, 30 July 1978. MRACAbout MRAC 80 51 P 840 –866, 16 females: 22.1–39.4 mm SL; 11 males: 24.8–43.7 mm SL; data as for holotype.
Diagnosis. Microsynodontis notatus can be distinguished from all congeners except for M. christyi and M. laevigatus in having a deeper caudal peduncle (9.6–11.9 % SL vs. 5.8–9.8). It differs from M. christyi in having a larger eye (17.2–25.7 % HL vs. 13.6–17.9) and from M. laevigatus in having a serrated (vs. smooth) anterior edge of the pectoral spine ( Fig. 4View FIGURE 4) and a rounded (vs. truncate) caudal fin ( Fig. 9View FIGURE 9). It also differs from all congeners in frequently having numerous faint, dark brown elongate spots on the body (vs. spots always absent).
Description. Biometric and meristic data as in Table 8. Body compressed. Predorsal profile steep; postdorsal body sloping gently ventrally. Preanal profile horizontal. Anus and urogenital openings located at vertical through middle of pelvic fin. Skin smooth. Lateral line complete and midlateral.
Head depressed and broad, broadly rounded when viewed laterally and with rounded snout margin when viewed from above. Gill openings narrow, extending from immediately ventral to posttemporal to immediately ventral to base of pectoral spine. Gill membranes united to, and attached across, isthmus. Bony elements of dorsal surface of head covered with thin skin. Nuchal shield large and terminating posteriorly with two rounded processes on each side. Supracleithral process thin, extending just short of vertical through posteriormost tip of nuchal shield.
Barbels in three pairs. Maxillary barbel long and slender, extending to just beyond base of last pectoralfin ray. Inner mandibularbarbel origin close to midline, extending to base of pectoral spine and with 2 short, thin branches on anterior half and 3–4 long, thin branches on posterior half. Outer mandibular barbel originates posterolateral of inner mandibular barbel, extending to middle of pectoralfin base and with 3–4 long, thin branches.
Eye large and ovoid, horizontal axis longest; located entirely in dorsal half of head. Orbit without free margin.
Mouth inferior and crescentshaped; lips plicate. Oral teeth in rows on all toothbearing surfaces. Premaxillae narrow, with narrow ventral shelf and partially exposed when mouth closed. Primary teeth 11–14, conical and separated from secondary teeth by distinct gap. Secondary teeth 30–40, acutely pointed and recurved; disposed in 3–4 rows. Tertiary teeth 16–20, elongate, villiform and extending over full width of premaxillae. Dentary teeth 15–19, acutely pointed, strongly recurved and broader than secondary teeth; disposed in one or two transverse bands.
Dorsal fin located at anterior third of body, with II, 6 * (14) or II, 7 (20) rays and convex margin. Dorsalfin spine long, stout and slightly curved; smooth on both anterior and posterior margins. Adipose fin moderately long; margin slightly convex for entire length and posterior end deeply incised. Caudal fin rounded, with i,5,6,i (1) or i,6,6,i* (33) principal rays. Procurrent rays symmetrical and extend only slightly anterior to fin base. Analfin base located ventral to posterior half of adipose fin. Anal fin with iii, 7 (1); iii, 8 (4); iv, 7 * (11) or iv, 8 (18) rays and convex margin. Pelvicfin origin at vertical ventral to posterior end of dorsalfin base. Pelvic fin with i, 6 (34) rays and slightly convex margin; tip of appressed fin not reaching analfin origin. Pectoral fin with I, 6 *(32) or I, 6,i (2) rays; spine slightly curved and stout ( Fig. 4View FIGURE 4 e). Anterior spine margin with 3–16 small serrations along entire length of spine; serrations antrorse (distally directed) on distal twothirds and anteriorly directed on proximal third. Posterior spine margin with 6–12 strong serrations along entire length. Pectoralfin margin convex posteriorly. Vertebrae 12 + 23 (2); 12 + 24 (6); 13 + 22 (1); 13 + 23 * (10); 13 + 24 (12) or 14 + 23 (3).
Males with numerous tubercles on sides of head on region extending from snout to preopercle, and long genital papilla situated immediately posterior to anus. Females with fewer tubercles on sides of head, and with smaller, distally flattened genital papilla.
Coloration. In 70 % ethanol: dorsal and lateral surfaces and of head and body light to medium brown, fading to cream on belly and ventral surfaces ( Fig. 15View FIGURE 15). Dorsal and lateral surfaces of head and body frequently with dark brown elongate spots evenly distributed and forming a reticulate pattern. Snout with a series of cream spots delineating anterior and posterior nares. Cheek region with one or two cream spots immediately ventral to orbit. Cream band encircling nape at supraoccipital. Dorsal third of body with series of five cream vertical barshaped marks extending to lateral midline of body: first at middle of dorsalfin base, second at adiposefin origin, third at middle of adiposefin base, fourth at posteriormost point of adiposefin base and last on caudal peduncle immediately posterior to adipose fin, sometimes encircling caudal peduncle as cream band. Ventral third of flanks with a longitudinal series of four to seven cream spots or vertical barshaped marks. Adipose fin brown, with an extensive hyaline margin and sometimes with dark brown spots and vermiform marks. Dorsal, pectoral, pelvic and anal fins hyaline and with one to two rows of elongate spots forming longitudinal brown rows. Caudal fin hyaline, with elongate brown spots forming two to three irregular columns.
Distribution. Known only from the lower Ogooué River in Gabon ( Fig. 5View FIGURE 5).
Etymology. From the Latin notatus , meaning marked. In reference to the dark elongate spots frequently present in this species. Used as an adjective.
|Outer mandibular barbel length|
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