| การวินิจฉัย |
Diagnosis: Marcusenius caudisquamatus can be distinguished from its congeners by the following characters: middle body depth 23.8-25.9% of standard length; dorsal fin length 15.4-19.2% of standard length; anal fin length 23.0-24.9% of standard length; pre-dorsal length 61.7-66.7% of standard length; pre-anal length 60.7-62.8% of standard length; caudal peduncle depth 40.4-51.7% of its length; dorsal fin rays 20-22; anal fin rays 27-28; scales around caudal peduncle 19; lateral line scales 72-73; anterior gill rakers (4)+(5-6), total anterior gill rakers 9-10; posterior gill rakers (6)+(9), total posterior gill rakers 15; conical teeth on upper/lower jaws 5-5 (Ref. 95448).
Description: Head with terminal mouth well in front of eye; mental lobe on lower jaw protruding in front of upper jaw; snout rounded and blunt; pre-anal distance shorter than pre-dorsal distance; distance from origin of anal fin to origin of dorsal fin greater than middle body depth; pre-pelvic distance twice as long as distance between pelvic and anal fin (Ref. 95448). Dorsal and anal fins set well back on the body, dorsal fin situated about three fourths of standard length from snout and opposite anal fin; dorsal fin shorter, originating on vertical at 4th or 5th anal fin ray and ending before anal fin base; distal margin of dorsal and anal fins obliquely orientated, with rays becoming gradually shorter posteriorly; dorsal fin rays 20-22, its anterior rays highest, with distal margin rounded and slightly concave; anal fin rays 27-28; anterior anal fin rays of sexually mature males strong and sometimes darker, 3rd-5th rays longer than the first two rays, crescentic and rounded or curved backwards, but are anteriorly sharp or pointy in females and juveniles; pectoral fin rays 10; pectoral fin length 73.4-96.9% of head length (Ref. 95448). Middle body depth 23.7-25.9% of standard length; caudal peduncle thicker and stronger, subcylindrical across its entire length, 18.6-21.6% of standard length; caudal peduncle depth 40.4-51.7% into its length (Ref. 95448). Lateral line scales 72-73; lateral line scales cycloid with reticulate striae; scales along the caudal peduncle circumference, 19 (Ref. 95448). Jaws with 5-5 conical teeth; 44 vertebrae; total anterior gill rakers 9-10 on the first gill arch, gill rakers of the anterior row on first arch conicals, thin and more developed; total posterior gill rakers 15 on the first gill arch; rakers on the posterior row shorter, thicker and with flattened tips (Ref. 95448).
Colouration: In preservation, specimens are grey to blackish; in 70% alcohol the upper back and belly are covered with a milky-grey mucus layer, especially on the head where opaque 'mormyrid skin' is present (Ref. 95448). |