Distichodus microps Schmidt, Knobloch & Barrientos, 2021

Family:  Distichodontidae (Distichodus)
Max. size:  11.05 cm SL (male/unsexed)
Environment:  benthopelagic; freshwater
Distribution:  Africa: Mbia River drainage in Equatorial Guinea (Ref. 127217).
Diagnosis:  Dorsal spines (total): 0-0; Dorsal soft rays (total): 15-17; Anal spines: 0-0; Anal soft rays: 12-13. Diagnosis: Distichodus microps is readily distinguished from the larger-bodied, higher-scale count Distichodus species (D. antonii, D. atroventralis, D. fasciolatus, D. lusosso, D. mossambicus, D. sexfasciatus, D. langi, D. rostratus, D. engycephalus, D. kasaiensis, D. ingae, D. polli, D. petersii, D. nefasch, D. brevipinnis and D. schenga) in having fewer lateral line scales, 40-41 vs. more than 60, and in achieving a smaller maximum standard length, less than 15 cm vs. more than 30 cm (Ref. 127217). This species is also distinguished from the smaller-bodied, lower-scale count Distichodus species in the following ways: Distichodus microps is distinguished from D. decemmaculatus and D. teugelsi in having two rows of teeth on the lower jaw vs. one; it can be readily distinguished from D. noboli, D. hypostomatus and D. maculatus in having fewer scales along the lateral line, 40-41 vs. 45, 53-60 and 75 respectively; and distinguished from D. rufigiensis in not having prominent vertical bars along the sides (Ref. 127217). Distichodus microps is distinguished from D. kolleri and D. altus in having fewer dorsal-fin rays, 15-17 total rays vs. 21-26 and 17-18 respectively, and further distinguished from D. altus and D. affinis in having fewer total anal-fin rays, 12-13 vs. 21-22; it is distinguished from D. notospilus in having more scales along the lateral line, 41, rarely 40, vs. 37-39, rarely 40, a nearly inferior mouth vs. subterminal in D. notospilus, a curved posterolateral margin of the opercle vs. straight in D. notospilus, a smaller eye, 56.7-80.4% of snout length vs. 70.1-104.3%, and a less prominent elongated spot at the base of the caudal fin; it is distinguished from D. mbiniensis in having a shallower body, usually six scales from lateral line to the pelvic fin vs. 7, 34.1-38.7% of standard length vs. 33.6-42.4%, fewer anal-fin rays, usually 12 total rays vs. 13-14, a longer anal fin, 15.0-17.8% of standard length vs. 13.4-17.3%, a more inferior mouth vs. the subterminal mouth in D. mbiniensis, a deeper, 12.4-14.2% of standard length vs. 11.8-13.0%, and a longer caudal peduncle , 11.9-14.8% of standard length vs. 9.7-12.6%, a smaller eye, 56.7-80.4% of snout length vs. 58.6-88.0%, a more narrow and elongate subopercle, and a deeper infraorbital 1 with a more rectangular anterolateral margin vs. a more shallow infraorbital 1 with a curved anterolateral margin in D. mbiniensis (Ref. 127217).

Description: Body laterally compressed and moderately elongate; dorsal profile with convex curve from snout to anterior margins of head; weakly convex to dorsal-fin origin; profile from origin of dorsal fin to adipose fin straight to slightly convex; concave from adipose to caudal fin; ventral profile broadly convex from tip of snout to the terminus of the anal fin; slightly concave in area from anal-fin terminus to caudal fin; body covered in relatively large ctenoid scales; extending over proximal half of adipose and caudal fins; extending beyond proximal half in lobes of caudal fin (Ref. 127217). Mouth inferior to nearly subterminal; two rows of bicuspid teeth in upper and lower jaws (Ref. 127217). Dorsal fin with straight to slightly concave distal margin; its origin anterior to vertical of pelvic-fin origin; adipose fin origin nearly two thirds the distance from dorsal-fin terminus to caudal fin; anterior to vertical of anal-fin terminus and extends beyond vertical of anal-fin terminus; caudal fin forked; tips of upper and lower lobe slightly rounded with moderate point; anal fin with slightly concave margin; base about five-sixths the length of longest ray; not reaching caudal fin when flexed to body; pelvic-fin origins at mid-length of snout to caudal fin distance; nearly as long as head length; pectoral-fin origin posterior to vertical of posterior edge of subopercle; horizontal of pectoral-fin origin near or slightly inferior to mouth; nearly as long as pelvic fin (Ref. 127217).

Colouration: Live colouration: specimens silver with some red and gold flecks along head and sides anteriorly and becoming more diffuse posteriorly; pectoral and anal fins red; dorsal fin cream at based with black band beginning about one-third the length of the third ray stretching nearly to the distal tip and roughly to the base of the fourth ray through the base of the tenth ray; diffuse ovoid black spot at base of caudal fin (Ref. 127217). Colouration of preserved specimens: light grey to silver along sides; scales darker grey on upper quarter of sides; pores along the lateral line with melanophores forming a diffuse stripe; faint black ovoid spot at base of caudal fin; fins clear with black spot in dorsal fin (Ref. 127217).
Biology: 
IUCN Red List Status: Endangered (EN); Date assessed: 21 July 2020 (B1ab(iii)) Ref. (130435)
Threat to humans:  harmless
Country info:   
 


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