Microthrissa moeruensis (Poll, 1948)
Lake Mweru sprat
photo by FAO

Family:  Clupeidae (Herrings, shads, sardines, menhadens), subfamily: Dorosomatinae
Max. size:  4.1 cm SL (male/unsexed)
Environment:  pelagic; freshwater,
Distribution:  Africa: endemic to Lake Mweru (Ref. 188, 28136) in Democratic Republic of the Congo (Ref. 47399) and Zambia (Ref. 52959).
Diagnosis:  Dorsal spines (total): 0-0; Dorsal soft rays (total): 12-15; Anal spines: 0-0; Anal soft rays: 15-22; Vertebrae: 39-41. Diagnosis: Body slender, its depth about 20-25% of standard length; scutes strongly keeled, beginning just behind base of last pectoral fin ray, about 10-12 pre-pelvic and 5-8 post-pelvic scutes; snout rather pointed; lower jaw not or slightly projecting, with small teeth limited to anterior part; pre-maxillae with a single row of 11-24 small conical teeth directed inwards; maxilla slender, its blade a little more than 3 times longer than deep, upper edge a little ridged; posterior supra-maxilla slender, spatulate, with distinct anterior shaft, shaft longer than blade; lower gillrakers 18-20 (Ref. 188, 47399). Also characterized by 33-40 scales in a longitudinal series and anal fin with 15-22 rays (Ref. 47399, 93833). It resembles small Microthrissa congica, which has a much blunter snout and less scales in a longitudinal series, 26-35 vs. 33-40 (Ref. 188, 47399). Description: Lower jaw not or slightly projecting; premaxilla with 11-24 conical teeth; maxillary with 13-30 small conical teeth (Ref. 47399). Gillrakers slender and elongated, 18-20 in the lower branch of the first gill arch, 26-31 total gillrakers (Ref. 2266, 47399). Dorsal fin base slightly before or above origin of pelvic fins, at equal distance between tip of snout and base of caudal fin; pectoral fins not reaching pelvic fins; dorsal fin with 12-15 rays; anal fin with 15-22 rays; pectoral fin with 10-13 rays; pelvic fin with 8 rays (Ref. 2266, 47399). Cycloid scales; 33-40 scales in longitudinal series, 8-9 transversal scales (Ref. 2266, 47399, 93883). Scutes strongly keeled; with 10-12 pre-pelvic scutes and 5-8 post-pelvic scutes; first 1-2 scutes without ascending arms (Ref. 47399). Number of vertebrae 39-41; with 20-21 abdominal vertebrae and 19-20 caudal vertebrae (Ref. 47399). Colouration: body colouration is yellowish-brown, lighter on ventral side; flanks more or less silvery (Ref. 2266). No black spot on base of lower lobe of caudal fin (Ref. 47399).
Biology:  A lacustrine species, but perhaps also in small streams or rivers feeding Lake Mweru (Ref. 188).
IUCN Red List Status: Vulnerable (VU); Date assessed: 16 February 2009 (B1ab(v)) Ref. (124695)
Threat to humans:  harmless
Country info:   

Entered by: Binohlan, Crispina B. - 17.10.90
Modified by: Boden, Gert - 25.07.18
Checked by: Binohlan, Crispina B. - 23.07.94

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