Microthrissa minuta Poll, 1974
Dungu sprat
photo by FAO

Family:  Dorosomatidae (Gizzard shads and sardinellas)
Max. size:  4.3 cm SL (male/unsexed)
Environment:  pelagic; freshwater
Distribution:  Africa: Congo River system in Dungu River and its tributary Garamba River (Ref. 188), and Lower Congo River (Ref. 188) in Democratic Republic of the Congo (Ref. 47399). Also reported as Microthrissa cf. minuta from mouth of Niemba River, Lukuga River, an outflow of Lake Tanganyika, in Democratic Republic of the Congo (Ref. 93587).
Diagnosis:  Dorsal spines (total): 0-0; Dorsal soft rays (total): 12-15; Anal spines: 0-0; Anal soft rays: 18-21; Vertebrae: 40-44. Diagnosis: Body moderately deep, its depth about 22-30% of standard length; scutes strongly keeled, 1 or 2 before base of first pectoral fin ray, 11-12 pre-pelvic and 6-8 post-pelvic scutes; snout pointed; lower jaw not or slightly projecting, included in upper when mouth closed, with small teeth limited to anterior part; pre-maxilla with 12-30 small conical teeth directed inwards; maxilla blade slender, more than 3 times as long as deep, upper edge with a ridge flared outward; posterior supra-maxilla small, spatulate, shaft as long as blade; lower gillrakers 18-22 (Ref. 188, 47399, 93833). Also characterized by 37-43 scales in a longitudinal series and anal fin with 18-21 rays (Ref. 47399). It resembles Microthrissa royauxi, which has fewer gillrakers but more anal fin rays, 14-17 and 23-27 respectively (Ref. 188). It is distinguished from Microthrissa whiteheadi by a lower number of teeth on the pre-maxilla, 12-30 vs. 32-40 in M. whiteheadi; and additionally by a higher number of lower gillrakers, 18-22 vs. 14-18, a lower number of anal fin rays, 18-21 vs. 20-25, and a lower number of pre-pelvic scutes, 11-12 vs. 13-16 (Ref. 46514, 47399). Description: Body depth 21.7-30.0% of standard length; head length 11.1-12.7% of standard length (Ref. 188, 93833). Lower jaw not or slightly projecting; premaxilla with 12-30 conical teeth directed inwards; maxillary with 10-25 small conical teeth (Ref. 47399, 93833). First gill arch with 18-22 gillrakers on lower limb, 27-32 total gillrakers (Ref. 47399). Dorsal fin origin closer to snout than caudal fin base, inserted behind pelvic fin base; dorsal fin with 12-15 fin rays; anal fin with 18-21 fin rays; pectoral fin with 10-13 fin rays; pelvic fin with 1 unbranched and 6-7 branched rays (Ref. 47399, 93833). Cycloid scales; 37-43 on longitudinal line (Ref. 188, 47399). Scutes strongly keeled; 11-12 pre-pelvic scutes, with 1-2 scutes without ascending arms before base of pectoral fin, other 10 pre-pelvic scutes with ascending arms; 1 subpelvic scute without ascending arms; 6-8 post-pelvic scutes with ascending arms (Ref. 188, 93833). Number of vertebrae 40-44; with 20-23 abdominal vertebrae and 19-22 caudal vertebrae (Ref. 47399). Colouration: Colouration of preserved specimens yellow greyish, occiput blackish by presence of numeral melanophores; a weak pigmented trace on caudal peduncle ending in a small black spot at base of lower lobe of caudal fin (Ref. 47399, 93833).
Biology:  A riverine species (Ref. 188).
IUCN Red List Status: Vulnerable (VU); Date assessed: 16 February 2009 (D2) Ref. (130435)
Threat to humans:  harmless

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