| Family: |
Nothobranchiidae (African rivulines) |
| Max. size: |
3.69 cm SL (male/unsexed) |
| Environment: |
pelagic; freshwater; pH range: 6.88 - 6.88 |
| Distribution: |
Africa: ephemeral pools in the Lushiba Marsh, part of Lake Mweru drainage, in Zambia (Ref. 95524). |
| Diagnosis: |
Dorsal spines (total): 0-0; Dorsal soft rays (total): 15-17; Anal spines: 0-0; Anal soft rays: 15-18. Diagnosis: Nothobranchius milvertzi belongs to the Nothobranchius taeniopygus species-group, presenting the diagnostic characters of this complex of caudal and anal fin with broad light submarginal band and dark distal margin in males (Ref. 95524). Nothobranchius milvertzi is distinguished from all other species of this complex, with the exception of N. malaissei and N. hassoni, by having an anal fin with orange submarginal band and a dark red-brown distal margin (Ref. 95524). It is distinguished from these two last mentioned species by having a red caudal fin with narrow orange semicircular submarginal band and wide dark red-brown distal margin (Ref. 95524). Furthermore, the species presents within the species-group the unique morphometric characters of head length 28.5-31.5% of standard length, interorbital width 39-46% of head length, and snout length 18-20% of head length (Ref. 95524).
Description: General body shape robust, laterally compressed and deep (Ref. 95524). Head short, laterally compressed, deeper than wide; snout slightly pointed, shorter than eye diameter; mouth supraterminal; lower jaw longer than upper; orbit in anterior half of head; branchiostegal membrane projecting posteriorly from operculum (Ref. 95524). Dorsal profile convex from snout tip to base of last fin ray of dorsal fin, slightly concave on caudal peduncle; ventral profile convex from lower jaw to base of last fin ray of anal fin, slightly concave on caudal peduncle (Ref. 95524). Dorsal fin origin anterior to anal fin origin, both fins posterior to mid-length of body; dorsal and anal fins rounded, with small contact organs in form of papillae on fin rays and distal margin with short filamentous ray; posterior extremity of dorsal fin reaching caudal fin base (Ref. 95524). Scales cycloid, body and head entirely scaled, except for ventral surface of head; scales on mid-longitudinal series 28-31 plus 2 or 3 small scales on caudal fin base; transverse rows of scales in front of origin of dorsal fin 10-11; scale rows around caudal peduncle 12 (Ref. 95524). Cephalic squamation pattern variable, some specimens prsenting irregular G-type; neuromasts at anterior supraorbital level open type, sensitive in shallow grooves, each with two neuromasts; sensitive system at posterior supraorbital level curved with two neuromasts; one neuromast on each scale along trunk lateral line (Ref. 95524).
Colouration: Live males: scales on trunk and head light blue with broad dark red posterior margin, creating reticulated pattern on body; scales on abdomen with narrow margin; snout, dorsal portion of head red, throat blue; exposed part of branchiostegal membrane white; iris golden to pale blue, with faint black vertical bar through the centre of eye; dorsal fin yellow with irregular brownish red stripes and spots, becoming smaller and denser towards distal edge of fin; anal fin red proximally, with elongated light blue transverse spots, followed by irregular red-brown band, narrow orange submarginal band and wide dark red-brown distal margin; caudal fin red with faint narrow orange semicircular submarginal band and wide dark red-brown distal margin; ventral fin light blue procimally, orange and dark red-brown distally; pectoral fin hyaline with light blue posterior distal margin (Ref. 95524). Live females: scales on trunk and head pale grey-brown, darker on back and lighter to silver on abdomen; dark grey reticulation on the posteroventral portion of the falnk; blue iridescence on trunk and opercular region; iris golden, with faint black vertical bar through centre of eye; all fins hyaline (Ref. 95524). |
| Biology: |
The accompanying fauna of the ephemeral pools consisted of non-annual species, such as Barbus haasianus, Lacustricola moeruensis, Protopterus sp. and Pseudocrenilabrus cf. philander (Ref. 95524). The type locality was a large ephemeral pool formed in a river bed, as a standing fragment of the seasonal river, about 50 m long and 10 m wide, and about 2 m deep at its deepest point; the edge of the habitat was heavily overgrown by grass and the aquatic vegetation consisted of Nymphea species; the water was brown and slightly turbid, whereas at shallower parts the bottom of the pool was visible (Ref. 95524). Eggs slightly oval, measuring 1.27-1.36 mm on average, with short filaments on chorion (Ref. 95524). |
| IUCN Red List Status: |
Endangered (EN); Date assessed: 04 January 2019 (B1ab(iii)+2ab(iii)) Ref. (130435)
|
| Threat to humans: |
harmless |
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