THE NOTHOBRANCHIUS SITE

MRAC 79-07-P-144, male 50.9 mm SL; Tanzania, large pool near Nsuyanga (Sonyanga), ± 50 km east of Mbeya, along the road Zambia to Morogoro (approx. 08°46’ S, 33°45’ E); J. Pap, 9 June 1976.

MRAC 79-07-P-145 (1), MRAC 76-49-P-147-149 (3)

Nothobranchius usanguensis is distinguished from all other members of the N. neumanni species group by the following combination of characters: In the male, the dorsal profile is convex with almost no transition between the head and body. The anal fin is yellow with a dark red marbled pattern, a distinct dark red, or less commonly black, margin and a light bluegray proximal part. The caudal fin is red or partially red with a darker red or red-gray terminal band that may be preceded by a narrow relatively light red band (Wildekamp et al., 2014).

Subgenus: Zononothobranchius

Species group: N. neumanni group

Populations of this species were regarded as N. aff. neumanni in Wildekamp (2004) before morphometric and molecular analyses confirmed it to be a distinct species and it was described as N. usanguensis by Wildekamp et al. in 2014.

Tanzania: large pool near Nsuyanga (Sonyanga), ± 50 km east of Mbeya, along the road Zambia to Morogoro (approx. 08°46’ S, 33°45’ E).

This species is endemic to seasonal freshwater habitats in south-central Tanzania. It is known from ephemeral pools and swamps on the Usangu Flats, part of the upper Great Ruaha River system, south-central Tanzania.

Coastal East Africa (564)

1070–1144 m

Water parameters (Watters personal data) are as follows: temperature of 18–29°C; pH of 7.6–8.3; conductivity of 120–240 µS; and typically turbid (Nagy & Watters, 2019).

None

This species has an annual life cycle.

Embryonic development under captive conditions in peat moss is about three to five months at room temperature.

Maximum size reported: 50.9 mm SL (MRAC 79-07-P-144, holotype, male).

Diploid chromosome number 2n = 36, NF = 54, karyotype structure 6m+12sm+18st/a (Krysanov & Demidova, 2018).

Karyotype structure unique in the genus.

The specific name is given in reference to the Usangu Flats, the area of origin.

Vulnerable B1ab(iii) (Nagy & Watters, 2019)

    Wildekamp, R. H., B. R. Watters & K. M. Shidlovskiy. 2014. Review of the Nothobranchius neumanni species group with descriptions of three new species from Tanzania (Cyprinodontiformes: Nothobranchiidae). Journal of the American Killifish Association, 47 (1): 2–30. [taxonomy as Nothobranchius usanguensis]

    Watters, B. R., B. Nagy, P. D. W. van der Merwe, F. P. D. Cotterill & D. U. Bellstedt. 2019. Review of the Nothobranchius taeniopygus species group from central and western Tanzania with descriptions of five new species and redescription of Nothobranchius taeniopygus (Teleostei: Nothobranchiidae). Ichthyological Exploration of Freshwaters, IEF-1110, pp. 1–41. [phylogeny]

    Nagy, B. & B. R. Watters. 2019. Nothobranchius usanguensis. The IUCN Red List of Threatened Species: e.T88026448A88026458. [conservation]