THE NOTHOBRANCHIUS SITE

MRAC 2020.007.P.0001, male, 31.9 mm SL; Uganda: upper Nile drainage: Achwa drainage: ephemeral swamp in the Aringa system, about 2.6 km south of Madi Opei township, 3.575556 N, 33.079167 E; B. Nagy, K.
Østergaard & G. Petneházy, 6 June 2017 [field code: Madi Opei UGN 17-11].

MRAC 2020.007.P.0002-7 (6), MRAC 2020.007.P.0008

Nothobranchius elucens is distinguished from all other members of the genus by the following characters in males: body colouration golden-grey with brown scale margins creating irregular vertical stripes on trunk;
anal fin yellow with brown spots proximally, with slender brown median band, followed by a slender light blue subdistal band and a slender black distal band; caudal fin brown proximally and medially, followed by a slender light blue subdistal band and a slender black distal band; dorsal fin golden with irregular brown blotches and stripes, with narrow light blue subdistal band and narrow black distal band.

Furthermore, it differs from N. taiti by the morphometric characters of having a smaller head length of 29.5–33.1 % SL (vs. 35.0–38.6 %); smaller prepectoral length of 31.2–33.9 % SL (vs. 34.2–38.6 %); greater head depth of 81–87 % HL (vs. 71–80 %); greater interorbital width of 43–49 % HL (vs. 31–40 %); and greater caudal peduncle length of 145–152 % of its depth (vs. 134–143 %).

​Subgenus: Zononothobranchius

Species group: N. rubroreticulatus group

Specimens of this species were referred to in the field as N. sp. Madi Opei, when first collected in 2017. It was retrieved in van der Merwe et al. (2020) as a phylogenetically distinct lineage. Nothobranchius elucens was established as a species by Nagy (2021).

Uganda: upper Nile drainage: Achwa drainage: ephemeral swamp in the Aringa system, about 2.6 km south of Madi Opei township (3.575556 N, 33.079167 E).

This species is endemic to northern Uganda. It is currently known from temporary swamps formed in the floodplain of the seasonal Aringa River system. The Aringa flows into the Pager, which is a tributary of the Achwa within the upper Nile drainage in northern Uganda.

Upper Nile (522)

1006 m

Water parameters at the type locality are as follows: water temperature  33.6° C, pH 7.8 and 107 ppm of total dissolved solids (Nagy, 2021)

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: 35.7 mm SL (MRAC 2020.007.P.0008, paratype, male).

Karyotype structure unique in the genus (Krysanov, pers. comm.)

The specific name elucens is a Latin participial adjective meaning ‘shining out’ and is given with reference to the distinctive light blue subdistal band in the anal and caudal fins, contrasting and shining out of the overall dark colouration of body and fins of the males (Nagy, 2021).

Vulnerable B1ab(iii) (Nagy & Watters, 2021)

    Nagy, B. 2017. Searching for a mystery Nothobranchius in Uganda.  Journal of the American Killifish Association, 50 (6): 162–174. [collecting as Nothobranchius sp. Madi Opei]

    Nagy, B. & B. R. Watters. 2018. Distribution and habitat conditions of Nothobranchius fishes in Uganda. Journal of the American Killifish Association, 51 (5–6): 176–192. [distribution, ecology as Nothobranchius sp. Madi Opei]

    van der Merwe, P.  D. W., F. P. D. Cotterill, M. Kandziora, B. R. Watters, B. Nagy, T. Genade,  T. J. Flügel,  D. S. Svendsen, & D. U. Bellstedt. 2020. Genomic Fingerprints of Palaeogeographic History: The tempo and mode of Rift tectonics across tropical Africa has shaped the diversification of the killifish genus Nothobranchius (Teleostei:  Cyprinodontiformes), Molecular Phylogenetics and Evolution, 158: 106988. [phylogeny as Nothobranchius sp. Madi Opei]

    Nagy, B. 2021. Nothobranchius elucens, a new species of seasonal killifish from the upper Nile drainage in Uganda (Cyprinodontiformes: Nothobranchiidae). Zootaxa, 4915 (1): 133–147. [taxonomy as Nothobranchius elucens]

    Nagy, B. & B. R. Watters. 2021. Nothobranchius elucens. The IUCN Red List of Threatened Species: e.T195440796A195440816. [conservation]