THE NOTHOBRANCHIUS SITE

BMNH 2006.7.31.82, holotype, male, 38.5 mm SL; Sudan: Khor Morung, approx. 10°32' N, 31°03' E; Irwin, 1950-1951.

BMNH 2006.7.31.105 (1), BMNH 2006.7.31.79-81, 85-90, 95 (5), BMNH 2006.7.31.83-84 (2)

Nothobranchius occultus can be distinguished from all other species of the genus by the following unique combination of characters: 15–18 dorsal fin rays; 15–18 anal fin rays; 26–29 scales in longitudinal series; relatively long pelvic fin, tip reaching anal fin; terminal portion of snout on ventral profile wide and rounded; body, paired and unpaired fins of male completely dark red brown in preserved specimens (Valdesalici, 2014).

Subgenus: Plesiobranchius [probably]

Nothobranchius occultus was established as a species by Valdesalici in 2014.

The species is currently known only from its type locality and a second locality around the southern foothills of the Nuba Mountains. Both collections originate from the early 1950s. Sandon (1957) reported, after the original collector Irwin, this species as being bright red in colouration.

However, the species is not known live and the first description was based on the old material, that is in poor state of preservation. The known sites for members of the genus in the area around the foothills of the Nuba Mountains are scattered due to a limited number of localities that provide suitable conditions for Nothobranchius fishes. The few recent surveys carried out in the area did not detect this species at localities where other members of the genus occurred.

Sudan: Khor Morung, approx. 10°32' N, 31°03' E.

This species is endemic to southern Sudan. It is known from the type locality Gebel Morung (Khor Morung) and near Kadugli (Khor Kidda), in southern Nuba mountains, Sudan.

Upper Nile (522)

436–590 m

Not reported

Probably N. virgatus and N. nubaensis.

Not known. Embryonic development should not differ significantly to that of N. virgatus.

Maximum size reported: 38.5 mm SL (BMNH 2006.7.31.82, holotype, male)

Not known

The specific name is formed from occultus (in Latin for hidden, secret), in reference to the long time period that this species remained hidden following its discovery.

Data Deficient (Nagy & Watters, 2019)

    Sandon, H. 1957. Problem Fish from Kordofan. Sudan Silva, 5 (1): 1–5. [mentioned as Nothobranchius sp. of bright red colouration]

    Valdesalici, S. 2014. Nothobranchius bellemansi and Nothobranchius occultus (Cyprinodontiformes: Nothobranchiidae) two new annual killifish from Sudan. Killi-Data Series, 2014: 4–19. [taxonomy as Nothobranchius occultus]

    Nagy, B. & B. R. Watters. 2019. Nothobranchius occultus. The IUCN Red List of Threatened Species 2019: e.T131471725A131471738. [conservation]