Nannaethiops, Günther, 1872

Moritz, Timo, Dayem, Zuheir Nour El, Abdallah, Mohammed Abakar & Neumann, Dirk, 2019, New and rare records of fishes from the White Nile in the Republic of the Sudan, Cybium 43 (2), pp. 137-151 : 143

Nannaethiops / Neolebias

The true identity of a small distichodontid ( Fig. 2E, F ) collected in 2016 from beach seine hauls through submerged vegetation and dense Eichhornia standings, blocking the beach at the rocky outcrops at the southern end of Al Jabalayn, is still unclear. In 2018, we encountered a similar individual in shallow water on the southern tip of Aba Island in Kosti. Boulenger (1907) referred to this species as Nannaethiops unitaeniatus Günther, 1872 , but when Poll and Gosse (1963) described Neolebias trewavasae Poll & Gosse, 1963 , they stated only one species, namely Neolebias trewavasae , to occur in the Nile. Bailey (1994) followed this view by referring to the species as “ Neolebias trewavasae Poll and Gosse, 1963 (= Nannaethiops unitaeniatus auct. nec Günther, 1871)” indicating by the use of ‘auct. nec’ that he doubts N. unitaeniatus sensu Günther (1871) to occur in the Nile. The interpretation that N. trewavasae is the only native species in the Nile was also shared in the checklist of African freshwater fishes ( Daget and Gosse, 1984). Poll and Gosse (1963) included in their study among other specimens comparative material from the White Nile like those into the lot BMNH 1948.1.14.1-11. This lot, now subdivided in several lots, apparently harbours two different species: at least two specimens are very close to those recorded during our surveys ( Fig. 2E, F ) and represent in our view the same species ( Fig. 2G ), and at least one divergent specimen likely representing N. trewavasae ( Fig. 2H ). Forty years after the description of N. trewavasae , Nannaethiops bleheri Géry & Zarske, 2003 was described as new species for the Nile from the Baro River drainage in Ethiopia. In their work the authors synonymised the genus Neolebias with Nannaethiops , but subsequent authors did not support this view (e.g. Vari, 2007; Fricke et al., 2018).

Figures

Figure 2. – Selected fishes recorded from the White Nile. A-F and I-J from Al Jabalayn. A: Brevimyrus niger, male, 137 mm SL; B: Mormyrus hasselquistii, 282 mm SL; C: Petrocephalus keatingii, male, 145 mm SL; D: Pollimyrus petherici, 200 mm SL; E: Neolebias unifasciatus, female, 22mm SL; F: N. unifasciatus, male, 20 mm SL; G: N. unifasciatus, 18.2 mm SL, BMNH 1948.1.14.6-8; H: N. trewavasae, 19.7 mm SL, BMNH 1948.1.14.11; I. Paradistichodus dimidiatus, 42 mm SL; J: Enteromius macrops, 39 mm SL. (Photos G & H by The Trustees of the Natural History Museum, London).