Enteromius, Neumann & Obermaier & Moritz, 2016

Neumann, Dirk, Obermaier, Henriette & Moritz, Timo, 2016, Annotated checklist for fishes of the Main Nile Basin in the Sudan and Egypt based on recent specimen records (2006 - 2015), Cybium 40 (4), pp. 287-317 : 294-296

For the following small Enteromius barbs (cf. Yang et al., 2015) mentioned by Bailey (1994) the occurrence in the Sudd is unclear: Enteromius sp. nov. 1 & sp. nov. 2 (Bianco in Bailey, 1994), E. cercops (Whitehead, 1960) and E. kerstenii (Peters, 1868) . The same applies for E. yongei (Whitehead, 1960) and E. leonensis (Boulenger, 1915) . Enteromius werneri Boulenger, 1905 is currently in synonymy with Enteromius stigmatopygus (Boulenger, 1903) ( Lévêque,

1989; based on Banister, 1987), but a first comparison of the type material of E. werneri suggests that this placement might be erroneous and should be carefully reevaluated to clarify the taxonomic status of this species. Enteromius perince (Rüppell, 1835) specimens from the Blue Nile tend to display only two instead of three or more flank spots. The Common carp, Cyprinus carpio Linnaeus, 1758 , is intensively reared in the Delta region and seems to be restricted to aquaculture ponds in the Nile Delta ( FAO, 2010). Ctenopharyngodon idella (Valenciennes, 1844) is still heavily stocked in the Delta region. Both carps account for 10% of landed catches in Egypt ( FAO, 2010). Pseudorasbora parva (Temminck & Schlegel, 1846) was accidentally introduced to Lake Mariut and likely other Delta lakes together with stocked carps.

Shallow sand banks seem to serve as nursery sites for Chelaethiops bibie and Leptocypris niloticus ; larvae and young-of-the-year are available in high abundance towards the end of the flood season in the Blue Nile (Khartoum) and White Nile (Aba Island and Khartoum). Populations of Chelaethiops bibie seem to vary in lower jaw length (isognathous vs protruding lower jaws), eye diameter and lateral dimension of orbit, pectoral fin extension (in relation to pelvic fin insertion). The pigmentation on the body can vary from a vaguely dusky to a dark back in single specimens (in combination with an intensive lateral stripe) the unpaired fins in living specimens sometimes are coloured distinctly yellowish. High phenotypic variation is observed in Labeo forskalii Rüppell, 1835 : at the 4 th cataract, two morphotypes occur syntopically. One appears dark grey with a pronounced falciform dorsal fin, and has a slightly elongated caudal fin with black-rimmed scales on the caudal peduncle and the caudal fin base. In the second, body and tail appear more truncated, the dorsal fin distally less falciform, and the body colour is light grey while dark-rimmed scales only appear on to the caudal peduncle. In both forms the position of the eye is either below or in the lower third of the lateral line level. Labeo forskalii originating from the 6 th cataract at Sabaloqa appear much more elongated, the eyes are situated in a more dorsolateral position and approximately on the same level as the lateral line, the anteriorly dark centred body scales shift gradually towards dark rimmed scales on the distal part of the tail. Specimens from the Blue Nile collected in the outlet canal of Sennar Dam share the elongated appearance and dorsolateral eye position, but tend to have dark rimmed scales on the whole body in combination with a dark grey life colouration with a distinctive blue-green hue which is rarely shared by other L. forskalii populations in the Sudan. The diversity and variability of the African Labeo species seems still puzzling. Since Reid McGregor (1985), only selected species underwent further investigation ( Tshibwabwa, 1997; Tshibwabwa et al., 2006). A thorough revision especially of Sahelan Labeo or other enigmatic species-groups, such as “ Labeo parvus ”, is pending. We follow Kottelat (2013) and treat L. niloticus (Linnaeus, 1758) as a valid name. A new species L. sp. nov. “redeye” has been discovered during our surveys in the White Nile and is presently under description.

The Nile at Taraq Island below the Hamdab Dam at the former 4 th cataract harbours two distinct Garra species ( Fig. 3 ). The first is a round headed Garra which differs from G. dembeensis sensu Stiassny & Getahun (2007) but seems close to G. vinciguerrae as originally described by Boulenger (1901) from the 3 rd cataract. It further differs from G. blanfordii ( Boulenger, 1901) and G. dembeensis in a scaled post-pelvic area (vs. asquamate post-pelvic area). We identify this population tentatively as G. cf. vinciguerrae until the taxonomic status and the available valid name for this species is resolved (pers. comm. F. Wicker 03 Dec. 2015.)

The second Taraq- Garra is new to science (description in prep.) and characterized among other characters by its flat but wide head. A third abberant Garra has been recorded from the Blue Nile below the Sennar Dam, but we currently have only three dried up specimens that got stranded ( Fig. 4 ). However, to allow proper evaluation, more adequately preserved specimens are needed. Raiamas senegalensis (Steindachner, 1870) is assumed to be common, but has been observed in only one specimen in the Upper Atbara so far; the exact range and abundance in the Sudan and Egypt is unclear.

Figures

Figure 3. – Live specimens of Garra from Lower Nile at Taraq Island (8/9 Apr. 2008). A: Garra cf. vinciguerrae; B-C: Garra sp. “Taraq-flathead”.

Figure 4. – Stranded Labeo forskalii specimens of the Blue Nile below the dam of Sennar after water level fluctuation (17 Jan. 2007).