A new species of Enteromius (Actinopterygii, Cyprinidae, Smiliogastrinae) from the Awash River, Ethiopia, and the re-establishment of E. akakianus

Abstract

In the present study, populations of small-sized smiliogastrin barbs with a thickened and serrated last simple dorsal-fin ray distributed in the Main Ethiopian Rift were analysed. An integrated approach combining genetic markers and a variety of morphological methods based on a wide set of characters, including osteology and sensory canals, proved to be very productive for taxonomy in this group of fishes. The results showed that Ethiopian Enteromius species with a serrated dorsal-fin ray are distant from the true E. paludinosus (with E. longicauda as a synonym) and the so-called E. paludinosus complex involves several supposedly valid species with two distinct species occurring in the Main Ethiopian Rift area. A new species, Enteromius yardiensissp. nov., is described from the Afar Depression in the north-eastern part of the Northern Main Ethiopian Rift. Enteromius akakianus is resurrected as a valid species including populations from the Central Main Ethiopian Rift (basins of lakes Langano, Ziway, and Awasa). No genetic data were available for E. akakianus from its type locality. Enteromius yardiensissp. nov. is clearly distant from E. akakianus from the Central Main Ethiopian Rift by CO1 and cytb barcodes: pairwise distances between the new species and the Ethiopian congeners were 5.4 % to 11.0 %. Morphologically, the new species most clearly differs from all examined Ethiopian congeners by three specialisations which are unique in the group: the absence of the anterior barbel, the absence of the medial branch of the supraorbital sensory canal, and few, 1–3, commonly two, scale rows between the lateral line and the anus.

Genetic diversity of Nile tilapia (Oreochromis niloticus) populations in Ethiopia: insights from nuclear DNA microsatellites and implications for conservation

“…In particular in Ethiopia substantial phylogeographic structure of Nile tilapia had been suggested by studies that include morphological observations [ 25 , 62 ]. A strong influence by the complex geological and hydrogeographic history of Ethiopia had been concluded, similarly to patterns that have recently been observed for the Labeobarbus intermedius complex [ 5 ] and small smilogastrin barbs [ 17 ]. These studies stress the importance of paleo-geographic, climatic and tectonic events for the ichthyofauna of the region.…”

“…This is also shown by Nei’s genetic distances (Additional file 1 : Table S1) that indicated the lowes values for the comparison between Langano and Ziway populations. Distances and clustering clustering patterns precisely reflect the sub-regions of the Main Ethiopian Rift, which is traditionally divided into the Southern (Lakes Abaya and Chamo), the Central (Lakes Hawassa, Langano, and Ziway) and the Northern (Yardi and Kadbada) Ethiopian Rift Valley including the Awash River systems (see [ 1 , 8 , 17 ], and references therein).…”

Longitudinal river zonation in the tropics: examples of fish and caddisflies from the endorheic Awash River, Ethiopia

“…Furthermore, our results show that the fish fauna is dominated by cyprinids of the genera Labeobarbus, Garra and Enteromius. Except for the widespread O. niloticus (Nilo-Sudan), C. gariepinus (Pan-African), G. dembeensis (Nilo-Sudan), and L. intermedius (Nilo-Sudan), the fish species are endemic to Ethiopia (Golubtsov et al, 2002;de Graaf et al, 2007;Stiassny & Getahun, 2007;Englmaier et al, 2020). Indeed, it has been recognized that the northern and central parts of the Main Ethiopian Rift exhibit a fish species composition distinct from the Nilo-Sudan ichthyofaunal province, with affinities to the freshwater ecoregions of the Ethiopian Highlands and the Western Red Sea Drainages (Roberts, 1975;Paugy, 2010).…”

“…The Lower Awash is inhabited by widely distributed generalists like O. niloticus, C. gariepinus, and L. intermedius. Others such as E. yardiensis, M. antinorii, and G. makiensis are highly specialized and show affinities to the Nile drainage (Englmaier et al, 2020), the central East African rift (Golubtsov et al, 2002) and the Arabian Peninsula (Englmaier et al, unpublished data) respectively.…”

“…Geological data give evidence for frequent tectonic and volcanic activities in the history of the Main Ethiopian Rift (Benvenuti et al, 2002;Abbate et al, 2015). These events presumably not only affected the geomorphology and connectivity of the Paleo-Awash (Sagri et al, 2008) but also the distribution of fish species (Beshera & Harris, 2014;Englmaier et al, 2020). Moreover, thermal springs may have considerable influence on the water temperature at higher altitudes (e.g.…”