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| Enteromius yardiensis |
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 yardiensis sp. 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 yardiensis sp. 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.
Keywords: East Africa, Main Ethiopian Rift, morphology, CO1 and cytb sequences, zoogeography
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| Dorsal fin in Enteromius yardiensis sp. nov., paratype, NMW 99259, side channel of Awash R. at Kada Bada (site 2), 37.6 mm SL, with four unbranched rays. Arrow 1 showing first unbranched dorsal-fin ray, arrow 2 showing relative positions of tip of penultimate (3rd) unbranched dorsal-fin ray and lowermost limit of serrated part of last (4th) unbranched dorsal-fin ray. |
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| Enteromius yardiensis sp. nov. alive, paratype, NMW 99640, Awash R. at Aditu (site 3), 35.4 mm SL. Photograph by W. Graf. |
Enteromius yardiensis sp. nov.
Diagnosis: Enteromius yardiensis sp. nov. belongs to a phenotypic group characterised by small size and the last unbranched dorsal-fin ray thickened and serrated. The new species is readily distinguished from its Ethiopian congeners by three unique specialisations: the absence of the anterior barbel, the absence of the medial branch of the supraorbital cephalic canal and few, 1–3, commonly two, scale rows between lateral line and anus. It further differs by posterior barbel usually shorter than half eye diameter; eye large, its diameter 24–34 % HL; snout short and pointed; lateral line complete and strongly curved; scales in the lateral series 32–35; few transversal scale rows between lateral line and pelvic-fin base (1–3); scale rows between dorsal- and pelvic-fin origins 7–10; often four unbranched dorsal-fin rays; few branched pectoral-fin rays, commonly 12 or 13; 17 or 18 abdominal vertebrae; 10–12 predorsal abdominal vertebrae; and 6–9 vertebrae between first pterygiophores of dorsal and anal fins.
Etymology: The species name yardiensis refers to Lake Yardi [the Lower Awash River and interconnected lakes], where the new species is abundant.
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| Alizarin-stained specimens showing cephalic sensory canals and infraorbitals in A Enteromius yardiensis sp. nov. (same specimen as in Fig. 8) B Enteromius sp. CMER, NMW 99237, Lake Ziway (site 8), 34.8 mm SL. Arrows showing part of frontal with no canal in A and medial branch of supraorbital canal (CSO) in B. |
Gernot K. Englmaier, Genanaw Tesfaye and Nina G. Bogutskaya. 2020. A New Species of Enteromius (Actinopterygii, Cyprinidae, Smiliogastrinae) from the Awash River, Ethiopia, and the Re-establishment of E. akakianus. ZooKeys. 902: 107-150. DOI: 10.3897/zookeys.902.39606
