Stone loaches from the headwaters of the Bulgan River (Mongolian Altai) (Teleostei: Cypriniformes: Nemacheilidae: Barbatula)

Abstract :

Two sympatric species of loaches, Barbatula cf. altayensis Zhu, 1992 and B. karabanowi Prokofiev, 2018, occur in the upper reaches of the river Bulgan in Mongolia. They represent the only fish taxa found in the studied part of the river. Significant morphological differences between these species support their apparent belonging to the different phyletic lineages. Barbatula cf. altayensis is characterized by the following combination of characters: nostrils closely set; lips furrowed, upper lip with medial indentation weak to absent, lower lip with medial lobes barely separated, furrowed, lateral lobes absent; scale cover well developed; broad head with muscular cheeks; 44–45 vertebrae; 89–105 lateral-line pores; pigmentation pattern consisting of transverse bars or isolated well spaced blotches. A set of peculiar features (mouth structure and position of nares, characters of sexual dimorphism, strong ossification of the otic portion of the cephalic laterosensory system) supposes an isolated position of B. altayensis within the genus. The second species, B. karabanowi,belongs to the “blunt-snouted” complex of species related to B. toni sensu stricto. Within the other members of this complex it is most similar to B. dsapchynensis from the basin of Zavhan River (Lake Valley, Mongolia) but differs from this and other species of Barbatula by the following combination of characters: nostrils widely spaced; snout relatively broad, ratio between maximum head width and width of snout at anterior nares equal to 1.44–1.57; lips smooth, upper lip with short indentation; lower lip with short but well developed lateral lobes and oval mental lobes lacking conical protrusions; scale cover reduced; 42–44 vertebrae (usually 43); 75–88 lateral-line pores; paired fins with rounded tips; pigmentation pattern usually with densely distributed and partially fused irregular spots and streaks. The morphological proximity between B. karabanowi and B. dsapchynensis may indicate a possibility of links between the basins of Bulgan and Zavhan in the past

Keyword :

Siberian loaches, western Mongolia, systematics, zoogeography, sympatry

Author(s) : Prokofiev, A. M.
Downloads : 474
Published Issue : 2018 Vol. 13 Number 2

2018 Vol. 13 Number 2