23 Kas 2024 Cumartesi
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
Siberian
loaches, western Mongolia, systematics, zoogeography, sympatry