Desmopuntius mahakamensis, a new cyprinid species (Teleostei, Cyprinidae) from East Kalimantan, Indonesia

<i>Desmopuntius mahakamensis</i> <b>sp. nov.</b>, is described based on specimens from East Kalimantan, Indonesia. The new species, <i>D. mahakamensis</i> is distinguished from all congeners by the following combination of characters: anal-fin rays iii,5½; lateral line scales 26-27 (mode 26); predorsal scales 9-11 (mode 10); gill rakers 9-11 (mode 10); total vertebrae 29; axial streak present; presence of 5-6 black lateral stripes in adults (>30 mm SL), with stripe +1 extending from behind the gill opening along scale row 1 and reaching only to midbody, between the origin and end of the dorsal-fin base. Molecular evidence further supports the assignment of the new species in the genus <i>Desmopuntius</i> and its clear separation from congeners.