Abstract
This study describes Glyptothorax sulculus, a new species of sisorid catfish from the Mekong River drainage in northern Cambodia, and provides a key to the Glyptothorax species known from this drainage. The new species differs from congeners in the Mekong River drainage by a unique combination of the following characters: area between anterior and posterior fontanels on neurocranium sharply delineated by absence of tubercles on dorsal surface of head; eye diameter 14% HL; broader lateral processes of the nuchal plates set at about 90° to the median axis; thoracic adhesive apparatus lacking both anteromedial striae and a medial pit, its width 1.7 times in its length; dorsal-fin spine length 18.7% SL; dorsal to adipose distance 15.6% SL; caudal peduncle length 17.3% SL; caudal peduncle depth 2.9 times in body depth at dorsal origin; color pattern of two indistinct dark saddles on body connected by indistinct dark midlateral stripe to form elongate pale ovoid patch on dorsolateral surface of body; and absence of distinctly pale nuchal shield.
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