Hassar shewellkeimi, a New Species of Thorny Catfish (Siluriformes: Doradidae) from the upper Tapajós Basin, Brazil

摘要: ABSTRACT. Routine examination of gas bladders uncovered a new species Hassar from the upper Tapajos basin, Mato Grosso, Brazil The species, shewellkeimi, is distinguished all congeners by its relatively long snout and narrow interorbital, distance to anterior naris 2.2–3.1 times interorbital width (vs. 1.1–2.2 in congeners). shewellkeimi most closely resembles H. orestis, but further that having bladder with few, weakly developed peripheral diverticula restricted anterolateral shoulder posterolateral face chamber, sometimes posterior chamber well developed, multiple branches grouped into fascicles encircling horizontal periphery orestis), smooth, broadly narrowly rounded chambers expanded posteriorly medially conjoined terminal diverticula, effecting acutely subtriangular, cone-shaped p...