Dolichancistrus is a genus of armored suckermouth catfish (family Loricariidae) in the ancistrine group of plecos — the same lineage as the familiar bristlenose plecos (Ancistrus) — native to river drainages of Colombia and Venezuela. The atlas's 4 species range 3–6.5 in, with an elongated, slender body form (the genus name reflects this: dolicho- means long) suited to holding position among rocks and wood in flowing water, along with the ventral sucker mouth and bony armor plating typical of the family.
Dolichancistrus has a modest aquarium presence; the Cobres pleco (D. cobrensis) is the one species in the atlas with an English common name, and the genus as a whole is more familiar to specialist pleco keepers than the general trade. Conservation data are thin and mixed: the four atlas species carry a Data Deficient, a Least Concern, an Endangered, and a Near Threatened rating between them, one apiece — a spread that points to real, uneven pressure on this Colombia/Venezuela-endemic genus without enough survey coverage yet to resolve the full picture.