Dolichancistrus cobrensis, photo by K.S. Cummings
Dolichancistrus is easily identified (at least when they are large) because they will usually only have one or two very thick, very long hypertrophied cheek odontodes (although this isn't always the case). The species are all described from around the same basic area of the Andes along the Venezuela/Colombia border, making me doubt that all of the species are distinct. There are few specimens in collections making it difficult to determine what species is what.
Dolichancistrus is diagnosed by the presence of elongate pectoral-fin spines in the males.
Like the rest of the Chaetostoma group, Dolichancistrus differs from all Ancistrini
on the basis of a lack of odontodes on the nuchal plate and dorsal-fin
spinelet (breeding males will occasionally develop odontodes on the nuchal
plate and spinelet) and 8+ dorsal-fin rays. Dolichancistrus
differs from all other Ancistrini except Leptoancistrus
based on the presence of a single (occasionally 2) incredibly elongate odontode in the cheek mass of adult males and from all other Ancistrini except Pseudolithoxus by having elongate pectoral-fin spines in breeding males, and from Leptoancistrus
having adipose and anal fins.
Among the Chaetostoma group, Dolichancistrus is the only genus known to develop hypertrophies odontodes on the head and anterior plates in nuptial males. In the larger males, often even the nuchal plate and spinelet will develop odontodes unlike other members of the Chaetostomagroup.
Known from both sides of the Andes in Colombia and Venezuela.
Found in high montane, torrential streams.
Armbruster, J.W. 1997. Phylogenetic relationships of the sucker-mouth
armored catfishes (Loricariidae) with particular emphasis on the Ancistrinae,
Hypostominae, and Neoplecostominae. Unpubl. Ph.D. dissertation. University
of Illinois, Urbana-Champaign. 409 pp.