Acanthicini Bleeker, 1862

Tribe Acanthicini Bleeker, 1862 -1863

Included genera.

Acanthicus Agassiz, 1829:2 View in CoL (in Spix, Agassiz, 1829).

Type-species: Acanthicus hystrix Spix & Agassiz, 1829 View in CoL .

Leporacanthicus Isbrücker, Nijssen, 1989:544 View in CoL . Type-species: Leporacanthicus galaxias Isbrücker & Nijssen, 1989 View in CoL .

Megalancistrus Isbrücker, 1980:52 . Type-species: Chaetostoma gigas Boulenger, 1895 .

Pseudacanthicus Bleeker, 1862:2 . Type-species: Chaetostomus serratus Valenciennes, 1840 (in Cuvier, Valenciennes, 1840). Synonym: Stoniella Fowler, 1914.

Phylogenetic diagnosis. Anterohyal greatest width greater than half its length (1:1), loss of flap on quadrate extending below symplectic foramen (66:0), mesethmoid disk extending anterior to main body of mesethmoid (101:1), large fenestrae in compound pterotic (109:1, reversed in Leporacanthicus ), tip of transverse process of Weberian complex centrum not contacting compound pterotic (135:1, reversed in Leporacanthicus ), eight or more dorsal-fin rays (142:1), hypertrophied odontodes along snout margin (188>1), and keels of lateral plates well developed (198:1).

Comparative diagnosis. Acanthicini can be separated from all other Hypostominae except some Pterygoplichthys Gill, 1858 (particularly P. weberi ) by having lateral-plate keels made of long, stout odontodes, from all other Hypostominae except Colossimystax and Pterygoplichthys by having more than seven dorsal-fin rays, and from Pterygoplichthys with keels by having strongly evertible cheek odontodes ( vs. weakly evertible), by having fewer odontodes dorsal and ventral to keel rows ( vs. odontodes normally distributed). In addition, Acanthicus can be separated from Pterygoplichthys by lacking an adipose fin ( vs. adipose fin present), Acanthicus and Megalancistrus can be separated from Pterygoplichthys by having compound pterotic extending beyond posteriormost insertion of pectoral fin ( vs. maximally through ~3/4 of pectoral-fin base); and Leporacanthicus and Pseudacanthicus can be separated from Pterygoplichthys by having 10 or fewer teeth per jaw ramus ( vs. more than 20).

Geographical distribution. Restricted to larger, main river channel habitats in cis-Andean drainages from the Paraná and São Francisco basins northward, including the Amazon and Orinoco basins and north-flowing Guiana Shield basins.