Chaetostomatini Fowler, 1958

Tribe Chaetostomatini Fowler, 1958

Included genera. Andeancistrus Lujan et al., 2015b:652 . Type-species: Chaetostomus platycephalus Boulenger, 1898 . Chaetostoma Tschudi, 1846:25 . Type-species: Chaetostomus loborhynchos Tschudi, 1846 . Synonyms:

Hypocolpterus Fowler, 1943 , Lipopterichthys Norman, 1935 , and Loraxichthys Salcedo, 2013 . Cordylancistrus Isbrücker, 1980:48 . Type-species: Pseudancistrus torbesensis Schultz, 1944 . Dolichancistrus Isbrücker, 1980:47 . Type-species: Pseudancistrus pediculatus Eigenmann, 1918 [a junior synonym of Dolichancistrus fuesslii (Steindachner, 1911]. Leptoancistrus Meek, Hildebrand, 1916:254 . Type-species: Acanthicus canensis Meek & Hildebrand, 1913 . Transancistrus Lujan et al., 2015b:657 . Type-species: Cordylancistrus santarosensis Tan & Armbruster, 2012 .

Phylogenetic diagnosis. Anterior edge of the anterohyal sinusoidal (2:1, reversed in Cordylancistrus torbesensis and Dolichancistrus cobrensis ), mesial facing process on branchiostegal 3 (6:1, unique), reversal to a large interhyal (27:0), long opercular condyle of the hyomandibula (38:1), tall levator arcus palatini crest (44:2), mesial wall of metapterygoid channel much taller than lateral wall (55:1, reversed in Cordylancistrus torbesensis ), ventral process on quadrate for articulation with canal plate (65:1), wide, blunt articular condyle of quadrate (67:1), bar-shaped opercle (75:2), maximum forward position of opercle to posterolateral corner of the quadrate (77:1, reversed in Andeancistrus and some Chaetostoma ), canal plate covered in skin or plates and not directly supporting odontodes (84:1, unique), tall ridge on lateral ethmoid for contact with metapterygoid (97:2), mesethmoid flares anteriorly (102:1), eight or more dorsal-fin rays (142:1), nuchal plate covered by skin or plates (147:1, nuchal plate may be exposed and supporting odontodes in nuptial male Dolichancistrus ), reversal to a large space between posterior process of coracoid strut and posterior process of coracoid (164:0), reversal to tall ventral ridge of pelvic basipterygium (172:0), and widened first (unbranched) ray of pelvic fin (177:1, reversed in Dolichancistrus ).

Comparative diagnosis. Chaetostomatini can be separated from all other Hypostominae except Acanthicini , Collosimystax new genus, and Pterygoplichthys by having eight or more branched dorsal-fin rays (vs. seven); from Acanthicini and Pterygoplichthys by lacking elongate patches of sharp odontodes on lateral plate keels (most species lack lateral plate keels entirely, Andeancistrus platycephalus and Chaetostoma spondylus have round patches of elevated, keel-like odontodes on lateral plates); from Collosimystax new genus by mature males having usually zero and maximally two cheek odontodes extending past the head (vs.>40), and by having plates in ventral series posterior to anal fin broadly convex (vs. dorsal halves of plates concave, forming a strong keel); and from Pterygoplichthys by lacking plates on abdomen (vs. abdominal plates present), and by having caudal fin truncate or maximally emarginate (vs. forked).

Geographical distribution. Most species with exclusively Andean distribution, including cis-Andean streams from southern Peru to the Caribbean Andes west of Caracas (including the Caribbean slope) and trans-Andean basins from the Tumbes River in Northern Peru to the Chagres River of Panamá. Three species of Chaetostoma occur in scattered drainages east of the Andes, such as the Caroni, Caura, and Branco rivers draining the Guiana Shield north in Venezuela and south in Brazil, and a few northern and southern tributaries of the lower Amazon in Brazil (Meza-Vargas et al., 2022).