Hypostominae, Kner, 1853

Armbruster, Jonathan W. & Lujan, Nathan K., 2024, New tribe-level classification of Hypostominae (Loricariidae) based on optimization of morphological states on DNA-based relationships, with descriptions of three new tribes and two new genera, Neotropical Ichthyology 22 (4), pp. e 240108-e 240108 : e240108-240108

Subfamily Hypostominae

Included tribes (with unrecognized tribes and subtribes listed as synonyms).

Acanthicini Bleeker, 1862 –63:2. Synonym: Pseudacanthicini Isbrücker, 1980.

Ancistrini Kner, 1854:256 . Synonyms: Corymbophanini Armbruster, 2004a, Hopliancistrini Isbrücker & Nijssen, 1989.

Chaetostomatini Fowler, 1958 :14

Hypostomini Kner, 1853 a:279. Synonyms: Plecostiformes Bleeker, 1862, Pterygoplichthyini Armbruster, 2004a

Lithoxini Isbrücker, 1980 :77

Peckoltini , new tribe

Pseudancistrini , new tribe

Spectracanthicini Isbrücker & Nijssen, 1989

Stellantini , new tribe

Phylogenetic diagnosis. Accessory process of first ceratobranchial same length as main body and wide (7:2, 8:2), interhyal contacting bony portion of quadrate (26:2), either hyomandibula, quadrate or both with projections towards one another or sutured (33:1), preopercle with short posterior section appearing to be oriented almost vertically (61:1), quadrate with posteroventral projection that extends below symplectic foramen (66:1), a sickle-shaped opercle (75:1; note that opercle shape is especially variable within Hypostominae ), one or more plates between suprapreopercle and opercle (81:1), one small canal plate (83:1), canal plate contacting the suspensorium (85:1), two or more plates between canal plate and opercle (88:2), 8–11 vertebrae from first normal neural spine behind dorsal fin up to, but not including, the hypural plate (121:2), ventral half of hypural plate longer than dorsal (123:1), reversal to a V-shaped spinelet (148:0), anterolateral process of basipterygium wide through entire length (169:1), posterovenral ridge of basipterygium present (173:1), hypertrophied cheek odontodes present regardless of season or sex (183:2), fully or slightly evertible cheek plates (184:1– 2; ability to at least partially evert cheek plates is unique to Hypostominae with the possible exception of ‘ Pseudancistrus ’ genisetiger ), pectoral fin inserted ventrally such that it is aligned with and reaches or overlaps the pelvic fin (190:1; only seen in Pogonopoma outside of Hypostominae and reversed in Corymbophanes ).

Comparative diagnosis. There are no universal character states that diagnose all Hypostominae from all other Loricariidae . The most widely diagnostic character states are cheek plates that evert forming a 30° to just greater than 90° from side of head ( vs. not evertible; angle depends on species) and pectoral fin inserted ventrally such that it is aligned with and reaches or overlaps the pelvic fin ( vs. pectoral fins distinctly dorsal to pelvic fins in all loricariids except Pogonopoma ; Corymbophanes of the Hypostominae has the pectoral fins just slightly dorsal to the pelvics). Hypostominae can be separated from Lithogeninae by having the body fully plated ( vs. anterior plates missing or nonoverlapping); from Delturinae by having an adipose-fin spine followed by a membrane or a postdorsal ridge made of azygous plates with maximally a very small membrane ( vs. postdorsal ridge made of azygous plates followed by an adipose-fin spine and membrane); from Rhinelepinae and Loricariinae by generally having an adipose fin or postdorsal ridge of azygous plates ( vs. adipose fin and postdorsal ridge absent), from Rhinelepinae by generally having an iris operculum ( vs. absent, some hypostomines lack an iris operculum, but they all have adipose fins or postdorsal ridges); from Loricariinae by generally not being extremely dorsoventrally flattened and elongated (only exceptions may be members of Lithoxini , which have evertible cheek plates present vs. absent and an adipose fin, and Isorineloricaria which has an adipose fin and five rows of plates on the caudal peduncle vs. three); from Hypoptopomatinae (except Neoplecostomini) by having maximally the lateral portion of the pectoral girdle exposed and supporting odontodes ( vs. most or all of pectoral girdle exposed and supporting odontodes); from Hypoptopomatinae : Neoplecostomini by having hypertrophied odontodes generally absent along the snout of nuptial males or, when hypertrophied odontodes are present, they are not in thick integument ( vs. generally having males with hypertrophied snout odontodes that are embedded in integument skin); and from ‘ Pseudancistrus ’ genesetiger and ‘ P.’ papariae by having three or five rows of plates on the caudal peduncle ( vs. four), and by either not having hypertrophied odontodes along the snout or on the cheek or having them clearly separated by plates contiguous with remaining plates of the snout and head ( vs. hypertrophied snout and cheek odontodes supported by deeply embedded, flesh-covered, hidden plates that are sunken medially such that other snout plates and the opercle form a shelf dorsal and lateral to the bases of the odontodes).

Geographical distribution. Hypostominae is broadly distributed throughout cis-Andean South America from the Parana basin northward, and throughout trans-Andean drainages from the Tumbes basin in northern Peru to the Terraba River in eastern Costa Rica.