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 (e 240108) 22 (4) : -

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.