Isbrueckerichthys duseni, photo by K.S. Cummings
Neoplecostominae is not diagnosed by any unique characteristic. Characteristics considered synapomorphic for Neoplecostominae are: a widened pelvic-fin spine (lost in Hemipsilichthys bahianus) and a loss of abdominal plates (reversed in Isbrueckerichthys and Neoplecostomus).
Species of Neoplecostominae are convergent with Chaetostoma with which they share a high-montane, swift-flowing river habitat. Color pattern typically dark brown and mottled or with dorsal saddles. Abdomen usually unplated although some deeply embedded plates present in Isbrueckerichthys and Neoplecostomus. Four or more predorsal plates. Spinelet a small, square ossification or absent. Generally at least one column of plates on caudal peduncle with three rows of plates (except Isbrueckerichthys and Hemipsilichthys sp. 2 which have five or more rows of plates on the caudal peduncle).
Neoplecostominae is very similar to Chaetostoma of Ancistrini; however, members of Neoplecostominae lack evertible cheek odontodes, the spinelet usually does support odontodes (the spinelet is covered with skin in Chaetostoma) or is absent, and the nuchal plate is exposed (vs. covered by plates). Also, Chaetostoma is restricted to the Andes and some of the Tipuis of the Guiana Shield while Neoplecostominae is found in southeastern Brazil. Neoplecostominae differs from Lithogeneinae by being completely plated laterally and dorsally (Pareiorhaphis nudulus is incompletely plated and can be separated from Lithogeneinae by having hypertrophied odontodes on the leading edge of the pectoral fins and along the snout in nuptial males, and by having plates anterior to the dorsal fin); from Delturus + Hemipsilichthys by lacking a postdorsal ridge of several median preadipose plates (Pareiorhaphis nudulus does have numerous, median, preadipose plates but they are not raised and the adipose fin is absent); from Hypoptopomatinae by having, maximally, only a small part of the coracoid strut of the pectoral girdle exposed ventrally (vs. all or most of the girdle exposed and supporting odontodes); from Loricariinae by having a round to oval (vs. a compressed, rectangular) caudal peduncle; from most Hypostominae by having a square (vs. triangular) dorsal-fin spinelet or lacking the spinelet; and from Chaetostoma as above.
Armbruster, J. W. 2004. Phylogenetic relationships of the suckermouth armored catfishes (Loricariidae) with emphasis on the Hypostominae and the Ancistrinae. Zoological Journal of the Linnean Society 141:1-80.
Gosline, W.A., 1947. Contributions to the classification of the loricariid catfishes. Arquivos do Museu Nacional Rio de Janeiro 41:79?134.
Regan, C.T., 1904. A monograph of the fishes of the family Loricariidae. Transactions of the Zoological Society of London 17:191-350.