Genus Neoplecostomus Eigenmann & Eigenmann, 1888

Neoplecostomus Eigenmann & Eigenmann, 1888: 171 . Type species: Plecostomus microps Steindachner, 1877 . Type by original designation.

Included species. Neoplecostomus bandeirante Roxo, Oliveira & Zawadzki, 2012; N. botucatu Roxo, Oliveira & Zawadzki, 2012; N. corumba Zawadzki, Pavanelli & Langeani, 2008; N. doceensis Roxo, Silva, Zawadzki & Oliveira, 2014; N. espiritosantensis Langeani, 1990; N. franciscoensis Langeani, 1990; N. granosus (Valenciennes, 1840); N. jaguari Andrade & Langeani, 2014; N. langeanii Roxo, Oliveira & Zawadzki, 2012; N. microps (Steindachner, 1877); N. paranensis Langeani, 1990; N. ribeirensis Langeani, 1990; N. selenae Zawadzki, Pavanelli & Langeani, 2008; N. variipictus Bizerril, 1995; and N. yapo Zawadzki, Pavanelli & Langeani, 2008 .

Diagnosis. Neoplecostomus is diagnosed by the following exclusive synapomorphies: Pectoral-fin spine distinctly curved, forming wide and conspicuous arch (Char. 164.1), and lateropterygium club-shaped with a spatulate distal tip (except in N. ribeirensis; Char. 195.1). Non-exclusive synapomorphies include: Anterior margin of mesethmoid rounded (Char. 2.1), ventral process of mesethmoid aligned with its anterior tip (Char. 5.1), olfactory organ completely encapsulated by lateral ethmoid (Char. 7.0), compound pterotic approximately square to slightly oval-shaped posteriorly, its longitudinal axis approximately equal to its transverse axis (Char. 10.0), branchiostegal ray 2, almost as long as branchiostegal ray 3 (Char. 17.1), anterior margin of anterohyal expanded centrally, and becoming narrower again towards articulation with posterohyal (Char. 22.0), anterior and posterior margins of each branchial filament fringed and ornamented with small epithelial expansions (Char. 27.1), cartilage cap of ceratobranchial 1 slightly narrower than bony tip (Char. 34.0), anteroventral process of ceratobranchial 5 long with distinctly pointed distal tip (Char. 38.1), teeth on ceratobranchial 5 robust and well developed (Char. 39.0), posterodorsal laminar expansions in upper pharyngeal tooth plate absent (Char. 48.0), medium-sized palatine splint, never reaching anterior border of nasal fossa (Char. 60.1), coronoid process with short dorsolateral expansion (Char. 65.1), dorsal articular condyle of hyomandibula very broad (Char. 72.0), crest for insertion of levator arcus palatini long, extending to margin of hyomandibula (Char. 78.1), lateral wall of metapterygoid lower than mesial wall (Char. 89.0), articulation between posterior margin of metapterygoid and hyomandibula by means of incomplete suture (Char. 90.1), interoperculo-mandibular ligament present between anguloarticular and opercle (Char. 91.0), preopercle with small ventrolateral expansion forming concave area laterally (Char. 100.1), ventral margin of quadrate not expanded (Char. 103.2), canal plate bent and with ventral expansion directed mesially (Char. 109.1), notch on posterior margin of hypural plate deep, extending to half length of hypural plate (Char. 218.1), possession of cluster of enlarged papillae in region immediately posterior to each dentary (Char. 253.1), premaxillary and dentary tooth crowns short and robust (Char. 259.1), and tooth cusps asymmetric with minor lateral cusp long, reaching to or beyond half length of main mesial cusp (Char. 260.2).

Comparisons. Neoplecostomus species are distinguished from the remaining neoplecostomines by possessing the olfactory organ completely encapsulated by the lateral ethmoid (vs. olfactory organ not completely encapsulated by the lateral ethmoid) and a conspicuous cluster of enlarged papillae on the lower lip, immediately posterior to each dentary (a similar but non-homologous cluster of papillae is also present in Pareiorhaphis lophia Pereira & Zanata, 2014). It is further differentiated from all other neoplecostomines by having the abdomen covered by a set of rounded, compact plates forming a dense plate shield between the pectoral and pelvic-fin insertions (vs. abdomen naked or with small platelets embedded in the skin). Neoplecostomus (except N. espiritosantensis) is further distinguished from the remaining members of the subfamily by possessing short and robust dentary and premaxillary teeth (vs. teeth being more slender and delicate in all other neoplecostomines except Kronichthys M). Neoplecostomus is differentiated from Pareiorhina by the possession of an adipose fin (except N. paranensis, which sometimes lack this fin). It is further distinguished from Pareiorhaphis species by males lacking hypertrophied odontodes on the cheeks, and from Kronichthys by its broad and rounded head shape (vs. head approximately rectangular in adult specimens in dorsal view). Neoplecostomus species are distinguished from Hirtella by lacking elongate, hairy odontodes on the head and body plates of adult males, and by lacking a long mid-dorsal ridge between the dorsal as well as caudal fins, both of which are present in Hirtella . Neoplecostomus is also distinguished from Euryochus by having the caudal peduncle approximately ovoid in cross-section (vs. caudal peduncle flat when viewed ventrally).

Geographic distribution. Neoplecostomus species are relatively widely distributed on the southeastern and eastern Brazilian Shield. Most species occur in the upper Paraná River basin, though others are found in the Iguaçu, Ribeira de Iguape , Paraíba do Sul, upper São Francisco, and some smaller coastal rivers of eastern Brazil .