Taxonomy & naming
Neoplecostomus langeanii was formally described by Roxo, Oliveira & Zawadzki in 2012 in Zootaxa (volume 3233, pages 1–21), as one of three new Neoplecostomus species from the upper Rio Paraná basin of southeastern Brazil. The other two species described in the same paper are N. bandeirante (from Salesópolis, São Paulo) and N. botucatu (from Botucatu, São Paulo). The type locality of N. langeanii is a stream of the Rio Muzambinho drainage in the municipality of Muzambinho, Minas Gerais state, within the upper Rio Paraná basin. The Catalog of Fishes (Eschmeyer, CAS) recognises N. langeanii as a valid species.
The original description placed the genus Neoplecostomus in subfamily Neoplecostominae — a small, morphologically coherent clade recognised by many Loricariidae specialists. For site faceting purposes, the species is filed here under Hypoptopomatinae, following the broader convention adopted for the site's pleco section. The species carries no L-number and has not entered the ornamental trade.
The species was distinguished from its congeners through a combined analysis of mitochondrial DNA (COI barcoding), morphology, meristics, and colour pattern — a multi-evidence framework increasingly standard for Neotropical loricariid descriptions.
Morphology
Neoplecostomus langeanii reaches a maximum recorded standard length of 3.5 in SL, making it substantially larger than the other two species described in this article and placing it in the middle of the size range for the genus. FishBase characterises the body form as elongated, consistent with the generally slender, fusiform build of Neoplecostominae.
The species is distinguished from its congeners by a combination of morphological characters, meristic counts, colour pattern features, and molecular sequence data as detailed in Roxo et al. (2012). The ventral suckermouth, bony scute armour, and general body architecture follow the typical loricariid plan. No sexual dimorphism has been formally documented for this species.
Habitat
Neoplecostomus langeanii is known only from the Rio Muzambinho drainage in the municipality of Muzambinho, Minas Gerais, southeastern Brazil — a headwater system of the upper Rio Paraná basin. The upper Paraná basin in this region consists of fast-flowing, rocky upland streams draining the cerrado and Atlantic Forest mosaic of the Minas Gerais highlands.
Streams of this type are typically clear to lightly stained, well-oxygenated, and characterised by alternating riffles and pools over a substrate of bedrock, cobble, and gravel. No water-chemistry measurements are on record for the specific type locality. The elongated body form of N. langeanii is consistent with a rheophilic lifestyle, as is typical for Neoplecostomus, whose members are generally associated with fast-water rocky environments in southeastern Brazil.
Feeding
Neoplecostomus langeanii is an algae and periphyton grazer, consistent with the family's trophic guild and the foraging ecology documented for other Neoplecostomus species. The suckermouth and associated dentition are adapted for scraping biofilm — diatoms, green algae, and associated fine organic matter — from rocky substrates in current-exposed environments.
No aquarium feeding data exist for this species. Based on congener biology and general loricariid ecology, algae wafers, spirulina-based foods, and blanched vegetables would be the appropriate dietary basis in captivity, supplemented by naturally developing biofilm on textured hard surfaces. The species is not available in the trade.
Mating
No courtship or mating observations have been published for Neoplecostomus langeanii. The species is unknown in captivity and no field behavioural data are available. By analogy with other Neoplecostomus and broader loricariid patterns, males likely defend sheltered microhabitats during the reproductive season, but this has not been verified for this species.
Breeding
No breeding data are available for Neoplecostomus langeanii. The species has not been kept or bred in captivity, and no field reproductive observations have been published. Reproductive biology remains entirely undescribed.
In the aquarium
Neoplecostomus langeanii is not available in the aquarium trade and is effectively unknown to hobbyists. Its moderate size (up to 3.5 in SL), upland Paraná origin, and rheophilic habits suggest that a well-oxygenated aquarium with substantial water movement, a rocky substrate, and soft to moderately hard slightly acidic to neutral water (matching general upper Paraná conditions) would be appropriate — but this is habitat inference rather than documented husbandry.
Given the species' Data Deficient IUCN status and highly restricted known range, any encounter with live specimens outside a research context would be exceptional.
Conservation
The IUCN Red List assessed Neoplecostomus langeanii as Data Deficient (DD) in November 2018. The DD designation reflects the species' highly restricted known range — limited to a single drainage system in Muzambinho municipality, Minas Gerais — combined with an absence of sufficient population data to determine whether the species qualifies as threatened.
Data Deficient does not mean safe: the Roxo et al. (2012) paper itself notes that restricted range and limited data at the time of assessment drove the DD outcome. The headwater streams of the upper Rio Paraná basin in Minas Gerais face ongoing pressure from agricultural intensification, deforestation of riparian gallery forest, cattle access, water abstraction, and altered hydrology from eucalyptus and sugar-cane cultivation in the broader landscape. N. langeanii is absent from the ornamental trade, has no captive population, and has received no targeted conservation attention. Its status warrants reassessment as survey data from the Muzambinho drainage accumulate.