Taxonomy & naming
Parotocinclus cesarpintoi was described by Miranda Ribeiro in 1939 in the Boletim Biológico (São Paulo, Nova Série), volume 4, number 3, page 364. The type specimens were collected from Riacho Quebrângulo, a stream in the Rio Paraíba do Meio drainage, near Quebrângulo, Alagoas State, northeastern Brazil.
A distributional discrepancy exists between sources: FishBase lists the species range as the Paraíba do Sul River basin in southeastern Brazil, whereas PlanetCatfish cites the type locality in the Paraíba do Meio drainage of Alagoas — a separate Atlantic coastal river more than 1,0 mi to the north. These are distinct river systems. The type locality in the original description and PlanetCatfish records (the Paraíba do Meio) should be considered the authoritative basis for distribution; the FishBase attribution to the Paraíba do Sul may represent a data-entry error or a specimen misassignment that has not yet been corrected in that database.
Like several congeners, P. cesarpintoi may be affected by the generic revision of Roxo et al. (2020), which erected the genus Rhinotocinclus for a portion of Parotocinclus. The Catalog of Fishes (Eschmeyer, CAS) is the site authority for valid names, and P. cesarpintoi is followed here under the name accepted therein.
The genus name Parotocinclus pairs the Greek para (beside, near) with Otocinclus, denoting the close relationship between these two groups of small sucker-mouth catfishes; Parotocinclus is distinguished from Otocinclus by the presence of an adipose fin. The species epithet honours Dr. César Ferreira Pinto (1896–1964), a Brazilian entomologist and helminthologist who contributed significantly to tropical parasitology.
Morphology
Adults of Parotocinclus cesarpintoi reach a maximum recorded standard length of 1.5 in (male/unsexed), placing this species at the larger end of the Parotocinclus size range while still firmly within the dwarf category for loricariids. The body conforms to the typical hypoptopomatine plan: a dorsoventrally flattened profile, bony scutes covering the flanks, and a ventrally placed sucking mouth with fine teeth suited to scraping biofilm and algae from substrate surfaces. The adipose fin — the diagnostic character separating Parotocinclus from Otocinclus — is present.
Detailed colouration records for P. cesarpintoi specifically have not been published in accessible sources. Atlantic-drainage Parotocinclus are typically cryptically patterned in browns and tans, often with fine spotting or faint banding that matches the substrate of small coastal streams.
Sexual dimorphism in Parotocinclus is generally subtle. In related species, males are distinguished by a urogenital papilla behind the anus and by slightly more elongated pelvic fins; females tend to be broader-bodied when gravid. Whether additional characters documented for Rhinotocinclus males — such as enlarged nostrils and a skin fold on the first pelvic-fin ray — apply across all former Parotocinclus is not confirmed for this species in published sources.
Habitat
The confirmed type locality of Parotocinclus cesarpintoi is Riacho Quebrângulo, a stream in the Paraíba do Meio drainage, Alagoas State, northeastern Brazil. The Paraíba do Meio is a relatively short Atlantic coastal river descending rapidly from the Borborema Plateau to the coast, with a drainage that encompasses seasonally dry and semi-arid inland areas as well as more humid coastal zones.
Published physico-chemical data for the Riacho Quebrângulo are not available in the sources consulted. Northeast Brazilian coastal streams typically experience pronounced seasonal variation in discharge, and the shallow, cobble or pebble-bedded reaches most suitable for a periphyton-grazing loricariid would be those with reliable year-round flow and biofilm-covered hard substrate.
FishBase characterises P. cesarpintoi as a freshwater, demersal, tropical species; the genus has a capacity for facultative air-breathing, which may be advantageous in streams subject to low-oxygen conditions during the dry season. No water temperature or pH data specific to this species have been published.
Feeding
Parotocinclus cesarpintoi is inferred to be a periphyton grazer in the field, consistent with the feeding biology of the genus and subfamily. The ventrally placed mouth with fine multi-cusped teeth is adapted for scraping the aufwuchs community — the mixed assemblage of microalgae, diatoms, cyanobacteria, and associated organic detritus — from the surface of rocks, wood, and submerged plant material.
No published dietary analysis or trophic-level data specific to P. cesarpintoi have been found in the sources consulted.
Mating
No mating or courtship observations are available for Parotocinclus cesarpintoi in the scientific or hobbyist literature. The species has no registered keepers or spotters on PlanetCatfish, and water parameter requirements have not been established for captive conditions.
By analogy with better-studied relatives, courtship in small Hypoptopomatinae is presumed to be substrate-associated, with males displaying to females via fin posturing and lateral presentation near preferred spawning sites on hard substrate. Further details specific to P. cesarpintoi are unknown.
Breeding
No breeding observations have been recorded for Parotocinclus cesarpintoi in captivity or described in field studies. The species is absent from the ornamental fish trade and has generated no aquarium breeding reports.
By comparison with other small Hypoptopomatinae — including Otocinclus species, whose breeding biology is better documented — adhesive egg deposition on smooth hard surfaces (plant leaves, glass, smooth rock) is the most probable spawning mode, with no parental care following spawning. These inferences remain unconfirmed for P. cesarpintoi and should not be treated as established fact without direct observation.
In the aquarium
Parotocinclus cesarpintoi is not established in the aquarium hobby. No pH, temperature, or other husbandry parameters have been published specifically for this species, and no keeper reports exist on PlanetCatfish.
Should specimens become available, the general principles applicable to small Atlantic-drainage suckermouth loricariids would provide a starting framework: mature, stable aquaria with established biofilm on hard surfaces, clean well-oxygenated water, and supplemental feeding with algae wafers or fresh vegetable matter. Its origin in a northeastern Brazilian coastal drainage suggests tolerance of a range of temperatures typical of tropical Brazil, though the Alagoas streams from which it was collected likely experience some seasonal temperature variation. A shoal rather than a single specimen is generally preferable for small gregarious loricariids. Beyond these generalities, specific husbandry requirements for P. cesarpintoi are unknown.
Conservation
Parotocinclus cesarpintoi was assessed as Least Concern on the IUCN Red List, with the evaluation completed on 7 November 2018 by the Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio). The species is known from the Paraíba do Meio drainage in Alagoas State, a northeastern Atlantic coastal river system.
Northeastern Brazil's coastal river systems are among the more ecologically stressed in the country, subject to historical deforestation, water abstraction for irrigation and urban supply, and pollution from agricultural runoff. The semi-arid interior portions of these drainages are particularly vulnerable to reduced base flow under changing precipitation patterns. While the LC assessment reflects the situation as of 2018, the restricted range of P. cesarpintoi in a single coastal drainage system warrants continued monitoring, particularly given the distributional confusion between this species and the Paraíba do Sul River populations attributed to it in some databases.