Taxonomy & naming
Hypostomus denticulatus was formally described by Zawadzki, Weber, and Pavanelli in 2008. The Catalog of Fishes (Eschmeyer, CAS) recognises the valid name Hypostomus denticulatus Zawadzki, Weber & Pavanelli, 2008. FishBase assigns this species ID 64675 and places it in family Loricariidae, subfamily Hypostominae.
The species was collected from the Rio Corumbá in the vicinity of the Corumbá Reservoir, in Goiás state, within the upper Rio Paraná drainage of central Brazil. It is one of several Hypostomus species described from the upper Paraná system, a region that has received increasing taxonomic attention following the discovery of endemic or near-endemic populations isolated by reservoir construction.
Within the large and taxonomically complex genus Hypostomus Lacépède, 1803, H. denticulatus is notable for possessing smaller and more numerous teeth than the great majority of its congeners; the authors noted at description that only H. multidens and H. ternetzi share a comparable dental formula.
Morphology
Hypostomus denticulatus reaches a recorded maximum of 7.5 in standard length (SL). The name-giving character is the dentition: the teeth on both the dentary and premaxilla are described as smaller (denticulate) and proportionally more numerous than in most Hypostomus species, a feature diagnostic enough to serve as the basis for the specific epithet.
Beyond this dental character, detailed colouration or external morphology data for H. denticulatus are not available in the sources consulted. The species shares the general Hypostomus body plan — a depressed, armoured body with overlapping bony scutes, an inferior suctorial mouth, a high dorsal fin with a single stout spine, and a forked caudal fin. Facultative air-breathing has been noted on FishBase, suggesting the ability to supplement gill respiration in hypoxic conditions, as recorded in multiple Hypostomus from seasonally variable South American rivers.
Habitat
The type locality of Hypostomus denticulatus is the Rio Corumbá near the Corumbá Reservoir, in Goiás, upper Rio Paraná basin. The Corumbá Reservoir is an impoundment on the Rio Corumbá, a left-bank tributary of the Paranaíba, itself a major headwater of the Paraná system. The upper Paraná is a plateau river system draining the cerrado (Brazilian savanna) and transitional forest zones of central Brazil.
Field water-parameter data specific to H. denticulatus at its type locality are not available in the sources consulted. Upper Paraná waters in the Goiás region are generally clear to lightly turbid, warm (mid-20s °C typical during austral summer), and variable in pH depending on local geology and reservoir stratification. The association with a reservoir habitat is notable: the species was described from an impounded reach, which may have implications for its ecology and its potential vulnerability to future hydrological changes.
Feeding
No specific diet studies for Hypostomus denticulatus are available in the sources consulted. The reduced, more numerous (denticulate) teeth described at species diagnosis suggest a feeding strategy somewhat different from the typical Hypostomus rasp-grazing on hard substrates. Finer, more numerous teeth may be better suited to scraping soft periphyton mats, ingesting fine detritus, or processing softer plant material than the coarser tooth rows of congeners.
In the absence of gut-content data, the dietary ecology of this species remains inferential. Hypostomus in the upper Paraná broadly consume algae, biofilm, and detrital material. Whether the distinctive dentition of H. denticulatus correlates with dietary specialisation in the reservoir environment is an open question.
Mating
No specific mating behaviour data for Hypostomus denticulatus have been published in the sources consulted. Male Hypostomus in general are territorial around potential spawning sites and develop more pronounced interopercular and body odontodes during reproductive condition, which serve in male–male competition. Whether H. denticulatus shows sexually dimorphic odontode development comparable to other congeners has not been documented in available literature.
Breeding
No breeding records for Hypostomus denticulatus in captivity or the wild were located in the sources consulted. Hypostomus species are typically cavity spawners — males select burrows in earthen banks, hollow wood, or rocky crevices, and guard and fan adhesive egg clutches until hatching. Whether this general pattern applies to H. denticulatus in its reservoir habitat, where suitable spawning cavities may differ from those in unmodified riverine settings, is not documented. Data sparse.
In the aquarium
Hypostomus denticulatus does not appear in the ornamental trade by this name in any source consulted, and no aquarium husbandry accounts were found. At approximately 7.5 in SL it is a moderately sized pleco — smaller than many common Hypostomus offered in shops, but still requiring a substantial aquarium (50 US gal or more would be a reasonable minimum) with strong filtration.
Given its origin in the upper Paraná basin — a warm, moderately mineralised system — water kept at 72–81 °F, near-neutral pH, and moderate hardness would represent a reasonable starting point. Smooth rocks, caves or pipe-section hiding spots, and some driftwood would suit its general loricariid biology. Specific husbandry refinements based on this species' dental and dietary peculiarities cannot be determined from available data.
Conservation
Hypostomus denticulatus is assessed as Least Concern on the IUCN Red List (assessed 7 November 2018). The assessment reflects that no major immediate threats have been identified, though the species has a restricted known range centred on the Corumbá Reservoir area in the upper Paraná.
The association of the type locality with an existing reservoir is worth noting: the species was described from a habitat already significantly modified by impoundment. Future hydrological changes, additional damming, water quality degradation from agriculture in the cerrado catchment, or further drawdown events affecting the Corumbá system could affect populations. The restricted distribution means monitoring would be prudent even under a Least Concern designation.