Taxonomy & naming
Hypostomus myersi was described by William A. Gosline in 1947, published in the Arquivos do Museu Nacional de Rio de Janeiro (volume 41, pages 116 with Plate 5, figures 9–10). The type locality is the Rio Iguaçu at Porto União, Paraná, southern Brazil. The Catalog of Fishes (Eschmeyer, CAS) recognises the valid combination Hypostomus myersi; the junior synonym Plecostomus myersi refers to the same taxon under an older and now invalid generic assignment.
The species belongs to the genus Hypostomus Lacépède, 1803, the largest genus in Loricariidae with several hundred described species distributed across South America. Armbruster (2004) placed Hypostomus within subfamily Hypostominae, one of five subfamilies recognised in the family. H. myersi has no assigned L-number and is not commonly encountered in the ornamental trade.
The species epithet honours Dr George Sprague Myers (1905–1985), one of the most influential American ichthyologists of the twentieth century. Myers was Professor Emeritus at Stanford University, a pioneering biogeographer of freshwater fishes, and author of a prolific body of work on neotropical ichthyofaunas. The dedication reflects Gosline's acknowledgement of Myers's formative contributions to the field.
Morphology
Hypostomus myersi reaches a maximum recorded size of 8 in standard length (SL), placing it in the lower-to-mid range of the genus. The body plan is typical of Hypostomus: dorsoventrally flattened, covered in interlocking bony scutes on the flanks and dorsal surface, with the ventral surface either unplated or lightly plated depending on the body region. The ventral sucker mouth bears numerous small, elongated teeth suited to rasping periphyton and biofilm from hard substrates.
Colour pattern and detailed meristic data for H. myersi are not fully described in the general references available for this account. The species can be distinguished from sympatric loricariids by a combination of characters including the meristic count of scutes, tooth morphology, and proportional measurements — features addressed in the original description and in more recent regional checklists.
As with most Hypostomus, sexual dimorphism is reported to be subtle. Males of the genus typically develop elongated interopercular odontodes (cheek spines) during the breeding season, while gravid females show a noticeably broader body profile when viewed from above. Species-specific dimorphic characters for H. myersi are not confirmed in available sources.
Habitat
Hypostomus myersi occurs in the Iguaçu River basin and the Urugua-í Creek (Urugua-í drainage) in the southern Paraná system, straddling southern Brazil and northeastern Argentina. The Iguaçu is a large right-bank tributary of the Paraná River, draining the subtropical highlands of Paraná state before reaching the spectacular Iguaçu Falls — a major biogeographic barrier that has driven significant endemism in the river's ichthyofauna above and below the falls. The Urugua-í is a smaller tributary of the middle Paraná in Misiones province, Argentina.
This is a subtropical rather than tropical distribution: southern Brazil and Argentine Misiones experience cold winters and warm summers, with water temperatures fluctuating considerably between seasons. The Iguaçu system runs through relict Atlantic Forest; the rivers are well-oxygenated and subject to seasonal flood pulses. Like all Hypostomus, H. myersi is characterised as demersal, benthic, and a facultative air-breather — capable of gulping atmospheric air through the mouth under hypoxic conditions.
No detailed field water chemistry data (temperature range, pH, hardness) specific to H. myersi collection sites are available in the sources consulted.
Feeding
Hypostomus myersi feeds in the manner characteristic of the genus: as a benthic grazer rasping periphyton, algae, diatoms, and biofilm from rock and wood surfaces using its ventrally positioned sucker mouth and fine elongated teeth. Detritus and the micro-invertebrates and bacteria embedded within periphyton mats contribute to the diet alongside plant-derived material. Field and aquarium data on diet composition specific to H. myersi are not available in the literature consulted.
The genus Hypostomus is noted as opportunistically ingesting organic detritus and, in some species, a degree of wood material, though members of this genus are generally less committed xylophages than genera such as Panaque or Panaqolus. The suite of dietary behaviours associated with Hypostomus — algae-scraping, detritus-ingestion, occasional plant material — is the reasonable baseline for this species.
Mating
No species-specific mating data for Hypostomus myersi have been documented in literature or hobbyist records consulted. No registered keepers and only two wild-capture records are noted in PlanetCatfish's database, confirming the species' near-absence from the ornamental trade and from captive observation.
At the genus level, Hypostomus males establish territories around burrow sites — typically excavated cavities in earthen banks or found beneath large rocks and submerged wood — which function as breeding chambers. Seasonal cuing by water temperature and flow shifts likely triggers reproductive activity, consistent with the subtropical seasonality of the Iguaçu drainage. Interopercular odontode development in males and broadening of the female body are the principal dimorphic indicators of breeding condition across the genus.
Breeding
No breeding records for Hypostomus myersi are available in the literature or hobbyist sources consulted, and no captive spawnings have been reported. PlanetCatfish records zero breeding reports for this species.
Broadly within Hypostomus, spawning takes place inside excavated burrows or natural cavities, where the male deposits and guards an adhesive egg clutch. Paternal care — including fin-fanning to oxygenate eggs and removal of dead or fungused eggs — is the genus-typical pattern. Incubation duration and clutch sizes vary across the genus with water temperature. Specific data for H. myersi cannot be provided from available sources.
In the aquarium
Hypostomus myersi is essentially unknown in the aquarium hobby. PlanetCatfish's database records no registered keepers and only two wild-specimen locality records, confirming the species has not entered mainstream trade. No common name exists for it.
At 8 in SL, adult H. myersi falls into the medium pleco category — large enough to require a spacious aquarium (55 US gal or more for an adult) but not in the size bracket of giant suckermouth species. Its subtropical origin in the Iguaçu system suggests tolerance for cooler water temperatures than many Amazonian Hypostomus; the region experiences winter lows that could translate to keeping this species at the lower end of tropical temperatures or even in a cool-temperate setup. However, no specific water parameter data are available in the sources consulted, and precise care guidance cannot be offered from the current evidence base.
General Hypostomus husbandry principles apply in principle: robust filtration, significant hard-substrate décor (rock, driftwood), regular partial water changes, and a diet centred on algae-based foods and sinking vegetable matter. The species' subtropical provenance distinguishes it from many congeners and warrants attention if ever encountered.
Conservation
The IUCN Red List assessed Hypostomus myersi as Least Concern, with the assessment completed on 12 November 2020. The species occurs in the Iguaçu River and Urugua-í Creek systems of southern Brazil and northeastern Argentina. No specific major threats were documented at the time of assessment.
The Iguaçu drainage above the Iguaçu Falls is a notable centre of endemism, and the broader system is subject to significant human pressure including hydroelectric dams, agricultural runoff, and introduced species. The Itaipu and Salto Caxias dams have substantially altered flow regimes and fish communities in the middle and lower Iguaçu. While H. myersi is not currently considered threatened, the long-term trajectory of loricariid diversity in modified Paraná tributaries merits ongoing monitoring.