Taxonomy & naming
The species was originally described by Franz Steindachner in 1877 under the name Tetragonopterus rutilus jequitinhonhae, treating it as a geographic subspecies of T. rutilus (now Astyanax rutilus). Steindachner based the description on material collected from the Jequitinhonha River basin of Minas Gerais, Brazil. Over the following century the taxon was variously placed in synonymy with Astyanax fasciatus or treated as a junior synonym of A. rutilus, and it attracted little systematic attention.
The validity of the species was re-established through work involving DNA analysis of 19th-century museum specimens (including MNRJ 22505, 2.36 in SL), which demonstrated that the Jequitinhonha population is genetically and morphologically distinct from both A. fasciatus and A. rutilus. The name was elevated to full species rank, credited to Melo (2005), and listed as Psalidodon jequitinhonhae in the subsequent literature. Following the broad revision of Astyanax sensu lato, the species has been transferred to the resurrected genus Psalidodon, reflecting molecular phylogenetic evidence that the old, inclusive Astyanax was not monophyletic. However, Psalidodon jequitinhonhae remains in use as the reference name in many databases and checklists, and the parenthetical authority — (Steindachner, 1877) — reflects the original description under a different genus.
Eschmeyer's Catalog of Fishes is the authority for valid nomenclature; researchers working with this taxon should check the current catalogue entry, as the Psalidodon reclassification and its cascading synonymies are still being worked through the literature.
This fish was long listed as Astyanax jequitinhonhae; Eschmeyer's Catalog of Fishes places the species in Psalidodon, and the current combination Psalidodon jequitinhonhae is followed here.
Morphology
Psalidodon jequitinhonhae is a small, laterally compressed characid reaching approximately 2.4 in standard length (SL) at maximum recorded size. It shares the generalised body plan common to the Astyanax / Psalidodon lineage: a moderately deep, oval-profile body, a small adipose fin between the dorsal and caudal fins, a complete lateral line, and the toothed upper and lower jaws characteristic of the family Characidae.
The species is morphologically similar to other species in the A. bimaculatus and A. fasciatus species groups, and reliable distinction in the field or from photographs requires meristic data and, ideally, molecular identification. Museum material held at the Museu Nacional (MNRJ) is the main physical reference for the species. No detailed published colour description from life is available in the open literature surveyed for this account; preserved specimens display the silvery to pale-brown coloration typical of small Atlantic Forest Astyanax relatives, often with a dark caudal peduncle spot and a mid-lateral stripe of variable intensity.
Habitat
The species is known from the Jequitinhonha River basin, specifically the upper reaches in Minas Gerais state, eastern Brazil. The Jequitinhonha is one of the major rivers of the Atlantic Forest drainage on the eastern Brazilian shield, flowing from the highlands of Minas Gerais northeast to the Atlantic Ocean. Its upper basin is largely within the Cerrado-Atlantic Forest transition zone, a region of complex topography, seasonal rainfall, and streams varying from clear to moderately turbid depending on substrate and land use.
Detailed habitat data for this specific species at the population level are sparse in the available literature. By analogy with other Astyanax sensu lato in comparable Atlantic Forest tributaries, the species likely occupies small to medium river channels, margin vegetation, and pools within the fluvial network, tolerating a range of substrates and moderate seasonal fluctuation in water level and temperature typical of subtropical highland rivers in Brazil.
Feeding
FishBase records a trophic level of 3.0 for this species, placing it among the planktivores and insectivores — a broadly omnivorous guild typical of small Astyanax relatives. Based on this trophic assignment and the feeding ecology of congeners, the diet likely includes small invertebrates such as aquatic insect larvae, microcrustaceans, and terrestrial insects that fall to the surface, supplemented by algae and plant material.
No specific published gut-content study for Psalidodon jequitinhonhae is available in the sources surveyed. In an aquarium context, fish of this genus and size are routinely maintained on high-quality flake food, small pellets, and frozen or live invertebrates such as brine shrimp, Daphnia, and bloodworm, with plant-based foods rounding out the diet.
Mating
Specific mating observations for Psalidodon jequitinhonhae are not documented in the literature available for this account. The broader Astyanax / Psalidodon lineage is characterised by egg-scattering open spawning without parental care, and this species is expected to follow that pattern. Males of Astyanax species typically display subtle colour intensification and active pursuit of females during courtship, with no pair bond formed.
As with other characins in this guild, spawning activity in the wild is likely triggered or amplified by seasonal cues — rising water temperature, increased day length, and flooding associated with the wet season in the Jequitinhonha catchment — although no field documentation for this species exists in the current record.
Breeding
In common with Astyanax sensu lato broadly, Psalidodon jequitinhonhae is expected to be an egg-scatterer that deposits small, non-adhesive to slightly adhesive eggs among fine-leaved aquatic vegetation or over the substrate, with no subsequent parental care. Adults readily consume their own eggs. No captive breeding account specific to this species has been located in the sources reviewed.
For hobbyists who encounter the species, protocols successful with closely related Atlantic Forest Astyanax — a separate breeding tank with dense fine-leaved plants or spawning mops, slightly cooler water to trigger spawning, removal of adults after egg deposition, and rearing of free-swimming fry on infusoria followed by newly hatched brine shrimp — represent the most likely effective approach, pending species-specific published accounts.
In the aquarium
Psalidodon jequitinhonhae is not an established aquarium species and is essentially unknown in the hobby outside Brazil. It does not appear in mainstream ornamental-fish trade channels, and no keeping or care information specific to this species has been published in the hobbyist literature surveyed. Any specimens in aquaria would be uncommon locality fish or specimens incidentally collected with other Atlantic Forest characins.
As a small (2.4 in SL) member of the Astyanax lineage from subtropical highland Brazil, the species would be expected to suit conditions similar to other small Atlantic Forest tetras: temperatures in the low-to-mid 20s Celsius, neutral to slightly acidic to neutral pH, moderate water movement, and a well-planted tank with open swimming space. A schooling disposition would be assumed. However, these details are inferences from the broader genus — direct keeping data are absent, and aquarists working with any such material should treat it accordingly.
Conservation
Psalidodon jequitinhonhae has not been assessed by the IUCN Red List; its conservation status is Not Evaluated (NE). This reflects the species' relatively recent confirmation as a valid taxon and the generally limited evaluation coverage for small Atlantic Forest stream fishes in IUCN processes.
The Jequitinhonha River basin has experienced significant land-use change, including agricultural expansion, deforestation, and water extraction, over the past century. The Atlantic Forest is one of the most threatened biomes on Earth, retaining only a fraction of its original extent, and stream fish endemic to single river basins within it are inherently exposed to catchment-level pressures. While no population trend data exist for this species, the broader context of Atlantic Forest fish diversity suggests that formal conservation assessment and monitoring would be warranted.