Taxonomy & naming
Rineloricaria buckupi was described in 2025 by Mejia, Ferraro and Souto-Santos in Neotropical Ichthyology, volume 23, number 2 (article e240087), under the title 'A new species of whiptail catfish Rineloricaria from Macaé and São João river basins, southeastern Brazil.' The Catalog of Fishes (Eschmeyer, CAS) lists it as a valid species (species id 78099), and FishBase carries it under SpecCode 71326.
The species belongs to Rineloricaria, the large genus of whiptail catfishes within subfamily Loricariinae of the armoured catfish family Loricariidae. Its description adds to the cluster of Rineloricaria endemic to the coastal river basins of southeastern Brazil, a region whose isolated drainages harbour several narrowly distributed loricariids.
The specific epithet honours the Brazilian ichthyologist Paulo A. Buckup, recognising his work as a teacher and advisor to many students, including the authors of the description.
Morphology
Rineloricaria buckupi reaches at least 7 in standard length (largest measured male or unsexed specimen), making it one of the larger members of the genus. It has the elongate, dorsoventrally flattened, whip-tailed body typical of Rineloricaria, the head and trunk armoured in overlapping bony plates and the body drawn out into a long, slender caudal peduncle.
Recorded fin-ray counts are seven soft dorsal rays and five soft anal rays. The original description provides the diagnostic morphology distinguishing it from congeners in the southeastern Brazilian coastal drainages, but a detailed popular account of its life coloration has not been published. As in other whiptails, the ventral mouth forms a sucker disc adapted for clinging to the substrate.
Habitat
Rineloricaria buckupi is endemic to Brazil, described from the Macaé and São João river basins, coastal drainages of Rio de Janeiro state in southeastern Brazil. These are independent coastal river systems rather than part of a major continental basin, a setting that favours localised endemism.
The species is a freshwater, demersal fish of tropical conditions, with FishBase rating its resilience as medium. As with other Rineloricaria, it can be expected to associate with the river bottom among sand, wood and leaf litter, and the genus is noted for facultative air-breathing in low-oxygen water, though microhabitat specifics for this species have not been detailed beyond its basins of origin.
Feeding
No dedicated feeding study of Rineloricaria buckupi has been published. Its FishBase trophic level of 2.5 indicates a low-level omnivore, in line with the genus, whose members rasp biofilm, algae, microorganisms and fine detritus from submerged surfaces.
Until species-specific observations exist, only the general Rineloricaria pattern of aufwuchs- and detritus-based grazing can be stated for this fish.
Mating
No mating or courtship behaviour has been documented for Rineloricaria buckupi. Whiptail catfishes in this genus typically spawn in crevices or tubes with the male attending the site, but no observation specific to this species exists, and nothing about its reproductive behaviour should be asserted.
Breeding
There are no published breeding reports for Rineloricaria buckupi. Many Rineloricaria are substrate egg-layers with paternal care, the male guarding and fanning a clutch, but whether this species conforms to that pattern is unrecorded. No data published.
In the aquarium
As a species described only in 2025, Rineloricaria buckupi has no presence in the ornamental trade, no L-number, and no hobbyist husbandry record. Any care guidance would be extrapolation from the genus rather than experience with this fish.
In general, whiptail catfishes of this size are kept over soft sand with gentle to moderate flow, driftwood and refuges, good filtration and stable tropical temperatures. Because no specific husbandry has been recorded for R. buckupi, it should be treated as an undocumented species and approached through general Rineloricaria care principles only.
Conservation
Rineloricaria buckupi has not been evaluated by the IUCN Red List, which is expected given that it was only described in 2025. No conservation status or population assessment is therefore available.
The coastal river basins of Rio de Janeiro state face well-documented pressures from urbanisation, water abstraction, pollution and habitat alteration, factors that are generally of concern for range-restricted endemics in this region. A formal assessment of the species would require dedicated survey and population data.