Taxonomy & naming
Loricaria birindellii was formally described by Thomas and Sabaj Pérez in 2010 in the journal Copeia (volume 2010, number 2, pages 274–283), based on two specimens — including holotype ANSP 188498 — collected during the 2007 Pipe Expedition to Serra do Cachimbo, conducted by the Academy of Natural Sciences of Philadelphia. The type locality is the Rio Curuá, a tributary of the Rio Iriri within the broader Xingu drainage, in Altamira Municipality, Pará, Brazil, near Castelo dos Sonhos.
The Catalog of Fishes (Eschmeyer, CAS) recognises the valid name Loricaria birindellii Thomas & Sabaj Pérez, 2010. The species was placed squarely within the large, diverse genus Loricaria (subfamily Loricariinae), which comprises the archetypal whiptail catfishes of South America. Within the genus, L. birindellii was compared most closely to the geographically proximate L. lata and L. simillima, but is distinguished from all known congeners by a unique combination of characters: an unusually elongate dorsal-fin spine reaching 36.0 % of standard length (SL), far exceeding the 16–29 % SL range documented across the rest of the genus; and an inconspicuous post-orbital notch that is conspicuous in most relatives.
The species honours Brazilian ichthyologist José Luís O. Birindelli (b. 1979, Universidade de São Paulo), who participated in the 2007 Serra do Cachimbo expedition and assisted with specimen collection.
Morphology
Adults of L. birindellii are slender, flattened whiptail catfishes reaching approximately 14.5 in total length (TL); the examined type series yielded a standard length of roughly 9.5 in SL, illustrating the proportionally long caudal filament characteristic of Loricariinae.
The defining diagnostic character is the first dorsal-fin spine, which in L. birindellii reaches 36.0 % SL — substantially longer than the 16–29 % SL documented across all other examined Loricaria species, giving the fish a distinctive sail-like first dorsal even at rest. The head is notably narrow and slender, with head width measuring 13.9–14.9 % SL. The post-orbital notch, a groove behind the eye visible in most Loricaria, is inconspicuous in this species.
The lateral plate formula includes 21 divergent lateral plates and 13 coalesced plates along the caudal peduncle — counts that fall within the general Loricaria range but help place the species in relation to congeners. The body is otherwise consistent with genus-level Loricaria anatomy: a complete armour of keeled scutes, a ventrally positioned suctorial mouth adapted for grazing biofilm and fine detritus from hard substrate, and elongated caudal filaments extending beyond the hypural plate.
Habitat
The two type specimens were collected from the Rio Curuá in the Iriri-Xingu drainage, at a site characterised by clear water approximately 3–7 ft deep with moderate current. The substrate consisted predominantly of sand interspersed with patches of exposed bedrock and large lateritic boulders — a classic clear-water Xingu rapid microhabitat. Water chemistry at similar Xingu clear-water localities runs soft and mildly acidic: pH values of roughly 6.0–7.0 and temperatures in the 75–82 °F range are consistent with field data from comparable Rio Curuá and Iriri sites.
The broader Iriri-Xingu drainage is one of the most biodiverse river systems in Amazonia, draining the Serra do Cachimbo plateau across a mosaic of savannas, cerrado, and lowland forest before joining the main Xingu channel near Altamira. Clear-water, boulder-rapid habitats in this region support a high degree of local endemism among loricariids, and L. birindellii's apparent restriction to the Rio Curuá system is consistent with the pattern of drainage-level specialisation seen repeatedly in Xingu catfishes.
Feeding
No direct dietary observations exist for L. birindellii, and the tiny known sample precludes stomach content analysis. Based on its trophic level assignment of 2.4 on FishBase — typical for detritivore-grazer loricariids — and the suctorial ventral mouth shared by all Loricaria, the species almost certainly grazes biofilm, periphyton, algae, and fine organic detritus from the surfaces of boulders and bedrock in moderate current. This is the standard foraging mode across Loricariinae, and the moderate-current, hard-substrate rapids habitat at the type locality is precisely the environment that supports productive periphyton mats in clear, nutrient-poor Amazonian water.
Mating
No observational data on the mating behaviour of L. birindellii exist, given that the species is known from two museum specimens. The broader subfamily Loricariinae, however, shows a consistent reproductive pattern that almost certainly applies here: males develop well-developed odontodes (tiny tooth-like spines) on the cheeks and snout during the breeding season, which are used in male-male competition and serve as secondary sexual characters. Males are typically the parental sex in Loricariinae, and pair formation occurs at carefully selected spawning substrates — typically flat, clean surfaces of rock or submerged wood in areas of current.
Breeding
No breeding data exist for L. birindellii in nature or in captivity. The species is essentially unknown in the aquarium trade given its discovery from a single scientific expedition and lack of subsequent collection. What is understood comes from subfamily-level inference: Loricariinae are characterised by paternal egg-guarding, in which the male remains with the egg mass after spawning and fans the clutch to maintain oxygenation. Eggs in most Loricaria species are adhesive and deposited on hard surfaces. Clutch sizes and incubation periods for this species remain entirely undocumented.
In the aquarium
Loricaria birindellii is not an established aquarium species. No specimens are known to have entered the ornamental trade, and there are no published or documented accounts of the fish being kept in captivity. Its known habitat — clear, oxygenated, moderately fast-flowing water over sand and laterite boulders in a remote Xingu tributary — suggests that, were it to become available, it would require well-filtered, highly oxygenated water with significant current, a spacious aquarium allowing full extension of its long caudal filament, and a substrate that replicates its natural boulder-sand environment. At up to 14.5 in TL it would need a large tank. All care considerations remain speculative in the absence of any captive experience.
Conservation
The IUCN Red List assessed Loricaria birindellii as Least Concern (LC) in 2018, and a 2022 assessment maintained that status. The designation reflects the absence of evidence for population decline rather than evidence of abundance — the species is known from only two specimens from a single collecting event. The Rio Curuá falls within the broader Xingu basin, which has faced substantial hydrological disruption from the Belo Monte hydroelectric complex, completed in 2019. Belo Monte is one of the world's largest hydroelectric dams and has significantly altered flow regimes, sediment dynamics, and temperature in the main Xingu channel and portions of its tributaries. The specific impact on the Rio Curuá and the boulder-rapid microhabitats used by L. birindellii has not been formally assessed. Given the species' apparently restricted distribution and the lack of any population data, Least Concern should be understood as a data-limited assessment rather than a reassuring one.