Taxonomy & naming
The species was described by Charles Tate Regan in 1906 as Lithoxus bovallii. It was later transferred to the genus Paralithoxus by Isbrücker (1979), and FishBase and the Catalog of Fishes (Eschmeyer, CAS) treat the valid name as Paralithoxus bovallii (Regan, 1906) — the parentheses on the authority marking the change from the original genus. The genus Paralithoxus carries CoF genus id 7497.
The fish belongs to the subfamily Hypostominae, tribe Ancistrini — specifically the dwarf, flat-headed 'Lithoxus group' of rock-clinging loricariids. Its morphology and type material have been treated by Nijssen and Isbrücker (1990) and Müller and Isbrücker (1993), and Schindler (1996) redescribed material from the Ireng River; Fisch-Müller (2003) listed it in her checklist of the family.
The species epithet bovallii honours Carl Erik Alexander Bovallius (1849–1907), a Swedish biologist.
Morphology
Paralithoxus bovallii is a small loricariid reaching about 2.5 in standard length (SL). It belongs to the dwarf flathead Lithoxus assemblage — fishes with a depressed, broad-headed body built for life pressed against rock in flowing water, sheathed in the bony plates characteristic of the family.
Detailed morphology of the type material is documented by Müller and Isbrücker (1993), with a redescription of Ireng River specimens by Schindler (1996). No reliable account of external sexual dimorphism for this species is available in the sources consulted.
Habitat
The species is recorded from the Ireng River basin in the upper Branco–Negro River drainage of Guyana, on the Guiana Shield in South America. It is a freshwater, demersal, tropical fish that inhabits stony rivulets — a fast-water, rock-dwelling dwarf.
A notable biological trait is that it is a facultative air-breather, able to supplement gill respiration with atmospheric air, an adaptation useful in warm, shallow, fast-flowing rocky streams where dissolved oxygen can fluctuate. Beyond these notes, finer habitat data — water chemistry, depth, and seasonal regime — have not been published in the sources available here.
Feeding
No dedicated feeding study has been published for Paralithoxus bovallii. As a small, benthic, rock-dwelling loricariid of stony rivulets, it is most plausibly a grazer of the biofilm and associated invertebrates coating rocks in fast water, in keeping with related dwarf flathead plecos, but its specific diet has not been documented.
Mating
No data on courtship or mating behaviour have been published for Paralithoxus bovallii. The species is essentially absent from the aquarium hobby, and the literature consulted addresses taxonomy and morphology rather than reproductive behaviour.
Breeding
No data on reproduction, spawning mode, clutch size, or parental care have been published for Paralithoxus bovallii. There are no documented wild breeding observations and no captive breeding accounts.
In the aquarium
Paralithoxus bovallii has little to no presence in the aquarium hobby. It carries no L-number and is not regularly imported, so there are no established husbandry or breeding reports. A rheophilic dwarf flathead from stony Guiana Shield rivulets would, in principle, require strong, well-oxygenated current, stable warm water, and a rocky aquascape, but in practice the species is unavailable and undocumented in captivity.
Conservation
The IUCN Red List assessed the species (listed as Lithoxus bovallii) as Least Concern (LC), with the assessment dated 1 March 2007. The classification indicates no evidence of significant decline at the time of evaluation. No specific threats to the species have been documented, though as a narrowly distributed rheophilic specialist it would be sensitive to changes in flow regime and water quality in its Guiana Shield streams.