Taxonomy & naming
Pareiorhina sofiae was formally described in 2026 by Valter M. Azevedo-Santos, Paulo L. C. Uzeda, André M. Katz, Wilson J. E. M. Costa, Francisco Langeani and Felipe P. Ottoni, within a paper authored by Uzeda, Sartori, Katz, Ottoni, Costa, Langeani & Azevedo-Santos describing four new Pareiorhina species from the upper Paraná basin (Journal of Fish Biology, volume 108, issue 6, pages 1906-1933). The Catalog of Fishes (Eschmeyer, CAS) recognises Pareiorhina sofiae as a valid species with no synonyms.
The genus Pareiorhina sits in subfamily Hypoptopomatinae, within the tribe Neoplecostomini — a group of small, heavily plated, rheophilic loricariids that some earlier classifications treated as its own subfamily, 'Neoplecostominae,' now placed as a tribe within Hypoptopomatinae. Molecular analysis in the description paper found Pareiorhina to be polyphyletic, and placed P. sofiae in a clade with a postdorsal ridge and unicuspid teeth alongside P. carrancas, P. aiuruoca, P. hyptiorhachis, P. isabelae and P. mystica, rather than with the type species P. rudolphi. Within that clade, P. sofiae and P. isabelae form a distinct pair restricted to the Serra da Canastra ecoregion of the middle Grande River drainage, apart from the Serra da Mantiqueira-associated species.
The genus name Pareiorhina combines Greek pareia (cheek or jaw) and rhinos (nose). The specific epithet sofiae honours Marlene Sofia Arcifa, a leading figure in Brazilian limnology, for her contributions to the ecological knowledge and conservation of Neotropical aquatic ecosystems; it is a noun in the genitive case.
Morphology
The holotype is a 1.36 in standard length (SL) male; among the nine measured specimens of the type series, standard length ranges from 1.15–1.36 in (mean 31.2 ± 0.08 in), making it the smallest of the four newly described Pareiorhina. Unlike its three sibling species, P. sofiae carries two genuinely autapomorphic (unique-to-species) characters: the tip of the adpressed pectoral-fin spine reaches the base of the dorsal-fin spine — normally as far as the nuchal plate — versus only the first half of the dorsal-fin base in every other congener, and it has just four infraorbital bones versus five in all other Pareiorhina. Like P. aiuruoca, P. carrancas, P. hyptiorhachis, P. isabelae and P. mystica, it carries a postdorsal ridge and unicuspid teeth (39-50 premaxillary and 38-54 dentary teeth), unlike the type species P. rudolphi.
It further differs from P. carrancas by lacking keels on the dorsal and mid-dorsal plate series, by a snout tip covered with platelets rather than naked, a wider mandibular ramus, and 29 total vertebrae (P. carrancas has 31); from P. hyptiorhachis by an elliptical rather than rounded snout profile, a shorter pectoral-fin spine, a shallower caudal peduncle, and a single pelvic-girdle fenestra rather than two. Among the other three new species it is distinguished from P. aiuruoca by the absence of dark body spotting, a fringed rather than smooth lower lip, a platelet-covered snout tip, a shorter pectoral-fin spine, and a single pelvic-girdle fenestra; from P. isabelae by lower counts of postdorsal-ridge plates and premaxillary teeth and by 29 rather than 31 vertebrae; and from P. mystica by a wider mandibular ramus and a single pelvic-girdle fenestra rather than two.
In life the body is homogeneously dark brown with no spots or vermiculations, set off by four pale saddles on the dorsum — at the dorsal-fin origin, the dorsal-fin end, mid-caudal-peduncle, and the caudal-peduncle end. The venter is light beige except over plated areas, with a few melanophores clustered near the fin bases; the interradial membranes of all fins are hyaline, with dusky-brown pigment on the rays themselves that does not form distinct bars.
Habitat
Pareiorhina sofiae is known from a single, unnamed first-order stream affluent to Ribeirão do Turvo, a small drainage feeding the Grande River at the present-day Furnas Reservoir on the southern slope of Serra da Canastra, in the municipality of Capitólio, Minas Gerais (20°37'25"S, 46°13'49"W, 2631 ft above sea level). The stream is steep, narrow (under 7 ft wide) and shallow (under 15.7 in deep) — so shallow that an unpaved road crosses it directly rather than by bridge, where the water is forced into a thin sheet flowing over the road surface before the channel resumes and drops through a sequence of short waterfalls to its confluence with Ribeirão do Turvo.
Few specimens were captured on either side of the road crossing, and the species has never been recorded from the main channel of Ribeirão do Turvo itself, underscoring how narrowly it is confined to this single tributary.
Feeding
No dedicated dietary study exists for Pareiorhina sofiae; the original description is a taxonomic account and reports no feeding observations. Like other small Neoplecostomini within Hypoptopomatinae, the ventral, disc-shaped mouth and rasping, bronze-tipped teeth are consistent with grazing aufwuchs — algae, diatoms and biofilm — from rock surfaces in fast-flowing water, but this is a genus-level inference rather than a species-specific finding.
Mating
No courtship or spawning behaviour has been documented for Pareiorhina sofiae. The original description records only that reproductively active females develop a marked widening of the body between the dorsal-fin and anal-fin origins, producing a bulging trunk in dorsal view — a state absent in males — alongside the conical urogenital papilla and pelvic-fin-spine flap that mark mature males. Beyond these external signs of reproductive condition, nothing about courtship or pair formation is known.
Breeding
No breeding has been recorded for Pareiorhina sofiae, in the wild or in captivity — the species was described in 2026 and has no aquarium history. Like other small rheophilic Hypoptopomatinae, it is presumed to be a cave- or crevice-spawner with some form of paternal guarding, but this is inferred from related genera rather than observed in P. sofiae itself.
In the aquarium
Pareiorhina sofiae is not in the aquarium trade; it was described from scientific collections only months before this account was written, and no L-number or hobbyist husbandry record exists. Its very small size (under 1.4 in SL) and its habitat — a narrow, shallow, steep first-order stream — suggest it would, in principle, suit only a small, well-aerated biotope aquarium modelled on Atlantic Forest headwater streams, but this is extrapolation from the wild habitat data in the original description, not aquarium experience with the species. Given its single-stream distribution and Endangered status as assessed by its describers, this is not a species that should be collected for the trade.
Conservation
Pareiorhina sofiae has not yet been formally assessed by the IUCN Red List; it was described in 2026. In the original description, the authors estimated its extent of occurrence at approximately 73 mi² across the entire Ribeirão do Turvo microbasin, but noted that the species is known from only the single stream where it was collected and was not found in adjacent streams inside or outside that basin. Habitat alteration from the unpaved road crossing the stream — impoundment upstream and siltation downstream — poses a significant threat to this sole known population; applying IUCN criteria themselves, the authors recommended a status of Endangered (EN), the most severe assessment among the four species described in the same paper. This is the describing authors' own risk assessment, not an official Red List determination.