Taxonomy & naming
Microlepidogaster discontenta was described by Calegari, Silva and Reis in 2014 in Ichthyological Exploration of Freshwaters (volume 25, number 3, pages 213–221). It belongs to the family Loricariidae, subfamily Hypoptopomatinae, and is recognised as valid by the Catalog of Fishes (Eschmeyer, CAS). The authority is occasionally rendered as 'Calgari' in secondary lists — a typographical error for Calegari.
The genus name Microlepidogaster refers to the small bony plating of the belly. The specific epithet discontenta is built from Latin dis- (not) and contentus (satisfied), meaning 'regretful' or 'discontented' — a deliberate allusion to the type locality, the córrego Arrependido, whose Portuguese name means 'regretful stream.'
Morphology
Microlepidogaster discontenta is a small, elongated loricariid reaching about 1.5 in standard length in the known material. Published meristics record 2 dorsal spines, 7 dorsal soft rays, 6 anal soft rays, and 30 vertebrae.
Diagnostic features noted in the original description include odontodes arranged in longitudinal lines on the caudal peduncle and a wide naked (plate-free) area at the tip of the snout. No detail on live coloration is given in the consulted sources, and FishBase carries no image of the species.
Habitat
The species occurs in the rio São Francisco basin of Brazil. The type locality, the córrego Arrependido, is a stream captured from the upper rio Paraná drainage into the rio Preto, a tributary of the rio São Francisco — a stream-capture setting that helps explain the faunal mixing at this drainage divide.
It inhabits clear, fast-flowing shallow water and is consistently associated with marginal grasses and aquatic weeds along stream edges. As with other members of the genus, it is a facultative air-breather, an asset in shallow, oxygen-variable headwaters.
Feeding
No dietary study specific to Microlepidogaster discontenta is available in the consulted sources. As a small hypoptopomatine with a ventral suckermouth living among marginal vegetation, it is consistent with the subfamily's general habit of grazing biofilm — algae, diatoms, and associated micro-organisms — from plant stems and submerged surfaces. Direct dietary observations have not been published.
Mating
No courtship or mating behaviour has been documented for Microlepidogaster discontenta in the consulted sources.
Breeding
No breeding data have been published for Microlepidogaster discontenta in the consulted sources. Spawning mode, clutch size, and any parental care remain undocumented.
In the aquarium
Microlepidogaster discontenta is a small, range-restricted stream species with no established presence in the aquarium hobby, and no husbandry information is available in the consulted sources. It is documented here as a wild species rather than an aquarium subject.
Conservation
Microlepidogaster discontenta has not been evaluated for the IUCN Red List (status Not Evaluated, per FishBase, Version 2025-2). No formal conservation assessment exists. Its known distribution is restricted to clear, fast-flowing headwater streams associated with marginal vegetation; the consulted sources do not detail specific threats.