Taxonomy & naming
Microlepidogaster negomata was described by Martins, Cherobim, Andrade and Langeani in 2017 in Zootaxa (volume 4276, number 2), from material collected in the upper rio São Francisco basin of Minas Gerais, southeastern Brazil. The type locality is the Ribeirão Bebedouro at Fazenda Nego Matá. The Catalog of Fishes (Eschmeyer, CAS) recognises the species as valid.
The genus Microlepidogaster belongs to the subfamily Hypoptopomatinae, the group of small armoured catfishes Brazilian hobbyists call cascudinhos. Members of the genus are characterised by their diminutive size and the reduced, fine bony plating on the abdomen that gives the genus its name.
Morphology
Microlepidogaster negomata is a very small loricariid, reaching about 1.5 in standard length in the largest examined specimens. Like other Hypoptopomatinae it carries the family's armour of overlapping bony plates over an elongate, dorsally flattened body, with a ventral suckermouth.
Detailed colour and pattern notes beyond the original description are not published here, and no photograph is available on FishBase. As with the rest of the genus, the species is a facultative air-breather, able to gulp atmospheric air in poorly oxygenated water. No information on sexual dimorphism has been published for this species.
Habitat
The species is known from a very small stream with a bottom of gravel, stones and sand, where it associates with marginal vegetation. The water is clear and the environment is freshwater, demersal and tropical.
At the type locality it occurs syntopically with a varied small-fish community, including Astyanax bimaculatus, Astyanax rivularis, Cetopsorhamdia iheringi, an undescribed Harttia, an Imparfinis, Parotocinclus prata and several Trichomycterus. The fish lives in the upper rio São Francisco drainage of Minas Gerais. No published water-chemistry measurements (temperature, pH, hardness) are available for the locality.
Feeding
No diet study has been published for Microlepidogaster negomata. Members of the subfamily Hypoptopomatinae are typically grazers that rasp biofilm, algae and fine detritus from rocks, wood and plant surfaces with their suckermouths, and this species is expected to feed similarly, but direct dietary data are not published.
Mating
No data on courtship or mating behaviour have been published for this species.
Breeding
No breeding data have been published for Microlepidogaster negomata. The species is not known to have been bred or maintained in aquaria.
In the aquarium
Microlepidogaster negomata is not part of the ornamental trade and there is no published husbandry information for it. As a small stream-dwelling cascudinho from clear, well-structured water, it would in principle require cool to warm, clean, oxygenated conditions with a fine substrate and surfaces for grazing, but any care recommendation would be speculative — no aquarium experience with the species has been documented.
Conservation
The IUCN Red List assessed Microlepidogaster negomata as Near Threatened in 2020, under criterion B1b(iii), reflecting its very restricted known range in the upper rio São Francisco basin. The São Francisco drainage faces pressures from agriculture, water abstraction and habitat modification, and a species confined to a single small stream is inherently vulnerable to local disturbance. Continued monitoring of its limited range is the principal conservation need.