Taxonomy & naming
Microlepidogaster perforata was described by Carl H. Eigenmann and Rosa Smith Eigenmann in 1889, in their 'Preliminary notes on South American Nematognathi, II' (Proceedings of the California Academy of Sciences, 2: 28–56). The type specimen (MCZ 8181), a single individual, was collected by the Thayer Expedition naturalist Orestes H. St. John on 1 June 1865 from the Rio Carandahy (= Rio Carandaí), a tributary of the Rio das Velhas in the upper Rio Paraná drainage, at the town of Carandaí, Minas Gerais, Brazil. The Catalog of Fishes (Eschmeyer, CAS) lists the valid name as Microlepidogaster perforata Eigenmann & Eigenmann, 1889. The specific epithet is feminine in grammatical gender, agreeing with the feminine genus name — the form 'perforatus' is a misspelling.
The genus Microlepidogaster belongs to tribe Hypoptopomatini within subfamily Hypoptopomatinae (Loricariidae). Microlepidogaster perforata is the type species of the genus. As of 2025, the genus encompasses eight described species (Fricke et al. 2025), of which several others occur in the upper Paraná, São Francisco, Jequitinhonha, and Pardo basins.
M. perforata is distinguished from all its congeners except M. dimorpha by having leaf-shaped odontodes on the anterior portion of the snout (vs. pointed odontodes in other species); it is separated from M. dimorpha by its 9–13 mid-dorsal plate series (vs. 24–27), nostrils of equivalent size in both sexes, and 31 vertebrae (vs. 29–30 in M. dimorpha) (Marques-Frisoni et al. 2025, Biota Neotropica).
Morphology
Adults reach approximately 2 in standard length, making M. perforata among the smallest loricariids known. Specimens in the 2012 collection (DZSJRP 16171) measured 1 in SL, suggesting that individuals well under 1.5 in SL are sexually mature or at least reproductively active; 2 in SL represents the apparent upper bound.
The body is flattened and armoured in the loricariid fashion, covered with overlapping keeled scutes. The ventral mouth is equipped for scraping biofilm from hard surfaces. The most distinctive morphological character is the snout: the anterior portion bears conspicuous leaf-shaped (foliaceous) odontodes — flattened, broad-tipped spinules rather than the simple pointed odontodes seen in most other Hypoptopomatinae. This character is shared only with Parotocinclus jumbo among non-congeners.
Other diagnostic characters include the relatively low number of mid-dorsal lateral plates (9–13), 31 vertebrae, and nostrils of equal size regardless of sex. Overall colouration is brownish with a fine pattern of darker spots or mottling; the belly is pale. The genus name refers to the characteristic small scales of the abdomen: from Greek mikros (small), lepis (scale), and gaster (belly). The specific epithet perforata likely refers to the perforated or fenestrated texture visible in the ventral surface scutation of the holotype.
Habitat
The entire confirmed range of Microlepidogaster perforata is restricted to the Rio Carandaí, a small tributary of the Rio das Mortes → Rio Grande → upper Rio Paraná drainage, within the urban and peri-urban area of the municipality of Carandaí, Minas Gerais, Brazil (approximately 20°55'–20°58'S, 43°46'–43°48'W; altitude approximately 1,060–1,262 ft above sea level). This is an exceptionally restricted range — an Extent of Occurrence calculated in 2024 covers only 81 mi² (Marques-Frisoni et al. 2025).
Field observations during 2012 and 2024 surveys describe the species' preferred microhabitat as shallow, sunny, open-water stretches with moderate to fast current over a bottom of sand, clay, gravel, and stones, with marginal vegetation (grasses and other riverside plants) partially hanging into or submerged in the channel. Individuals are typically found clinging to submerged grass stems and leaves in these open, well-lit riffle margins. The species is absent from shaded stretches with well-developed arboreal riparian canopy, and was not found above a waterfall that appears to act as a dispersal barrier.
Sympathic fish at confirmed collection sites include Astyanax lacustris, Neoplecostomus paranensis, Characidium gomesi, Geophagus iporangensis, and several trichomycterid catfishes. Water temperature at this elevation in the upper Paraná is cool-tropical to subtropical, probably ranging from 59–68 °F in winter to 72–77 °F in summer.
Feeding
Based on field observations and the microhabitat association with submerged marginal vegetation, Microlepidogaster perforata is inferred to be a periphytivore — scraping and ingesting the periphyton biofilm (algae, diatoms, bacteria, fungi, and associated detritus) that coats submerged grass stems and other plant surfaces in the shallow, sunny reaches it occupies. This is consistent with the feeding ecology of Hypoptopomatini more broadly (Langeani, pers. obs., cited in Marques-Frisoni et al. 2025).
The ventral mouth with multicusped teeth is adapted for scraping relatively smooth or lightly textured surfaces, such as grass blades and sedge stems, rather than for excavating hard wood or rock. The small body size and shallow, vegetated microhabitat suggest a diet that is predominantly periphyton with incidental ingestion of fine organic detritus, diatom frustules, and micro-invertebrates entangled in the biofilm matrix.
In the aquarium — were it to become available, which it effectively is not — diet should consist of algae wafers, spirulina products, and blanched soft vegetables. A tank with live marginal-grass planting or algae-covered decor would most closely replicate natural feeding conditions.
Mating
No observations of mating behaviour have been made for Microlepidogaster perforata, either in the field or in captivity. The species has never been kept in aquaria by hobbyists, and fieldwork has focused on simple presence-absence surveys and conservation assessment rather than behavioural ecology.
In common with other Hypoptopomatinae, males likely become territorial during the breeding season, positioning themselves on preferred substrates and displaying to females. The equal nostril size in both sexes distinguishes M. perforata from M. dimorpha (where males have noticeably enlarged nostrils), suggesting that olfactory signalling during courtship may be less differentiated sexually in M. perforata. Standard papilla morphology differences between sexes are expected and would be the most practical means of sexing live specimens, as in other small loricariids.
The cool-subtropical headwater climate at 1,060–1,262 ft elevation in Minas Gerais means the species likely experiences a seasonal temperature cycle with marked cool winters, which may serve as the primary reproductive cue.
Breeding
No breeding data of any kind exists for Microlepidogaster perforata. The species has been collected in total fewer than 50 individuals over 135 years of known scientific history, and no specimen has been maintained alive in captivity long enough for observations to be made.
By analogy with other Hypoptopomatini, spawning is expected to occur on firm submerged substrates — the undersides of stones, submerged root mats, or leaf surfaces — with adhesive eggs and some form of male guarding during incubation. Clutch size in such a small species is probably small, likely on the order of 10–30 eggs, consistent with the energetic constraints on very small loricariids.
The combination of restricted range, microhabitat specificity, and extremely small known population makes any disturbance to breeding habitat a potentially severe threat. The 2024 discovery of individuals in a rural upstream site (DZSJRP 24902) is significant precisely because it expands the known breeding habitat away from the heavily urbanised portions of the stream that dominate the historical record.
In the aquarium
Microlepidogaster perforata is not available in the aquarium trade and, given its extreme rarity and formal protection under Brazil's national action plan for endangered upper Paraná fish species (PAN Alto Paraná, ICMBio 2024), should not be collected for hobby purposes. The species is listed in the Brazilian national threatened species list (MMA Portaria 148/2022), which restricts collection without scientific permit.
Were it to become the subject of a captive assurance colony for conservation purposes, the care requirements would broadly resemble those of other small, cool-highland Hypoptopomatinae: a cool-subtropical tank (61–72 °F), soft to slightly hard water (pH 6.5–7.2), shallow depth, moderate current, a sandy substrate, and dense marginal vegetation — or at minimum algae-covered flat stones and plant stems simulating the grass-edge microhabitat. A photosynthetic light cycle promoting algae and periphyton growth on substrate surfaces would provide both food and shelter.
Its extreme rarity means this species functions best as a conservation flagship for the threatened small-stream fauna of the upper Rio Paraná — a role it currently serves within Brazil's formal conservation planning framework — rather than as an aquarium species.
Conservation
Microlepidogaster perforata presents one of the most extreme range restrictions known for any freshwater fish. For over 130 years it was known from fewer than 30 specimens, all from a few hundred metres of urban stream in Carandaí, Minas Gerais — a stretch heavily impacted by domestic and industrial sewage, urbanisation, and channelisation. This led to its classification as Critically Endangered (CR) under Brazilian national legislation (ICMBio 2018; MMA Portaria 148/2022).
A 2024 expedition (Marques-Frisoni et al. 2025, Biota Neotropica 25(3): e20241732) extended the confirmed range to a rural upstream site on the Rio Carandaí and confirmed persistence at the bridge-area site previously documented in 2007 and 2012. The authors calculated an Extent of Occurrence of 81 mi² and, finding no current evidence of declining habitat or extreme population fluctuation at confirmed sites, proposed a reassessment to Near Threatened (NT, approaching EN under criterion B1). This proposed improvement has not yet been formally adopted by IUCN, whose 2025-2 global list shows the species as Not Evaluated at the global level; the CR designation applies under Brazilian national assessment.
The species is included in the National Action Plan for the Conservation of Endangered Fish Species of the Upper Rio Paraná Basin (PAN Alto Paraná, ICMBio 2024). Ongoing threats include sewage pollution, urban expansion around Carandaí, and the potential impact of continued riparian canopy encroachment at previously open microhabitat sites. The species' apparent preference for sunny, open grass-margin microhabitats means that natural vegetation succession — as well as invasive riparian planting — can eliminate suitable habitat even in the absence of more acute anthropogenic impacts.