Taxonomy & naming
Aspidoras maculosus was described in 1976 by Han Nijssen and Isaäc Isbrücker, in their landmark revision of the South American plated catfish genus Aspidoras, which added nine new species at once. It is placed in Aspidoras R. von Ihering, 1907, a genus of corydoradine armoured catfishes (family Callichthyidae) endemic to Brazil and diagnosed by its divided cranial fontanel — the 'twin-windowed' skull that distinguishes Aspidoras from Corydoras and its kin.
In the large 2024 phylogenomic revision of the Corydoradinae by Dias, Tencatt and colleagues (Zoological Journal of the Linnean Society, zlae053) — the study that broke the unwieldy old Corydoras into several genera such as Brochis, Hoplisoma, Gastrodermus and Osteogaster — Aspidoras was confirmed as a valid natural genus, and A. maculosus remains among its listed species. The name therefore stands unchanged in both the hobby and the current Catalog of Fishes lineage: Aspidoras maculosus. The specific epithet is Latin maculosus, 'spotted' or 'full of spots', for the eye-sized dark blotches along the middle of the body.
Morphology
This is a small catfish, reaching about 1.5 in in standard length. It carries the standard corydoradine armour — two rows of overlapping bony plates along each flank, a hard helmeted head, and three pairs of barbels around the small ventral mouth — and the dorsal and pectoral fins each bear a stiff leading spine.
The diagnostic feature, and the source of both the scientific and common names, is colour: a row of roughly eye-sized dark spots runs along the middle of the body over a paler ground, giving the 'dappled' or 'spotted' look. As in other Aspidoras the eye is comparatively large and the body slim and active. Detailed sexual-dimorphism notes are sparse, but as in the genus generally, egg-bearing females are expected to be the broader, rounder sex.
Habitat
Aspidoras maculosus is restricted to the rio Itapicuru basin in the state of Bahia, northeastern Brazil — a coastal river system of the semi-arid to sub-humid northeast. It is a freshwater, benthopelagic fish, living close to the bottom of streams and rivers within that drainage.
Like all callichthyids it is a facultative air-breather, gulping air at the surface and extracting oxygen through a vascularised hindgut, which suits the warm and seasonally variable waters of a northeastern Brazilian river. Specific published figures for temperature, pH and hardness at its localities are scarce, but the fish lives under warm tropical conditions in a drainage subject to strong wet–dry seasonality.
Feeding
No targeted diet study has been published for A. maculosus, but it shares the benthic micro-omnivore habits of the genus. It works sandy and silty bottoms with its barbels and snout, sifting the substrate for small invertebrates, insect larvae, micro-crustaceans and organic detritus. Such small Aspidoras form part of the unobtrusive bottom-cleaning fauna of their streams, turning over the substrate as they feed.
Mating
Mating in A. maculosus has not been described from the wild, but Aspidoras follow the corydoradine pattern: egg-laying shoalers with no pair bond, in which a male presses against a receptive female's head in the 'T-position' while she gathers a few eggs in a basket formed by her clamped pelvic fins and then presses them onto a cleaned surface or into cover. The cycle repeats a few eggs at a time. As elsewhere in the group, the readiest external sex cue is the broader, rounder body of the gravid female.
Breeding
There is no published breeding account for Aspidoras maculosus, and it is not an established aquarium fish. By analogy with the better-known members of the genus it is expected to be an egg-scatterer, depositing small batches of adhesive eggs among vegetation or fine cover with no parental care — Aspidoras do not guard their eggs, and the parents may consume them. Spawning in related species is generally triggered by the cooler, fresher water of the rains. Specific clutch sizes, incubation periods and fry data for this species remain unrecorded.
In the aquarium
Aspidoras maculosus is rarely if ever traded and is little known in aquaria; the following is inferred from its relatives. Were it kept, it would require what other small Aspidoras need: a shoal of six or more, as these are social fish that suffer in isolation; a soft sand substrate to protect the barbels from the abrasion and infection that coarse gravel causes; and clean, warm, well-oxygenated water with gentle flow and regular changes. A quiet, shaded tank with fine substrate, smooth stones and some cover, stocked only with small and peaceful tankmates, would suit it. Given how localised and poorly known the wild population is, it is better considered a fish to study and protect than one to collect for the hobby.
Conservation
Aspidoras maculosus was assessed by the IUCN as Data Deficient, in an evaluation dated 7 November 2018 — meaning there is not enough information on its range, population and threats to assign a meaningful category. That uncertainty matters, because the species is a narrow endemic of a single northeastern drainage, the rio Itapicuru, where rivers are subject to water abstraction, agriculture, damming and the pressures of a semi-arid, drought-prone region. A Data Deficient listing is not reassurance; for a localised fish like this it is a flag that the species needs proper study before its true status can be judged.