Taxonomy & naming
Spectracanthicus tocantinensis was described by Chamon and Rapp Py-Daniel in 2014, in their taxonomic revision of the genus Spectracanthicus, which also described three other new species (Neotropical Ichthyology 12(1): 1–25). The Catalog of Fishes (Eschmeyer, CAS) recognises it as valid (species id 73243).
The species belongs to the subfamily Hypostominae, within the tribe Ancistrini. The describing authors diagnosed it within Spectracanthicus by a combination of characters: infraorbital 4 forming most of the posterior edge of the orbit, large basipterygium fenestrae, a color pattern of small yellowish dots, thick teeth (8–16 on the dentary), a bar-shaped eversible opercle bearing conspicuous odontodes, four unbranched anal-fin rays, and a slightly pointed snout in dorsal view.
Morphology
Spectracanthicus tocantinensis reaches a maximum of about 3.5 in standard length. The body is fusiform and of normal proportions for the genus. Meristic counts from the description include 8 dorsal soft rays, 5 anal soft rays (with four unbranched anal-fin rays), and 26 vertebrae.
The coloration is a pattern of small yellowish dots over a darker ground. Diagnostic features include thick dentary teeth numbering 8 to 16, infraorbital 4 forming most of the posterior orbital margin, large basipterygium fenestrae, and a bar-shaped eversible opercle armed with conspicuous odontodes. The snout is slightly pointed when viewed from above. No data on sexual dimorphism were available in the source consulted.
Habitat
The species is known from the lower Rio Tocantins in the state of Pará, northern Brazil. It is characterised as a freshwater, demersal, tropical fish — a bottom-associated species of warm inland waters.
No detailed habitat parameters (current, substrate, water chemistry, or seasonal regime) were available in the source consulted. The lower Tocantins is a large clearwater Amazonian river system, heavily modified downstream by the Tucuruí dam, but site-specific microhabitat data for this species were not on hand.
Feeding
No species-specific feeding data were available for Spectracanthicus tocantinensis. The thick dentary teeth described for the species are consistent with a substrate-rasping habit. Members of the Ancistrini generally graze biofilm, algae and associated invertebrates from hard surfaces, but no diet study or aquarium feeding observations could be sourced for this species, so no specific claim is made.
Mating
No data on courtship or mating behaviour have been published for Spectracanthicus tocantinensis. The species is known essentially from its type series, and its reproductive behaviour has not been described in the source consulted.
Breeding
No breeding data are available for Spectracanthicus tocantinensis. There are no documented spawning reports, egg counts, or descriptions of parental care for this species. Many ancistrine loricariids are cave-spawners with paternal egg care, but this has not been confirmed for the present species and is not asserted here.
In the aquarium
Husbandry data for Spectracanthicus tocantinensis are not available; the species is not documented in the ornamental trade and no species-specific aquarium guidance could be sourced. No tank, water-parameter, or compatibility recommendations are offered, as doing so would require invention.
At under 4 in it would in principle be a manageable size were it ever to enter the hobby, but this is a general observation about its size rather than tested husbandry advice.
Conservation
Spectracanthicus tocantinensis has not been evaluated by the IUCN Red List; no published Red List assessment was located (Not Evaluated per the FishBase IUCN field). The absence of an assessment means its extinction risk has not been formally judged.
As a species of the lower Rio Tocantins — a river system heavily altered by the Tucuruí hydroelectric dam and ongoing development — any narrowly distributed endemic of that drainage could be vulnerable to habitat change, but no species-specific threat data were available in the source consulted.