Taxonomy & naming
Curculionichthys coxipone was formally described by Roxo, Silva, Ochoa and Oliveira in 2015 in ZooKeys (volume 534, pages 103–134), in a paper that erected the genus Curculionichthys and described three new species simultaneously. The Catalog of Fishes (Eschmeyer, CAS) recognises the valid combination Curculionichthys coxipone under the authority of those four authors.
The genus Curculionichthys was placed in the tribe Otothyrini within subfamily Hypoptopomatinae — the small, often rheophilic loricariids that cling to hard substrates in fast-flowing Neotropical streams. The name Curculionichthys alludes to the weevil-like snout profile shared across the group; the species epithet coxipone honours the Coxiponé indigenous people, whose traditional territory borders the banks of the Rio Cuiabá near the municipality of Cuiabá in Mato Grosso state, Brazil — the region where the type specimens were collected.
C. coxipone is diagnosed within the genus by its elevated vertebral count of 29–30, compared with 28 in all other described congeners. This osteological character provides a clean, count-based distinction even in the absence of colour or soft-tissue preservation.
Morphology
Adults measure approximately 1 in SL in males and up to 1 in SL in females — among the smallest loricariids recorded. The holotype measured 1 in SL; the type series spans 1 in SL across 38 specimens. The body follows the compact, dorsoventrally flattened plan of the Hypoptopomatinae, with a rounded anterior head profile characteristic of the genus.
Meristic data from the original description record 9 dorsal soft rays and 6 anal soft rays, consistent with the tribe. The diagnostic vertebral count of 29–30 is confirmed osteologically; all other Curculionichthys species possess 28 vertebrae. Body scutation is the typical overlapping loricariid armour of bony plates; the precise plate arrangement within the genus follows patterns described in the original paper but is not reproduced here from secondary sources alone.
Sexual dimorphism has not been documented in the literature accessible from the type series data.
Habitat
The type locality is a small tributary of the Rio Aricá Mirim, itself a tributary within the Rio Cuiabá drainage of the upper Rio Paraguay basin, Mato Grosso state, Brazil (15°46′03″S, 55°30′44″W). The Rio Cuiabá system drains the eastern Pantanal headwaters — a broad lowland mosaic of gallery forest, savanna, and seasonally flooded fields.
Specific water-chemistry measurements at the collection site are not available in accessible literature. The Rio Cuiabá drainage in the Mato Grosso piedmont generally carries warm water (approximately 79–90 °F in the warm season), slightly acidic to neutral pH (roughly 6.5–7.5), and moderately soft to moderately hard conductivity, though values fluctuate substantially with season and local substrate. Small tributary streams in this region often carry clearer, faster-flowing water over gravel and rock, providing the biofilm-covered hard substrates favoured by Hypoptopomatinae.
Feeding
A trophic level of 2.4 (± 0.1 se) is assigned to the species on FishBase, consistent with algae and detritus feeding — the standard guild for Hypoptopomatinae. All members of Curculionichthys are classified as algivores and detritivores that rasp biofilm, periphyton, and fine organic matter from hard substrates in fast-flowing water. No direct gut-content analyses specific to C. coxipone are available in the literature consulted.
Mating
Reproductive behaviour has not been documented for Curculionichthys coxipone in the wild or in captivity. General patterns in small hypoptopomatine loricariids involve substrate-associated spawning, often in crevices or beneath rocks in current, but no species-specific data exist for this taxon.
Breeding
No breeding records for Curculionichthys coxipone in captivity are known. The species has not been established in the ornamental trade, and no hobbyist accounts of reproduction have been located. Data on clutch size, incubation duration, or parental behaviour cannot be reported without fabrication.
In the aquarium
Curculionichthys coxipone is essentially absent from the aquarium trade and has not been kept or bred in captivity in any documented account. Its extreme small size — under 1 in SL at maturity — and its apparent restriction to a narrow drainage in Mato Grosso mean that any hypothetical husbandry would need to replicate the warm, well-oxygenated, fast-moving, biofilm-rich conditions of its native streams. No practical husbandry guidance can be offered in good conscience beyond the general requirements of small rheophilic loricariids: clean water, ample current, hard surfaces colonised by algae and biofilm, and extremely small food items if supplementary feeding were attempted.
Conservation
Curculionichthys coxipone has not been evaluated by the IUCN Red List. Its known distribution is limited to the Rio Cuiabá drainage in Mato Grosso, and the available specimen data (type series collected from a single tributary) suggest a geographically restricted range. The Pantanal headwaters of Mato Grosso face ongoing pressure from agricultural expansion, sedimentation, and water extraction. Without systematic surveys across the Rio Cuiabá drainage, the true extent of the species' distribution — and whether populations are stable, fragmented, or declining — remains unknown.