Taxonomy & naming
Harttiella intermedia was described by Covain and Fisch-Muller in 2012 in Cybium (volume 36, number 1, pages 115–161), part of a major revision of the genus Harttiella. The Catalog of Fishes (Eschmeyer, CAS) recognises it as valid (spid 72278). It belongs to the subfamily Loricariinae, tribe Harttiini, within the armoured catfish family Loricariidae.
The species name reflects a genuine taxonomic tension. In overall build, H. intermedia is stocky, recalling the crassicauda group of its genus, yet its mitochondrial barcode is typical of the longicauda group. This contradiction between morphometry and genetics is exactly what the Latin epithet intermedius — 'intermediate' — was chosen to mark. No synonyms are recognised.
Morphology
Harttiella intermedia is a miniature loricariid, reaching only about 1.5 in standard length (largest measured specimen, sex undetermined). The body is elongated, with a stocky overall build that resembles the crassicauda group of the genus despite its longicauda-type genetics.
Reported fin counts are 7 dorsal soft rays, and an anal fin with 1 spine and 5 soft rays. Detailed colour-in-life description and the full suite of plate and meristic characters are treated in the original revision but not elaborated in the available summary sources.
No information on sexual dimorphism has been published for this species.
Habitat
Harttiella intermedia is known only from its type locality: the headwaters of Crique Grand Leblond, on the Tabular Mountain of the Trinite Massif, French Guiana. It is a freshwater, demersal fish of tropical headwater streams.
The genus Harttiella is characteristic of cool, clear, fast-flowing, well-oxygenated upland creeks over rock and gravel, and this species' headwater habitat on a tabular mountain is consistent with that profile. However, specific water-chemistry measurements (temperature, pH, conductivity) for the type locality are not published in the available sources. The extreme localisation of the species to a single creek's headwaters is its defining ecological feature.
Feeding
With a trophic level of about 2.8, Harttiella intermedia is a grazer of aufwuchs — the algae, biofilm, microorganisms and fine detritus coating rocks and submerged surfaces in its headwater stream — which it rasps using the ventral sucker-mouth typical of the family.
No direct gut-content or feeding study specific to this species has been published; the trophic estimate is the only quantitative dietary indicator available.
Mating
No data on courtship or mating behaviour have been published for Harttiella intermedia. The species has not been the subject of a reproductive study or documented in captivity.
Breeding
No breeding data have been published for this species. No spawning, clutch size, incubation or parental-care information specific to H. intermedia exists in the literature.
In the aquarium
There is no aquarium history for Harttiella intermedia. As a Critically Endangered single-creek micro-endemic, it has no presence in the ornamental trade, and collection for the hobby would be inappropriate given its conservation status. No care information specific to this species can be stated. No data published.
Conservation
Harttiella intermedia was assessed as Critically Endangered by the IUCN Red List in 2020, under criterion B2ab(iii). This is among the most severe categories on the Red List, signalling an extremely high risk of extinction in the wild.
The listing follows directly from the species' biology: it is a single-locality micro-endemic, known only from the headwaters of one creek (Crique Grand Leblond) on the Trinite Massif of French Guiana. With such a minuscule range, any localised disturbance — habitat degradation, changes to stream flow or water quality, mining, or deforestation in the catchment — could affect the entire global population at once. The criterion B2ab(iii) assessment reflects a very small area of occupancy combined with a continuing decline in habitat quality. For a fish confined to a single tabular-mountain headwater, the protection of that one watershed is effectively the protection of the species.