Taxonomy & naming
Harttiella lucifer was described by Covain and Fisch-Muller in 2012 in their revision of the Harttiini of the Guianas (Cybium 36(1): 115–161). It is a member of subfamily Loricariinae within the armoured catfish family Loricariidae, and is catalogued in FishBase under SpecCode 66588.
The species is notable as the most divergent of all Harttiella in DNA-barcode terms, which figured prominently in its diagnosis — externally these miniature catfishes are very similar, and molecular data are essential to separating them. H. lucifer is placed within the crassicauda species group. Relative to its close relatives it has a longer caudal peduncle, and it differs from H. intermedia in having a smaller predorsal length. Its specific name is a toponym referring to the Lucifer Mountains, its type locality.
Morphology
Harttiella lucifer is a tiny loricariine, with type material reaching about 1.5 in standard length. It shows the elongated, armour-plated body form typical of the genus. Distinguishing features are mostly subtle and partly molecular: within the crassicauda group it has a comparatively long caudal peduncle, and it is separated from H. intermedia by a smaller predorsal length. Recorded fin-ray counts are seven dorsal soft rays, one anal spine, and five anal soft rays.
No detailed account of sexual dimorphism specific to this species has been published.
Habitat
Harttiella lucifer occurs in the Lucifer and Galbao massifs of central French Guiana. It is a freshwater, demersal fish of tropical upland streams. In its habitat it has been recorded living alongside the killifish Anablepsoides (Rivulus) igneus and an undescribed Ituglanis catfish.
No published water-chemistry measurements (temperature, pH, hardness) for its streams are available in the consulted sources.
Feeding
No direct dietary study of Harttiella lucifer has been published. FishBase assigns a modelled trophic level of about 2.8, in line with the general loricariine habit of grazing biofilm, attached algae, and associated micro-organisms and fine detritus from submerged surfaces. Specific gut-content or feeding observations for the species are not available.
Mating
No data on the courtship or mating behaviour of Harttiella lucifer has been published.
Breeding
No data on the reproduction, spawning mode, clutch size, or parental care of Harttiella lucifer has been published.
In the aquarium
Harttiella lucifer is not an aquarium fish. It is an Endangered upland endemic with no presence in the ornamental trade and no documented husbandry; there are no captive-care guidelines to offer. Its relevance is to field biology and conservation rather than the hobby.
Conservation
The IUCN Red List assessed Harttiella lucifer as Endangered (EN) under criteria B1ab(iii)+2ab(iii), with the assessment dated 14 January 2021. The listing reflects a very small, fragmented range confined to two upland massifs in central French Guiana, coupled with a projected continuing decline in habitat quality.
As a narrowly endemic stream specialist, the species is vulnerable to localised threats such as deforestation, sedimentation, and disturbance of its headwater catchments. Its restriction to the Lucifer and Galbao massifs means that habitat degradation in even a single area could remove a substantial fraction of the known population.