The Harttiini are a tribe of Loricariinae poorly characterized morphologically. Within the guianas (French Guiana, Suriname, and Guyana), six valid species were recognized, including five Harttia, and the monotypic Harttiella crassicauda. Recent investigations conducted during the last decade by the authors and their co-workers, revealed several unidentified populations of Harttiini. Using a multivariate and multi-table approach unifying morphometry, genetics through DNA barcodes, and ecology-distribution of all populations and species, the global diversity and main evolutionary trends of this group were assessed. The separate analyses highlighted strong structures supporting the validity of three genera: Harttiella, Harttia, and Cteniloricaria, as well as nine new species (six Harttiella, two Harttia, and one Cteniloricaria), and one synonym. The combined analysis established a compromise between the preliminary ones, and revealed their common structure. This structure was found to be linked to the evolutionary history of Harttiini. Their evolution was driven toward adaptations to a definite type of biotope. These included modifications in size and shape, particularly of the caudal peduncle, depending on whether the species colonised rivers or mountainous forest creeks. A longitudinal evolutionary gradient was also highlighted in the geographical distribution of the species despite large overlaps. Notably, Harttiella possessed the greatest number of species with the smallest distribution, making each of them highly vulnerable to anthropic perturbations of their environment. Nine new species are described and a key to all species from the guianas is proposed. Les Harttiini representent une tribu de Loricariinae assez peu differenciee morphologiquement. Dans les guyanes (guyane francaise, Suriname et guyana), six especes valides etaient reconnues, incluant cinq Harttia et le monotypique Harttiella crassicauda. De recentes collectes realisees lors de la derniere decennie par les auteurs et leurs collegues, ont revele la presence de plusieurs populations non identifiees de Harttiini. En utilisant une approche multivariee et multitableaux unifiant morphometrie, genetique aux travers des codes barres ADN et ecologie-distribution de toutes les populations et especes, la diversite globale et les principales tendances evolutives de ce groupe ont ete evaluees. Les analyses separees ont revele de fortes structures supportant la validite de trois genres : Harttiella, Harttia et Cteniloricaria, ainsi que neuf nouvelles especes (six Harttiella, deux Harttia et une Cteniloricaria) et un synonyme. L'analyse combinee etablit un compromis entre les analyses preliminaires et revele leur structure commune. Cette structure s'est averee liee a l'histoire evolutive des Harttiini. Leur evolution a conduit a des adaptations a un type defini de biotope. Celles-ci incluent des modifications de taille et de forme, en particulier du pedoncule caudal, selon que l'espece a colonise les rivieres ou les criques forestieres de montagne. Un gradient evolutif longitudinal de la distribution geographique des especes a egalement ete mis en evidence malgre de forts chevauchements. Le genre Harttiella possede ainsi le plus grand nombre d'especes ainsi que la plus petite distribution, rendant chacune d'entre elles particulierement vulnerable aux perturbations anthropiques de leur environnement. neuf nouvelles especes sont decrites et une cle de toutes les especes des guyanes est proposee. Key words.--Morphometry--DNA barcodes--COI gene--Ecology--Multiple co-inertia analysis--new species descriptions.