Aim In island‐like habitats, geographic isolation facilitates population and species divergence by constraining gene flow, while environmental isolation can enhance divergence. We tested the relative contribution of geographic and environmental isolation in genetic and phenotypic divergence within and between two species of the figwort Ameroglossum (Scrophulariaceae) inhabiting spatially isolated habitats, known as inselbergs. Location Borborema Plateau, north‐eastern Brazil. Methods Multivariate models of redundancy (RDAs) and partial redundancy analyses (pRDAs) were used to partition the geographic and climate components of genetic variation in 48 microsatellite alleles, and phenotypic variation in 11 leaf and flower traits. We also used linear mixed‐effect models (LMEs) to test independent associations of floral tube length variation among inselbergs with local pollinator phenotypes, climate and geography. In each approach, we analysed the data for each species separately and in pooled models for both species. Results RDAs revealed that genetic variation within and between the species of Ameroglossum was associated similarly with geography and climate. Phenotypic variation within A. manoel‐felixii and between species was also associated similarly with geography and climate but, within A. pernambucense, phenotype was more strongly associated with climate. Linear mixed‐effect models revealed that flower divergence in A. manoel‐felixii was associated only with the bill length of local hummingbirds, whereas floral variation in A. pernambucense was associated with geography, bill length and climate. Only climate was associated with flower divergence between species. Main conclusions Genetic and phenotypic variation in Ameroglossum are associated with geographic and environmental isolation. These findings indicate a significant role of ecological factors shaping plant divergence among inselbergs, irrespective of their spatial distances.

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During field studies of the inselbergs of northeastern Brazil, two potentially new species of were discovered. They share morphological characters with several genera of Linderniaceae (Lamiales) such as Ameroglossum, Cubitanthus and Stemodiopsis, but the morphological differences are such that they do not make a good fit with any of the known genera in Linderniaceae. They are most likely related to Ameroglossum, and like most members of this genus the plants have a conserved chromosome number of 2n = 60. Their exclusive occurrence on inselbergs in northeastern Brazil also hint at this relationship, but because their morphology differs greatly from Ameroglossum and each other, the two new species are described in separate genera. Catimbaua is a pendent plant somewhat similar to Cubitanthus, but with different stem morphology and indumentum. Isabelcristinia grows in habitats similar to, but drier than, Ameroglossum and is vegetatively similar. However, it is covered in glandular hairs and has open-throated white flowers rather than the red or orange tubular flowers found in Ameroglossum. Catimbaua pendula and Isabelcristinia aromatica are rare, and both are likely to fall in a category of threat.