A new species from an inselberg in the Brazilian Atlantic forest: Stachytarpheta forzzae (Verbenaceae), supported by morphological, palynological and anatomical evidence

Abstract

We describe Stachytarpheta forzzae, a new species from an inselberg located in the municipality of Guaratinga, state of Bahia, within the Brazilian Atlantic forest. Morphologically, it resembles S. sprucei, the only other species of the genus known to inhabit inselbergs. Both species share winged branches, petiolate leaves, 4-toothed calyces, and blue corollas. However, S. forzzae can be distinguished by its sparsely strigose branches, leaf blades with abundant capitate glandular trichomes, sparsely strigose along the veins, wider and oblanceolate bracts, with the basal third fused to the calyx tubes, acuminate or cuspidate at apex, and calyces densely minutely strigose on the inner surface. Importantly, the presence of fused bracts to the calyx tubes is recorded for the first time within the genus, representing a diagnostic trait of the new species. Furthermore, differences in trichome structure, especially the number of cells in both glandular and non-glandular types, and in the pollen grain margin, provide additional evidence supporting the separation of these two species. Known from just a single collection record, S. forzzae is assessed as ‘Critically Endangered' due to anthropogenic pressures on its habitat, the ‘Pedra do Oratório' inselberg. It is noteworthy that the discovery of this new species stemmed from an initial record on iNaturalist, underscoring the increasing relevance of citizen science platforms in biodiversity research and conservation.