Lobelia bahiana (Campanulaceae, Lobelioideae), a new narrow endemic species from Chapada Diamantina, Northeastern Brazil

Lobelia bahiana is here described as a new species endemic from the Chapada Diamantina region in Bahia state, Brazil. The new taxon belongs to Lobelia section Rhynchopetalum, the most speciose clade of Lobelia in Brazil. This section includes tall robust herbs with unbranched stems and typical unilabiate or sub-bilabiate corolla tubes.

Lobelia bahiana looks morphologically similar to L. organensis, but can be distinguished from it by the dense tomentum on the abaxial surface of leaves, peduncles and rachis of the inflorescences and in the pedicels of flowers (vs. glabrous), by the strong purple color in calyx lobes and hypanthium (vs. greenish), and by the erect calyx lobes, which are bent towards the flower apex (vs. patent, not curved). The new species shares also similarities with Lobelia brasiliensis, being distinguished mainly by the white tomentum (vs. yellowish) and the glabrous ovary and outer surface of corolla (vs. densely tomentose).

A full description together with a distribution map, original photographs and line drawings are provided. In addition, a key for the South American species of Lobelia sect. Rhynchopetalum as well as the inclusion of L. bahiana under the vulnerable (VU) category of the IUCN Red List due to its narrow distribution and a restricted area of occupancy are proposed.