Ditassa scholaris, a new species of Apocynaceae from Bahia (Brazil), in honour of a distinguished scholar of “Asclepiadaceae”

As part of ongoing taxonomic studies on Brazilian Apocynaceae and floristic inventories in the state of Bahia, Brazil, we describe and illustrate a new species of Asclepiadoideae. Ditassa scholaris Rapini & Giul. sp. nov. is named in honour of Jorge Fontella Pereira, who dedicated most of his life to studying the “Asclepiadaceae” (now Apocynaceae, subfamily Asclepiadoideae), and described over 90 new species, made 95 new combinations and even more synonyms within the group. The new species is known only from the type specimen within the Caatinga dominion, collected in a northern fragment of the Espinhaço range with an Extent of Occurrence of no more than 10,000 km2. It is threatened by anthropogenic pressure and climate changes and is provisionally assessed as Vulnerable [VU B1ab(i,ii,iii) + D2]. Ditassa scholaris is vegetatively similar to Metastelma giuliettianum Fontella, mainly because of the ovate leaves and the hirsute indumentum covering branches and leaves. Its flowers resemble those of Ditassa glaziovii E.Fourn., particularly due to its double corona, with lobes fused at the base and an internally digitiform segment. However, the erect habit of D. scholaris differentiates it from these twining species. Erect growth has evolved independently in several lineages within the Metastelmatinae core group, predominantly comprising twining plants. We provide a key to distinguish D. scholaris from the other erect species of Metastelmatinae in the Caatinga dominion.