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| Ditassa scholaris Rapini & Giul. and D. glaziovii E.Fourn. in Rapini, Bitencourt, Giulietti et Harley, 2026. |
Summary
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.
Key Words: Asclepiadoideae, Caatinga, Carrasco, Fontella, Metastelmatinae, taxonomy
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| Ditassa scholaris (A – D, F – L) and comparison with D. glaziovii (E). A branches with leaves, flowers and buds; B a pair of leaves showing the hirsute indumentum; C an inflorescence with two open flowers; D, E flowers of Ditassa scholaris (D) and D. glaziovii (E) shown at the same scale for direct comparison of size and morphology; F inner portion of the flower, with calyx and corolla removed, displaying the corona with double lobes positioned in front of the anthers and the apex of the style head in the centre; G – J corona lobe, viewed abaxially (G), laterally (H) and adaxially (J); K anther, abaxial view; L pollinarium. A – D, F – L from the holotype Harley & Giulietti 57032 (HUEFS), E from Rapini et al. 1315 (HUEFS). drawn by a. rapini. |
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| Ditassa scholaris (A – C) and comparison with D. glaziovii (D). Ditassa scholaris: A branches with leaves, flowers and buds; B portion of a branch showing a closer view of leaves and inflorescences; C close-up of a branch, highlighting the flowers, with lobes burgundy towards the corolla base transitioning to green along the lobe margins, white corona lobes and a greenish style head in the centre. Ditassa glaziovii: D inflorescence. A – C from the holotype Harley & Giulietti 57032, in Umburanas, State of Bahia, Brazil, D from Rapini et al. 1315, in Licínio de Almeida, State of Bahia, Brazil. photos: A – C R. M. harley; D A. rapini. |
Alessandro Rapini, Cassia Bitencourt, Ana Maria Giulietti and Raymond Mervyn Harley. 2026. Ditassa scholaris, A New Species of Apocynaceae from Bahia (Brazil), in honour of a distinguished scholar of “Asclepiadaceae”. Kew Bulletin. DOI: doi.org/10.1007/s12225-025-10276-x [05 February 2026]
