A taxonomic revision of Keraunea, including three new species and its phylogenetic realignment with Ehretiaceae (Boraginales)

Abstract

Keraunea is an enigmatic genus of lianescent shrubs endemic to Brazil and found within the Caatinga and Mata Atlântica phytogeographic regions. When first published, Keraunea was included in the Convolvulaceae and there has been considerable recent disagreement about its true family placement on the Angiosperm tree of life. Based on further assessment of morphology and a new comprehensively-sampled combined phylogenetic analysis of nuclear and plastid genes from recently published DNA sequence data, we settle the position of the genus within the Ehretiaceae as sister to the Australian genus Halgania Gaudich. and provide an expanded family description. We recognize five species within Keraunea, three of them newly described here: K. brasiliensis Cheek & Simão-Bianchini, K. bullata Moonlight & D.B.O.S.Cardoso, sp. nov., K. capixaba Lombardi, K. confusa Moonlight & D.B.O.S.Cardoso, sp. nov. and K. velutina Moonlight & D.B.O.S.Cardoso, sp. nov. We also provide a full taxonomic revision of the genus, including a key, descriptions, map of geographical distribution and provisional IUCN threat assessments for all species.