Wellstedia

Abstract: Five species are here recognized in Wellstedia: W. socotrana on Socotra, W. somalensis sp. nov. and W. laciniata sp. nov. in Somalia, W. filtuensis in Ethiopia, and W. dinteri in Namibia and the adjacent Cape Province. A preliminary phylogenetic analysis suggests that W. dinteri is the sister group to the rest of the genus, while W. filtuensis, W. somalensis and W. socotrana are vicarious sister species. Wellstedia has usually been treated either as a separate subfamily within the Boraginaceae or as a family of its own close to Boraginaceae. Its most notable feature is the capsular fruits (here shown to be hygrochastic), capsules otherwise being unknown in Boragina­ceae. It is suggested that the nearest relative of Wellstedia may be Tiquilia in Boraginaceae subfamily Ehretioideae.

Abstract: This regional taxonomic revision of the genus Wellstedia Balf.f., a member of the family Boraginaceae s.I. (including Hydrophyllaceae s.str.), is part of a series of publications on the Boraginaceae in southern Africa. Wellstedia comprises six species, five in Socotra, Somalia and Ethiopia with the remaining one. W. dinteri Pilg.. occurring in southern Africa. W dinteri Pilg. subsp. dinteri occurs in Namibia and the Northern Cape, whereas the newly instated subspecies W. dinteri subsp. gracilior (D.R.Hunt) Retief & A.E.van Wyk, based on W. dinteri Pilg. var. gracilior D.R.Hunt, is confined to Namibia only. The disjunct distribution of Wellstedia and numerous other plant and animal taxa between the arid regions of northeastern Africa and southern Africa is usually explained by the postulated periodic existence of an arid corridor between the two regions during the arid phases of the Pleistocene and even earlier. Wellstedia is treated here in Wellstedioideae, a subfamily of Boraginaceae s.I. but is sometimes placed in a family of its own, Wellstediaceae Pilger. Morphologically Wellstedia displays strong similarity to genera of the Ehretioideae and also to certain members of the Hydrophyllaceae. The genus is characterized by a perennial, dwarf shrub habit, densely hairy leaves. 4-merous flowers, a terminal, bifid style and a 1- or 2-seeded capsule. A key to the two subspecies, diagnostic characters, a distribution map and illustrations of various macro- and micromorphological features are provided.

Abstract: The new species Wellstedia robusta, from mountain ridges and slopes south-west of Qandala in north-eastern Somalia, is described and illustrated.