Two new species of Zygotritonia Mildbr. (Iridaceae: Crocoideae) from eastern tropical Africa with notes on the morphology of the genus

Abstract

The tropical African genus Zygotritonia Mildbr., now with six species, extends from the Fouta Djalon highlands of Guinea in West Africa to southern South Sudan, southern Congo, northern Malawi, Tanzania, Zambia, and western Ethiopia. Two new species are described: Zygotritonia benishangula Goldblatt & Sebsebe from western Ethiopia has a basal foliage leaf clasping the stem up to the base of the spike or first branch, with a short, closely pleated-foliose blade that differs from the simply pleated blades of most other species; Zygotritonia teretifolia Goldblatt & J.C. Manning from the Uzondo Plateau, Mpanda District, Tanzania, is distinguished by its narrow, compressed-terete leaves and short stature, up to 200mm high. Flowers of both Z. benishangula and Z. teretifolia conform to those of other species of the genus in their small size, bilateral symmetry with large hooded dorsal tepal and much shorter, spooned lower tepals. The style in both species ultimately divides into three short branches, not undivided as has been described for other species of Zygotritonia.