A new species of Kosteletzkya (Hibisceae, Malvoideae, Malvaceae) and notes on a second species, both from eastern Democratic Republic of the Congo

摘要

A new species, Kosteletzkya rotundalata, is described from northeastern Democratic Republic of the Congo. A second species, K. borkouana, originally characterized as endemic to northern Chad, is here documented from several localities in the AlbertineRift of eastern Democratic Republic of the Congo. Kosteletzkya Presl (1835: 130; Hibisceae, Malvoideae, Malvaceae) is a genus of 17 species that are distributed mainly in Africa and the northern Neotropics, with outliers in the southeastern United States and the Philippines. The plants are mostly herbaceous perennials or subshrubs with small Hibiscus-like flowers and a tendency toward locally moist habitats. Kosteletzkya falls within the complexly paraphyletic Hibiscus Linnaeus (1753: 693; Pfeil & Crisp 2005), but it has depressed, pentagonal capsules that disintegrate at maturity and contain one seed per locule. These characters combine to uniquely distinguish the genus within the tribe Hibisceae. Chromosome numbers, all of which are based on jc = 19, support the morphological circumscription of the genus. Recent counts have identified a polyploid series in Africa that suggests that the genus originated there (Blanchard 2012). Several other taxa described under Kosteletzkya, and especially those unique to Madagascar, have their true affinities elsewhere (Blanchard unpublished data; Koopman & Baum 2008).