On the status of Bazzania madagassa (Marchantiophyta: Lepidoziaceae) from Madagascar

Madagascar is a center of diversity in Africa for the liverwort genus Bazzania Gray (1821: 704), with about 80% of African Bazzania species (11 out of 14 spp.) occurring on Madagascar and about half of them being endemic to the island (Wigginton 2018, Sass-Gyarmati & Pocs 2019, 2021; Sass-Gyarmati & Reeb 2021). In this paper we deal with the taxonomic and nomenclatural status of Bazzania madagassa (Stephani 1924: 473) Arnell (1965: 66), a species known only from Madagascar. This species was first described by Stephani (1924) as Mastigobryum madagassum Stephani (1924: 473) and was transferred to Bazzania by Arnell (1965). The new combination Bazzania madagassa was not validly published there, however, because the basionym was not cited. Ten years later, Jones (1975) suggested that B. madagassa might be a synonym of the common and variable B. decrescens (Lehm. & Lindenb., in Lehmann 1832: 57) Trevisan (1877: 414), but the type specimen of B. madagassa was not studied. A phytochemical analysis, however, showed that B. madagassa differs from B. decrescens in the presence of myltaylane- and cyclomyltaylane-type sesquiterpenes (Harinantenaina et al. 2005, 2006). The latter are rare metabolites that have also been detected in B. japonica (Sande Lacoste 1864: 303) Lindberg (1872: 224) and B. tridens (Reinwardt, Blume & Nees 1824: 228) Trevisan (1877: 415), but not in B. decrescens. As the name B. madagassa is invalid, the species was not included in the World Checklist (S8derstr8m et al. 2016). In the course of the work of the first author on Bazzania in Madagascar, we have studied the type of B. madagassa and found that the species merits recognition. The purpose of this paper is to validate and lectotypify the name Bazzania madagassa and provide a description and illustration of the species together with a brief discussion of its taxonomic affinity.