Psoroma capense and P. esterhuyseniae (Pannariaceae), two new alpine species from South Africa

Abstract

The new species Psoroma capense and P. esterhuyseniae are described from altogether four alpine localities in the Western Cape Province of South Africa, and are the only known Psoroma species from Africa. The specimens were all collected from moist sites near watercourses, in cool and mostly south-facing cliffs. Psoroma capense has a gross morphology resembling that of P. tenue, although it has ascending thallus squamules and lack secondary compounds, in addition to having shorter and ellipsoid to ovoid ascospores. However, a phylogenetic analysis involving the markers ITS, nucLSU, mtSSU, and MCM7, comparing the only recent collection of P. capense with previously published sequences, show that the species instead belongs to the P. hypnorum lineage. Here it does not appear to have any known, closely related species, discussed among candidates originating from three major migration routes northwards from a hypothesized evolutionary origin in Antarctica. Psoroma esterhuyseniae instead resembles P. hypnorum, but has subglobose to short-ellipsoid ascospores without apical perispore extensions. The two species are thought to have evolved from one or two long-distance dispersal events during the Pleistocene.