The genus Melanophloea, an example of convergent evolution towards polyspory

摘要

The species described in or referred to the genus Melanophloea, traditionally referred to the Thelocarpaceae, are discussed. Detailed observations on two species, including the type species, show that they have not much more in common than their polysporous ascus. Melanophloea is reduced to the type species, M. pacifica. It shows a close resemblance to Aptrootia in the Trypetheliaceae, and it is therefore tentatively referred to this family. Melanophloea americana is shown to be close to Thelenella in the Thelenellaceae. The latter species and the related M. montana are newly combined into this genus as Thelenella americana and T. montana. Thelocarpon nigrum, which was recently compared to Melanophloea, is retained in Thelocarpon in the Thelocarpaceae. Polyspory is suggested to facilitate dispersion, especially when compared to parent taxa that produce large muriform ascospores. Based on the current classification, polyspory originated at least 57 times within the lichenized ascomycetes, a clear example of convergent evolution.