Heterocyphelium leucampyx (Arthoniales, Ascomycota): another orphaned mazaediate lichen finds its way home

Abstract

Heterocyphelium is a mazaediate genus containing a single species, H. leucampyx. The species was originally described from Cuba within the genus Trachylia (Arthoniales, Arthoniaceae) and later placed in various genera of the collective order Caliciales s. lat. For the past three decades, Heterocyphelium was considered an orphaned genus (incertae sedis) within the Ascomycota, since morphology alone could not resolve its systematic position. In this study, we added molecular data with the aim of resolving this uncertainty. Bayesian and maximum likelihood analyses of newly generated sequence data from the mitochondrial ribosomal RNA small subunit (mtSSU) and the RNA polymerase II second largest subunit gene (RPB2) provide clear evidence that Heterocyphelium leucampyx is nested within the order Arthoniales, in the family Lecanographaceae, sister to the genus Alyxoria. Heterocyphelium is a further example of parallel evolution of passive spore dispersal, prototunicate asci and the occurrence of a mazaedium in the Ascomycota, and another calicioid genus whose systematic placement could be eventually clarified by means of molecular data. Heterocyphelium is the fourth mazaediate genus in Arthoniales, in addition to Sporostigma, Tylophorella and Tylophoron.