Abstract The family Trypetheliaceae is a diverse lineage of crustose lichenized fungi occurring almost exclusively in the tropics. Based on material collected in eastern Colombia in the region of the so-called Piedemonte Llanero, we describe here a new species for this family, in the genus Marcelaria , the fourth species known in the genus. The new species, Marcelaria casanarensis , is characterized by a clear hamathecium and large ascospores, similar to the neotropical M. purpurina , but it produces orange instead of red superficial pigmentation, outwardly agreeing with the two paleotropical species, M. benguelensis and M. cumingii. The new species thus appears to provide a morphological link between the currently known neotropical and paleotropical taxa. However, the pigment chemistry is closer to that of M. purpurina , so the orange colour is to be interpreted as homoplasy. Phylogenetically, based on an analysis of two markers, M. casanarensis and M. purpurina are closely related but M. casanarensis differs in two larger insertions in two different regions of the mitochondrial small subunit rDNA (mtSSU). A key to the four species currently accepted in Marcelaria is presented.
Torres et al. (Thu,) studied this question.