Two new common, previously unrecognized species in the Sticta weigelii morphodeme (Ascomycota: Peltigeraceae)

Sticta is a subcosmopolitan genus most diverse in the tropics. Traditionally, many taxa were considered to be widespread and morphologically variable, following broadly circumscribed morphodemes. Among these is the S. weigelii morphodeme, characterized by a cyanobacterial photobiont and rather narrow, flabellate to truncate or tapering lobes producing predominantly marginal isidia. Molecular phylogenetic analyses focusing on the ITS fungal barcoding marker revealed that this morphodeme represents several species, some of which are only distantly related to each other. Here we describe two species and one subspecies of this morphodeme as new to science, based on analysis of 400 specimens, for 344 of which we generated ITS barcoding data. The two new species, S. andina and S. scabrosa, are broadly distributed in the Neotropics and also found in Hawaii, where the latter is represented by the new subspecies, S. scabrosa subsp. hawaiiensis; in the case of S. andina, the species is also found in the Azores. Sticta andina exhibits high phenotypic variation and reticulate genetic diversification, whereas the phenotypically rather uniform S. scabrosa contains two main haplotypes, one restricted to Hawaii. Sticta andina occurs in wellpreserved montane to andine forests and paramos, whereas the two subspecies of S. scabrosa are found in tropical lowland to lower montane forests, tolerating disturbance and extending into anthropogenic habitats.

Automated summary

Sticta is a subcosmopolitan genus with the greatest diversity in the tropics. Molecular phylogenetic analyses have revealed that the S. weigelii morphodeme actually represents several species, with high phenotypic and genetic variation. Two new species and one new subspecies within this morphodeme have been described, with broad distribution in the Neotropics and Hawaii. The species show differences in habitat preference and genetic diversity.