Unveiling the cryptic Neotropical species of Phaeoclavulina from the Southern Cone: phylogenetic and morphological analysis.

Global fungal diversity is estimated at about 6.2 million species, but only 150 000 are currently described. Molecular studies reveal that this diversity is often underestimated, especially in less-studied regions. Phaeoclavulina, a genus of ramarioid fungi, has a wide distribution in areas with temperate and tropical climates. However, in southern South America, research on Phaeoclavulina species has been scarce, with only a few studies conducted in Argentina covering the morphology of a few species. This research aims to analyze Phaeoclavulina species in Argentina, exploring their morphology, ecological roles, and distribution. Four different ecological regions across Argentina were sampled. Molecular data (Sanger and next-generation sequencing [NGS] technology) were obtained to construct their phylogenetic relationships. Our results show a greater diversity of Phaeoclavulina than previously known. Eight taxa are described here, four of which are new species to science (Phaeoclavulina aena, P. angularis, P. prasina, and P. stelligera). Additionally, a neotypification is proposed for Phaeoclavulina camellia. For the other three species (P. articulotela, P. campoi, and P. minutispora), we provide new molecular data and elucidate their phylogenetic relationships with other previously described species. In addition, a key to species of Phaeoclavulina from Argentina and Chile is included to facilitate identification of known taxa. Finally, most Phaeoclavulina species richness is associated with tropical and subtropical forests.