Two new species of Tulostoma from the tropical dry forest of Mexico

Mexican dry ecosystems, mainly tropical dry forests, harbor a vast and largely undiscovered fungal diversity. The stalked puffballs of Tulostoma (Basidiomycota: Agaricales) are highly cryptic, necessitating detailed and expert examination to accurately distinguish the species. A revision of the MEXU national fungarium and recent sampled specimens revealed fruiting bodies that did not match any known species. This led us to propose T. parvirufula and T. chamelensis as new species. Six collections were morphologically characterized using two microscopy techniques: light and scanning electron microscopy. DNA was extracted, the nuc rDNA internal transcribed spacer region ITS15.8S-ITS2 (ITS barcode) and D1–D2 domains of the nuc 28S rDNA were amplified and sequenced. Phylogenetic analyses were conducted using maximum likelihood and Bayesian inference methods, incorporating sequences from previous studies. Tulostoma chamelensis is distinguished by its medium-sized spore sac, a hyphal exoperidium that persists at the base, a tubular ostiole, and verrucose to subreticulate basidiospores. Tulostoma parvirufula is characterized by minute spore sacs, a tubular ostiole, a hyphal exoperidium, a reddish-brown endoperidium, and spiny basidiospores. Phylogenetic analyses place both species in a sister clade to clade 11, alongside other taxa with tubular ostioles and coarsely ornamented basidiospores, further expanding our understanding of the Tulostoma genus and its diversity in dry ecosystems.