Two new species of <i>Tulostoma</i> 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 <i>Tulostoma</i> (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 <i>T. parvirufula</i> and <i>T. chamelensis</i> 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. <i>Tulostoma chamelensis</i> is distinguished by its medium-sized spore sac, a hyphal exoperidium that persists at the base, a tubular ostiole, and verrucose to subreticulate basidiospores. <i>Tulostoma parvirufula</i> 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 <i>Tulostoma</i> genus and its diversity in dry ecosystems.