Updates on Geastrum sect. Exareolata, with a description of a striking new species from the Neotropics

Geastrum is a genus with worldwide distribution and the most species-diverse in the family Geastraceae and is easily recognized by the star-like basidioma in the majority of species. The most recent and accepted classification based on phylogenetic, morphological and chemical data, subdivided the genus into 14 sections. The section Exareolata is formed by eleven species from which only G. echinulatum and G. verrucoramulosum are truly stipitate. During field trips in Brazilian Amazonia, we found a stipitate species of Geastrum. Based on morphological and phylogenetic data, we propose it as a new species for the genus, which forms a sister group of G. verrucoramulosum and is allocated in sect. Exareolata. Geastrum squameoramulosum sp. nov. is characterized by a prominent and well-developed ramified stipe and the presence of scales on the outer surface of the exoperidium. It is known so far only from the Amazon rainforest. We also provide an updated key to the species in this section.

Automated summary

Geastrum is a worldwide distributed genus with diverse species, easily recognized by the star-like basidioma. The most recent classification subdivided the genus into 14 sections. During field trips in Brazilian Amazonia, a stipitate species of Geastrum, named Geastrum squameoramulosum sp. nov., was found. It is currently known to be the only species discovered in the Amazon rainforest.