Geastrum minutisporum sp. nov. from Polylepis australis woodlands in central Argentina

•We describe a new species from Argentina: Geastrum minutisporum.•It was collected in the endangered ecosystem of Polylepis australis woodlands.•Molecular and morphological analyses support G. minutisporum as a new species.•We discuss on the position of the new species within Geastrum species.•We provide full plates to illustrate G. minutisporum.

Geastrum minutisporum is characterized by a basidioma up to 25 mm wide, exoperidium saccate to planar, non-hygroscopic; a globose to subglobose, sessile and greyish brown endoperidium; a silky fibrillose peristoma, lighter or darker than the endoperidium and with globose, slightly asperulate basidiospores, 2–2.5–3 μm in diam, with a short apiculus up to 0.5 μm long. Specimens were collected at the Reserva Hídrica Provincial Pampa de Achala located in the upper portion of Sierras Grandes from Córdoba, central Argentina. Morphology and phylogenetic analysis based on sequences of the ribosomal DNA internal transcribed spacer region support Geastrum minutisporum as a new species.