Discovery of Pleurotus cystidiosus (Agaricales, Pleurotaceae) in the north of Mexico

Abstract

Background and Aims: Some species of Pleurotus form anamorphs that produce coremia and arthrospores, which are classified in the subgenus Coremiopleurotus and are morphologically very similar. In Mexico, seven species of the genus are known; however, only P. smithii, described from Mexico City, is known to form coremia. Recent collections of Pleurotus from Chihuahua, Mexico, showed distinct characteristics from the known species for the country, whose morphological and molecular characterization allowed us to identify P. cystidiosus in Mexico. The objective of this work was to document the presence of P. cystidiosus in Mexico and provide a detailed description of the specimens found in the country. Methods: The material was collected in Ciudad Juárez, Chihuahua, Mexico. Specimens were characterized macro- and microscopically through in situ photographs, polyfocal, and light microscopy. Morphological identification was performed using specialized literature. DNA extraction was carried out following a 3% CTAB protocol. The ITS region was amplified using the primer pairs ITS5/ITS4. Phylogenetic analyses were conducted using Maximum Likelihood and Bayesian Inference. Key results: Pleurotus cystidiosus, a species previously unreported in Mexico, is morphologically and taxonomically described, confirmed with barcode sequences. The species is distinguished by the presence of abundant clavate to pyriform pleurocystidia and subglobose cheilocystidia in the teleomorph, as well as the formation of coremia with a white stipe, black head, and segments of arthrospores up to 17-25 × 5-7.5 µm in the anamorph. Conclusions: The presence of P. cystidiosus in the north of Mexico is confirmed. With this study, the number of known Pleurotus species for Mexico increases to eight.