Russula brunneoaurantiaca, a novel taxon of Russula subg. Crassotunicata from West Bengal, India, with morpho-molecular analysis and scanning electron microscopy.

This paper describes a new Russula species, R. brunneoaurantiaca, from India with morphological and molecular sequence (nrITS) data, field pictures of basidiocarps, and comparisons with close relatives. Russula brunneoaurantiaca has a brownish orange pileus with a mucilaginous surface, sub-decurrent lamellae that are white to pale orange, a white stipe that turns yellowish brown to brown when bruised, a strong, unpleasant smell, globose to subglobose basidiospores (5.0-9.0 5.0-7.8 m) with an inamyloid suprahilar spot and ornamentation of small isolated conical warts, fusiform hymenial cystidia on gill sides (62.5-82 × 7.5-12.5 μm) and lageniform to sub-lageniform cystidia with filiform apex near the gill edge (80-113 × 7.5-10 μm), fusiform to spindle-shaped pileocystidia, and habitat in association with Castanopsis sp. A complete morphological description, photographs, and molecular sequence-based phylogenetic trees demarcating the position of the novel taxon are provided. RESEARCH HIGHLIGHTS: Scanning electron microscopy (SEM) and subsequent DNA analysis revealed a new species of the genus Russula. SEM analysis is an additional technique to describe the size and shape of its basidiospores as well as their ornamentation. The diagnostic characteristics, habit, habitat, and similarities to related species are given.