We describe a new species of Rhodocybe, R. brunneoaurantiaca, from West Bengal, India. Field photographs of the collected basidiocarps are provided and the new species is compared with its allied taxa based on morphological and molecular (nrITS and nrLSU sequence) data. Rhodocybe brunneoaurantiaca is characterized by clitocyboid basidiomata with a small (25–41 mm), infundibuliform, brownish orange to brown pileus; decurrent, brittle, greyish orange to light brown lamellae; a smooth light brown to brown stipe; ellipsoid to broadly ellipsoid basidiospores; 2–4-spored basidia; cylindrical to slender clavate, flexuous cheilocystidia; and unique sequences. A full description with illustrations, and phylogenetic trees showing the placement of the new species based on molecular sequence data are provided as well as an artificial key to the reported species of Rhodocybe from India.

Morphological studies

Specimens were collected from the Burdwan district of the state West Bengal in August 2019; a detailed description of the macro-morphological features was made from the fresh collections. Colour determination codes followed Kornerup and Wanscher (1978). Collected specimens were taken to the laboratory and dried by a cost effective, handmade field drier using a 40-watt bulb as the heat source (40–50°C). 
To examine the microscopic features, thin handmade sections were made from different parts of the dried basidiomata and rehydrated in 5% KOH and distilled water and stained with Congo Red. Melzer’s reagent was used to test the amyloid or inamyloid nature of the basidiospores. Measurements of the basidiospores were based on 30 spores from each of the two collections. Basidiospore measurements exclude the apiculus. Minimum and maximum measured values are given in parentheses. Xm denotes mean spore length ± SD × mean spore width ± SD. Q values were calculated from length/width ratio of each of the measured basidiospores and are provided as range variation. Qm denotes mean of Q values ± SD. The holotype specimen was deposited in the Central National Herbarium, Howrah (CAL) and the paratype specimen was deposited in the Calcutta University herbarium (CUH).

DNA extraction, PCR amplification and sequencing

Genomic DNA was extracted following Dutta et al. (2020). The primer pairs, ITS1/ITS4 (White et al. 1990) and LR0R/LR3 (Vilgalys and Hester 1990), were used for selective amplification of the nrITS and nrLSU regions. The PCR cycling conditions for the amplification of desired regions followed Dutta et al. (2015b). Sequencing of the amplified regions was done using the same primers used for PCR amplifications. The qualities of the generated sequences were determined by observing the chromatogram with BioEdit v. 7.2.5 (Hall 1999). The newly generated sequences were deposited in GenBank (<www.ncbi.nlm.nih.gov>), and their accession numbers along with details of vouchers are listed in Table 1.