Morphological Studies and Phylogenetic Analyses Unveil Two Notable New Species of Russula Subg. Heterophyllinae from China

Russula, a prominent genus of ectomycorrhizal fungi, is notably abundant and diverse in China. We present here the findings from studies on various Chinese Russula collections. Two notable species within subg. Heterophyllinae, namely Russula leucoviridis and R. subswatica, were described and illustrated based on comprehensive morphological characteristics and molecular evidence. Morphologically, Russula leucoviridis is characterized by its pastel-green to green pileus center with light-yellow spots, a white to greenish-white pileus margin, and a cuticle that cracks and breaks into small green patches after maturation, whereas R. subswatica is distinguished by an infundibuliform pileus with a deeply depressed center after maturation, a light-orange to grayish-orange pileus center, and a yellowish-white to light-orange margin with a purplish to purplish-black hue, and a white to yellowish-white stipe that exhibits a purplish hue at the junction with the pileus. The phylogenetic analyses were conducted using a combined dataset of ITS, nrLSU, RPB2, and mtSSU. Relying on both morphological characteristics and multigene phylogeny, the former species is classified within subsect. Virescentinae, while the latter is affiliated with subsect. Griseinae. In this study, we provide new scientific data that enhance the comprehension of species diversity within the subgenus Heterophyllinae in China.