Four new species of Collybiopsis (Omphalotaceae, Agaricales) from subtropical regions of China

Four new species of <i>Collybiopsis</i>, namely <i>C.subpolygramma</i>, <i>C.fucata</i>, <i>C.dentata</i>, and <i>C.latispora</i>, were discovered in the subtropical regions of China. These species were identified based on morphological characteristics and molecular analysis. Morphologically, <i>C.subpolygramma</i> is characterized by its pileal surface, white in color with a light brown center; slender, cylindrical cheilocystidia; and absence of pleurocystidia. <i>C.fucata</i> is recognized by the reddish-brown, hygrophanous pileus; adnate to adnexed lamellae; and relatively broad basidiospores. <i>C.dentata</i> is identified by free lamellae, fusiform to utriform pleurocystidia, and relatively broad basidiospores. <i>C.latispora</i> is distinct by relatively broad basidiospores and a minute, snow-white ring or ruff at the stipe base. In the phylogenetic analysis based on combined ITS and LSU sequences, the four new species formed distinct and stable branches (BI-PP = 1; ML-BP = 100%), respectively. <i>Collybiopsissubpolygramma</i> formed a sister lineage with <i>C.polygramma</i>. The new species <i>C.fucata</i>, <i>C.dentata</i>, and <i>C.latispora</i> were found to be nested within the <i>C.ramealis</i> species complex clade. Detailed descriptions, color photos, and a key to related species are presented.