Plagiomnium guizhouense Y.-J.Yi & S.He sp. nov. (Mniaceae) found in southwestern China

A new species of Plagiomnium (Mniaceae), P. guizhouense Y.-J.Yi & S.He from Guizhou, China is described and illustrated. The new species is similar to P. affine in having spinosely serrate leaf margins with teeth consisting of up to 4 or more cells, a broadly elliptic leaf shape, and a decurrent leaf base, but is distinguished from the latter species by having a cuspidate leaf apex, broader marginal differentiation with borders consisting of 4–5 rows of linear, thick-walled cells, strongly ciliate marginal teeth that are sometimes branched and up to 7 cells long in upper fertile stem leaves and perichaetial leaves, and a much shorter leaf costa that ends just above mid-leaf in the lower leaves.