Plynnon Deeleman-Reinhold, 2001 is a small phrurolithid spider genus distributed in Southeast Asia, with three currently known species: P. longitarse Deeleman-Reinhold, 2001 and P. zborowskii Deeleman-Reinhold, 2001 from Borneo and P. jaegeri Deeleman-Reinhold, 2001 from Sumatra.Plynnon aduncum sp. n. (♂, ♀) from Yunnan Province, China is described, representing the northernmost record for the genus. Illustrations and morphological descriptions are provided.