Leptogium chibaense H.Harada in the family Collemataceae is described as new from a warm- temperate forest in Chiba-ken, central Japan. This species is closely related to /.. subtile, but the thallus consists of linear lobes with very dark grey dorsal surface, and the cortices are thinner (5 - 10 |.im). It differs ecologically by growing on rocks In the warm-temperate zone. Leptogium, lichens, new species, taxonomy