Abstract
Diplomaragnidae are currently represented in Japan by ten species in three genera. One species is described here as new to science: Tokyosoma flexuosum sp. n. Maritimosoma hokkaidense (Verhoeff, 1939) is returned to Diplomaragna: Diplomaragna hokkaidensis (Verhoeff, 1939). The distributions of the Japanese species of Diplomaragnidae are mapped.