Microscopic features show this species very close to Conocybe filaris. Conocybe(Pholiotina) arrhenii (ツチイチメガサ), was excluded because there is a clear germ pore on spore.  The striate of cap margin, which exist on cap surface of C. filaris,  can not be observed.  This mushroom always grows on dong of Japanese antelope. These seems to show that this is not exactly C. filaris.