Coprinopsis asiaticiphlyctidospora sp. nov., an agaric ammonia fungus from Amami and Okinawa, southern Japan

•A new ammonia fungus, Coprinopsis asiaticiphlyctidospora is described.•This new taxon belongs to the C. phlyctidospora species complex.•This new species is distinguished from the related one in basidiospore morphology.

Coprinopsis asiaticiphlyctidospora (Basidiomycota, Psathyrellaceae), is a new Coprinoid ammonia fungus from Amami and Okinawa, Japan. In macro- and micro-morphology, this species is similar to C. phlyctidospora and C. austrophlyctidospora, but differs in having smaller basidiospores and spiny basidiospore ornamentation. Phylogenetic analysis with the nuclear ribosomal internal transcribed spacer (ITS) data also supports this new taxon.