Cryptic diversity in the sequestrate genus Stephanospora (Stephanosporaceae: Agaricales) in Australasia.

Historically a single name, Stephanospora flava, was applied to all collections of Stephanospora in Australasia. We used morphological characters with molecular support to differentiate and describe nine novel cryptic species, and refine the circumscription of S. flava. Stephanospora flava is herein restricted to bispored collections from Tasmania, and the quadrisporic Stephanospora tetraspora is raised to species level. Six species (four new) are endemic to Australia, S. flava s.s, S. tetraspora comb. nov., Stephanospora sheoak, Stephanospora cribbae, Stephanospora hystrispora, and Stephanospora occidentiaustralis. Three species Stephanospora poropingao, Stephanospora pounamu, and Stephanospora kanuka are endemic to New Zealand; and one species, Stephanospora aorangi occurs in both Australia and New Zealand. Two other new species, Stephanospora novae-caledoniae and Stephanospora papua, are endemic to New Caledonia or Papua New Guinea, respectively. Analyses of three nuclear gene regions (ITS, ef-1, and LSU) are consistent with current classifications of the family Stephanosporaceae. Athelidium aurantiacum is an outlier, with a strongly supported core of Cristinia (Clade I), Lindtneria (Clade II), Stephanospora, Mayamontana, and Lindtneria trachyspora (Clade III), and a novel lineage of environmental and sporocarp sequences (Clade IV). Taxonomic and nomenclatural issues raised by the presence of both type species of Stephanospora (Stephanospora caroticolor) and Lindtneria (L. trachyspora) in the same clade are discussed.