Hidden diversity of powdery mildews belonging to the recently re-discovered genus Salmonomyces

Powdery mildew on various Acalypha spp. has previously been assigned to Erysiphe acalyphae (≡ Uncinula acalyphae). In a recently published phylogenetic-taxonomic reassessment, it has been revealed that sequences retrieved from this Acalypha powdery mildew form a separate lineage representing a genus of its own for which the old genus name Salmonomyces was reinstated, with the new combination Salmonomyces acalyphae. Pseudoidium javanicum, described from Indonesia on Acalypha javanica, was reduced to synonymy with Salmonomyces acalyphae. Attempts to obtain sequence data from type material of Uncinula acalyphae, described from Kunming, Yunnan Province, China, on Acalypha supera (= Acalypha brachystachya), and efforts to collect fresh Chinese samples for epitypification purposes failed during the course of the works for the abovementioned studies. Therefore, the name Salmonomyces acalyphae was applied to all collections on Acalypha, first and foremost on the basis of the congruence of the morphological characteristics of the asexual morphs on Acalypha supera and other Acalypha spp. Meanwhile, attempts to trace new collections of this powdery mildew on Acalypha supera in Kunming, Yunnan Province, were successful and allow epitypification of Uncinula acalyphae with ex-epitype sequence data. Phylogenetic analyses surprisingly revealed the hidden diversity that two sister species are involved within Salmonomyces, viz., Salmonomyces acalyphae with both anamorph and teleomorph, confined to Acalypha supera in South China as host, and a second species, so far only known as anamorph, with wider host range and distribution, for which the new combination Salmonomyces javanicus, based on Pseudoidium javanicum, being introduced.