Morphological and molecular analyses reveal two new species of Microcera (Nectriaceae, Hypocreales) associated with scale insects on walnut in China

The fungal genus Microcera consists of species mostly occurring as parasites of scale insects, but are also commonly isolated from soil or lichens. In the present study, we surveyed the diversity and assess the taxonomy of entomopathogenic fungi in Sichuan Province, China. Two new species of Microcera, viz. M. chrysomphaludis and M. pseudaulacaspidis, were isolated from scale insects colonising walnut (Juglans regia). Maximum Likelihood and Bayesian Inference analyses of ITS, LSU, tef1-α, rpb1, rpb2, acl1, act, tub2, cmdA and his3 sequence data provide evidence for the validity of the two species and their placement in Nectriaceae (Hypocreales). Microcera pseudaulacaspidis primarily differs from similar species by having more septate and smaller cylindrical macroconidia, as well as DNA sequence data. Meanwhile, Microcera chrysomphaludis has elliptical, one-septate ascospores with acute ends and cylindrical, slightly curved with 4–6 septate macroconidia up to 78 µm long. Morphological descriptions with illustrations of the novel species and DNA-based phylogeny generated from analyses of multigene dataset are also provided to better understand species relationships.