Towards a natural classification of Ophiobolus and ophiobolus-like taxa; introducing three novel genera Ophiobolopsis, Paraophiobolus and Pseudoophiobolus in Phaeosphaeriaceae (Pleosporales)

Abstract

Ophiobolus is a large genus of Phaeosphaeriaceae comprising more than 350 possible species, most of which are saprobes on herbaceous plants in Europe and North America. Ophiobolus species are polyphyletic and the type of Ophiobolus is not represented in GenBank. Therefore, an increased taxon sampling of ophiobolus-like taxa and epitypification of the type species, O. disseminans is reported. Multigene phylogenetic analyses of combined LSU, SSU, TEF1-α and ITS sequence data position O. disseminans in a sister clade with O. ponticus and several Entodesmium species in Phaeosphaeriaceae with high support. Therefore, Entodesmium is synonymized under Ophiobolus. Premilcurensis with it type species, P. senecionis also clusters within the Ophiobolus clade and is synonymized under Ophiobolus. Ophiobolus rossicus sp. nov. is introduced and a reference specimen is designated for O. ponticus. Other ophiobolus-like taxa (Ophiobolus sensu lato) can be distinguished as three main groups, which are introduced as new genera. Ophiobolopsis is introduced to accommodate the new species, Ophiobolopsis italica. The new genus Paraophiobolus is introduced to accommodate P. arundinis sp. nov. and P. plantaginis comb. nov. This genus is characterized by hyaline to pale yellowish ascospores, some green-yellowish at maturity, with a swollen cell, terminal appendages and ascospores not separating into part spores. Pseudoophiobolus gen. nov. is introduced to accommodate six new species and two new combinations, viz. Ps. achilleae, Ps. erythrosporus, Ps. galii, Ps. italicus, Ps. mathieui, Ps. rosae, Ps. subhyalinisporus and Ps. urticicola. Pseudoophiobolus is characterized by subhyaline to pale yellowish or yellowish ascospores, with a swollen cell, lack of terminal appendages and ascospores that do not separate into part spores and is related to Nodulosphaeria. An updated tree for Phaeosphaeriaceae based on multigene analysis is also provided.