Morphology, phylogeny, and sexual stage of <i>Fusarium caatingaense</i> and <i>Fusarium pernambucanum</i>, new species of the <i>Fusarium incarnatum-equiseti</i> species complex associated with insects in Brazil

Based on morphological and molecular phylogenetic markers and the fertility of sexual crosses, two novel species of <i>Fusarium</i> associated with <i>Dactylopius opuntiae</i> (Hemiptera: Dactylopiidae) and <i>Aleurocanthus woglumi</i> (Hemiptera: Aleyrodidae) from northeastern Brazil are described as <i>Fusarium caatingaense</i> and <i>F. pernambucanum</i>. Partial sequences of five loci were generated for 29 entomopathogenic <i>Fusarium</i> isolates. Multilocus phylogenetic analyses demonstrated that <i>F. caatingaense</i> and <i>F. pernambucanum</i> belong to the Incarnatum clade of the <i>Fusarium incarnatum-equiseti</i> species complex (FIESC). These species displayed common morphological characters such as the production of various types of aerial conidia formed on monophialides and polyphialides and differ from each other mainly in the dimensions and morphology of their sporodochial conidia. Mating type polymerase chain reaction (PCR) revealed 17 <i>MAT1-1</i> isolates and 12 <i>MAT1-2</i> isolates, all of them heterothallic. Fertile perithecia were produced in 4.2% of infraspecific crosses of <i>F. caatingaense</i> and in 13.3% of infraspecific crosses of <i>F. pernambucanum</i> after 2–3 wk. Crosses between <i>F. caatingaense</i> and <i>F. pernambucanum</i> did not result in fertile perithecia. We demonstrate the existence of a sexual stage in species of the Incarnatum clade and describe the morphological characters of these sexual morphs for the first time. These results suggest that previously unknown sexual cycles contribute to the high genetic diversity within FIESC.