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

ABSTRACT

Based on morphological and molecular phylogenetic markers and the fertility of sexual crosses, two novel species of Fusarium associated with Dactylopius opuntiae (Hemiptera: Dactylopiidae) and Aleurocanthus woglumi (Hemiptera: Aleyrodidae) from northeastern Brazil are described as Fusarium caatingaense and F. pernambucanum. Partial sequences of five loci were generated for 29 entomopathogenic Fusarium isolates. Multilocus phylogenetic analyses demonstrated that F. caatingaense and F. pernambucanum belong to the Incarnatum clade of the Fusarium incarnatum-equiseti 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 MAT1-1 isolates and 12 MAT1-2 isolates, all of them heterothallic. Fertile perithecia were produced in 4.2% of infraspecific crosses of F. caatingaense and in 13.3% of infraspecific crosses of F. pernambucanum after 2–3 wk. Crosses between F. caatingaense and F. pernambucanum 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.

KEYWORDS:

• Entomopathogenic fungi
• mating type
• polyphasic taxonomy
• sexual compatibility
• 2 new taxa

ACKNOWLEDGMENTS

We are grateful to Roger F. R. Melo for his assistance in obtaining images and preparation of the photographic plates and for suggestions on taxonomic descriptions. We thank David M. Geiser and Keith A. Seifert for encouragement and for the clarifications concerning taxonomic issues in the FIESC.

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Funding

We thank Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for the scholarship for Renan N. Barbosa. This research was supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes) (grant number 23038.007642/2011-79) and by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (grant number 486855/2013-9).