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United States Department of Agriculture

Agricultural Research Service

Research Project: Systematics and Diagnostics of Emerging and Quarantine-Significant Plant Pathogenic Fungi

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Title: Pseudocosmospora, a new genus to accommodate Cosmospora vilior and related species

item Herrera, Caesar
item Rossman, Amy
item Samuels, Gary
item Chaverri, Priscila

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2013
Publication Date: 4/4/2013
Citation: Herrera, C., Rossman, A.Y., Samuels, G.J., Chaverri, P. 2013. Pseudocosmospora, a new genus to accommodate Cosmospora vilior and related species. Mycologia. 105(5):1287-1305.

Interpretive Summary: Fungi are a large and diverse group of organisms that cause serious diseases of crops and forest plants. Some fungi that cause diseases can be controlled by other fungi that parasitize them. In this paper a group of fungi were studied that live on other fungi that cause canker diseases of woody crops such as grapes and nut trees. Isolates of the parasites were characterized using sequences of several genes and analyzed to determine what species exist and how they are related. It was determined that each group of canker pathogen harbors a different species of fungal parasite. Because the group of fungi parasitizing the canker pathogens is different from anything known, they are described in a new genus. The new genus is named and described and each species in the genus is described and illustrated. This research will be used by plant pathologists to determine if these parasites can be used to control canker diseases of grapes and nut trees.

Technical Abstract: Cosmospora sensu Rossman accommodated nectroid fungi with small, reddish, smooth, thin-walled, laterally collapsing when dry, non- or weakly stromatic perithecia. Recently, the group was found to be polyphyletic based on molecular data, and has been segregated into multiple genera. Not all Cosmospora-like fungi have been treated systematically. Some of these species include C. vilior and many specimens often labeled as “Cosmospora sp.” The objectives of this research were to establish the identity of C. vilior through epitypication using a recent collection that agrees with the type specimen in morphology, host and geography, and to determine its phylogenetic position within Cosmospora sensu lato and the Nectriaceae. A multilocus phylogeny was constructed based on six loci (ITS, LSU, MCM7, rpb1, tef1, and tub) to estimate a phylogeny. Results from the phylogenetic analyses indicated that C. vilior forms a monophyletic group with other cosmopora-like fungi that have an acremonium-like anamorph and that parasitize Eutypa and Eutypella (Ascomycota, Sordariomycetes, Xylariales, Diatrypaceae). The group is phylogenetically distinct from other previously segregated genera. A new genus, Pseudocosmospora, is described to accommodate the type species, P. eutypellae, and nine additional species in this clade.

Last Modified: 06/23/2017
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