Polyphyletic origins of species of the anamorphic genus Geosmithia and the relationships of the cleistothecial genera: Evidence from 18S, 5S and 28S rDNA sequence analyses

Abstract

The anamorphic genus Geosmithia, with the type species G. lavendula, includes species strictly lacking a teleomorph as well as species associated with the teleomorphs Talaromyces and Chromocleista. Our 18S rDNA sequence-based tree, inferred from 1586 alignable sites from 57 selected taxa within the Ascomycota and using two basidiomycetes as out-groups, clearly demonstrates that Geosmithia is a polyphyletic taxon with evolutionary affinities to at least three groups of the euascomycete lineage within the Ascomycota: (1) Geosmithia lavendula, the type of the genus, G. putterilli, and the hypocrealean fungi, Gliodadium-producing Hypocrea lutea and Verticillium/Sepedonium-producing Hypomyces chrysogenum within the pyrenomycete lineage, appear as a monophyletic group with 100% bootstrap support; (2) G. cylindrospora and the Geosmithia-producing Talaromyces species (i.e., T. bacillisporus, T. ebruneus, and T. emerson- ii) group with the Penicillium-producing T. flavus var. macrosporus of the Trichocomaceae within the plectomycete lineage in 57% of bootstrap replicates; (3) G. namyslowskii, the Geosmithia-producing Chromocleista malachitea, the Penicillium-producing Eupenicillium crustaceum and the Merimbla-producing Talaromyces avellaneus (≡ Hamigera avellanea) of the same higher categories appear to be a monophyletic group in 74% of bootstrap replicates. The bootstrapped NJ and MP analyses, using 1706 sites of the same gene only from plectomycetes and pyrenomycetes, demonstrate similar phylogenetic relationships. The bootstrapped NJ and MP analyses, based on 70 alignable sites of 5S rDNA, support the results from 18S rDNA sequence analyses. Within the Hypocreales, G. lavendula and G. putterillii group with the hypocrealean fungi, cleistothecial, Acremonium-producing Mycoarachis inversa and Emericellopsis terricola, and the strictly anamorph species of Acremonium-in 66% or greater of the bootstrapped NJ and MP trees derived from 28S rDNA partial (580 sites) sequences. Phylogenetic considerations are also presented for several cleistothecial taxa.