Abstract
Coniochaeta (Coniochaetaceae, Ascomycota) is a diverse genus that includes a striking richness of undescribed species with endophytic lifestyles, especially in temperate and boreal plants and lichens. These endophytes frequently represent undescribed species that can clarify evolutionary relationships and trait evolution within clades of previously classified fungi. Here we extend the geographic, taxonomic, and host sampling presented in a previous analysis of the clade containing Coniochaeta endophytica, a recently described species occurring as an endophyte from North America; and C. prunicola, associated with necroses of stonefruit trees in South Africa. Our multi-locus analysis and examination of metadata for endophyte strains housed in the Robert L. Gilbertson Mycological Herbarium at the University of Arizona (ARIZ) (1) expands the geographic range of C. endophytica across a wider range of the USA than recognized previously; (2) shows that the ex-type of C. prunicola (CBS 120875) forms a well-supported clade with endophytes of native hosts in North Carolina and Michigan, USA; (3) reveals that the ex-paratype for C. prunicola (CBS 121445) forms a distinct clade with endophytes from North Carolina and Russia, is distinct morphologically from the other taxa considered here, and is described herein as Coniochaeta lutea; and (4) describes a new species, Coniochaeta palaoa, here identified as an endophyte of multiple plant lineages in the highlands and piedmont of North Carolina. Separation of CBS 120875 and CBS 121445 into C. prunicola sensu stricto and C. lutea is consistent with previously described genomic differences between these isolates, and morphological and functional differences among the four species (C. endophytica, C. prunicola, C. palaoa, and C. lutea) underscore the phylogenetic relationships described here. The resolving power of particular loci and the emerging perspective on the host- and geographic range of Coniochaeta and the C. endophytica / C. prunicola clade are discussed.
Highlights
Fungal endophytes occur in healthy tissues of plants worldwide (Rodriguez et al 2009)
Our work provides evidence based on multiple loci, coupled with morphological data, that the C. prunicola / C. endophytica clade contains at least four species: C. endophytica, for which this study expands the number of known isolates and the known geographic range; C. prunicola, here enriched with endophytes and retaining the ex-type CBS 120875; and two new species
Phylogenetic analyses of endophytes within the C. endophytica / C. prunicola clade reveal four distinct lineages based on maximum likelihood and parsimony analyses of the concatenated dataset (ITS rDNA, actin-related protein 3 (ACT), glyceraldehyde-3-phosphate dehydrogenase (GPD), translation elongation factor 1-alpha (TEF-1a), and RPB2) (Fig. 1)
Summary
Fungal endophytes occur in healthy tissues of plants worldwide (Rodriguez et al 2009). As described in Harrington et al (2019), Coniochaeta is a diverse genus with species that inhabit a wide range of substrates, including butter, dung, wood, soil, uranium mine wastewater, lichens, and healthy, diseased, or senescent tissues of mosses, ferns, conifers, and angiosperms (see Weber 2002; García et al 2006; del Olmo Ruiz 2012; Rafa et al 2012; Vázquez-Campos et al 2014; Xie et al 2015; Chen 2017; U’Ren et al 2019). Harrington et al (2019) notes the teleomorph-anamorph connection of Coniochaeta and Lecythophora, significant in this context because of the high isolation frequency of morphologically cryptic, asexually reproducing fungi in endophyte surveys (Melin & Nannfeldt 1934; Gams & McGinnis 1983; Weber 2002; del Olmo Ruiz 2012; Khan et al 2013; Réblová et al 2016)
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