Two new endophytic species enrich the Coniochaeta endophytica / C. prunicola clade: Coniochaeta lutea sp. nov. and C. palaoa sp. nov.

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.