Phylogeny and character evolution in the Dacrymycetes, and systematics of Unilacrymaceae and Dacryonaemataceae fam. nov.

Abstract

We present a multilocus phylogeny of the class Dacrymycetes, based on data from the 18S, ITS, 28S, RPB1, RPB2, TEF-1α, 12S, and ATP6 DNA regions, with c. 90 species including the types of most currently accepted genera. A variety of methodological approaches was used to infer phylogenetic relationships among the Dacrymycetes, from a supermatrix strategy using maximum likelihood and Bayesian inference on a concatenated dataset, to coalescence-based calculations, such as quartet-based summary methods of independent single-locus trees, and Bayesian integration of single-locus trees into a species tree under the multispecies coalescent. We evaluate for the first time the taxonomic usefulness of some cytological phenotypic characters, i.e., vacuolar contents (vacuolar bodies and lipid bodies), number of nuclei of recently discharged basidiospores, and pigments, with especial emphasis on carotenoids. These characters, along with several others traditionally used for the taxonomy of this group (basidium shape, presence and morphology of clamp connections, morphology of the terminal cells of cortical/marginal hyphae, presence and degree of ramification of the hyphidia), are mapped on the resulting phylogenies and their evolution through the class Dacrymycetes discussed. Our analyses reveal five lineages that putatively represent five different families, four of which are accepted and named. Three out of these four lineages correspond to previously circumscribed and published families (Cerinomycetaceae, Dacrymycetaceae, and Unilacrymaceae), and one is proposed as the new family Dacryonaemataceae. Provisionally, only a single order, Dacrymycetales, is accepted with in the class. Furthermore, the systematics of the two smallest families, Dacryonaemataceae and Unilacrymaceae, are investigated to the species level, using coalescence-based species delimitation on multilocus DNA data, and a detailed morphological study including morphometric analyses of the basidiospores. Three species are accepted in Dacryonaema, the type, Da. rufum, the newly combined Da. macnabbii (basionym Dacrymyces macnabbii), and a new species named Da. macrosporum. Two species are accepted in Unilacryma, the new U. bispora, and the type, U. unispora, the latter treated in a broad sense pending improved sampling across the Holarctic.

Complementary molecular methods reveal comprehensive phylogenetic diversity integrating inconspicuous lineages of early-diverged wood-decaying mushrooms

“…Although OTUs belonging to clades H, I, K, P, and Q were detected using the eDNA or culture method, their fruiting bodies were not identified at any time during this investigation. Clades I and Q, Unilacryma spp., and Dacryonaema spp., which branched deep in the phylogenetic tree, are considered to be important lineages for studying the early evolution of Dacrymycetes 29,33 . Lineages that diverged early in the phylogeny of Dacrymycetes tend to feature small or thin fruiting bodies 4,33 .…”

“…are as small as ≤ 2 mm in diameter, and Cerinomyces spp. harbour inconspicuous thin resupinate basidiocarps 29,31,34,35 . Other mushroom-forming basidiomycetes, Agaricomycetes, and Tremellomycetes, which constitute Agaricomycotina with Dacrymycetes, display variously shaped fruiting bodies, such as stipitate agaricoid, coralloid, and corticoid fruiting bodies, yet their early-diverged lineages tend to feature inconspicuous small or thin fruiting bodies 1,3 .…”

“…Molecular phylogenetic analysis. The dataset of LSU rDNA sequences was assembled to include the representative sequences of each OTU obtained using each detection method and the sequences of Dacrymycetes downloaded from the National Center for Biotechnology Information (NCBI, 30 June 2019) regarding previous studies 4,29,32,49,50 . Multiple alignments were generated using MAFFT 7 (https://mafft.cbrc.jp/alignment/server/) 51 with the G-INS-i option.…”

“…Dacrymycetes species are considered to represent an ancestral lineage of wood-decaying basidiomycetes that diverged approximately 350 million years ago 1,28,29 and brown rot fungi that are critical for understanding the early evolution of fungal wood decomposers 30 . Diversity surveys and phylogenetic analyses of Dacrymycetes have been conducted primarily based on visible fruiting bodies [29][30][31][32] . Thus, the phylogenetic position of newly obtained dacrymycetous sequences can be estimated based on accumulating reference sequences.…”

Competing sexual-asexual generic names in Agaricomycotina (Basidiomycota) with recommendations for use

“…Ditiola radicata was designated as type of Ditiola by Brongniart ( 1824 ). This species was included in a study of Dacrymyces with Ditiola radicata grouping inside Dacrymyces (Shirouzu et al 2013 ; Zamora and Ekman 2019 ), thus Ditiola is a synonym of Dacrymyces . The type specimen of the type of Pionnotes , P. capitata based on Fusarium capitatum , was re-examined by Seifert ( 2013 ) and determined to be Dacrymyces chrysospermus .…”