Donald H. Pfister


         Pfister CV

Our lab group does research in the area of fungal biology in which we study taxonomy, life histories, and systematics – particularly of fungi in the Pezizomycetes, the Orbiliomycetes and recently in the Laboulbeniomycetes.  We are interested in the relationships among the members of these groups, their geographic distribution, and the associations of these fungi with other organisms.  Prof. Pfister has conducted research on topics related to documentation of collections and collectors of natural history specimens; particularly in relationship to the rich and varied collections at Harvard.  Our fieldwork ranges from collecting locally to southern South America.

Recent Publications

Cones, needles and wood: Micraspis (Micraspidaceae, Micraspida/es /am. et ord. nov.) speciation segregates by host plant tissues

L, Q., et al., Forthcoming. Cones, needles and wood: Micraspis (Micraspidaceae, Micraspida/es /am. et ord. nov.) speciation segregates by host plant tissues. Fungal Systematics and Evolution , 5 , pp. 99-111.Abstract

Micraspis acicola was described more than 50 years ago to accommodate a phacidium-like fungus that caused a foliar disease of Picea mariana. After its publication, two more species were added, M. strobilina and M. tetraspora, all of them growing on Pinaceae in the Northern Hemisphere, but each species occupying a unique type of host tissue (needles, cones or wood). Micraspis is considered to be a member of class Leotiomycetes, but was originally placed in Phacidiaceae (Phacidia/es), later transferred to Helotiaceae (Helotia/es) and recently returned to Phacidiales but in a different family (Tympanidaceae). The genus remains poorly sampled, and hence poorly understood both taxonomically and ecologically. Here, we use morphology, cultures and sequences to provide insights into its systematic position in Leotiomycetes and its ecology. Our results show that the genus should not be included in Tympanidaceae or Phacidiaceae, and support the erection of a new family and order with a unique combination of morphological features supported by molecular data. 

Effectively published online: 24 September 2019. Fungal Systematics and Evolution is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License © 2020 Westerdijk Fungal Biodiversity Institute 

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Disentangling the identity of the genus Biatorellina (Leotiomycetes, Ascomycota)

Quijada, L., et al., 2019. Disentangling the identity of the genus Biatorellina (Leotiomycetes, Ascomycota). Phytotaxa , 411 (3) , pp. 183-193. Publisher's VersionAbstract
The monotypic genus Biatorellina is currently considered a taxonomic synonym of Tryblidiopsis but has an obscure and complicated history. During the revision of the genus Tympanis a syntype of Biatorellina buchsii was fortuitously found and reviewed. Initially our revision led to the hypothesis that B. buchsii could be conspecific with Tympanis confusa. A bibliographic and morphological revision, together with a biometric study, was done using the syntype of B. buchsii and specimens of Tympanisconfusa to verify the identity of the genus Biatorellina. Our results show an overlap in the morphology, biometry, distribution and ecology of B. buchsii (≡ Tympanis buchsii) and Tympanis confusa. The identity and the placement of Biatorellina is resolved and B. buchsii is proposed as a synonym of Tympanis confus.
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A multigene phylogeny toward a new phylogenetic classification of Leotiomycetes

Johnston, P.R., et al., 2019. A multigene phylogeny toward a new phylogenetic classification of Leotiomycetes. IMA Fungus , 1 (1) , pp. 1. Publisher's VersionAbstract

Fungi in the class Leotiomycetes are ecologically diverse, including mycorrhizas, endophytes of roots and leaves, plant pathogens, aquatic and aero-aquatic hyphomycetes, mammalian pathogens, and saprobes. These fungi are commonly detected in cultures from diseased tissue and from environmental DNA extracts. The identification of specimens from such character-poor samples increasingly relies on DNA sequencing. However, the current classification of Leotiomycetes is still largely based on morphologically defined taxa, especially at higher taxonomic levels. Consequently, the formal Leotiomycetes classification is frequently poorly congruent with the relationships suggested by DNA sequencing studies. Previous class-wide phylogenies of Leotiomycetes have been based on ribosomal DNA markers, with most of the published multi-gene studies being focussed on particular genera or families. In this paper we collate data available from specimens representing both sexual and asexual morphs from across the genetic breadth of the class, with a focus on generic type species, to present a phylogeny based on up to 15 concatenated genes across 279 specimens. Included in the dataset are genes that were extracted from 72 of the genomes available for the class, including 10 new genomes released with this study. To test the statistical support for the deepest branches in the phylogeny, an additional phylogeny based on 3156 genes from 51 selected genomes is also presented. To fill some of the taxonomic gaps in the 15-gene phylogeny, we further present an ITS gene tree, particularly targeting ex-type specimens of generic type species.
A small number of novel taxa are proposed: Marthamycetales ord. nov., and Drepanopezizaceae and Mniaeciaceae fams. nov. The formal taxonomic changes are limited in part because of the ad hoc nature of taxon and specimen selection, based purely on the availability of data. The phylogeny constitutes a framework for enabling future taxonomically targeted studies using deliberate specimen selection. Such studies will ideally include designation of epitypes for the type species of those genera for which DNA is not able to be extracted from the original type specimen, and consideration of morphological characters whenever genetically defined clades are recognized as formal taxa within a classification.

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Placement of Triblidiaceae in Rhytismatales and comments on unique ascospore morphologies in Leotiomycetes (Fungi, Ascomycota)

JM, K., et al., 2019. Placement of Triblidiaceae in Rhytismatales and comments on unique ascospore morphologies in Leotiomycetes (Fungi, Ascomycota). MycoKeys , 54 , pp. 99–133.Abstract

Triblidiaceae is a family of uncommonly encountered, non-lichenized discomycetes. A recent classification circumscribed the family to include Triblidium (4 spp. and 1 subsp.), Huangshania (2 spp.) and Pseudographis (2 spp. and 1 var.). The apothecia of these fungi are persistent and drought-tolerant; they possess stromatic, highly melanized covering layers that open and close with fluctuations of humidity. Triblidialean fungi occur primarily on the bark of Quercus, Pinaceae and Ericaceae, presumably as saprobes. Though the type species of Huangshania is from China, these fungi are mostly known from collections originating from Western Hemisphere temperate and boreal forests. The higher-rank classification of triblidialean fungi has been in flux due in part to an overemphasis on ascospore morphology. Muriform ascospores are observed in species of Triblidium and in Pseudographis elatina. An intense, dark blue/purple ascospore wall reaction in iodine-based reagents is observed in species of Pseudographis. These morphologies have led, in part, to these genera being shuffled among unrelated taxa in Hysteriaceae (Dothideomycetes, Hysteriales) and Graphidaceae (Lecanoromycetes, Ostropales). Triblidiaceae has been placed within the monofamilial order Triblidiales (affinity Lecanoromycetes). Here, we demonstrate with a three-gene phylogenetic approach that triblidialean fungi are related to taxa in Rhytismatales (Leotiomycetes). We synonymize Triblidiales under Rhytismatales and emend Triblidiaceae to include Triblidium and Huangshania, with Pseudographis placed within Rhytismataceae. A history of Triblidiaceae is provided along with a description of the emended family. We discuss how the inclusion of triblidialean fungi in Rhytismatales brings some rarely observed or even unique ascospore morphologies to the order and to Leotiomycetes.

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On the co-occurrence of species of Wynnea (Ascomycota, Pezizales, Sarcoscyphaceae) and Armillaria (Basidiomycota, Agaricales, Physalacriaceae)

Xu, F., LoBuglio, K.F. & Pfister, D.H., 2019. On the co-occurrence of species of Wynnea (Ascomycota, Pezizales, Sarcoscyphaceae) and Armillaria (Basidiomycota, Agaricales, Physalacriaceae). Fungal Systematics and Evolution , 4 , pp. 1-12.Abstract

Abstract: Species of the genus Wynnea are collected in association with a subterranean mass generally referred to as a sclerotium.

This is one of the few genera of the Sarcoscyphaceae not associated with plant material – wood or leaves. The sclerotium is

composed of hyphae of both Armillaria species and Wynnea species. To verify the existence of Armillaria species in the sclerotia of

those Wynnea species not previously examined and to fully understand the structure and nature of the sclerotium, molecular data

and morphological characters were analyzed. Using nuclear ITS rDNA sequences the Armillaria species co-occurring with Wynnea

species were identified from all examined material. These Armillaria symbionts fall into two main Armillaria groups – the A. gallicanabsnona-

calvescens group and the A. mellea group. Divergent time estimates of the Armillaria and Wynnea lineages support a

co-evolutionary relationship between these two fungi.

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