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

Laboulbeniomycetes: Evolution, natural history, and Thaxter’s final word

Blackwell, M., Haelewaters, D. & Pfister, D.H., 2020. Laboulbeniomycetes: Evolution, natural history, and Thaxter’s final word. Mycologia , 112. Publisher's VersionAbstract
Historically, thallus-forming Laboulbeniomycetes, including the orders Laboulbeniales and Herpomycetales, were set apart because of their distinctive morphology and ecology. Although some biologists correctly interpreted these arthropod ectoparasites as fungi, even ascomycetes, others thought they were worms, red algae, or members of taxa described especially for them. Speculation on the evolution of the group involving red algae, the morphology-based Floridean Hypothesis, persisted deep into the 20th century, in part because valid alternatives were not presented. Although the distinctive features of Laboulbeniales clearly set them apart from other fungi, the difficulty was in the absence of characters grouping them among the fungi. Thaxter considered the Laboulbeniales to be ascomycetes, but he avoided phylogenetic discussions involved in the Floridean Hypothesis all of his life. Eventually, developmental studies of the life history of Pyxidiophora species, hyphal perithecial ascomycetes with 2-celled ascospores, revealed characters connecting Laboulbeniales to other ascomycetes. The distinctive morphological features of Laboulbeniales (absence of mycelium, a thallus developed from 2-celled ascospores by cell divisions in several planes, arthropod parasitism) can be best understood by comparison with Pyxidiophora. The development of a 3-dimensional thallus composed of true parenchyma occurs not only in Laboulbeniales, but also in Pyxidiophora species. The life history of arthropod ectoparasitism of Laboulbeniales as well as mycoparasitism and phoretic dispersal by arthropods of Pyxidiophora species can be explained by Tranzschel’s Law, originally applied to rust fungi. Molecular analyses including other arthropod-associated fungi have contributed to a better understanding of an enlarged class, Laboulbeniomycetes, which now includes a clade comprising Chantransiopsis, Tetrameronycha, and Subbaromyces. A two-locus phylogenetic tree highlights evolutionary and life history questions with regard to the placement of Herpomycetales as the first diverging lineage of the Laboulbeniomycetes. The sister group for all the Laboulbeniomycetes remains to be discovered.
Read more

Sareomycetes cl. nov.: A new proposal for placement of the resinicolous genus Sarea (Ascomycota, Pezizomycotina)

Beimforde, C., et al., 2020. Sareomycetes cl. nov.: A new proposal for placement of the resinicolous genus Sarea (Ascomycota, Pezizomycotina). Fungal Systematics and Evolution , 6. Publisher's VersionAbstract

Full citation: Beimforde, C., Schmidt, A.R., Rikkinen, J. and J.K. Mitchell. 2020. Sareomycetes cl. nov.: A new proposal for placement of the resinicolous genus Sarea (Ascomycota, Pezizomycotina). Fungal Systematics and Evolution.

Resinicolous fungi constitute a heterogeneous assemblage of fungi that live on fresh and solidified plant resins. The genus Sarea includes, according to current knowledge, two species, S. resinae and S. difformis. In contrast to other resinicolous discomycetes, which are placed in genera also including non-resinicolous species, Sarea species only ever fruit on resin. The taxonomic classification of Sarea has proven to be difficult and currently the genus, provisionally and based only on morphological features, has been assigned to the Trapeliales (Lecanoromycetes). In contrast, molecular studies have noted a possible affinity to the Leotiomycetes. Here we review the taxonomic placement of Sarea using sequence data from seven phylogenetically informative DNA regions including ribosomal (ITS, nucSSU, mtSSU, nucLSU) and protein-coding (rpb1rpb2mcm7) regions.

We combined available and new sequence data with sequences from major Pezizomycotina classes, especially Lecanoromycetes and Leotiomycetes, and assembled three different taxon samplings in order to place the genus Sarea within the Pezizomycotina. Based on our data, none of the applied phylogenetic approaches (Bayesian Inference, Maximum Likelihood and Maximum Parsimony) supported the placement of Sarea in the Trapeliales or any other order in the Lecanoromycetes. A placement of Sarea within the Leotiomycetes is similarly unsupported. Based on our data, Sarea forms an isolated and highly supported phylogenetic lineage within the "Leotiomyceta". From the results of our multilocus phylogenetic analyses we propose here a new class, order, and family, SareomycetesSareales and Sareaceae in the Ascomycota to accommodate the genus Sarea. The genetic variability within the newly proposed class suggests that it is a larger group that requires further infrageneric classification.

Read more

Draft Genome Sequence of the Globally Distributed Cockroach-Infecting Fungus Herpomyces periplanetae Strain D. Haelew. 1187d

Haelewaters, D., et al., 2020. Draft Genome Sequence of the Globally Distributed Cockroach-Infecting Fungus Herpomyces periplanetae Strain D. Haelew. 1187d. Microbiology Resource Announcements , 9 (6). Publisher's VersionAbstract
Herpomyces periplanetae is an obligate biotroph of Periplaneta americana, the American cockroach. Its nearly cosmopolitan distribution is shaped by its globally invasive host and the international pet trade. Here, we report the draft genome sequence of H. periplanetae, based on a thallus from P. americana collected in Cambridge, Massachusetts
Read more

Geodina (Pezizomycetes: Wynneaceae) has a single widespread species in tropical America

Pfister, D.H., Quijada, L. & LoBuglio, K.F., 2020. Geodina (Pezizomycetes: Wynneaceae) has a single widespread species in tropical America. Fungal Systematics and Evolution , 5 (June 2020) , pp. 131-138. Publisher's VersionAbstract

Geodina salmonicolor is shown to be a synonym of G. guanacastensis, the type and only species of the genus. Comparisons of ITS rDNA sequences of a paratype and two recent collections of G. guanacastensis with published ITS sequences of G. salmonicolor, from the Dominican Republic, show that these are nearly identical. When G. salmonicolor was erected no sequences of the type species were available. Morphological comparisons supports the conspecificity. Details regarding the description of G. salmonicolor are pointed out. A four-gene phylogeny places Geodina and Wynnea as a supported sister group to the rest of the Sarcoscyphaceae. Species in these genera share morphological traits of cyanophobic spore markings, dark angular outer excipular cells that give rise to hairs and the origin of several apothecia from a common basal stalk. Their occurrence on soil rather than on wood or plant material distinguish them from other Sarcoscyphaceae. Based on morphology, phylogenic relationships and trophic interactions we erect a new family, Wynneaceae, for Geodina and Wynnea.

Read more

Cones, needles and wood: Micraspis (Micraspidaceae, Micraspidales fam. et ord. nov.) speciation segregates by host plant tissues

L, Q., et al., 2020. Cones, needles and wood: Micraspis (Micraspidaceae, Micraspidales fam. et ord. nov.) speciation segregates by host plant tissues. Fungal Systematics and Evolution , 5 , pp. 99-111. Publisher's VersionAbstract
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 (Phacidiales), later transferred to Helotiaceae (Helotiales) 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
Read more