Brigitte Volkmann-Kohlmeyer

Reconstructing the early evolution of Fungi using a six-gene phylogeny

The ancestors of fungi are believed to be simple aquatic forms with flagellated spores, similar to members of the extant phylum Chytridiomycota (chytrids). Current classifications assume that chytrids form an early-diverging clade within the kingdom Fungi and imply a single loss of the spore flagellum, leading to the diversification of terrestrial fungi. Here we develop phylogenetic hypotheses for Fungi using data from six gene regions and nearly 200 species. Our results indicate that there may have been at least four independent losses of the flagellum in the kingdom Fungi. These losses of swimming spores coincided with the evolution of new mechanisms of spore dispersal, such as aerial dispersal in mycelial groups and polar tube eversion in the microsporidia (unicellular forms that lack mitochondria). The enigmatic microsporidia seem to be derived from an endoparasitic chytrid ancestor similar to Rozella allomycis, on the earliest diverging branch of the fungal phylogenetic tree.

The ascomycota tree of life: A phylum-wide phylogeny clarifies the origin and evolution of fundamental reproductive and ecological traits

We present a 6-gene, 420-species maximum-likelihood phylogeny of Ascomycota, the largest phylum of Fungi. This analysis is the most taxonomically complete to date with species sampled from all 15 currently circumscribed classes. A number of superclass-level nodes that have previously evaded resolution and were unnamed in classifications of the Fungi are resolved for the first time. Based on the 6-gene phylogeny we conducted a phylogenetic informativeness analysis of all 6 genes and a series of ancestral character state reconstructions that focused on morphology of sporocarps, ascus dehiscence, and evolution of nutritional modes and ecologies. A gene-by-gene assessment of phylogenetic informativeness yielded higher levels of informativeness for protein genes (RPB1, RPB2, and TEF1) as compared with the ribosomal genes, which have been the standard bearer in fungal systematics. Our reconstruction of sporocarp characters is consistent with 2 origins for multicellular sexual reproductive structures in Ascomycota, once in the common ancestor of Pezizomycotina and once in the common ancestor of Neolectomycetes. This first report of dual origins of ascomycete sporocarps highlights the complicated nature of assessing homology of morphological traits across Fungi. Furthermore, ancestral reconstruction supports an open sporocarp with an exposed hymenium (apothecium) as the primitive morphology for Pezizomycotina with multiple derivations of the partially (perithecia) or completely enclosed (cleistothecia) sporocarps. Ascus dehiscence is most informative at the class level within Pezizomycotina with most superclass nodes reconstructed equivocally. Character-state reconstructions support a terrestrial, saprobic ecology as ancestral. In contrast to previous studies, these analyses support multiple origins of lichenization events with the loss of lichenization as less frequent and limited to terminal, closely related species.

A class-wide phylogenetic assessment of Dothideomycetes

We present a comprehensive phylogeny derived from 5 genes, nucSSU, nucLSU rDNA, TEF1, RPB1 and RPB2, for 356 isolates and 41 families (six newly described in this volume) in Dothideomycetes. All currently accepted orders in the class are represented for the first time in addition to numerous previously unplaced lineages. Subclass Pleosporomycetidae is expanded to include the aquatic order Jahnulales. An ancestral reconstruction of basic nutritional modes supports numerous transitions from saprobic life histories to plant associated and lichenised modes and a transition from terrestrial to aquatic habitats are confirmed. Finally, a genomic comparison of 6 dothideomycete genomes with other fungi finds a high level of unique protein associated with the class, supporting its delineation as a separate taxon.

Molecular systematics of the marine Dothideomycetes

Phylogenetic analyses of four nuclear genes, namely the large and small subunits of the nuclear ribosomal RNA, transcription elongation factor 1-alpha and the second largest RNA polymerase II subunit, established that the ecological group of marine bitunicate ascomycetes has representatives in the orders Capnodiales, Hysteriales, Jahnulales, Mytilinidiales, Patellariales and Pleosporales. Most of the fungi sequenced were intertidal mangrove taxa and belong to members of 12 families in the Pleosporales: Aigialaceae, Didymellaceae, Leptosphaeriaceae, Lenthitheciaceae, Lophiostomataceae, Massarinaceae, Montagnulaceae, Morosphaeriaceae, Phaeosphaeriaceae, Pleosporaceae, Testudinaceae and Trematosphaeriaceae. Two new families are described: Aigialaceae and Morosphaeriaceae, and three new genera proposed: Halomassarina, Morosphaeria and Rimora. Few marine species are reported from the Dothideomycetidae (e.g. Mycosphaerellaceae, Capnodiales), a group poorly studied at the molecular level. New marine lineages include the Testudinaceae and Manglicola guatemalensis in the Jahnulales. Significantly, most marine Dothideomycetes are intertidal tropical species with only a few from temperate regions on salt marsh plants (Spartina species and Juncus roemerianus), and rarely totally submerged (e.g. Halotthia posidoniae and Pontoporeia biturbinata on the seagrasses Posidonia oceanica and Cymodocea nodosum). Specific attention is given to the adaptation of the Dothideomycetes to the marine milieu, new lineages of marine fungi and their host specificity.

Independent terrestrial origins of the Halosphaeriales (marine Ascomycota)

A phylogenetic study of marine ascomycetes was initiated to test and refine evolutionary hypotheses of marine-terrestrial transitions among ascomycetes. Taxon sampling focused on the Halosphaeriales, the largest order of marine ascomycetes. Approximately 1050 base pairs (bp) of the gene that codes for the nuclear small subunit (SSU) and 600 bp of the gene that codes for the nuclear large subunit (LSU) ribosomal RNAs (rDNA) were sequenced for 15 halosphaerialean taxa and integrated into a data set of homologous sequences from terrestrial ascomycetes. An initial set of phylogenetic analyses of the SSU rDNA from 38 taxa representing 15 major orders of the phylum Ascomycota confirmed a close phylogenetic relationship of the halosphaerialean species with several other orders of perithecial ascomycetes. A second set of analyses, which involved more intensive taxon sampling of perithecial ascomycetes, was performed using the SSU and LSU rDNA data in combined analyses. These second analyses included 15 halosphaerialean taxa, 26 terrestrial perithecial fungi from eight orders, and five outgroup taxa from the Pezizales. In these analyses the Halosphaeriales were polyphyletic and comprised two distinct lineages. One clade of Halosphaeriales comprised 12 taxa from 11 genera and was most closely related to terrestrial fungi of the Microascales. The second clade of halosphaerialean fungi comprised taxa from the genera Lulworthia and Lindra and was an isolated lineage among the perithecial fungi. Both the main clade of Halosphaeriales and the Lulworthia/Lindra clade are supported by the data as being independently derived from terrestrial ancestors.

Lulworthiales, a new order of marine Ascomycota.

Based on molecular studies using 1031 bp of the nuclear small subunit (SSU) gene and 594 bp of the nuclear large subunit (LSU) rDNA gene and using morphological characters, the genera Lulwor- thia and Lindra are removed from Halosphaeriales and assigned to the new order Lulworthiales and new family Lulworthiaceae in the class Sordariomycetes. Eleven accepted species of Lulworthia and 6 species of Lindra are listed.

A re-evaluation of Lulworthiales : relationships based on 18S and 28S rDNA

The Lulworthiales consists of four genera: three that were removed from the Halosphaeriales, namely Lulworthia, Lindra, and Kohlmeyeriella; and Spathulospora, reassigned from the Spathulosporales. However, studies have shown that neither Lulworthia nor Lindra are monophyletic genera. This study was therefore undertaken to re-evaluate the genera of the Lulworthiales based on the SSU and LSU rDNA genes. Taxonomic revisions are proposed here for Lulworthia crassa, L. lignoarenaria, L. uniseptata and Lindra marinera: Lulworthia crassa is transferred into the genus Kohlmeyeriella; Lulwoidea gen. nov. is established for L. lignoarenaria; Lulwoana gen. nov. is established for L. uniseptata; and Lindra marinera is reduced to synonymy with L. thalassiae. Taxonomic descriptions are emended for the genus Lulworthia s. str., and for L. grandispora and Lindra thalassiae. A neotype is designated for Lulworthia grandispora.

Fungi on Juncus roemerianus 2. New Dictyosporous Ascomycetes

Tremateia halophila gen. et sp. nov. and Lautospora simillima sp. nov. are described from Juncus roemerianus in saltmarshes of North Carolina. Tremateia is compared with Diademosa and Lewia. Tremateia halophila grows throughout the year in the lower and middle parts of the culms and is classified as a facultative marine species. It forms a Phoma type anamorphic state in pure culture. Lautospora simillima is a rarely collected species which develops in small colonies near the base of very soft old culms. It is found predominantly in the winter months (November-February) and is considered to be an obligate marine fungus. The new species is compared with the type species of the genus, L. gigantea, and a new family, Lautosporaceae (Ascomycotina incertae sedis), is described.

The phylogenetic position of Spathulospora based on DNA sequences from dried herbarium material

The phylogenetic position of the marine ascomycete genus Spathulospora was investigated using partial SSU and LSU DNA sequences obtained from dried herbarium specimens. Spathulospora was represented by the two species S. adelpha and S. antarctica. Phylogenetic analyses using Bayesian, parsimony, and neighbour-joining algorithms on SSU and LSU data sets agreed with the placement of Spathulospora. Both Spathulospora species are each others closest relatives, and group within the Lulworthiales (Sordariomycetes, Ascomycota) with support in all analyses. Members of the morphologically similar insect parasites in the Laboulbeniomycetes are not closely related to Spathulospora. Despite several striking morphological differences between Spathulospora and Lulworthiales, an important shared morphological character was found that until now had not been recognized. Ascospores of Spathulospora and some members of the Lulworthiales have apical chambers containing mucus believed to be involved in ascospore attachment. A closest relative to Spathulospora could not be determined.

Observations on two marine and maritime "borderline" lichens: Mastodia tessellata and Collemopsidium pelvetiae

Among marine fungi, the submerged lichens are a small and rarely investigated group. The two species examined have been known for a long time; Mastodia tessellata (syn. Turgidosculum complicatulum) was first described in 1845, and Collemopsidium pelvetiae (syn. Pyrenocollema pelvetiae) in 1915. Here we clarified the formerly confused nomenclature and provided full descriptions and detailed illustrations, made with a camera lucida. The name Ulva tessellata is lectotypified, a neotype is selected for Dothidella pelvetiae, and the new combination Collemopsidium pelvetiae (basionym D. pelvetiae) is made.