Christian Printzen

The delimitation of Antarctic and bipolar species of neuropogonoid Usnea (Ascomycota, Lecanorales): a cohesion approach of species recognition for the Usnea perpusilla complex

Species of the Neuropogon group in the lichen genus Usnea have their centre of distribution in polar regions of the Southern Hemisphere. Their morphological and chemical variability is poorly understood and several asexual taxa with uncertain relationships to fertile taxa occur in the group. The species concept is controversial. A phylogenetic analysis revealed three related complexes of mainly asexual lineages arranged around three fertile Usnea species: U. aurantiaco-atra, U. trachycarpa and U. perpusilla. In this study a dataset of 80 specimens was used to resolve species circumscriptions in the U. perpusilla complex. We used a phylogenetic and a haplotype network approach based on three gene fragments (ITS, IGS and RPB1) to detect distinct lineages. To support the hypothesis that these lineages represent different species, we tested for correlation of morphological and chemical characters with hierarchical nested haplotype groups, employing statistical tests of contingency tables and analysis of variance (ANOVA). This cohesion species recognition method detected three fertile U. perpusilla lineages. We could also delimit an undescribed fertile species with yellow apothecia and a new asexual species from the High Andes. Interestingly, there is an additional bipolar species, U. lambii, which was formerly confused with U. sphacelata. The fact that U. lambii shows a geographically disjunct distribution pattern, but the genetic distances among specimens are low, points to recent long-distance dispersal.

Pleistocene expansion of the bipolar lichen Cetraria aculeata into the Southern hemisphere

Many boreal and polar lichens occupy bipolar distributional ranges that frequently extend into high mountains at lower latitudes. Although such disjunctions are more common among lichens than in other groups of organisms, the geographic origin of bipolar lichen taxa, and the way and time frame in which they colonized their ranges have not been studied in detail. We used the predominantly vegetative, widespread lichen Cetraria aculeata as a model species. We surveyed the origin and history of its bipolar pattern using population genetics, phylogenetic and genealogical reconstruction methods. Cetraria aculeata originated in the Northern Hemisphere and dispersed southwards during the Pleistocene. The genetic signal suggests a Pleistocene dispersive burst in which a population size expansion concurred with the acquisition of a South‐American range that culminated in the colonization of the Antarctic.

The phylogeny and classification of Neuropogon and Usnea (Parmeliaceae, Ascomycota) revisited

The phylogeny of usneoid lichens with black pigmentation in the cortex was reconstructed using Bayesian and maximum parsimony analyses of nuclear ITS rDNA sequences. Fifty new partial sequences of 14 taxa were generated and assembled with 74 sequences from GenBank. Our results indicate that Neuropogon is polyphyletic with a core group nested within Usnea subgen. Usnea as sister-group to section Usnea. In addition an undescribed species is basal to the section Usnea clade and the Neuropogon species U. acanthella and U. durietzii have unresolved relationships in the Usnea subgen. Usnea clade. Monophyly of Neuropogon not nested within Usnea subgen. Usnea is rejected using three independent tests. Consequently, it is proposed to synonymise Neuropogon with Usnea. We recommend a conservative approach regarding nomenclatural changes from phylogenetic studies especially at the generic level when few taxa are studied.

Local population subdivision in the lichen Cladonia subcervicornis as revealed by mitochondrial cytochrome oxidase subunit 1 intron sequences.

A 753–771 bp long intronic sequence from the mitochondrial cox 1 gene of Cladonia subcervicornis (Cladoniaceae, Lecanorales, Ascomycota) was amplified with newly designed PCR primers. The cox 1 intron sequence, which apparently has not been used for phylogenetic or population genetic research in fungi, displays high infraspecific variation. Sequences were obtained from 124 specimens from four neighboring localities in coastal Hordaland, western Norway. An exact test of population differentiation and population pairwise fixation indices FST show significantly reduced gene flow between the northernmost locality and the other three populations. Although Cladonia subcervicornis frequently produces apothecia, we conclude that dispersal by ascospores over long distances is rather ineffective in this species.

Low genetic diversity in Antarctic populations of the lichenforming ascomycete Cetraria aculeata and its photobiont

Lichens, symbiotic associations of fungi (mycobionts) and green algae or cyanobacteria (photobionts), are poikilohydric organisms that are particularly well adapted to withstand adverse environmental conditions. Terrestrial ecosystems of the Antarctic are therefore largely dominated by lichens. The effects of global climate change are especially pronounced in the maritime Antarctic and it may be assumed that the lichen vegetation will profoundly change in the future. The genetic diversity of populations is closely correlated to their ability to adapt to changing environmental conditions and to their future evolutionary potential. In this study, we present evidence for low genetic diversity in Antarctic mycobiont and photobiont populations of the widespread lichen Cetraria aculeata. We compared between 110 and 219 DNA sequences from each of three gene loci for each symbiont. A total of 222 individuals from three Antarctic and nine antiboreal, temperate and Arctic populations were investigated. The mycobiont diversity is highest in Arctic populations, while the photobionts are most diverse in temperate regions. Photobiont diversity decreases significantly towards the Antarctic but less markedly towards the Arctic, indicating that ecological factors play a minor role in determining the diversity of Antarctic photobiont populations. Richness estimators calculated for the four geographical regions suggest that the low genetic diversity of Antarctic populations is not a sampling artefact. Cetraria aculeata appears to have diversified in the Arctic and subsequently expanded its range into the Southern Hemisphere. The reduced genetic diversity in the Antarctic is most likely due to founder effects during long-distance colonization.

Using haplotype networks, estimation of gene flow and phenotypic characters to understand species delimitation in fungi of a predominantly Antarctic Usnea group (Ascomycota, Parmeliaceae)

Species delimitations in the predominantly Antarctic and South American group of neuropogonoid species of the lichen-forming fungal genus Usnea are poorly understood. Morphological variability has been interpreted as a result of harsh ecological conditions, but preliminary molecular data have led to doubts about the current species delimitations in these lichenized fungi. We examined species boundaries using a phylogenetic approach and a cohesion species recognition method generating haplotype networks and looking at associations of phenotypic characters with clades found in the networks. In addition, we estimated gene flow among detected clades and currently circumscribed species. We identified several clades that were significantly associated with phenotypic characters, but did not necessarily agree with current species circumscriptions. In one case (U. aurantiaco-atra/U. antarctica), network analysis and the estimation of gene flow provided no evidence of distinct species. The distinctness of another species pair (U. subantarctica/U. trachycarpa) remains dubious, showing evidence for gene flow among currently accepted species.

Contributions to an epiphytic lichen flora of northwest North America: I. Eight new species from British Columbia inland rain forests

Abstract Recent surveys of the inland rain forests of British Columbia and adjacent regions have brought to light an unexpectedly rich epiphytic lichen flora, including several species apparently new to science. In the first of a series of papers, we describe eight species discovered during these surveys as new: Absconditella amabilis T. Sprib. (Ostropales), Bacidina contecta S. Ekman & T. Sprib., Biatora aureolepra T. Sprib. & Tønsberg, Biatora ligni-mollis T. Sprib. & Printzen (all Lecanorales), Collema coniophilum Goward (Peltigerales), Pertusaria diluta C. Björk, G. Thor & T. Wheeler (Pertusariales), Schaereria brunnea C. Björk, T. Sprib. & T. Wheeler (Ostropomycetidae incertae sedis) and Scoliciosporum abietinum T. Sprib. (Lecanorales). We also call attention to a ninth species, Bacidina sp. A, a poorly known and possibly undescribed colonizer of moribund cyanolichens. A majority of the above species appear to be confined to old-growth forests, while two (Biatora ligni-mollis and Schaereria brunnea) are currently known only from “antique” forests older than about 500 years. Many additional undescribed epiphytic lichens are known from inland rain forests, underscoring the need for further baseline biodiversity research in light of its ongoing disappearance as a result of resource extraction. In addition to the eight new species, we report Absconditella celata as new to North America, Absconditella lignicola as new to Canada and Montana, Bacidina chloroticula as new to British Columbia and Gyalideopsis piceicola as new to Montana.

Corticolous and Lignicolous Species of Lecanora (Lecanoraceae, Lecanorales) with Usnic or Isousnic Acid in the Sonoran Desert Region

Abstract A taxonomic study of corticolous species of Lecanora in the Sonoran Desert region containing usnic acids and not belonging to Lecanora s. str. is presented. Descriptions, notes on the ecology and distribution and a key to the 17 species recognized within the area are included. Lecanora coniferarum Printzen, L. latens Printzen, L. perconfusa Printzen, and L. substrobilina Printzen are described as new to science. The following new combinations are proposed: Lecanora densa (Śliwa & Wetmore) Printzen, L. laxa (Śliwa & Wetmore) Printzen, and L. americana (B. de Lesd.) Printzen.

A molecular phylogeny of the Lecanora varia group, including a new species from western North America

The phylogeny of the Lecanora varia group is inferred from ITS sequences using Bayesian and ML phylogenetic analysis methods. According to our data, usnic acid-containing, corticolous Lecanora species do not form a monophyletic group but occur in three major clades together with other groups of Lecanora and Protoparmeliopsis. The new combination Lecanora filamentosa (Stirt.) Elix & Palice is proposed. The new species Lecanora schizochromatica is described from northwestern North America. It produces atranorin as a major substance and is closely related to the morphologically and chemically similar L. filamentosa. The American Biatora pullula Tuck. is synonymised with Lecanora anopta Nyl., which is hereby reported for continental North America for the first time. The phylogenetic relationships between the major clades of Lecanora are still largely unresolved and require more intensive taxon and character sampling.

Genetic diversity of photobionts in Antarctic lecideoid lichens from an ecological view point

As part of a comprehensive study on lecideoid lichens in Antarctica, we investigated the photobiont diversity and abundance in 119 specimens of lecideoid lichens from 11 localities in the continental and maritime Antarctic. A phylogeny of these photobiont ITS sequences, including samples from arctic, alpine and temperate lowland regions, reveals the presence of five major Trebouxia clades in Antarctic lecideoid lichens. Two clades are formed by members of the T. jamesii and T. impressa aggregates but for all other clades no close match to any known Trebouxia species could be found in sequence databases. One genetically uniform and well-supported Trebouxia clade was found only in the climatically unique cold desert regions of the Antarctic (preliminarily called Trebouxia sp.URa1), where it is preferentially associated with the highly adapted Antarctic endemic lichen Lecidea cancriformis . Levels of genetic photobiont diversity differ slightly, but insignificantly among ecological regions of the Antarctic and do not decrease towards regions with more unfavourable ecological conditions. The genetic diversity of photobionts varies among mycobiont species. Most pairwise comparisons reveal that these differences are insignificant, probably due to the small sample size for most species. The Antarctic lichens studied here are predominantly not specific for a single photobiont species or lineage, except for Lecidella greenii and L. siplei . These two species are preferably associated with Trebouxia sp. URa2, although in the sampling areas of both species, a pool of several other photobionts is available. Lecidea cancriformis associates with the highest diversity of photobionts followed by L. andersonii.