Lars Hedenäs

An annotated checklist of the mosses of Europe and Macaronesia

Abstract The moss flora of Europe and Macaronesia comprises 278 genera, 1292 species, 46 subspecies and 118 varieties. Of the total 1292 species, 53 are confined to Macaronesia and 21 are thought to be non-native. The checklist was derived from those for the various component countries and regions. It is based on results published up to the end of 2005. Subspecies and varieties are included; hybrids are omitted. The taxonomic hierarchy is based on one published by Goffinet & Buck in 2004. While it has been strongly influenced by results of modern molecular methods, there are still many remaining uncertainties, even at family level. Because of these uncertainties, taxonomic innovation has generally been avoided. There are four new combinations and one change of status.

Sex ratio patterns in dioicous bryophytes re-visited

Abstract Based on a literature survey and our own investigations of selected species, we present a compilation of expressed sex ratios in 103 taxa of dioicous bryophytes, including 56 mosses and 47 liverworts. We grouped the approaches used to determine sex into two categories: (1) sex assessment per herbarium specimen or per patch in the field; (2) sex assessment by examination of individual shoots or thalli, usually in the field. Eighty-eight per cent of the taxa studied by the former methods, and 68% of those included in the latter, exhibited a female-biased sex ratio. The F : M values varied by a factor of 46 among species, excluding cases with only one sex expressing. There was also within-species variation of sex expression and ratio related to geographical area, altitude, year, substratum, plant maturity, and compared with cultivation conditions, and between the two method categories. Across taxa, proportions of non-expressing and sporophytic samples were negatively related to each other; however, there was no significant relationship between sex ratio and the proportion of sporophytic samples or shoots. The present data do not support the generalization that the most strongly female-biased sex ratios among dioicous bryophytes occur in extreme environments. On the other hand, it is suggested here that phylogenetic history may explain observed species-wide sex ratios better than current habitat conditions in at least some cases.

The First Sex-Specific Molecular Marker Discovered in the Moss Pseudocalliergon trifarium

Most dioecious plants do not exhibit discernible sexual dimorphism before sexual maturity. Therefore, it is impossible to address any sex-related questions during the prereproductive phase unless a genetic sex marker is available for gender determination. The aim of the present study was to develop a genetic sex marker for the moss Pseudocalliergon trifarium to allow gender and sex ratio determination at any stage in the life cycle. A high proportion of P. trifarium populations do not express sex. The screening of genomic DNA with inter simple sequence repeat (ISSR) primers was used to discover sex-specific polymerase chain reaction (PCR) amplification products. A presumably female-specific band was found, excised from the gel, cloned, and sequenced. A sequence-walking method was used to characterize the same region in males. A primer pair was designed to allow the amplification of a 159-bp portion of the female-specific DNA region. All tested material, up to 16-year-old herbarium specimens, provided unambiguous amplification products. This study successfully provides, for the first time in a moss, a sex-specific DNA marker. It allows reliable determination of gender and sex ratios. The short length of the amplification product is an advantage as satisfactory PCR products are more likely when the targeted sequence is short. The amount of variation in the DNA region shared by both sexes was relatively high. If the male sequence can be better characterized, the sex-specific regions could possibly be used to evaluate sex-specific phylogeographic patterns.

A herbarium-based method for estimates of temporal frequency changes: mosses in Sweden

Abstract A new, resource-efficient, herbarium-based method for estimating temporal frequency changes in species, especially of non-vascular plants and fungi, is presented. It is based on a reference data set for the temporal distribution of general collecting activity for the organism group and geographical area of interest. The reference data set includes the collecting year of 650–1000 randomly selected herbarium specimens. The technique relies on the assumption that the temporal distribution of herbarium collections reflects the collecting activity in a region. The temporal distribution of collections of example species is compared with that of the reference data set to correct for the collecting intensity. Thus, cases that are explained by changes in general collecting frequency can be separated from those where other causes are likely. Species of the latter category need to be examined individually in order to assess whether the actual causes for the detected frequency variations are due to environmental changes or other factors. The present method provides a tool to assess actual increases and decreases of moderately frequent to common taxa, to aid in tracing predicted or unpredicted changes in nature.

Phylogenetic analyses reveal high levels of polyphyly among pleurocarpous lineages as well as novel clades

Abstract Phylogenetic analyses of the Hypnales usually show the same picture of poorly resolved trees with a large number of polyphyletic taxa and low support for the few reconstructed clades. One odd clade, however, consisting of three genera that are currently treated either within the Leskeaceae (Miyabea) or Neckeraceae (Homaliadelphus and Bissetia), was retrieved in a previously published phylogeny based on chloroplast rbcL. In order to elucidate the reliability of the observed Homaliadelphus - Miyabea - Bissetia -clade (HMB-clade) and to reveal its phylogenetic relationships a molecular study based on a representative set of hypnalean taxa was performed. Sequence data from all three genomes, namely the ITS1 and 2 (nuclear), the trnS-rps4-trnT-trnL-trnF cluster (plastid), the nad5 intron (mitochondrial), were analyzed. Although the phylogenetic reconstruction of the combined data set was not fully resolved regarding the backbone it clearly indicated the polyphyletic nature of various hypnalean families, such as the Leskeaceae, Hypnaceae, Hylocomiaceae, Neckeraceae, Leptodontaceae and Anomodontaceae with respect to the included taxa. In addition the results favor the inclusion of the Leptodontaceae and Thamnobryaceae in the Neckeraceae. The maximally supported HMB-clade consisting of the three genera Homaliadelphus (2–3 species), Miyabea (3 species) and Bissetia (1 species) is resolved sister to a so far unnamed clade comprising Taxiphyllum aomoriense, Glossadelphus ogatae and Leptopterigynandrum. The well-resolved and supported HMB-clade, here formally described as the Miyabeaceae, fam. nov. is additionally supported by morphological characters such as strongly incrassate, porose leaf cells, a relatively weak and diffuse costa and the presence of dwarf males. The latter are absent in the Neckeraceae and the Leskeaceae. It is essentially an East Asian family, with one species occurring in North America.

Environmental Factors Potentially Affecting Character States in Pleurocarpous Mosses

Abstract The frequencies of states of 86 characters in 439 pleurocarpous moss species from all over the world are compared across climatic zones, general habitats, and the gradient wetland versus non-wetland. Forty-four percent of the characters are influenced by climatic zone, 35% by general habitat, and 23% by the wetland vs. non-wetland gradient. Most of the differences in character state frequencies among environmental categories seem to relate to two complex functions: 1) water conduction and retention, as expressed by differences in frequencies of states of the characters stem central strand, leaf orientation, leaf costa type, alar cells, paraphyllia, pseudoparaphyllia, inner perichaetial leaf plications, vaginular paraphyses, operculum type, stomatal pore, and possibly seta length and 2) spore dispersal, expressed by variation in frequencies of character states related to capsule shape and orientation, annulus, exostome and endostome appearance, spore size and maturation time, and possibly seta length. Besides the influence of the phylogenetic history, water availability and exposure to wind are suggested to be the most important habitat factors explaining the differences among habitats found for these character complexes.

New national and regional bryophyte records, 22

folium and S. recurvum have similar ranges and ecology. In S. angustifolium the stem leaves are more triangular and rarely erose while the branch leaves are narrower and more strongly 5-ranked (McQueen & Andrus, 2006). Sphagnum recurvum also has narrower and more distinctly 5-ranked branch leaves than S. flexuosum, as well as a much more strongly differentiated stem cortex. In S. flexuosum the branch leaves are only slightly recurved when dry whereas in S. recurvum they are sharply recurved (McQueen & Andrus, 2006). Until now, none of these species of the European S. recurvum complex has been identified in the Azores.

New national and regional bryophyte records, 18

Feddes Repertorium 87: 188. 1976 [Euosmolejeunea cedercreutzii H.Buch & Perss., Commentationes Biologicae 8 (7): 9. 1941]. MADEIRA: on bark of moribund Erica, north side of Pico Topeiro, to east of Encumeada, ca 1150 m a.s.l., 8 April 2007, leg. T.L. Blockeel no. 36/102 (LISU, duplicate in Hb. Blockeel). AZORES: Terceira: in damp crevice of lava field, Misterio Negro, 10 km N.W. of Angra do Heroismo, UTM 75–87-, ca 650 m a.s.l., 15 July 1994, leg. J.W. Bates & R. Gabriel, no. 3498 (Hb. Bates); Terceira: on Laurus bark in steep forest, Terra Brava, about 1 km N.E. of Algar do Carvao, UTM 82–87-, ca 640 m a.s.l, 21 July 1994, leg. J.W. Bates & R. Gabriel, no. 3650 (Hb. Bates); Terceira: epiphyte on Juniperus in upper caldeira forest, Juncal, about 11 km N. of Angra do Heroismo, 22 July 1994, leg. J.W. Bates no. 3682 (Hb. Bates).

Reproductive effort and costs of reproduction do not explain female-biased sex ratios in the moss Pseudocalliergon trifarium (Amblystegiaceae).

A fundamental assumption in life-history theory is that reproduction is costly. Higher reproductive investment for fruits than for flowers may result in larger costs of reproduction in females than in males, which is often used to explain male-skewed sex ratios in unisexual seed plants. In contrast, bryophytes have predominantly female-biased sex ratios, suggested to be a product of a higher average cost of sexual reproduction in males. Empirical evidence to support this notion is largely lacking. We investigated sex-specific reproductive effort and costs in the unisexual moss Pseudocalliergon trifarium that has a female-dominated expressed sex ratio and rarely produces sporophytes. Annual vegetative segment mass did not differ among male, female, and non-expressing individuals, indicating that there was no threshold-size for sex expression. Mean and annual mass of sexual branches were higher in females than in males, but branch number per segment did not differ between sexes. Prefertilization reproductive effort for females was significantly greater (11.2%) than for males (8.6%). No cost for sexual branch production in terms of reduced relative vegetative growth or decreased investment in reproductive structures in consecutive years was detected. A higher realized reproductive cost in males cannot explain the unbalanced sex ratio in the study species.

Phylogeny of the Plagiotheciaceae Based on Molecular and Morphological Evidence

Abstract The circumscription of the Plagiotheciaceae was evaluated cladistically, using anatomical and morphological data, plus rps4 and trnL-trnF gene sequences. Two analyses were conducted with 37 ingroup species, representing 14 genera, and eight outgroup species. First, the rps4 (73 informative nucleotide sites) plus trnL-trnF data set (39 sites) was analyzed alone. This initial analysis suggests a highly polyphyletic Plagiotheciaceae, with Acrocladium, Catagonium, Herzogiella, Isopterygiopsis pulchella (Hedw.) Iwats., Isopterygium, Plagiothecium piliferum (Sw.) Schimp., Pseudotaxiphyllum elegans (Brid.) Iwats., P. pohliaecarpum (Sull. & Lesq.) Iwats., Rhizofabronia, Struckia, and Taxiphyllum placed among the outgroup taxa. In a second analysis, the rps4 + trnL-trnF data set was combined with anatomical and morphological data (adding 53 informative characters). The results of the latter analysis are congruent with the first analysis regarding Herzogiella adscendens (Lindb.) Iwats., Isopterygium, and Taxiphyllum, but resolves the rest of the Plagiotheciaceae as a monophyletic group. The results suggest that the following genera belong to the family: Acrocladium, Bardunovia, Catagonium, Herzogiella, Isopterygiopsis, Orthothecium, Myurella, Plagiothecium, Platydictya, Pseudotaxiphyllum, Rhizofabronia, and Struckia. DNA sequence, morphological, and anatomical data are all important when evaluating the circumscription and internal relationships of the family. We suggest that especially the relationships among Plagiothecium, Pseudotaxiphyllum, and Struckia species can be better resolved by additional molecular evidence. The ancestor of the Plagiotheciaceae was most likely a southern temperate species, whereas most of the later diversification within the family occurred in the northern temperate zone. Only one genus, Rhizofabronia, evolved in tropical mountains, whereas scattered members of other genera occur in similar environments. Adaptations for calcareous substrates evolved either in the ancestor of the entire Isopterygiopsis-Plagiothecium clade and were lost twice, or they evolved independently in Isopterygiopsis and in a clade consisting of Bardunovia, Myurella, Orthothecium, and Platydictya.