Leucobryum Research Articles

Could the Canopy Structure of Bryophytes Serve as an Indicator of Microbial Biodiversity? A Test for Testate Amoebae and Microcrustaceans from a Subtropical Cloud Forest in Dominican Republic

The mechanisms that ultimately regulate the diversity of microbial eukaryotic communities in bryophyte ecosystems remain a contentious topic in microbial ecology. Although there is robust consensus that abiotic factors, such as water chemistry of the bryophyte and pH, explain a significant proportion of protist and microcrustacean diversity, there is no systematic assessment of the role of bryophyte habitat complexity on such prominent microbial groups. Water-holding capacity is correlated with bryophyte morphology and canopy structure. Similarly, canopy structure explains biodiversity dynamics of the macrobiota suggesting that canopy structure may also be a potential parameter for understanding microbial diversity. Canopy roughness of the dominant bryophyte species within the Bahoruco Cloud Forest, Cachote, Dominican Republic, concomitant with their associated diversity of testate amoebae and microcrustaceans was estimated to determine whether canopy structure could be added to the list of factors explaining microbial biodiversity in bryophytes. We hypothesized that smooth (with high moisture content) canopies will have higher species richness, density, and biomass of testate amoebae and higher richness and density of microcrustaceans than rough (desiccation-prone) canopies. For testate amoebae, we found 83 morphospecies with relative low abundances. Species richness and density differed among bryophytes with different bryophyte canopy structures and based on non-metric multidimensional scaling, canopy roughness explained 25% of the variation in species composition although not as predicted. Acroporium pungens (low roughness, LR) had the lowest species richness (2 ± 0.61 SD per gram dry weight bryophyte), and density (2.1 ± 0.61 SD individual per gram of dry weight bryophyte); whereas Thuidium urceolatum (high roughness) had the highest richness (24 ± 10.82 SD) and density (94 ± 64.30 SD). The fact that the bryophyte with the highest roughness had the highest levels of diversity for testate amoebae suggests that moisture levels at the level of the bryophyte canopy may not represent a biodiversity driver in a cloud forest with high relative humidity; however, high roughness could generate a dynamic and fluctuating moisture environment with concomitant alternating microbial communities. A total of 26 microcrustacean morphospecies were found across 11 bryophytes; however, no bryophyte canopy effect was detected on their richness and density. Microcrustacean mean density was low ranging from less than one individual per 50 cm2 of bryophyte in Leucobryum (LR) to a maximum of 6 ± 3.37 SD individuals/50 cm2 in Monoclea (LR). This lack of pattern suggests that possible explanatory variables may be related to larger scale processes than those examined in this study.

Patterns of Molecular and Morphological Variation in Leucobryum albidum, L. glaucum, and L. juniperoideum (Bryopsida)

Abstract Restriction digest patterns from 18S–26S nuclear ribosomal DNA internal transcribed spacers (ITS) were employed to investigate delineation between the morphologically similar moss species Leucobryum glaucum, L. juniperoideum, and L. albidum. Discriminant analysis allowed assignment of specimens to haplotypes based on their morphological features and supported the recognition of L. glaucum and L. albidum. In contrast, L. albidum and L. juniperoideum both corresponded to the same haplotype. Many populations could be readily assigned to either L. glaucum or L. albidum by their morphological features. However, morphological variation between these two species was continuous and one of the ITS haplotypes could not be unambiguously characterized by its morphology. Genetically and morphologically identifiable specimens of L. albidum were sampled in Europe and North America, in contrast to the traditional interpretation of L. albidum as a North American endemic. Although L. albidum seems to have a more s...

Three Mosses New to Vietnam

Splachnobryum indicum, Leucobryum microleucophanoides and Claopodium prionophyllum are reported as new from Vietnam, based on material collected by the author.

Notes on Leucobryaceae in Central America

Leucobryum incurvifolium C. Mill. is resurrected from the synonymy of L. albidum, and a new species, Ochrobryum crumii, is described from Mexico. The new combination L. propaguliferum (Dix.) Robins. is made.