New contributions to the biodiversity of ciliates (Protozoa,Ciliophora) from Antarctica,including a description of <Emphasis Type="Italic">Gastronauta multistriata</Emphasis> nov. spec.

Antarctica is a remote and isolated biotope which makes it an ideal location for studying new and endemic species. Since there is little literature available on the diversity of ciliates in this area, a taxonomic survey of ciliates from melt-water of Collins glacier, King George Island, was carried out from January to March 2006. As a result, the morphology and infraciliature of five ciliates, including one new species, are described using live observations and silver staining: Gastronauta multistriata nov. spec., Neokeronopsis asiatica Foissner et al., 2010, Paraholosticha muscicola Kahl, 1932, Oxytricha sp., and Cyclidium glaucoma Müller, 1786. Gastronauta multistriata nov. spec. is distinguished from its congeners by the following combination of characters: cell size in vivo on average 80 × 40 μm; 5–9 kineties in left ciliary field; 18–23 kineties in right ciliary field, including 10–12 postoral kineties; 7–10 preoral kineties; dorsal brush along anterior dorsal margin, consisting of 5–8 groups of basal bodies. The only minor differences between the current population of N. asiatica and a previously described Antarctic population are the numbers of caudal cirri (6–10 vs. 8–15) and dorsal kineties (11–13 vs. 12–18). Paraholosticha sterkii is synonymised with P. muscicola. The Antarctic population of C. glaucoma corresponds well with a former population from China, the only difference being the number of kinetids in SK _n (11–17 vs. 9–11). This work will contribute to the understanding of ciliate diversity in this little studied area.     

Morphology and SSU rDNA-based phylogeny of two Euplotes species from China: E. wuhanensis sp. n. and E. muscicola Kahl, 1932 (Ciliophora,Euplotida)

The living morphology, infraciliature and silverline system of two small Euplotes species, E. wuhanensis sp. n. and E. muscicola Kahl, 1932, isolated from Wuhan, central China, were investigated. Euplotes wuhanensis sp. n. is characterized by a combination of features including small size (40–50 × 25–30 μm), two conspicuously small and eight normal-sized frontoventral cirri, five transverse cirri in two groups, two marginal and two caudal cirri, seven dorsal kineties with about 12 dikinetids in the mid-dorsal row and a double-eurystomus type of dorsal silverline pattern. The Wuhan population of E. muscicola closely resembles previously described populations. The establishments of three subspecies of E. muscicola are not supported. The small subunit ribosomal RNA gene sequences were determined for both species. We propose that the two sequences under the name of E. muscicola (No. AJ305254, DQ917684 deposited in GenBank) are very likely from misidentified material. Phylogenetic analyses based on these data support the validity of both E. muscicola and E. wuhanensis as distinct species.     

Effects of nutritional input and diesel contamination on soil enzyme activities and microbial communities in antarctic soils

Pollution of Antarctic soils may be attributable to increased nutritional input and diesel contamination via anthropogenic activities. To investigate the effect of these environmental changes on the Antarctic terrestrial ecosystem, soil enzyme activities and microbial communities in 3 types of Antarctic soils were evaluated. The activities of alkaline phosphomonoesterase and dehydrogenase were dramatically increased, whereas the activities of β-glucosidase, urease, arylsulfatase, and fluorescein diacetate hydrolysis were negligible. Alkaline phosphomonoesterase and dehydrogenase activities in the 3 types of soils increased 3- to 10-fold in response to nutritional input, but did not increase in the presence of diesel contamination. Consistent with the enzymatic activity data, increased copy numbers of the phoA gene, encoding an alkaline phosphomonoesterase, and the 16S rRNA gene were verified using quantitative real-time polymerase chain reaction. Interestingly, dehydrogenase activity and 16S rRNA gene copy number increased slightly after 30 days, even under diesel contamination, probably because of adaptation of the bacterial population. Intact Antarctic soils showed a predominance of Actinobacteria phylum (mostly Pseudonorcarida species) and other phyla such as Proteobacteria, Chloroflexi, Planctomycetes, Firmicutes, and Verrucomicrobia were present in successively lower proportions. Nutrient addition might act as a selective pressure on the bacterial community, resulting in the prevalence of Actinobacteria phylum (mostly Arthrobacter species). Soils contaminated by diesel showed a predominance of Proteobacteria phylum (mostly Phyllobacterium species), and other phyla such as Actinobacteria, Bacteroidetes, Planctomycetes, and Gemmatimonadetes were present in successively lower proportions. Our data reveal that nutritional input has a dramatic impact on bacterial communities in Antarctic soils and that diesel contamination is likely toxic to enzymes in this population.     

Phylogenetic relationships between geographically separate Phormidium cyanobacteria: is there a link between north and south polar regions?

We present a phytogeographical comparison between polar (Arctic and Antarctic) and non-polar strains of the cyanobacterial genus Phormidium, which plays a key role in Arctic and Antarctic ecosystems as primary producer. A total of 26 Phormidium strains were studied using a polyphasic approach, 18 from Arctic (Svalbard, Ellesmere Island and Scandinavian Arctic—Abisko) and Antarctic (Antarctic Peninsula—King George and James Ross Island) regions, and 8 from temperate sites (mostly situated in Central Europe). A phylogenetic tree was constructed and compared with similar 16S rRNA sequences retrieved from Genbank. Within the Phormidium autumnale cluster, genetic similarity of 16S rDNA was more related to geographical proximity of strain origin than to morphological similarity. No genetic identity of Phormidium strains from north and south polar regions was found. The cluster Phormidium autumnale apparently belongs to generic entities in which geographical limitation plays a prominent role. However, the cyanobacterial strains found in Europe suggest that the distribution areas of some Phormidium cyanobacteria overlap. The Phormidium autumnale cluster is evidently a very characteristic type and represents an isolated clade within the traditional genus Phormidium. According to morphological features and the structure of trichomes, it is most similar and thus probably belongs to the genus Microcoleus.     

Molecular data support the existence of two species of the Antarctic fish genus <Emphasis Type="Italic">Cryodraco</Emphasis> (Channichthyidae)

Antarctic notothenioids represent one of the few strongly supported examples of adaptive radiation in marine fishes. The extent of population connectivity and structure is unknown for many species, thereby limiting our understanding of the factors that underlie speciation dynamics in this radiation. Here, we assess the population structure of the widespread species Cryodraco antarcticus and its sister species Cryodraco atkinsoni, whose taxonomic status is currently debated. Combining both population genetic and phylogenetic approaches to species delimitation, we provide evidence that C. atkinsoni is a distinct species. Our analyses show that C. atkinsoni and C. antarcticus are recently diverged sister lineages, and the two species differ with regard to patterns of population structure. A systematic and accurate account of species diversity is a critical prerequisite for investigations into the complex processes that underlie the history of speciation in the notothenioid adaptive radiation.     

The genus Pleurotus in Brazil: a molecular and taxonomic overview

Considering that the knowledge of Pleurotus in Brazil is very dispersed and fragmented, this work presents for the first time a discussion of the recognition of at least five species certainly known from the country. Maximum likelihood analysis was conducted with nrITS sequences to generate a phylogenetic tree with a better resolution, confirming the occurrence of P. albidus, P. djamor, P. fuscosquamulosus, P. pulmonarius, and P. rickii in Brazil. In addition, we present a list of all epithets that were recorded from Brazil and current update of their taxonomic status.     

Phylogenetic Diversity of the Bacillus pumilus Group and the Marine Ecotype Revealed by Multilocus Sequence Analysis

Bacteria closely related to Bacillus pumilus cannot be distinguished from such other species as B. safensis, B. stratosphericus, B. altitudinis and B. aerophilus simply by 16S rRNA gene sequence. In this report, 76 marine strains were subjected to phylogenetic analysis based on 7 housekeeping genes to understand the phylogeny and biogeography in comparison with other origins. A phylogenetic tree based on the 7 housekeeping genes concatenated in the order of gyrB-rpoB-pycA-pyrE-mutL-aroE-trpB was constructed and compared with trees based on the single genes. All these trees exhibited a similar topology structure with small variations. Our 79 strains were divided into 6 groups from A to F; Group A was the largest and contained 49 strains close to B. altitudinis. Additional two large groups were presented by B. safensis and B. pumilus respectively. Among the housekeeping genes, gyrB and pyrE showed comparatively better resolution power and may serve as molecular markers to distinguish these closely related strains. Furthermore, a recombinant phylogenetic tree based on the gyrB gene and containing 73 terrestrial and our isolates was constructed to detect the relationship between marine and other sources. The tree clearly showed that the bacteria of marine origin were clustered together in all the large groups. In contrast, the cluster belonging to B. safensis was mainly composed of bacteria of terrestrial origin. Interestingly, nearly all the marine isolates were at the top of the tree, indicating the possibility of the recent divergence of this bacterial group in marine environments. We conclude that B. altitudinis bacteria are the most widely spread of the B. pumilus group in marine environments. In summary, this report provides the first evidence regarding the systematic evolution of this bacterial group, and knowledge of their phylogenetic diversity will help in the understanding of their ecological role and distribution in marine environments.     

Diversity of Environmental Mycobacterium Isolates from Hemodialysis Water as Shown by a Multigene Sequencing Approach

Here we used a multigene sequencing approach for the identification and molecular typing of environmental mycobacteria of the fast-growing subgroup. Strains were isolated from hemodialysis water and clinical samples. Eleven type strains of related species of the genus were also included in this study. To gain further insight into the diversity of the environmental mycobacteria, we analyzed several housekeeping genes (16S rRNA, ITS1, gyrB, hsp65, recA, rpoB, and sodA). No individual phylogenetic tree allowed good discrimination of all of the species studied. However, a concatenated and a consensus analysis, combining the genes, allowed better discrimination of each strain to the species level, and the increase in sequence size also led to greater tree robustness. This approach is useful not only for the discrimination and identification of environmental mycobacteria but also for their molecular typing and studies of population genetics. Our results demonstrate high genetic diversity among the isolates obtained, which are probably new species of the genus.     

Cytogenetic and Molecular Analyses Reveal a Divergence between Acromyrmex striatus (Roger, 1863) and Other Congeneric Species: Taxonomic Implications

The leafcutter ants, which consist of Acromyrmex and Atta genera, are restricted to the New World and they are considered the main herbivores in the neotropics. Cytogenetic studies of leafcutter ants are available for five species of Atta and 14 species of Acromyrmex, both including subspecies. These two ant genera have a constant karyotype with a diploid number of 22 and 38 chromosomes, respectively. The most distinct Acromyrmex species from Brazil is A. striatus, which is restricted to the southern states of Santa Catarina and Rio Grande do Sul. Several cytogenetic and phylogenetic studies have been conducted with ants, but the karyotypic characterization and phylogenetic position of this species relative to leafcutter ants remains unknown. In this study, we report a diploid number of 22 chromosomes for A. striatus. The phylogenetic relationship between A. striatus and other leafcutter ants was estimated based on the four nuclear genes. A. striatus shared the same chromosome number as Atta species and the majority of metacentric chromosomes. Nuclear data generated a phylogenetic tree with a well-supported cluster, where A. striatus formed a different clade from other Acromyrmex spp. This combination of cytogenetic and molecular approaches provided interesting insights into the phylogenetic position of A. striatus among the leafcutter ants and the tribe Attini.     

Updates on East Asian <Emphasis Type="Italic">Asterostroma</Emphasis> (Russulales,Basidiomycota): new species and new records from Thailand and China

Two new species from northern Thailand, Asterostroma bambusicola and A. vararioides, are described and illustrated. Asterostroma bambusicola is characterized by globose, echinulate, and amyloid basidiospores and growing on rotten bamboo. Asterostroma vararioides is distinguished by the presence of Vararia-like dichohyphae, subglobose, smooth, and amyloid basidiospores and growing on bark of living angiosperm trees. In the phylogenetic tree inferred from a combined dataset of ITS and nLSU sequence data of Peniophoraceae, A. bambusicola forms a distinct lineage in the sect. Asterostroma clade, whereas A. vararioides and A. laxum form the sect. Laevispora clade. Asterostroma andinum, reported from China for the first time, forms a distinct lineage sister to Gloiothele spp. and Scytinostroma portentosum group. Asterostroma muscicola is reported from Thailand and China for the first time. A key to the species of Asterostroma from Thailand and China is provided.     

Diversity and distribution of hidden cultivable fungi associated with marine animals of Antarctica

In the present study, we surveyed the distribution and diversity of fungal assemblages associated with 10 species of marine animals from Antarctica. The collections yielded 83 taxa from 27 distinct genera, which were identified using molecular biology methods. The most abundant taxa were Cladosporium sp. 1, Debaryomyces hansenii, Glaciozyma martinii, Metschnikowia australis, Pseudogymnoascus destructans, Thelebolus cf. globosus, Pseudogymnoascus pannorum, Tolypocladium tundrense, Metschnikowia australis, and different Penicillium species. The diversity, richness, and dominance of fungal assemblages ranged among the host; however, in general, the fungal community, which was composed of endemic and cold-adapted cosmopolitan taxa distributed across the different sites of Antarctic Peninsula, displayed high diversity, richness, and dominance indices. Our results contribute to knowledge about fungal diversity in the marine environment across the Antarctic Peninsula and their phylogenetic relationships with species that occur in other cold, temperate, and tropical regions of the World. Additionally, despite their extreme habitats, marine Antarctic animals shelter cryptic and complex fungal assemblages represented by endemic and cosmopolitan cold-adapted taxa, which may represent interesting models to study different symbiotic associations between fungi and their animal hosts in the extreme conditions of Antarctica.     

Spatial structure of the soil seed bank of Poa annua L.—alien species in the Antarctica

Poa annua L. (annual bluegrass) is the only non–native flowering plant species that has successfully established a breeding population in the maritime Antarctic and has been shown to maintain a soil seed bank. The characteristic of the spatial structure of the Antarctic population of this species is the formation of distinct dense clumps—tussocks. In the temperate zone the species is only loosely tufted. We focused on the characteristics of seed deposition associated with the tussocks and some aspects of the spatial heterogeneity of the soil seed bank of P. annua in the Antarctic. We wanted to assess the microspatial structure of the soil seed bank of annual bluegrass at Arctowski Station. Therefore we compared the number of seeds deposited underneath and in the vicinity of P. annua clumps. Our results indicate that P. annua in the Antarctic maintains a soil seed bank comparable to species typical for the polar tundra. The microspatial structure of P. annua soil seed bank in the Antarctic is highly associated with the presence of tussocks. Seeds are deposited underneath the tussock rather than in the vicinity of the clump. Our results also indicate that seeds are able to survive the Antarctic winter and readily germinate under optimal conditions.     

Phylogenetic relationships of the endemic Antarctic benthic hydroids (Cnidaria, Hydrozoa): what does the mitochondrial 16S rRNA tell us about it?

Hydroidolinan hydrozoans are widely represented in the benthic Antarctic ecosystem, mainly by some endemic and putative monophyletic groups, never included in molecular phylogenetic analyses. 38 partial sequences of the mitochondrial 16S rRNA gene were obtained for 38 species belonging to 14 families (six anthoathecates and eight leptothecates) and 20 genera (7 anthoathecates and 13 leptothecates). These sequences were combined with 108 additional sequences retrieved from the GenBank to investigate both the hypothetical monophyletism and the phylogenetic relationships of those endemic Antarctic groups; the potential use of the marker for barcoding was also investigated. Our results uphold the monophyly of some important hydroidolinan groups, such as the superfamily Plumularioidea (together with all its families, including Schizotrichidae, fam. nov.) and the Aplanulata. Concerning the Antarctic endemic groups, most results as monophyletic (Oswaldella, Schizotricha and Staurotheca), some genera form part of the expectable groups (e.g. Abietinella, located into the monophyletic Zygophylacinae clade) and, finally, others have shown a surprising position (e.g. Stegella, closely related to Lafoeinae, or Billardia and Stegopoma, allied with Hebellidae). Finally, our study has shown the utility of the marker to recognize the Antarctic species considered, but the low genetic divergence in some of the most important Antarctic groups suggests being careful when using it for DNA barcoding in the case of the original Antarctic hydroid fauna.     

Multilocus phylogenetic analysis of the genus Aeromonas

A broad multilocus phylogenetic analysis (MLPA) of the representative diversity of a genus offers the opportunity to incorporate concatenated inter-species phylogenies into bacterial systematics. Recent analyses based on single housekeeping genes have provided coherent phylogenies of Aeromonas. However, to date, a multi-gene phylogenetic analysis has never been tackled. In the present study, the intra- and inter-species phylogenetic relationships of 115 strains representing all Aeromonas species described to date were investigated by MLPA. The study included the independent analysis of seven single gene fragments (gyrB, rpoD, recA, dnaJ, gyrA, dnaX, and atpD), and the tree resulting from the concatenated 4705 bp sequence. The phylogenies obtained were consistent with each other, and clustering agreed with the Aeromonas taxonomy recognized to date. The highest clustering robustness was found for the concatenated tree (i.e. all Aeromonas species split into 100% bootstrap clusters). Both possible chronometric distortions and poor resolution encountered when using single-gene analysis were buffered in the concatenated MLPA tree. However, reliable phylogenetic species delineation required an MLPA including several “bona fide” strains representing all described species.     

Data Concatenation,Bayesian Concordance and Coalescent-Based Analyses of the Species Tree for the Rapid Radiation of Triturus Newts

The phylogenetic relationships for rapid species radiations are difficult to disentangle. Here we study one such case, namely the genus Triturus, which is composed of the marbled and crested newts. We analyze data for 38 genetic markers, positioned in 3-prime untranslated regions of protein-coding genes, obtained with 454 sequencing. Our dataset includes twenty Triturus newts and represents all nine species. Bayesian analysis of population structure allocates all individuals to their respective species. The branching patterns obtained by data concatenation, Bayesian concordance analysis and coalescent-based estimations of the species tree differ from one another. The data concatenation based species tree shows high branch support but branching order is considerably affected by allele choice in the case of heterozygotes in the concatenation process. Bayesian concordance analysis expresses the conflict between individual gene trees for part of the Triturus species tree as low concordance factors. The coalescent-based species tree is relatively similar to a previously published species tree based upon morphology and full mtDNA and any conflicting internal branches are not highly supported. Our findings reflect high gene tree discordance due to incomplete lineage sorting (possibly aggravated by hybridization) in combination with low information content of the markers employed (as can be expected for relatively recent species radiations). This case study highlights the complexity of resolving rapid radiations and we acknowledge that to convincingly resolve the Triturus species tree even more genes will have to be consulted.     

Basis for the Resistance of Several Algae to Microbial Decomposition

The basis for the resistance of certain algae to microbial decomposition in natural waters was investigated using Pediastrum duplex, Staurastrum sp., and Fischerella muscicola as test organisms. Enzyme preparations previously found to convert susceptible algae into spheroplasts had no such effect on the resistant species, although glucose and galacturonic acid were released from P. duplex walls. Little protein or lipid but considerable carbohydrate was found in the walls of the refractory organisms, but resistance was not correlated with the presence of a unique sugar monomer. A substance present in Staurastrum sp. walls was characterized as lignin or lignin-like on the basis of its extraction characteristics, infrared spectrum, pyrolysis pattern, and content of an aromatic building block. Sporopollenin was found in P. duplex, and cellulose in Staurastrum sp. Cell walls of the algae were fractionated, and the fractions least susceptible to microbial degradation were the sporopollenin of P. duplex, the polyaromatic component of Staurastrum sp., and two F. muscicola fractions containing several sugar monomers. The sporopollenin content of P. duplex, the content of lignin or a related constituent of Staurastrum sp., and the resistance of the algae to microbial attack increased with age. It is suggested that resistance results from the presence of sporopollenin in P. duplex, a lignin-like material in Staurastrum sp., and possibly heteropolysaccharides in F. muscicola.     

Joint Loads in Marsupial Ankles Reflect Habitual Bipedalism versus Quadrupedalism

Joint surfaces of limb bones are loaded in compression by reaction forces generated from body weight and musculotendon complexes bridging them. In general, joints of eutherian mammals have regions of high radiodensity subchondral bone that are better at resisting compressive forces than low radiodensity subchondral bone. Identifying similar form-function relationships between subchondral radiodensity distribution and joint load distribution within the marsupial postcranium, in addition to providing a richer understanding of marsupial functional morphology, can serve as a phylogenetic control in evaluating analogous relationships within eutherian mammals. Where commonalities are established across phylogenetic borders, unifying principles in mammalian physiology, morphology, and behavior can be identified. Here, we assess subchondral radiodensity patterns in distal tibiae of several marsupial taxa characterized by different habitual activities (e.g., locomotion). Computed tomography scanning, maximum intensity projection maps, and pixel counting were used to quantify radiodensity in 41 distal tibiae of bipedal (5 species), arboreal quadrupedal (4 species), and terrestrial quadrupedal (5 species) marsupials. Bipeds (Macropus and Wallabia) exhibit more expansive areas of high radiodensity in the distal tibia than arboreal (Dendrolagus, Phascolarctos, and Trichosurus) or terrestrial quadrupeds (Sarcophilus, Thylacinus, Lasiorhinus, and Vombatus), which may reflect the former carrying body weight only through the hind limbs. Arboreal quadrupeds exhibit smallest areas of high radiodensity, though they differ non-significantly from terrestrial quadrupeds. This could indicate slightly more compliant gaits by arboreal quadrupeds compared to terrestrial quadrupeds. The observed radiodensity patterns in marsupial tibiae, though their statistical differences disappear when controlling for phylogeny, corroborate previously documented patterns in primates and xenarthrans, potentially reflecting inferred limb use during habitual activities such as locomotion. Despite the complex nature of factors contributing to joint loads, broad observance of these patterns across joints and across a variety of taxa suggests that subchondral radiodensity can be used as a unifying form-function principle within Mammalia.     

Asterostroma species (Basidiomycota) from mangrove forests in Japan

A new homobasidiomycete, Asterostroma macrosporum, was found in mangrove forests of Iriomote Island, Japan. This species is morphologically characterized by having resupinate basidiomata, a monomitic (asterodimitic) hyphal system, simple septate generative hyphae, dextrinoid asterosetae, four sterigmate basidia and globose, tuberculate and amyloid basidiospores measuring 8.5–11 × 7.5–9 μm. It is similar to A. muscicola, but basidiospores in the latter are smaller (7–8 × 5.5–7 μm). Furthermore, phylogenetic analysis using internal transcribed spacer (ITS) region revealed that A. macrosporum is distinctly separated from A. muscicola. In Japan, A. muscicola is widely distributed in warm-temperate to subtropical regions, growing on a variety of broadleaved trees including mangroves, while A. macrosporum has been found only on mangroves.