A taxonomic revision of the pipunculid fly genus Chalarus Walker, with particular reference to the European fauna

Twenty-one species of Chalarus Walker are described from Europe, 11 of them new. The puparial remains of 15 species are described. Type material of all previously described Chalarus species except C. velutinus (Macquart, 1835) was examined. The status of C. holosericeus (Meigen, 1824) is revised, and exiguus (Haliday, 1833) is confirmed as a valid species. Lectotypes are designated for C. holosericeus and C. spurius (Fallén, 1816). Five species-groups are tentatively proposed. Separate keys to females and males are given. The status of Chalarus species described from outside Europe is discussed, and two of these, C. kamijoi Morakote, in Morakote & Hirashima (1990) and C. konishii Morakote, in Morakote & Hirashima (1990), are synonymized with fimbriatus Coe and exiguus (Haliday) respectively. The functional significance of some taxonomic characters, particularly of the eyes and ovipositor, is discussed.     

High diversity of rabies viruses associated with insectivorous bats in Argentina: presence of several independent enzootics

Background

Rabies is a fatal infection of the central nervous system primarily transmitted by rabid animal bites. Rabies virus (RABV) circulates through two different epidemiological cycles: terrestrial and aerial, where dogs, foxes or skunks and bats, respectively, act as the most relevant reservoirs and/or vectors. It is widely accepted that insectivorous bats are not important vectors of RABV in Argentina despite the great diversity of bat species and the extensive Argentinean territory.

Methods

We studied the positivity rate of RABV detection in different areas of the country, and the antigenic and genetic diversity of 99 rabies virus (RABV) strains obtained from 14 species of insectivorous bats collected in Argentina between 1991 and 2008.

Results

Based on the analysis of bats received for RABV analysis by the National Rabies system of surveillance, the positivity rate of RABV in insectivorous bats ranged from 3.1 to 5.4%, depending on the geographic location. The findings were distributed among an extensive area of the Argentinean territory. The 99 strains of insectivorous bat-related sequences were divided into six distinct lineages associated with Tadarida brasiliensis, Myotis spp, Eptesicus spp, Histiotus montanus, Lasiurus blosseviilli and Lasiurus cinereus. Comparison with RABV sequences obtained from insectivorous bats of the Americas revealed co-circulation of similar genetic variants in several countries. Finally, inter-species transmission, mostly related with Lasiurus species, was demonstrated in 11.8% of the samples.

Conclusions

This study demonstrates the presence of several independent enzootics of rabies in insectivorous bats of Argentina. This information is relevant to identify potential areas at risk for human and animal infection.     

Two new species and new records of biting midges of the genus Culicoides from northwestern Argentina (Diptera: Ceratopogonidae)

The following two new species of Culicoides from the Argentinean Yungas are described, illustrated and placed to subgenus or species group and compared with related congeners: Culicoides calchaqui Spinelli & Veggiani Aybar and Culicoides willinki Spinelli & Veggiani Aybar. Culicoides daedaloides Wirth & Blanton is recorded for the first time for Argentina and Culicoides pseudoheliconiae Felippe-Bauer is firstly mentioned from the northwestern region of the country.     

Resistance to Centaurea solstitialis invasion from annual and perennial grasses in California and Argentina

A common explanation for Centaurea solstitialis invasion in California is that it occupies an ??empty niche?? created by the replacement of native perennial grasses by exotic annual grasses and concomitant increases in soil water availability. This hypothesis, however, cannot explain C. solstitialis invasion into perennial-dominated grasslands of central Argentina. We assessed invasibility of annual versus perennial grass communities in these regions through parallel field experiments where we created grass plots and, after one year of establishment, measured effects on water and light, and added C. solstitialis seeds in two successive trials. Additionally, we removed vegetation around naturally occurring C. solstitialis in both regions, and examined the performance of Californian and Argentinean C. solstitialis individuals when growing under common conditions simulating climate in California and Argentina. In California, both grass types offered high resistance to C. solstitialis invasion, water was generally greater under perennials than annuals, and light was similarly low beneath both types. In Argentina, invasibility was generally greater in annual than perennial plots, water was similar between groups, and light was much greater beneath annuals. Removal experiments showed that competition from annual grasses in California and perennial grasses in Argentina greatly reduce C. solstitialis performance. Additionally, Californian and Argentinean individuals did not exhibit genetic differentiation in studied traits. Our results suggest that dominant plant functional groups in both California and Argentina offer substantial resistance to C. solstitialis invasion. The success of this species might be tightly linked to a remarkable ability to take advantage of disturbance in both regions.     

Nitrogen-fixing rhizobial strains isolated from Desmodium incanum DC in Argentina: Phylogeny,biodiversity and symbiotic ability

Desmodium spp. are leguminous plants belonging to the tribe Desmodieae of the subfamily Papilionoideae. They are widely distributed in temperated and subtropical regions and are used as forage plants, for biological control, and in traditional folk medicine. The genus includes pioneer species that resist the xerothermic environment and grow in arid, barren sites. Desmodium species that form nitrogen-fixing symbiosis with rhizobia play an important role in sustainable agriculture. In Argentina, 23 native species of this genus have been found, including Desmodium incanum. In this study, a total of 64 D. incanum-nodulating rhizobia were obtained from root nodules of four Argentinean plant populations. Rhizobia showed different abiotic-stress tolerances and a remarkable genetic diversity using PCR fingerprinting, with more than 30 different amplification profiles. None of the isolates were found at more than one site, thus indicating a high level of rhizobial diversity associated with D. incanum in Argentinean soils. In selected isolates, 16S rDNA sequencing and whole-cell extract MALDI TOF analysis revealed the presence of isolates related to Bradyrhizobium elkanii, Bradyrhizobium japonicum, Bradyrhizobium yuanmingense, Bradyrhizobium liaoningense, Bradyrhizobium denitrificans and Rhizobium tropici species. In addition, the nodC gene studied in the selected isolates showed different allelic variants.Isolates were phenotypically characterized by assaying their growth under different abiotic stresses. Some of the local isolates were remarkably tolerant to high temperatures, extreme pH and salinity, which are all stressors commonly found in Argentinean soils. One of the isolates showed high tolerance to temperature and extreme pH, and produced higher aerial plant dry weights compared to other inoculated treatments. These results indicated that local isolates could be efficiently used for D. incanum inoculation.     

Morphometric analysis of varieties of Acacia caven: (Leguminosae, Mimosoideae): Taxonomic inferences in the context of other Argentinean species

The aims of this study were to evaluate the degree of morphological differentiation between six varieties of Acacia caven and to examine their taxonomic validity in the context of other Argentinean species of the genus. To accomplish these purposes, morphological traits have been analyzed using multivariate methods (non parametric ANOVA, phenetic analysis and principal component analysis) on the varieties of A. caven and other six species of the genus, represented in Argentina. The phenogram obtained showed two principal clusters, one grouping all the species of subg. Acacia and the other grouping the species of subg. Aculeiferum. This result agreed with Vassal's infrageneric classification. However, the results of the principal PCA gathered the seven species here included in three groups, which were consistent with Bentham's infrageneric treatment. The ANOVA method indicated that most of the morphometric characters used were statistically sound for differentiation between varieties of A. caven. Further studies, including more species and characters, must be performed in order to clarify the position of Acacia boliviana and the relationships between A. caven and A. curvifructa.     

Tracking the origin of an invasive species: Drosophila subobscura in Argentina

Biological invasions are excellent opportunities to study the evolutionary forces leading to the adaptation of a species to a new habitat. Knowledge of the introduction history of colonizing species helps tracking colonizing routes and assists in defining management strategies for invasive species. The Palearctic species Drosophila subobscura is a good model organism for tracking colonizations since it was detected in Chile and western North America three decades ago and later on in the Atlantic coast of Argentina. To unravel the origin of the Argentinean colonizers two populations have been analysed with several genetic markers. Chromosomal arrangements and microsatellite alleles found in Argentina are almost similar to those observed in Chile and USA. The lethal allelism test demonstrates that the lethal gene associated with the O₅ inversions in Argentina is identical to that found in Chile and USA, strongly supporting the hypothesis that all the American colonizing populations originated from the same colonization event. A secondary bottleneck is detected in the Argentinean populations and the genetic markers suggest that these populations originated from the invasion of 80–150 founding individuals from Chile.     

Prospection and Evaluation of (Hemi) Cellulolytic Enzymes Using Untreated and Pretreated Biomasses in Two Argentinean Native Termites

Saccharum officinarum bagasse (common name: sugarcane bagasse) and Pennisetum purpureum (also known as Napier grass) are among the most promising feedstocks for bioethanol production in Argentina and Brazil. In this study, both biomasses were assessed before and after acid pretreatment and following hydrolysis with Nasutitermes aquilinus and Cortaritermes fulviceps termite gut digestome. The chemical composition analysis of the biomasses after diluted acid pretreatment showed that the hemicellulose fraction was partially removed. The (hemi) cellulolytic activities were evaluated in bacterial culture supernatants of termite gut homogenates grown in treated and untreated biomasses. In all cases, we detected significantly higher endoglucanase and xylanase activities using pretreated biomasses compared to untreated biomasses, carboxymethylcellulose and xylan. Several protein bands with (hemi) cellulolytic activity were detected in zymograms and two-dimensional gel electrophoresis. Some proteins of these bands or spots were identified as xylanolytic peptides by mass spectrometry. Finally, the diversity of cultured cellulolytic bacterial endosymbionts associated to both Argentinean native termite species was analyzed. This study describes, for the first time, bacterial endosymbionts and endogenous (hemi) cellulases of two Argentinean native termites as well as their potential application in degradation of lignocellulosic biomass for bioethanol production.     

Diet of the invasive sea slug Pleurobranchaea maculata in Patagonian coastal waters

High densities of the invasive sea slug, Pleurobranchaea maculata, have been detected on the Argentinean coast, but studies on the species’ adaptation have been absent until now. Stomach contents of P. maculata in two sampling sites located at Golfo Nuevo, Patagonia Argentina, revealed animals as a major prey, but surprisingly algae ingestion on both sampling sites was abundant. This fact was not reported in previous studies that described opportunistic carnivorous feeding habits of species belonging to the genus Pleurobranchaea. Significant differences in the species prey items were found between sampling sites; however, sedentary polychaetes were the main consumed group at both sites. These results are useful to understand the adaptation of this invasive species in Argentinean waters and to monitor future changes in the benthic communities colonised by P. maculata.     

The Epidemiology of Mould Infections in Argentina: Review and Experience

During the last decades, there has been an increasing proportion of patients susceptible to invasive fungal disease (IFD). The epidemiology of IFD varies mainly due to geography, antifungal exposure, and nosocomial reservoirs. We reviewed the Argentinean epidemiology of invasive mold disease (IMD) by analyzing laboratory and clinical data. Invasive mold disease was the second most prevalent IFD following the yeasts, with a prevalence that ranged from 0.98 to 1.31/100,000 population. The majority (60?C85?%) of IMD was caused by hyalohyphomycetes followed by Mucorales (6?C21?%) and phaeohyphomycetes (7?C13?%). The most prevalent genera were Aspergillus (40?C67?% of IMD) followed by Fusarium (10?C14?%). The most prevalent species were A. fumigatus (38?C50?%) followed by A. flavus (27?C43?%). In immunocompromised patients in Argentina the most prevalent agents of IMD are Aspergillus, followed by Fusarium and Mucorales, while the most prevalent Aspergillus species are A. fumigatus followed by A. flavus.     

Presence of the telescope fish Mendosoma lineatum in Patagonian waters,a new species in the ichthyological fauna from the south‐west Atlantic Ocean

The presence of the telescope fish Mendosoma lineatum in Patagonian waters of Argentina is reported. Mendosoma lineatum is the second species of the Latridae recorded in the south‐west Atlantic Ocean and its presence in Patagonia is an addition to both the ichthyological fauna of the Argentinean Sea and the south‐west Atlantic Ocean.     

Different feeding behaviors in a single predatory mite species. 1. Comparative life histories of three populations of Phytoseiulus longipes (Acari: Phytoseiidae) depending on prey species and plant substrate

The spider mites Tetranychus evansi and T. urticae are key pests of tomato crops, for which no sustainable practical control strategy is available yet. A Brazilian (B) and an Argentinean (A) population of a phytoseiid predatory mite species, Phytoseiulus longipes, are able to develop and reproduce on T. evansi on tomato, whereas a Chilean (C) population is not. In order to better characterize the two distinct feeding behaviours of these three populations, life table data were assessed when the predator was offered T. evansi or T. urticae as prey on bean or tomato leaves. No effect of the prey offered nor the plant substrate was demonstrated on development durations of the three populations. However, immature mortality was low for the Argentinean and the Brazilian populations whatever the prey or plant substrate, whereas 89 % of P. longipes from Chile died before reaching adulthood when fed T. evansi on tomato. No difference in effect on female longevity was detected among the three populations. Finally, the demographic parameters of all populations were lower in presence of tomato compared to beans. Possible explanations for these results are discussed.     

Lycopodiopsids and equisetopsids from the Triassic of Quebrada de los Fósiles Formation,San Rafael Basin,Argentina

In the late 1960s, rests of a low-diversity flora dominated by the lycopsid Pleuromeia were reported. The specimens were recovered from a creek near San Rafael, Mendoza Province, western Argentina, in the lower section of the Puesto Viejo Group, the Quebrada de los Fósiles Formation, considered as Early Triassic in age. Despite the importance of this flora with respect to the end-Permian mass extinction event, it was not yet described nor illustrated. Since then, the age of the Puesto Viejo Group has been revised and the Quebrada de los Fósiles Formation is now considered to be early Middle Triassic. The fossil plants are here first described and interpreted. The most common element, Pleuromeia cf. sternbergii, a species known worldwide that characterizes the post-extinction flora recovery, is accompanied by sphenopsids such as Neocalamites and Equisetostachys, and an herbaceous lycopsid. This community grew up associated with transient water bodies in flood plain environments that developed under warm temperate, strongly seasonal climatic conditions. The landscape was stressed by volcanism, and the conjunction of these factors probably restricted the colonization and development of a full ecosystem, as happened worldwide after the end-Permian mass extinction.     

Isolation of tetranucleotide microsatellite loci in the burrowing parrot (Cyanoliseus patagonus)

We isolated seven novel polymorphic microsatellite DNA loci from the burrowing parrot (Cyanoliseus patagonus) and optimised them for future studies of population differentiation and genetic variation. The loci were screened for polymorphism using 38 samples from wild individuals from three neighbouring colonies in Argentina. The primers amplified highly variable loci characterised by 3–10 alleles per locus and their observed and expected heterozygosities ranged from 0.15 to 0.78 and 0.15 to 0.81, respectively. When we analysed 52 samples across Argentina and Chile, we found strong genetic differentiation between the Chilean and the Argentinean subspecies as well as significant differentiation between two geographically separated subspecies within Argentina. Our results indicate the suitability of these microsatellites for investigating further questions regarding the population genetics in this species.