Developmental rates and host specificity for Pseudacteon parasitoids (Diptera: Phoridae) of fire ants (Hymenoptera: Formicidae) in Argentina

This study extends our comparative knowledge of Pseudacteon interactions with Solenopsis fire ant workers. Reported in this work are development times for seven Argentinean parasitoid species reared on two hosts, Solenopsis richteri Forel and Solenopsis invicta Buren, under laboratory temperature regimes comparable with those of the climatic zones occupied by these host species. Developmental times spanned 31-66 d across phorid species, and in general did not differ between genders or host species, but were longer at lower temperatures. The size distribution of flies reared was bimodal, with a group of large (Pseudacteon borgmeieri, Pseudacteon nocens, Pseudacteon obtusus and Pseudacteon tricuspis) and small (Pseudacteon cultellatus, Pseudacteon curvatus, and Pseudacteon nudicornis) species. P. borgmeieri was exceptional with respect to length of developmental time. Also reported are results of initial oviposition and developmental studies of some of these phorid species on other Argentinean Solenopsis ant species; P. curvatus was the only species able to complete its development on nonhost fire ants. These results support the concept of incorporating several complementary species of Pseudacteon in the biological control of pest fire ants.     

Cytogenetic characterization of two species of Frieseomelitta Ihering, 1912 (Hymenoptera, Apidae, Meliponini)

The cytogenetic analysis of Frieseomelitta dispar and F. francoi revealed the chromosome numbers 2n = 30 and n = 15 and a karyotypic formula 2K = 4M+2M(t)+4A+20A(M). The number of chromosomes observed was consistent with those reported for other Frieseomelitta species. The occurrence of the M(t) chromosome and other features of the karyotype formulae suggest a close relationship between F. dispar, F. francoi and F. varia. Nevertheless, it was possible to differentiate the karyotypes of the species by DAPI/CMA(3) staining, which revealed GC-rich regions on two chromosome pairs of F. dispar: one acrocentric and one pseudoacrocentric. In F. francoi, the same kinds of regions were observed on a pair of metacentrics and on a pair of acrocentrics. Our analysis also confirmed the chromosome number conservation in Frieseomelitta and suggests that infrequent pericentric inversion could constitute a synapomorphy for the group including F. dispar, F. francoi, and F. varia.     

A new species group in Megaselia,the lucifrons group,with description of a new species (Diptera,Phoridae)

With 1,400 described species, Megaselia is one of the most species-rich genera in the animal kingdom, and at the same time one of the least studied. An important obstacle to taxonomic progress is the lack of knowledge concerning the phylogenetic structure within the genus. Classification of Megaselia at the level of subgenus is incomplete although Schmitz addressed several groups of species in a series of monographs published from 1956 to 1981. Another problem is the lack of molecular phylogenetic analyses to support morphology-based conclusions. As a contribution towards addressing these problems, we here circumscribe a previously unrecognized monophyletic lineage of Megaselia consisting of species similar to Megaselia lucifrons. We base this taxonomic decision on morphological study of an extensive phorid material from Sweden, complemented by molecular analyses of select exemplars using two markers (COI and 28S). We name the clade the lucifrons species group, and show that it contains three distinct species. Our results also demonstrate that Megaselia subnitida Lundbeck, 1920, previously treated as a synonym of Megaselia lucifrons Schmitz, 1918, is a separate species, and we remove it from synonymy. The third species in the group was previously unknown; we describe it here as Megaselia albalucifrons sp. n.     

Dynamic expansion in recently introduced populations of fire ant parasitoids (Diptera: Phoridae)

Combating invasive species requires a detailed, mechanistic understanding of the manner and speed with which organisms expand their ranges. Biological control efforts provide an opportunity to study the process of species invasions and range expansions under known initial conditions. This study examines the rate, pattern and mechanisms of spread for two populations of the biological control agent Pseudacteon tricuspis, phorid-fly parasitoids of imported fire ants. We employ a trap-based survey method that detects phorid flies in low-density populations, and provides data on abundance. This technique allows us to differentiate between continuous population spread and effective long-distance dispersal and to examine density gradients of phorid flies across the expanding population front. We find that occupied sites in front of the leading edge of continuous populations were common; forming small populations we refer to as satellite populations. Satellite populations are tens of kilometers from the nearest possible source. Wind governs the dynamics of spread in these two central Texas populations. Population edges expanding with the wind exhibited a higher frequency of effective long-distance dispersal than did populations expanding into the wind. This enhanced effective long-distance dispersal rate translated into a five times faster rate of spread for population edges traveling with the wind. This planned invasion shares many characteristics in common with unplanned species invasions including: protracted establishment phase during which densities were below detection thresholds, and slow initial spread immediately after establishment followed by rapid, accelerating spread rates as population sizes grew.     

A review of Rheocricotopus (Psilocricotopus) chalybeatus species group from China,with the description of three new species (Diptera,Chironomidae)

The Rheocricotopus (Psilocricotopus) chalybeatus species group from China is reviewed. Three new species, R. (P.) brochus sp. n., R. (P.) rotundus sp. n. and R. (P.) serratus sp. n. are described as adult males. R. (P.) imperfectus Makarchenko & Makarchenko, 2005, R. (P.) robacki (Beck & Beck, 1964) and R. (P.) valgus Chaudhuri & Sinharay, 1983 are recorded from China for the first time and annotated. The diagnosis for the species group is emended and a key to adult males of the species group in China is presented.     

Development of Pseudacteon nocens (Diptera: Phoridae) on Solenopsis invicta and Solenopsis richteri fire ants (Hymenoptera: Formicidae)

We studied the developmental performance of the large morph of Pseudacteon nocens Borgmeier (Diptera: Phoridae), a prospective biological control agent of imported fire ants (Hymenoptera: Formicidae). We measured selected life history traits of this parasitoid as a function of 1) host species (Solenopsis invicta Buren versus Solenopsis richteri Forel), 2) temperature (22 versus 28 degrees C), 3) source population of the fly (Corrientes and Santiago del Estero, Argentina), and 4) varied size distributions of offered host ants. Developmental periods were influenced by host species, although the populations responded in opposing manners. Developmental times, however, were most strongly influenced by temperature with total developmental periods lengthened by 17-32% at 22 degrees C. Pupal mortality was also significantly lower at this temperature. Although numbers of progeny per female were significantly higher for the Corrientes population, we found no significant differences in progeny per female according to host species. Interestingly, we found that females were larger than males, and flies from Corrientes were larger than those from Santiago del Estero, even after statistical adjustments for host size. The modal frequency of host size elected in all treatment combinations tested was identical (0.6 mm), a size that represented the apparent threshold for producing female progeny. These laboratory and additional field observations demonstrate considerable interpopulational variation in P. nocens and lend further support to the applied approach focusing at the population, as opposed to the species level, with respect to both source and target areas for classical biological control introductions of Pseudacteon flies.     

The karyotype of three Brazilian Terrarana frogs (Amphibia, Anura) with evidence of a new Barycholos species

A recent substantial rearrangement of the 882 described eleutherodactyline frog species has considerably improved the understanding of their systematics. Nevertheless, many taxonomic aspects of the South American eleutherodactyline species remain unknown and require further investigation using morphological, cytogenetic and molecular approaches. In this work, the karyotypes of the Brazilian species Ischnocnema juipoca (Atibaia and Campos do Jordão, SP), Barycholos cf. ternetzi (Uberlândia, MG, and Porto Nacional, TO), and Pristimantis crepitans (Chapada dos Guimarães and São Vicente, MT) were analyzed using Giemsa staining, Ag-NOR labeling, and C-banding techniques. All individuals had a diploid number of 22 chromosomes, but the Fundamental Numbers were different among species. The herein described low chromosome number of Pristimantis crepitans is unique within this genus, suggesting that cytogenetically this species is not closely related either to its congeneric species or to Ischnocnema. In addition, karyotype differences, mainly in the NOR position, clearly distinguished the two Barycholos populations, besides indicating the existence of a so far undescribed species in this genus. A taxonomic review could clarify the systematic position of P. crepitans and verify the hypothetic new Barycholos species.     

First cytogenetic information for Drymoreomys albimaculatus (Rodentia,Cricetidae), a recently described genus from Brazilian Atlantic Forest

The recently described taxon Drymoreomys albimaculatus is endemic to the Brazilian Atlantic Forest and its biology and genetics are still poorly known. Herein, we present, for the first time, the karyotype of the species using classical and molecular cytogenetics, which showed 2n=62, FN=62, and interstitial telomeric signals at the sex chromosomes. Nuclear and mitochondrial DNA sequences from the two karyotyped individuals verify the taxonomic identity as the recently described Drymoreomys albimaculatus and confirm the relationship of the species with other Oryzomyini. Additionally, external morphological information is provided.     

Comparative molecular cytogenetics of major repetitive sequence families of three Dendrobium species (Orchidaceae) from Bangladesh

Background and Aims

Dendrobium species show tremendous morphological diversity and have broad geographical distribution. As repetitive sequence analysis is a useful tool to investigate the evolution of chromosomes and genomes, the aim of the present study was the characterization of repetitive sequences from Dendrobium moschatum for comparative molecular and cytogenetic studies in the related species Dendrobium aphyllum, Dendrobium aggregatum and representatives from other orchid genera.

Methods

In order to isolate highly repetitive sequences, a c₀t-1 DNA plasmid library was established. Repeats were sequenced and used as probes for Southern hybridization. Sequence divergence was analysed using bioinformatic tools. Repetitive sequences were localized along orchid chromosomes by fluorescence in situ hybridization (FISH).

Key Results

Characterization of the c₀t-1 library resulted in the detection of repetitive sequences including the (GA)_n dinucleotide DmoO11, numerous Arabidopsis-like telomeric repeats and the highly amplified dispersed repeat DmoF14. The DmoF14 repeat is conserved in six Dendrobium species but diversified in representative species of three other orchid genera. FISH analyses showed the genome-wide distribution of DmoF14 in D. moschatum, D. aphyllum and D. aggregatum. Hybridization with the telomeric repeats demonstrated Arabidopsis-like telomeres at the chromosome ends of Dendrobium species. However, FISH using the telomeric probe revealed two pairs of chromosomes with strong intercalary signals in D. aphyllum. FISH showed the terminal position of 5S and 18S–5·8S–25S rRNA genes and a characteristic number of rDNA sites in the three Dendrobium species.

Conclusions

The repeated sequences isolated from D. moschatum c₀t-1 DNA constitute major DNA families of the D. moschatum, D. aphyllum and D. aggregatum genomes with DmoF14 representing an ancient component of orchid genomes. Large intercalary telomere-like arrays suggest chromosomal rearrangements in D. aphyllum while the number and localization of rRNA genes as well as the species-specific distribution pattern of an abundant microsatellite reflect the genomic diversity of the three Dendrobium species.     

Oviposition behaviour of four ant parasitoids (Hymenoptera, Braconidae, Euphorinae, Neoneurini and Ichneumonidae, Hybrizontinae), with the description of three new European species

The oviposition behaviour of four ant parasitoids was observed and filmed for the first time. The movies are available from YouTube (search for Elasmosoma, Hybrizon, Kollasmosoma and Neoneurus). Two of the observed species (Neoneurus vesculussp. n. and Kollasmosoma sentumsp. n.) are new to science. A third species (Neoneurus recticalcarsp. n.) is described from Slovakia and Norway. Keys to the Palaearctic species of the genera Neoneurus and Kollasmosoma are added.     

Comparative molecular cytogenetic analyses of a major tandemly repeated DNA family and retrotransposon sequences in cultivated jute Corchorus species (Malvaceae)

Background and Aims

The cultivated jute species Corchorus olitorius and Corchorus capsularis are important fibre crops. The analysis of repetitive DNA sequences, comprising a major part of plant genomes, has not been carried out in jute but is useful to investigate the long-range organization of chromosomes. The aim of this study was the identification of repetitive DNA sequences to facilitate comparative molecular and cytogenetic studies of two jute cultivars and to develop a fluorescent in situ hybridization (FISH) karyotype for chromosome identification.

Methods

A plasmid library was generated from C. olitorius and C. capsularis with genomic restriction fragments of 100–500 bp, which was complemented by targeted cloning of satellite DNA by PCR. The diversity of the repetitive DNA families was analysed comparatively. The genomic abundance and chromosomal localization of different repeat classes were investigated by Southern analysis and FISH, respectively. The cytosine methylation of satellite arrays was studied by immunolabelling.

Key Results

Major satellite repeats and retrotransposons have been identified from C. olitorius and C. capsularis. The satellite family CoSat I forms two undermethylated species-specific subfamilies, while the long terminal repeat (LTR) retrotransposons CoRetro I and CoRetro II show similarity to the Metaviridea of plant retroelements. FISH karyotypes were developed by multicolour FISH using these repetitive DNA sequences in combination with 5S and 18S–5·8S–25S rRNA genes which enable the unequivocal chromosome discrimination in both jute species.

Conclusions

The analysis of the structure and diversity of the repeated DNA is crucial for genome sequence annotation. The reference karyotypes will be useful for breeding of jute and provide the basis for karyotyping homeologous chromosomes of wild jute species to reveal the genetic and evolutionary relationship between cultivated and wild Corchorus species.     

Comparative cytogenetics of eight species of Cycloramphus (Anura, Cycloramphidae)

Several aspects of the biology of Cycloramphus species of the Atlantic Forest are still poorly known, which makes it difficult to understand their historical relationships. Therefore, we were stimulated to promote a comparative cytogenetic analysis of several species of the genus Cycloramphus. The study of Cycloramphus acangatan, C. boraceiensis, C. brasiliensis, C. carvalhoi, C. eleutherodactylus, C. fuliginosus, C. lutzorum, and C. rhyakonastes, revealed that these eight species share a diploid number 2n = 26. Cycloramphus fuliginosus presented the most distinct karyotype, due to the presence of subtelocentric chromosomes in pairs 1 and 4. The main diagnostic feature observed in the other species was the presence of one pair of telocentric chromosomes in C. boraceiensis, C. carvalhoi, and C. eleutherodactylus, while the remaining species presented karyotypes composed exclusively of biarmed chromosomes. Constitutive heterochromatin was predominantly located in pericentromeric regions in all species, although additional C-bands detected on telomeric and/or interstitial regions were partially species-specific. Silver staining revealed Ag-NORs located on the pair 6 in six species, whereas C. acangatan presented it on pair 1 and a multiple pattern was observed in C. fuliginosus with three Ag-NOR bearing chromosomes. Fluorescent in situ hybridization using rDNA probe was performed in specimens of C. eleutherodactylus from Paraná, C. lutzorum, and C. rhyakonastes, which did not reveal inactive NOR. Despite the apparent highly conserved diploid number, data on the karyotype microstructure characterize the cytogenetic profile of the genus and may contribute to clarify the phylogenetic relationships among Cycloramphus, the Cycloramphinae, or even the family Cycloramphidae.     

Three new species of European Platypalpus (Diptera,Hybotidae)

Platypalpus graecoides sp. n. (Italy), Platypalpus pyreneensis sp. n. (Andorra), and Platypalpus silvahumidus sp. n. (Czech Republic) are described. All three species are illustrated and keyed. Platypalpus hallensis Grootaert & Stark, 1997 is first reported from France and Spain.     

Palaearctic species of Rhamphomyia (Pararhamphomyia) anfractuosa group (Diptera,Empididae)

Palaearctic species of the Rhamphomyia (Pararhamphomyia) anfractuosa group are revised. Rhamphomyia (Pararhamphomyia) biflexata sp. n., Rhamphomyia (Pararhamphomyia) lineodorsata sp. n., Rhamphomyia (Pararhamphomyia) nudiscutellata sp. n., and Rhamphomyia (Pararhamphomyia) shatalkini sp. n. (all from Russian Far East) are described and illustrated. A key to Palaearctic species of the Rhamphomyia (Pararhamphomyia) anfractuosa group is provided.     

Non-destructive species identification of Drosophila obscura and D. subobscura (Diptera) using near-infrared spectroscopy

The vinegar flies Drosophila subobscura and D. obscura frequently serve as study organisms for evolutionary biology. Their high morphological similarity renders traditional species determination difficult, especially when living specimens for setting up laboratory populations need to be identified. Here we test the usefulness of cuticular chemical profiles collected via the non-invasive method near-infrared spectroscopy for discriminating live individuals of the two species. We find a classification success for wild-caught specimens of 85%. The species specificity of the chemical profiles persists in laboratory offspring (87–92% success). Thus, we conclude that the cuticular chemistry is genetically determined, despite changes in the cuticular fingerprints, which we interpret as due to laboratory adaptation, genetic drift and/or diet changes. However, because of these changes, laboratory-reared specimens should not be used to predict the species-membership of wild-caught individuals, and vice versa. Finally, we demonstrate that by applying an appropriate cut-off value for interpreting the prediction values, the classification success can be immensely improved (to up to 99%), albeit at the cost of excluding a considerable portion of specimens from identification.     

Six new species of Acomoptera from North America (Diptera, Mycetophilidae)

Six new species are described, raising the number of North American Acomoptera species to seven and the genus total to ten, and nearly doubling the number of species within the putative clade containing Acomoptera, Drepanocercus, and Paratinia. These novel species forms have implications for the concept of Acomoptera that in turn, may impact our understanding of its generic relationships and the evolution and composition of Gnoristinae and Sciophilinae. The new species, Acomoptera crispa, Acomoptera digitata, Acomoptera echinosa, Acomoptera forculata, Acomoptera nelsoni,and Acomoptera vockerothi, are compared with the type species of the genus, Acomoptera plexipus (Garrett), whose diagnostic features are imaged and illustrated for the first time. The European species, Acomoptera difficilis (Dziedzicki) is also illustrated and compared. Acomoptera spinistyla (Søli) comb. n. is transferred from Drepanocercus. A key to species is provided. Future work will seek to incorporate this knowledge into a systematic phylogenetic study of relationships between these species and their sister taxa.     

Five new species of Minettia (Minettiella) (Diptera,Lauxaniidae) from China

Five species of Minettia Robineau-Desvoidy, 1830 from the South of China are described as new to science: Minettia (Minettiella) bawanglingensis sp. n., Minettia (Minettiella) clavata sp. n., Minettia (Minettiella) plurifurcata sp. n., Minettia (Minettiella) spinosa sp. n. and Minettia (Minettiella) tianmushanensis sp. n. Minettiella elbergi Shatalkin, 1996 and Minettia japonica Sasakawa, 1995 are treated as junior synonyms of Minettia (Minettiella) dolabriforma (Sasakawa & Kozánek, 1995). A key to five subgenera of Minettia and eleven species of Minettia (Minettiella) is presented.     

Two new species of Oxycera (Diptera, Stratiomyidae) from Ningxia, China

Two new speices, Oxycera rozkosnyisp. n. and Oxycera ningxiaensissp. n., are described from Liupanshan Nature Reserve, Ningxia Hui Autonomous Region, Northwest China. All essential diagnostic characters are figured and possible relationships of both taxa are briefly discussed, and a new key to species of Oxycera from China. The type specimens are deposited in the Institute of Entomology, Guizhou University, Guiyang (GUGC).