Ultrastructural and molecular identification of a new Rickettsia endosymbiont in the springtail Onychiurus sinensis (Hexapoda, Collembola)

In this paper we provide microscopic and molecular evidence for the presence of an endosymbiontic bacterium in male and female gonads of the soil arthropod Onychiurus sinensis. The sequence of the gene encoding for the 16S rRNA shows that the bacterium is a member of the genus Rickettsia, and some anomalies presumably associated with the presence of these microorganisms have been detected. Although the Rickettsia found in O. sinensis has the smallest genetic divergence with Rickettsia bellii, the phylogenetic analysis fails to find support for a sister-group relationship between these two species, rather suggesting that most Rickettsia species/strains isolated in various arthropods have rapidly evolved and diversified in what appears to be a sudden burst of evolution.     

The ultrastructure of the ejaculatory duct in the springtail Orchesella villosa (Geoffroy) (Hexapoda, Collembola) and the formation of the spermatophore

The initial part of the ejaculatory duct of Orchesella villosa contains a “valve” and a “sorter” avoiding respectively the reflow and allowing the separation of the secretion for the spermatophore stalk from the sperm fluid. For most of its length, the ejaculatory duct lumen is divided into two parts: in the dorsal part the sperm fluid flows while in the ventral district the secretion for the stalk occurs. Laterally, on both sides of the duct, longitudinal muscle fibers are present. The epithelium of the dorsal region consists of two types of long secretory cells; the most peculiar of them are those provided with extracellular cisterns flowing directly into the duct lumen as it occurs in 1st type of epidermal cells. These cells could be involved in the control of the viscosity of the sperm fluid. The second type of cells produce a secretion probably involved in the formation of the outer coat of the apical sperm droplet. The ventral epithelium consists of short cells contributing to the enrichment of the secretion for the spermatophore stalk and perhaps also to the viscosity of the secretion flowing in the lumen. In the distal part of the ejaculatory duct, the ventral district is provided with a thick layer of muscle fibers and with 3 + 3 cuticular laminae dividing the lumen into a series of slits through which the secretion of the stalk is squeezed out into filaments. This organization allows the twisting and hardening of these filaments. A drop of sperm fluid is laid on top of the long and rigid spermatophore stalk.     

Springtails (Hexapoda,Collembola) of Tundra Landscapes of the Kola Peninsula

A quantitative study of collembolan assemblages on the Barents Sea coast of the Kola Peninsula was performed. Altogether, 104 collembolan species of 55 genera and 16 families were found. Analysis of the faunal composition revealed its high similarity to that of the faunas of the neighboring regions of Norway as well as a marked decline in species richness as compared to the Siberian analogues. A high share of littoral forms with increased vagility and the predominance of species with “southern” (= boreal) and “western” distribution patterns are the main characteristics of the fauna studied; only a few true arctic forms were found, always with low abundance and occurrence levels. Most of the studied collembolan assemblages are characterized by the dominance of a few species which inhabit a part of or the entire range of plant communities. As a result, collembolan assemblages under various types of vegetation cover in different landscape elements often show only insignificant differences.     

Formation of springtail (Collembola) communities during colonization of ant-hills

Formation of springtail assemblages in resettled nests of the ant Formica aquilonia was studied. The species composition and relative abundance of springtails was shown to depend on the age, hydrothermal regime, and condition of the ant nest. The abundance and species diversity of springtails increases during the initial period of the ant-hill growth. Old nests are characterized by the minimum species diversity, with one or two distinct dominants. High ecological plasticity, including resistance to high temperatures and low humidity, allows Lepidocyrtus violaceus to maintain its stable dominant position in the ant-hills. Species with relatively narrow hygro-and thermopreferenda quickly occupy temporal favorable niches, reach high abundance, and quickly disappear as the microclimatic conditions change.     

Springtail community (Hexapoda,Collembola) in arable chernozems of Kursk oblast

The composition of springtail communities (the ratio of taxa, species richness, morphoecological spectrum, and spatial organization) in typical deep chernozems of Kursk oblast has been studied in crop fields, forest strips, and an old fallow. Approximately 40 springtail species have been recorded, with the Onychiuridae being dominant with respect to species diversity and contribution to the total abundance. Springtails are distributed over the soil profile to a depth of no less than 50 cm. The pattern of their vertical distribution in areas with tree and shrub vegetation differs from that in arable land. The response of springtails to weakly expressed sheet erosion of chernozem proved to be insufficient for using them as bioindicators of the initial stages of soil erosion.     

Checklist of the springtails (Hexapoda: Collembola) of Turkey

A checklist of the species of springtails (Hexapoda: Collembola) hitherto recorded from Turkey is presented. This list contains 53 species belonging to 39 genera in 13 families. The diversity of Collembola in Turkey is poorly known and it is clear that numerous species wait to be discovered.     

Global diversity of springtails (Collembola; Hexapoda) in freshwater

Water-dependency appeared independently in several clades of the class Collembola, which is basically of terrestrial origin according to recent phylogenetic analyses. Though moderately diversified (less than 8,000 species), Collembola are among the most numerous terrestrial arthropods in wetland communities, with a small number of species living on the surface of water. Many species are dependent on water-saturated atmosphere of caves, and on snow or ice in high mountains. A total of 525 water-dependent species have been recognized, of which 103 are linked to free freshwaters and 109 to anchialine or marine waters. Many interstitial species are also dependent to an unknown extent on water saturation in the deep layers of the soil. The numbers provided here are underestimates, as Collembola are extremely poorly known outside the Holarctis, and the ecology of described species usually not documented. However, a general biogeographical pattern is emerging from available data. The most remarkable feature is that about 15% of the fauna is water-dependent in the holarctic region, compared to 4% in the tropics and southern hemisphere. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Embryogenesis of a springtail,Tomocerus ishibashii (Collembola,tomoceridae): External morphology

The external features of the developing embryos of the springtail, Tomocerus ishibashii, are described. The clypeolabral anlage arises as a single, unpaired swelling. The entognathy is completed by the ventral growth of the tergal anlagen of mandibular, maxillary, and labial segments. These anlagen also form the posterior part of the cranium. The palpi of maxilla and labium are homologous with the telopodites, and proximal parts of these head appendages are homologous with the coxopodites. The sternal element of the labial segment does not participate in the postmentum formation. The anlagen of abdominal appendages appear in the first to the fourth abdominal segments. The first, third, and fourth appendage anlagen form the ventral tube, tenaculum, and furcula, respectively. The fused proximal parts of the first, third, and fourth appendage anlagen are homologous with the coxopodites, and the distal parts which do not fuse are homologous with the telopodites. The anlagen of the second abdominal appendages become flattened and spread over the ventral side of this segment. The ventral structures of the first four abdominal segments are appendicular in origin.     

Experimental studies of ice nucleation in an Antarctic springtail (Collembola, Isotomidae)

Ice nucleation was studied in field-fresh and acclimated (4 degrees C without food for 11-20 days) samples of the springtail Cryptopygus antarcticus Willem (Collembola, Isotomidae) at Rothera Research Station, Adelaide Island on the Antarctic Peninsula. Ice nucleator activity (INA) was measured by a freezing droplet technique in addition to supercooling point (SCP) profiles and polyol, sugar, and water contents. Field and acclimated samples showed bimodal SCP distributions with a distinct high group (HG; mean SCP -8 to -10 degrees C) and low group (LG: mean SCP -23 to -25 degrees C), which were significantly different. Acclimation at 4 degrees C increased the proportion of individuals in the LG relative to that in the HG without significant effects on the mean SCP of both groups. INA of the HG was significantly greater than that of the LG, and acclimation further reduced the INA of the LG. The number of active ice nucleator agents (INAs) calculated for the HG of field samples increased by 23-100 times over the temperature range -5 to -8 degrees C compared to only 7 times for the LG over the same range. These differences were accentuated in the acclimation experiments. Glucose and galactose were the main carbohydrates in both field and acclimated springtails, with the latter compound occurring in almost twice the concentration in the LG compared with that in the HG. Acclimation reduced the concentration of both compounds (glucose by 77% and galactose by 54%), whereas water content increased significantly. Digestion of food may have continued during acclimation at 4 degrees C, which could reduce the LG INA. Lowering of temperature over time is more likely to elicit a cold hardening response than constant temperature acclimation. INA numbers calculated at the nucleation temperatures for C. antarcticus samples were higher in the LG than in the HG. However, inactivation of INAs may be a key mechanism underlying cold hardening in this species, either by sequestration within the cellular matrix or by being only seasonally active.     

Report of Akabosia matsudoensis Kinoshita (Collembola; Paronellidae) from Korea,with notes on the Korean aquatic springtail fauna

A hygrophilous collembolan species, Akabosia matsudoensis is redescribed and illustrated with a list and key to other aquatic fauna belonging to Entomobryoidea from Korea. Specimens inhabiting the damp area near a creek were collected with hand net and aspirator. This species is characterized by the absence of scale, having 2 + 2 macrosetae on the vertex of the head, 2 feathered prelabial setae, dens crenulated and the base of mucro with bladder like appendage. Genus Akabosia reported only one species, A. matsudoensis, that was originally recorded in Japan; Korea is the second recorded country and it is the only Paronellidae from Korea.     

Blastodermic cuticles of a springtail,Tomocerus ishibashii Yosii (Collembola : Tomoceridae)

The formation and structure of the blastodermic cuticles of a springtail, Tomocerus ishibashii Yosii (Collembola : Tomoceridae) are described together with the change of egg membrane. The blastodermic cuticles of the Collembola are 2-layered, and formed in the early stages of the embryonic development, preceding the differentiation of germ band. The first blastodermic cuticle is thicker (about 0.8-1.5 μm in thickness) and its surface is provided with complex structures, whereas the second one is thinner (about 0.2-0.4 μm in thickness) and smooth. About 3 days after oviposition, the chorion (about 2 μm in thickness) splits into 2 and the first blastodermic cuticle, provided with many projections and 4 large spines appear on the surface of the egg. Three types of projections are distinguished: button-, cone- and seta-like structures. The halves of the ruptured chorion are attached to the first blastodermic cuticle on both sides below the spines, and no projections are found in the regions concealed by the ruptured chorion. The projections of the first blastodermic cuticle are formed by cellular protrusions of the blastoderm. The conspicuous large spines on the first blastodermic cuticle are formed by the evaginations of the blastoderm. Tendrils of the primary dorsal organ run between the first and second blastodermic cuticles.     

Springtails (Hexapoda, Collembola) in karst landscapes of the Pinega State Reserve

The collembolan fauna of the Pinega State Reserve (Arkhangelsk Province) was examined. The study area is highly specific due to its karst topography. In all, 126 Collembola species were recorded in the reserve, a significant fraction of their diversity being restricted to karst habitats. Several species that had never been recorded in plain forest biotopes were of special interest. Such forms with distribution ranges mainly limited to the tundra zone comprised about 10% of the local fauna. Regarding the longitudinal sizes of the ranges, this group was not homogeneous and included both widespread circumpolar and east-Palaearctic (Siberian) species. Several arctoalpine forms were also recorded. Most of these arctic species were not numerous over the area studied and in general, the collembolan assemblages at the coldest sites of the reserve did not differ significantly from those typical of the forest zone, with the exception of two species, Desoria tshernovi and D. inupikella, which often predominated in the karst communities. The origin and appropriateness of the term relict for the revealed “insular” populations of arctic species are discussed.     

Diversity and distribution of Collembola (Arthropoda: Hexapoda) of Brazil

Objectives of this study are to summarize the current state of knowledge of the diversity and distribution of Collembola in Brazil; to identify areas of most importance, interest, and need of additional research; and to enable development of experimental hypotheses for future research on Collembola in this region. The total number of collembolan species currently known from Brazil is 199, distributed among 19 families and 80 genera. The greatest numbers of species have been recorded from the states of Rio de Janeiro and Amazonas (with 69 and 56 species, respectively). Few or no species are known from most Brazilian states. Most of the species for which specific Brazilian environmental habitat information is available (93, 66%) are known only from forest environments. Most of the species (127, 64%) are known only from Brazil (most likely being endemic); 33 species (17%) are known only from Brazil and other neotropical areas; and 39 species (20%) have a distribution beyond the neotropical region. Results of this study indicate that much remains to be learned about the Brazilian collembolan fauna. This is especially true for areas of the northeastern, central-western, and southern regions. Studies to determine the species composition of collembolan communities in specific environments in Brazil are needed. The great diversity of Collembola species in Brazil is largely unknown and there are many opportunities for additional research on these environmentally important organisms in this area. Such additional research on the Collembola in Brazil is also essential for a better understanding of the neotropical (and world) collembolan fauna.     

Two new chironomid species (Diptera,Chironomidae) from Wrangel Island

Two new species from Wrangel Island, Orthocladius (Eudactylocladius) tschernovi sp. n. and O. (E.) ushakovskiensis sp. n. (Orthocladiinae), are described and illustrated from on the male adults. Orthocladius (E.) tschernovi sp. n. is closely related to O. (E.) fuscimanus (Kieffer) and O. (E.) musester Sæther, but can be distinguished from both by an almost straight transverse sternapodema, a rounded triangular superior volsella, and a long phallapodema, as well as by the presence of a subapical crista dorsalis of the gonostylus and by the shape of the anal point. Orthocladius (E.) ushakovskiensis sp. n. differs from all the known species of the subgenus in the absence of superior and inferior volsellae and in the shape of both short gonostylus and the short and wide anal point.     

Mesoderm formation in a springtail,Tomocerus ishibashii Yosii (Collembola : Tomoceridae)

The mesoderm formation of Tomocerus ishibashii (Collembola : Tomoceridae) is described. Mesodermal cells are formed after the beginning of the formation of the primary dorsal organ, and originate from the entire region of the embryonic area. After completion of the blastodermic cuticles, cells of mesoderm and ectoderm concentrate towards a ventral midline and form a well-defined 2-layered germ band. The manner of mesoderm formation in the Collembola is similar to that in Diplura and Myriapods, except for the Chilopoda; the mesoderm of the Thysanura s. lat. and Pterygota originates from a localized zone of the embryo. Within the Hexapoda, mesoderm formation is categorized into 2 types: Type 1—unlocalized origin, in the Collembola and Diplura, and Type 2—localized origin, in the Thysanura s. lat. and Pterygota. Types 1 and 2 are thought to be plesiomorphic and apomorphic, respectively.     

Environmental correlates of species richness of European springtails (Hexapoda: Collembola)

Our knowledge about environmental correlates of the spatial distribution of animal species stems mostly from the study of well known vertebrate and a few invertebrate taxa. The poor spatial resolution of faunistic data and undersampling prohibit detailed spatial modeling for the vast majority of arthropods. However, many such models are necessary for a comparative approach to the impact of environmental factors on the spatial distribution of species of different taxa. Here we use recent compilations of species richness of 35 European countries and larger islands and linear spatial autocorrelation modeling to infer the influence of area and environmental variables on the number of springtail (Collembola) species in Europe. We show that area, winter length and annual temperature difference are major predictors of species richness. We also detected a significant negative longitudinal gradient in the number of springtail species towards Eastern Europe that might be caused by postglacial colonization. In turn, environmental heterogeneity and vascular plant species richness did not significantly contribute to model performance. Contrary to theoretical expectations, climate and longitude corrected species–area relationships of Collembola did not significantly differ between islands and mainlands.     

Spatial patterns in the distribution of European springtails (Hexapoda: Collembola)

Using a large database on the spatial distribution of European springtails (Collembola) we investigated how range sizes and range distribution across European countries and major islands vary. Irrespective of ecological guild, islands tended to contain more endemic species than mainland countries. Nestedness and species co‐occurrence analysis based on country species lists revealed latitudinal and longitudinal gradients of species occurrences across Europe. Species range sizes were much more coherent and had fewer isolated occurrences than expected from a null model based on random colonization. We did not detect clear postglacial colonization trajectories that shaped the faunal composition across Europe. Our results are consistent with a multiregional postglacial colonization. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 498–506.     

First fossil record of stalked spermatophores with sperm (Collembola: Hexapoda)

Spermatozoa and stalked spermatophores in Baltic amber represent the first report of these reproductive structures in the fossil record. A comparison of this material with sperm and simple stalked spermatophores from extant invertebrates indicates that the fossil structures originated from a springtail (Collembola: Hexapoda). This conclusion is supported by the presence of a female springtail, Sminthurus longicornis Kock and Berendt (Sminthuridae: Symphypleona), in the same piece of amber. This specimen, which appears to have been molting at the time of death, is adjacent to objects interpreted as springtail eggs. The present find establishes the existence of the indirect method of sperm transfer by the late Eocene (40 Ma).     

The terrestrial arthropod fauna of the Byers Peninsula,Livingston Island,South Shetland Islands – Collembola

 As an addendum to a recent publication on the terrestrial arthropod fauna of the Byers Peninsula Site of Special Scientific Interest (SSSI), which included preliminary identification of four Collembola, we now present detailed information on Collembola occurring within the SSSI. Five species were recorded [Friesea grisea (Schaffer), Tullbergia mixta Wahlgren, Isotoma (Folsomotoma) octooculata (Willem), Cyptopygus antarcticus Willem, and Cryptopygus sp. nov.]. Species occurrence and abundance differed between samples collected from poorly vegetated stony ground and vegetation cores. F. grisea was both the commonest (58% of individuals) and the most widely distributed (18/19 samples) springtail in the former habitat. Cryptopygus sp. nov. was recorded only in the vegetation core samples. All five species were more evenly distributed in vegetation samples, although C. antarcticus and Cryptopygus sp. nov. were again the least abundant. A list of the terrestrial arthropods of the SSSI is presented. Received: 7 June 1995/Accepted: 25 July 1995