Fine structure of the spermatheca and of the accessory glands in Orchesella villosa (Collembola, Hexapoda)

The spermatheca and the accessory glands of the collembolan Orchesella villosa are described for the first time. Both organs exhibit ultrastructural differences, according to the time of the intermolt in which the specimens were observed. A thick cuticular layer lines the epithelial cells of the accessory glands. In the reproductive phase, they are involved in secretory activity; a moderately dense secretion found in the apical cell region opens into the gland lumen. Cells with an extracellular cistern are intermingled with the secretory cells. These cells could be involved in fluid secretion, with the secretory product opening into the cistern which is filled with an electron-transparent material. After the reproductive phase, the gland lumen becomes filled with a dense secretion. The accessory gland secretion may play a protective role towards the eggs. The spermatheca is located between the accessory glands; its epithelium is lined by a thin cuticle forming spine-like projections into the lumen and consists of cells provided with an extracellular cistern. Secretory cells, similar to those seen in the accessory glands, are missing. Cells with a cistern could be involved in the production of a fluid secretion determining sperm unrolling and sperm motility.     

Rap-GEF/Rap signaling restricts the formation of supernumerary spermathecae in Drosophila melanogaster

Sperm storage in the female is a key factor for reproductive success in a variety of organisms, including Drosophila melanogaster. The spermathecae (SP) are the Drosophila organs for long-term storage. While wild-type female flies have two SP, occasionally, three or four SP have been observed in mutant flies. However, the molecular mechanism of SP formation is unknown. Here we show that loss of function of a Drosophila Rap-GEF (GEF26) result in an occurrence of the supernumerary SP; females have three SP (varies from 11 to 62% in different allele combinations) instead of the normal two SP. In addition, the Gef26 mutant flies also have ectopic wing veins and extra mechanosensory organs. The supernumerary SP phenotype of the Gef26 mutation can be enhanced by the Drosophila Rap mutations and rescued by overexpressing the cell adhesion molecule DE-cadherin. These data suggest that the Rap-GEF/Rap signaling controls the formation of supernumerary spermathecae through modulating cell adhesion in Drosophila.     

昆虫受精囊的结构与功能

昆虫受精囊是在雌雄交配之后,作为雌性贮存、释放精子和使卵受精的器官,其结构、功能及活动调节对保持精子活性和卵子受精有重要的影响。该文对昆虫受精囊结构、功能及其活动调节的研究进展做一介绍,以期为相关研究提供有益的资料。     

Ultrastructure of the annual cycle of female sperm storage in spermathecae of the torrent salamander, Rhyacotriton variegatus (Amphibia: Rhyacotritonidae)

This study is the first report on the ultrastructure of the sperm storage glands (spermathecae) in the salamander Rhyacotriton variegatus. The population studied is associated with cold-water, rocky streams of the redwood (Sequoia) zone in northern California. Males possess sperm in their vasa deferentia and undergo spermiation throughout the year, but mating is seasonal. Most females with large, vitellogenic follicles (2.0-3.9 mm mean dia.) collected from February-June contain sperm in their spermathecae, although some females with large follicles lack sperm. Other mature-size females collected during this period have small ovarian follicles (0.9-1.2 mm mean dia.) and lack stored sperm. All females collected from September-November have small follicles (0.6-1.6 mm mean dia.) and lack sperm, except in one instance in which a female collected in November had a small amount of degraded sperm, apparently retained from the previous breeding season. The spermathecae consist of simple tubulo-alveolar glands in which the neck tubules produce a mucoid secretory product, and the distal bulbs, where sperm are stored, contain secretory vacuoles of uniform density that stain positively for glycosaminoglycans. In specimens containing sperm, some bulbs have abundant sperm and others lack sperm, but the ultrastructure is similar in both conditions. The acini contain columnar epithelial cells with wide intercellular canaliculi, and a merocrine process releases the secretion. Spermiophagy occurs. In specimens from spring and summer with small ovarian follicles, the neck tubules are similar to those of breeding females, but the distal bulbs are reduced to cords of cells lacking a discernible lumen. Secretory activity in the distal bulbs is initiated in the fall. Spermathecae of R. variegatus are most similar to those of a stream-dwelling plethodontid, Eurycea cirrigera.     

Sperm storage in females of the smooth newt (Triturus v. vulgaris L.): II. Ultrastructure of the spermathecae after the breeding season

Sperm storage in cloacal spermathecae was studied in females of Triturus v. vulgaris from southern England killed at the end of the breeding season in June. This species mates and oviposits eggs in ponds from March to June. Included in the sample were 12 unmated females collected in terrestrial situations in March and mated in the laboratory. Some of these females oviposited viable eggs in the laboratory whereas others did not oviposit after mating. In addition, we examined five females with unknown mating histories that were collected from a breeding pond in June. We found that all of the specimens contained some stored sperm and were similar in spermathecal ultrastructure. The spermathecae exhibited characteristics of secretory epithelium at the end of a cycle, including irregular heterochromatic nuclei surrounded by scant cytoplasm, absence of organelles involved in synthetic activities, few secretory vacuoles, and wide intercellular canaliculi. Spermiophagy by the spermathecal epithelium was extensive. In contrast, spermathecae from females at the beginning of the breeding season as reported in our previous study were actively producing a PAS+ secretion and did not exhibit spermiophagy. Spermiophagy is a means of eliminating sperm prior to the next breeding season.     

Sperm storage by spermatodoses in the spermatheca of Trioza alacris (Flor, 1861) hemiptera,psylloidea, triozidae: A structural and ultrastructural study

Female insects generally store sperm received during mating in specific organs of their reproductive tract, i.e., the spermathecae, which keep the sperm alive for a long time until fertilization occurs. We investigated spermatheca morphology and ultrastructure in the psylloidean insect Trioza alacris (Flor, 1861 ) in which spheroidal sperm packets that we refer to as ‘spermatodoses’ are found after mating. The ectoderm‐derived epithelium of the sac‐shaped spermatheca that has a proximal neck, consists of large secretory and flat cuticle‐forming cells. Secretory cells are characterized by a wide extracellular cavity, bordered by microvilli, in which electron‐dense secretion accumulates before discharge into the spermathecal lumen. The cuticle‐forming cells produce the cuticular intima of the organ and a peculiar specialized apical structure, through which secretion flows into the lumen. At mating, the male transfers bundles of sperm cells embedded in seminal fluid into the spermathecal neck. Sperm cells proceed towards the spermathecal sac lumen, where they are progressively compacted and surrounded with an envelope that also encloses secretions of both male and female origin. We describe the formation of these sperm containing structures and document the contribution of the female secretion to spermatodose or female‐determined spermatophore construction. We also discuss the choice of the term ‘spermatodose’ for T. alacris and suggest it be used to refer to sperm masses constructed in the female reproductive organs, at least when they involve the contribution of female secretion. © 2011 Wiley Periodicals, Inc.     

The female genital morphology of the orb weaving spider genus Agriognatha (Araneae, Tetragnathidae)

The female genital morphology of the spiders in the araneoid genus Agriognatha (Tetragnathidae) is described and illustrated. The female genitalia of Agriognatha is characterized by a strong reduction of the sperm storage organs (spermathecae) and by the presence of a specialized distal compartment of the median membranous chamber that functions as a sperm storage organ (the posterior sac). The genital morphology of Agriognatha species is unique among Tetragnathidae and it provides robust synapomorphic evidence for the monophyly of genus. We discuss the phylogenetic implications of these new findings for the placement and monophyly of Agriognatha and for the monophyly of Tetragnathinae.     

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 ultrastructure of malpighian tubules and the chemical composition of the cocoon of Aeolothrips intermedius Bagnall (Thysanoptera)

The secretory activity of the two branched malpighian tubules (MTs) of the second‐instar larva in Aeolothrips intermedius is described. MTs of adult thrips have the typical ultrastructure of excretory epithelium with apical microvilli containing long mitochondria and a rich system of basal membrane infoldings. In the second‐instar larva just before pupation, the ultrastructure of MT epithelial cells is dramatically different, and there are numerous huge Golgi systems in the cytoplasm. These cells are involved in an intense secretory activity to produce an electron‐dense product which is released into the MTs lumen. This secretion is extruded from the hindgut and used by the second‐instar larva to build an elaborate protective cocoon for pupation. Electron‐spray‐ionization mass spectrometry analysis of the cocoon revealed the presence of a β‐N‐acetyl‐glucosamine, the main component of chitin, which is also present in the cocoons of Neuroptera and some Coleoptera. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

Four New Species of Symphypleona (Collembola) from Korea

ABSTRACT Four new species of Symphypleona, Ptenothrix plumiseta, Deuterosminthurus serratus, Sminthurus annulatus, Smithurinus distinctus , are described from Korea. Especially two genera, Deuterosminthurus and Sminthurinus are new record to Korea. Korean Collembola Symphypleona add up to 18 species, 11 genera in 6 family.     

The springtail (Hexapoda,Collembola) fauna of Wrangel Island

Analysis of the collembolan fauna of Wrangel Island based on published data and recent sampling was performed. The species richness of springtails on the island (89 species from 41 genera and 12 families) exceeds the levels characteristic of most other insular territories of the Arctic Ocean, except for Greenland and some small islands located within the southern tundra belt. The specificity of the species composition of the springtail fauna on the island depends on a high proportion of species with amphi-Pacific ranges, reflecting its formation within the Beringian Arctic sector. At the same time, the structure of the springtail fauna of the island is rather similar to those of the known tundra faunas of the Siberian sector, with no anomalies being detected.     

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.     

Structure and ultrastructure of spermatozoa and spermiogenesis in three species of Lucilia Robineau‐desvoidy, 1830 (Diptera: Calliphoridae)

Morphology of male internal reproductive organs, spermatozoa, and spermiogenesis of the blow‐flies Lucilia cuprina, Lucilia eximia, and Lucilia peruviana is first described here, using light and transmission electron microscopy. Spermiogenesis follows the characteristics described for others insect species. The spermatozoa of L. cuprina are similar to those described for other Brachycera. However, in L. eximia and L. peruviana, some differences were found. In L. cuprina and L. eximia species, the spermatozoa are long and thin, measuring about 211 μm and 146 μm in length, of which the head region measures approximately 19 μm and 17 μm, respectively. A polymorphism was observed in L. cuprina and L. eximia spermatozoa. In all three species, the head includes a monolayered acrosome with electron‐lucent material. The shape of the nucleus, in cross sections, varies from circular to oval with completely condensed chromatin. Implantation of the axoneme was observed in the middle region of the nucleus, known as the “peg” region. In the next region, the beginning of two mitochondrial derivatives of similar diameter and different lengths in L. cuprina and only one in L. eximia and L. peruviana was observed. In the overlap region, the following structures were observed: nucleus, centriolar adjunct, mitochondrial derivatives, and axoneme. The axoneme is of a conventional insectan type with a 9 + 9 + 2 microtubular arrangement. The male internal reproductive tract consists of testis, deferent ducts, a strongly developed seminal vesicle, accessory glands, and ejaculatory duct. These features are consistent with the structural diversity of the dipteran reproductive tract and spermatozoa, comprising an essential tool for understanding the complex variations found in the Diptera. J. Morphol. 2011. © 2011 Wiley Periodicals, Inc.     

Morphology of the male reproductive system and sperm ultrastructure of the egg parasitoid Gryon pennsylvanicum (Ashmead) (Hymenoptera,Platygastridae)

Gryon pennsylvanicum is a platygastrid hymenopteran that has lately received increasing attention in Europe due to its possible use in biological control of the conifer seed bug pest Leptoglossus occidentalis. Here the male reproductive system and the spermatogenesis of this species, along with those of Gryon muscaeformis, are examined ultrastructurally for the first time. The male genital system is formed by a pair of testes, each containing only one follicle, a pair of accessory glands and deferent ducts connected to a single ejaculatory duct. All the stages of spermatogenesis are described in detail. Characteristic features of the Gryon spp. sperm, which are 100 μm long, are the presence of a polygonal nucleus, only one mitochondrial derivative, the occurrence of the centriole adjunct and a typical insect 9 + 9 + 2 flagellar axoneme. The single derivative, however, results from a process in which one of the two mitochondria is lost during spermiogenesis. Unlike in other insects, two centrioles occur in spermatids as a consequence of the ameiotic parthenogenesis. These characteristics stand as a valuable tool for phylogenetic inferences. Furthermore this study suggests a useful strategy for laboratory mass rearing.     

A new genus of Symphypleona (Collembola) from West Africa

Abstract. Songhaica nigeriana gen. et sp.n. is described from tropical rain forest in Nieria. Sminthurus stylifer Murphy from wooded Savanna and cultivated soils in Gambia also belongs in this new genus.     

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.     

Spermatozoan ultrastructure and mitochondrial gene sequence of Caryocorbula caribaea (d'Orbigny, 1853) (Corbulidae: Bivalvia), a species with plasticity in shell morphology

Systematics of Corbulidae supported by anatomical and conchological studies remains confused and controversial because of the considerable phenotypic plasticity of their shells. Ultrastructural spermatozoan study and molecular analyses have been performed to contribute valuable information, which could be used in taxonomy. Electron microscopy was used to analyse sperm cells from specimens of Caryocorbula (Gardner, 1926) exhibiting shell differences. The spermatozoon was of the aquasperm type, showing short acrosome, barrel-shaped nucleus, midpiece composed of four spherical mitochondria and simple flagellum. In addition, about 860?base pairs of mitochondrial large ribosomal subunit (16S rRNA) were sequenced from each individual. The consistent similarity shared by spermatozoa and DNA sequences from all studied specimens indicated that they belonged to one coherent unit, Caryocorbula caribaea (d'Orbigny, 1853), despite the extraordinary plasticity exhibited by their shells.     

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     

The sperm pumps of Strepsiptera and Antliophora (Hexapoda)

Male genital structures of representatives of Strepsiptera, Siphonaptera and Diptera are described in detail, with special emphasis on sperm pumps. The parts involved in the apparatus are evaluated with respect to their homology. Functional interpretations are presented based on the morphological observations. The phylogenetic significance of characters related to the male genital apparatus is discussed. The sperm pumps differ strongly in Strepsiptera and Antliophora (s.s.) and are not homologous. The strepsipteran type, which lacks any sclerotized parts, has evolved independently. Autapomophies of the male genital apparatus are the compact testes, the large balloon‐shaped vesicula seminalis, the strongly developed musculature of the proximal ductus ejaculatorius, the strongly simplified copulatory organ, the unusual muscles of segments VIII and IX, and the complete absence of accessory glands. The median fusion and almost globular shape of the vesicula are potential autapomorphies of Corioxenidae. The absence of the furrow separating the testes from the vesicula seminalis is a derived condition found in Xenos and Myrmecolax. A sperm pump is absent in Boreus (Mecoptera) and Culicomorpha and the functionally relevant parts and their arrangement differ strongly in Siphonaptera, Pistillifera and Diptera (excl. Culicomorpha). The presence of a functional and homologous pumping apparatus does not belong to the groundplan of Antliophora, which implies that this alleged autapomorphy of the clade is invalid. A sperm pump belongs to the groundplan of Diptera and was secondarily reduced in Culicomorpha, many representatives of Bibionomorpha, and in Diopsidae. It was very likely primarily absent in Mecoptera. However, the precise reconstruction of the groundplan depends on the position of Nannochoristidae within Mecoptera and on the possible affinities of Siphonaptera and Boreidae. Sperm pumps should be considered as a functional term and not be used as a character for phylogenetic reconstruction, unless specific similarities are included in the character definition.     

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.