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We describe in this paper the morphology of the male reproductive system, the spermiogenesis and the sperm ultrastructure of the drugstore beetle S. paniceum (L) (Coleoptera, Ptinidae). The male reproductive apparatus has a pair of long testes with six follicles, filled with cysts, each containing 128 germ cells. The sperm is about 480 μm long and is endowed of an apical spiral cylindrical acrosome, 1.7 μm long. The nucleus, 25 μm long, is also cylindrical at maturity. During spermiogenesis the nuclear envelope gives rise to two ovoid membranous structures flanking the nucleus for its whole length. The centriole adjunct material is configurated as concentric electron-dense rings. The flagellar components have a helical array; the axoneme has the typical 9 + 9+2 pattern for most of its length, but in the posterior flagellar region it modifies greatly its ultrastructure and is embedded in an electron-dense material. The two accessory bodies have a crescent-moon shape in the mature sperm, but at the beginning of spermiogenesis they are small structures lateral to the axoneme, later assuming a crescent-moon structure. A flattened cistern located between the axoneme and the plasma membrane is present in the early spermatids, but soon it fuses with the plasma membrane. Two symmetrical, largely crystallized mitochondrial derivatives are present for most of the flagellar length. S. paniceum and Lasioderma serricorne share several sperm structures. Ultrastructural results and molecular data confirm a close relationship between these two species and support their positioning within Ptinidae.

Large-scale production of the black soldier fly [Hermetia illucens (L.) (Diptera: Stratiomyidae)] for use as aquaculture and poultry feed has developed into a global industry. Successful commercialization of the black soldier fly relies on optimizing the production of fecund adults. However, current mass-rearing protocols result in variable production of fertile eggs. To help lay a foundation for a better understanding of factors that may play a role in this variability, the morphology of the black soldier fly male reproductive tract and spermatozoa, associated spermatogenesis process, impact of age on the process, and the female spermatheca morphology were examined with various microscopic techniques (e.g., scanning electron microscope, transition electron microscope, and dissecting scope). The gross morphology of the male reproductive tract and female spermatheca appear to be similar to those found in other brachyceran flies. Male spermatozoa are long (~860 µm overall, ~8 µm head), apparently motile, and possess flagella with a typical 9 + 9 + 2 axoneme triplets. Germ cells go through incomplete mitotic divisions surrounded by somatic cyst cells in the testes. Spermatogenesis appears to be initiated during immature development (cryptocephalic pupa stage). From

In social wasps, female lifespan depends on caste and colony tasks: workers usually live a few weeks while queens as long as 1 year. Polistes dominula paper wasps infected by the strepsipteran parasite Xenos vesparum avoid all colony tasks, cluster on vegetation where parasite dispersal and mating occur, hibernate and infect the next generation of wasp larvae. Here, we compared the survival rate of infected and uninfected wasp workers. Workers’ survival was significantly affected by parasite sex: two-third of workers parasitized by a X. vesparum female survived and overwintered like future queens did, while all workers infected by a X. vesparum male died during the summer, like uninfected workers that we used as controls. We measured a set of host and parasite traits possibly associated with the observed lifespan extension. Infected overwintering workers had larger fat bodies than infected workers that died in the summer, but they had similar body size and ovary development. Furthermore, we recorded a positive correlation between parasite and host body sizes. We hypothesize that the manipulation of worker’s longevity operated by X. vesparum enhances parasite’s fitness: if workers infected by a female overwinter, they can spread infective parasite larvae in the spring like parasitized gynes do, thus contributing to parasite transmission.

The fine structural organization of the male and the female inner reproductive apparatuses of the water-strider Gerris lacustris was studied. The sperm of the species shows a long helicoidal acrosome provided with longitudinal tubules, and a short nucleus. The flagellum is characterized by crescent mitochondrial derivatives and a 9 + 9 + 2 axoneme, as occurs in all Heteroptera. The female reproductive apparatus is characterized by an extremely long spermathecal duct, filled with sperm, which plays the role of the main sperm storage organ. The duct has a thin epithelium surrounded by a complex of secretory and duct-forming cells. The spermathecal duct flows into the gynatrial sac. This region, together with the fertilization chamber, exhibits a simple epithelium with deep apical plasma membrane invaginations, and it does not show conspicuous secretions. The basal cell region shows plasma membrane infoldings forming thin cytoplasmic bands hosting mitochondria and large intercellular spaces. This organization is typical of epithelia active in fluid reabsorption. Two lateral large gynatrial glands open into the gynatrial sac. Such glands also exhibit secretory and duct forming cells. The same structure of these glands is also present along the proximal region of the fecundation canal. The duct forming cells of these regions have very wide ducts with peculiar cuticular finger-like structures at their opening into the gland duct lumen. The results of the present study suggest the occurrence of a coevolution between the sperm and the spermathecal duct lengths.

The coevolution between sperm length and size of the female sperm-storage organs is described for the first time within Heteroptera. The long sperm of the measurer bug Hydrometra stagnorum is characterized by the unusually long acrosome with its anterior region helically arranged, and by a very short nucleus. The sperm flagellum has a 9 + 9+2 conventional axoneme and crystallized mitochondrial derivatives. The female spermatheca consists of an extraordinarily long spermathecal duct ending with an apical spermathecal bulb into which flows also the secretions of a relatively short spermathecal gland. Both spermathecal duct and gland have a thin epithelium lined by a cuticle, beneath which a complex of secretory and duct forming cells are present. The secretions of these two structures flow into the apical spermathecal bulb. A thick layer of muscle fibers surrounds the epithelium. These results confirm the opinion that the dimensions of the female reproductive sperm-storage organs are able to drive the sperm morphology.

The sperm ultrastructure of some beetles of Tenebrionoidea was studied with particular attention to those of the Ripiphoridae, Mordellidae, and Meloidae. These three groups are often thought to form a clade, which is the sister group of the remaining Tenebrionoidea. The testes of the two former families have thinner but longer spermatic cysts containing fewer and longer sperm. Within each cyst all sperm cells have the same orientation, but cross sections showed that the orientation of the axonemes alternate between adjacent cysts, possibly due to the cysts bending on themselves. In both families the sperm has a bilayered acrosome and the flagellum, which shows mitochondrial derivatives starting laterally to the nuclear base, has a typical 9 + 9+2 axoneme with accessory tubules provided with 16 protofilaments in their wall, and well-structured triangular shaped accessory bodies. In Mordellistena sp (Mordellidae) sperm, both mitochondrial derivatives and accessory bodies are somewhat asymmetrical. Moreover, the flagellum shows a very thin and long tail end provided with only accessory tubules. Meloidae species have testes with thicker sperm cysts containing numerous shorter sperm. Within the individual cysts the sperm flagella exhibit an alternating orientation of their axonemes as consequence of a peculiar spermatogenetic process. The flagellar structure is similar to that of the above-mentioned species, but the accessory bodies are not well defined and constituted by fuzzy material. In Mylabris hieracii (Meloidae) sperm, the acrosome is flat with a conspicuous perforatorium and its nucleus has a peculiar quadrangular section. Berberomeloe majalis sperm has a large acrosome with an unusual pentagonal perforatorium. The centriolar structure of Mylabris variabilis shows a complex of dense radial links connecting the microtubular structures to the plasma membrane. These results suggest that Ripiphoridae have a closer relationship with Mordellidae than with Meloidae. These findings are in agreement with results obtained with molecular data.

The sperm ultrastructure of Pytho depressus (Pythidae) is described in this study. The sperm are short cells, about 85−90 μm long, with an acrosome consisting of three layers, a cylindrical nucleus, which at its base has the initial region of two mitochondrial derivatives. The flagellum has two well-developed triangular accessory bodies, and a 9 + 9+2 axonemal pattern with accessory tubules provided with 16 protofilaments in their wall. The structure and shape of the accessory bodies are diagnostic characters within the superfamily. The sperm morphology of P. depressus can be easily distinguished from those of Ripiphoridae, Meloidae and Tenebrionidae. The P. depressus sperm are organized in cysts as in other species of the group but the sperm are not well aligned and show an antiparallel orientation, a feature also observed in other tenebrionids. The phylogenetic implications of the observed sperm features are discussed in the context of comparative sperm ultrastructure of other insect species.

The sperm of three coccinellid species belonging to the subfamilies Chilocorinae, Coccinellinae and Epilachninae were studied under light and transmission electron microscopy. The basic sperm structure of these ladybirds is common to that of the other previously studied species, especially the acrosome in front of the basal body and not the nucleus, with this latter running parallel with the flagellar components. In the Chilocorinae Platynaspis luteorubra (Platynaspidini) the sperm are of the type 1, as in Scymnini and Coccinellini, since they exhibited a cylindrical basal body with 9 + 0 and then 9 + 2, microtubules continuing further in an initial flagellar portion with the only axoneme devoid of accessory structures. The sperm exhibits a thin nucleus and mitochondrial derivatives. Such uniformity of sperm ultrastructure could be indicative of the occurrence of a close relationship between Platynaspidini and Scymnini as also proposed in the previous studies. Conversely, they differ markedly from the sperm of type 3 observed in the Chilocorini Exochomus quadripustulatus. In the Coccinellini Propylea quatuordecimpunctata the sperm are also of the type 1, but they can be easily differentiated from those of the other Coccinellinae studied so far, because of their very short acrosome without the posterior extension, the relatively thicker mitochondrial derivatives and the cylindrical nucleus. Epilachna clandestina sperm resemble those of E. quadripustulatus but differ from them, because they exhibit an elliptical nucleus which is anteriorly very thin, and the asymmetrical mitochondrial derivatives in the anterior extremity, with the greater one starting at the same level of the basal body, rather than at the nucleus level, as it occurs in E. quadripustulatus. Because of the differences observed in the sperm ultrastructure we propose a new sperm type (Type 4) for E. clandestina. This study on ladybird spermatozoon ultrastructure clearly indicates that the current classifications of coccinellids do not reflect the natural history of this well-known insect family.

In the present study, we describe the sperm morphology of 11 species of Elateriformia (9 elaterids, 1 lampyrid and 1 buprestid) using transmission electron microscopy. All species exhibited sperm that is not usually observed in insects in general. The most highlighted features are the displacement of the nucleus running parallel to the flagellar components, hitherto observed only in coccinellid and carabid beetles, and the presence of thin and dense structures along the nucleus, probably derived from the centriole adjunct, a feature that is so far exclusive to these insects. The other structures are a typical axoneme for insects with 9 + 9 + 2 microtubules, in a position diametrically opposite relative to the nucleus, two slender, symmetrical mitochondrial derivatives and a pair of discrete accessory bodies. This arrangement provides a bilaterally symmetrical flagellum, which favourably influences sperm hydrodynamics, as will be discussed. The occurrence of this unusual structural arrangement in the sperm of species from superfamilies that are phylogenetically as distant as Elateroidea and Buprestoidea support the monophyly of the infraorder Elateriformia, as proposed by some previous molecular studies.

Popillia japonica is an invasive scarab beetle native to Japan that in 1916 invaded New Jersey in USA. From that moment onwards, the insect has spread invading several US states, Canada, the Azores, Italy and, recently, Switzerland. It is a severe agricultural pest included in the EU priority pest list being able to feed on more than 300 plant species and having an important biotic potential. The general morphology of the reproductive apparatus shows paired testes, each of them having six testicular lobes grouped in threes. From the ventral part of each testicular lobe, each containing about 20 follicles, an efferent vessel originates that fuses with the other efferent vessels to form the deferent duct. A pair of long tubular accessory glands is present. The deferent ducts and accessory glands fuse together into an ejaculatory duct before entering the aedeagus. The sperm is a typical pterygote sperm, 110 μm long, composed of a head and a tail. In the head a three-layered acrosome of about 6 μm in length and a nucleus of about 18 μm long are present. During sperm maturation two C-shaped structures appear in the cytoplasm from the opposite sides of the nucleus that then disappear in late spermatids. In the tail a typical 9 + 9 + 2 flagellar axoneme and two mitochondrial derivatives are present. Moreover, in the head-tail transition region the centriolar adjunct forms a sheath from which three elongated accessory bodies originate. Two of these accessory bodies are placed alongside the axoneme, whilst the third one is placed beneath the mitochondrial derivatives. Mature sperm are grouped in cysts containing about 256 sperm cells. A morphological comparison with related species is provided.

The ultrastructure of the complex organisation of the spermatozoa in Harmonia axyridis and Adalia decempunctata (Coccinellidae) was studied, with particular emphasis on the origin of the anterior shifting of the axonemal structure, which becomes parallel to the nucleus in the sperm flagellum. In studying the spermiogenesis, a centriolar remodelling was observed with the long centriole, present in the early spermatids, transformed in the spermatozoa into an exceptionally long and narrowed basal body (about 0.16 × 3.5–4.0 μm long) displaying a 9 + 0 microtubular pattern in the proximal part and a 9 + 2 pattern in the following part; this is a characteristic not observed in any other pterygotan insect. The sperm also have a very long acrosome surrounded by a dense layer of material extending along the whole basal body. These two uncommon features were discussed in the light of sperm movement.

Sperm structure of seven species from different Carabidae tribes was studied. Carabus preslii and Carabus granulatus interstitialis form sperm bundles (spermatozeugmata) in which the heads of conventional insect sperm cells are embedded in the apical cap (spermatostyle), leaving the posterior flagella free. On the contrary, Pterostichus morio, Pterostichus melas, Pterostichus melanarius and Amara aulica form complex spermatozeugmata bearing conspicuous axial spermatostyles associated with lateral groups of sperm. Individual sperm cells are contained in chambers delimited by laminar extensions of the cortical region of the spermatostyle. Demetrias atricapillus shares the general spermatozeugma structure with the above species, but the anterior spermatostyle region has a different structure and posteriorly, the lateral groups of sperm are separated from the spermatostyle but remain connected to it by peduncles consisting of extensions of the cortical region of the spermatostyle. The sperm of the species examined in the study consist of a short, flat acrosomal cap and, with the exception of the Carabus species, show long nuclei which extend parallel to the axonemes, along the flagella. Two relatively small mitochondrial derivatives and two small accessory bodies flank the axoneme. These bodies become very thick in the posterior flagellar region of D. atricapillus. The study revealed different spermatozeugma models and different sperm organization in the Carabidae family.

The sperm structure of several ladybird species belonging to different subfamilies of Coccinellidae was studied. Three main sperm types were clearly recognized, and were characterized by differences in acrosomal length, the presence of a dense coat around the acrosome, the length of the basal body, the amount of the centriole adjunct material, and the diameter of the mitochondrial derivatives. However, the whole group shares a pattern of the posterior sperm region uncommon for insects, in which the axoneme and other flagellar components are running parallel with the nucleus. As a general conclusion, this study has revealed an inconsistency between the sperm structure and the systematics of the group, indicating that the generic concepts within the group do not reflect a natural classification, a statement also shared by molecular studies.

We studied spermatogenesis and spermiogenesis in Adalia decempunctata (L), a beetle of the Coccinellidae family. The spermatocyte exhibits two centrioles which elongate to form a pair of primary cilia. A novel structure, appearing in cross sections as a dense droplet, is observed near the long centriole during spermiogenesis, and is soon accompanied by a procentriole (PCL). PCL structure consists of singlet microtubules, a central tubule and an incomplete cartwheel. The PCL persists until the end of spermiogenesis, when it vanishes together with the dense droplet. The sperm has an exceptionally long basal body and the nucleus is disposed parallel to the flagellar components, a peculiar trait shared by other species of the coccinellid group. The presence of a procentriole suggested by the use of antibodies is discussed.

The springtail Collembola are characterized by having rolled spermatozoa, with a long cylindrical extracellular structure adhering to the acrosome. This structure is produced by the secretory activity of the testes epithelial cells at almost the end of spermiogenesis. At the beginning of its formation, it is a thin extension with a helical wall and a dense axial region. Later the cylindrical structure shows an inner organization which is different in the several species examined: species of Entomobryidae contain material with a paracrystalline structure, whilst some of Symphypleona contain ovoid structures. The outer envelope of the extracellular structure consists of two overlapped layers orthogonally arranged, clearly identified by cryo-preparations. Immunoblot analysis and lectin stainings have indicated that the cylindrical structure has a glycoproteic composition. As the structure is no longer visible after the sperm transfer into the female spermatheca, it is suggested that it could contain enzymes able to activate the sperm unwinding process and possibly allowing the reacquisition of sperm motility.

The sperm structure of several species belonging to different tribes of the large Carabidae family is described. Some species of Nebriinae, such as Nebria brevicollis and Notiophilus biguttatus, have free conventional insect sperm. Their sperm type can be regarded as the ancestral model for Carabidae. All the other species examined, either with isolated sperm such as Calomera nemoralis, Scarites sp., Duvalius andreinii and Anillus florentinus or with spermatozeugmata and sperm associated to spermatostyles such as Typhloreicheia usslaubi, Brachinus italicus, Carabus convexus, Calathus fuscipes, Calathus montivagus, and Paraphorus mendax, showed sperm with long nucleus and a parallel axoneme running the length of the tail starting from the apical bell-like acrosome. C. nemoralis, like Cicindela campestris previously studied, has a sperm structure similar to that of several other Carabidae, confirming their correct assignment to the family. C. convexus has the same sperm structure as previously studied C. preslii and C. interstitialis, indicating that the spermatozeugmata of the group consist only of an apical cap in which the anterior sperm regions are embedded. Unlike other Carabidae with spermatozeugmata, Carabini have the typical sperm organization with acrosome, nucleus and flagellum in a regular sequence. A. florentinus, (Trechinae) shows major differences, such as the absence of an acrosome and an extremely long nucleus that reaches the end of the tail in close association with the axoneme. T. usslaubi (Scaritinae) has slender spermatozeugmata with orderly quartets of sperm. The posterior region of the sperm tail is also unusual, showing a perfect circular section and a plasma membrane reinforced by a dense underlying layer. The present observations confirm that spermatozeugmata, can vary in shape and size among different species of the Carabidae. Such diversity may be the result of the male reproductive strategy, different in each species, that enhances the efficiency of sperm transfer to the female.

Sperm of the dictyopteran key taxon Cryptocercus punctulatus was examined. It has largely maintained a blattodean groundplan condition, with a three-layered acrosome, an elongate nucleus, a single centriole, a conspicuous centriole adjunct material, two connecting bands (=accessory bodies), and a long functional flagellum with a 9+9+2 axoneme provided with accessory tubules with 16 protofilaments and intertubular material. These sperm characters are shared with several other polyneopterans. The sperm of C. punctulatus is very similar to what is found in Periplaneta americana and species of other groups of roaches, including the sperm of Loboptera decipiens described here for the first time. The general sperm organization here described can be assumed for the groundplan of Insecta and Pterygota. The following evolutionary path can be suggested: after the split between Cryptocercidae and the common ancestor of Isoptera, the typical pattern of sperm formation was altered very distinctly, resulting in a duplication or multiplication (Mastotermitidae) of the centrioles. Mastotermes has maintained a certain sperm motility, but with a very unusual apparatus of multiple flagella with a 9+0 axoneme pattern. After the split into Mastotermitidae and the remaining Isoptera, sperm motility was completely abandoned, and different modifications of sperm components occurred, and even the loss of the sperm flagellum. J. Morphol. 276:361–369, 2015. © 2014 Wiley Periodicals, Inc.

The Ephemeroptera sperm axoneme is devoid of outer dynein arms (ODA) and exhibits a pronounced modification of the central pair complex (CPC), which is substituted by the central sheath (CS): a tubular element of unknown molecular composition. We performed a detailed ultrastructural analysis of sperm axonemes in the genera Cloeon and Ecdyonurus using quick-freeze, deep-etch electron microscopy, showing that the loss of the conventional CPC is not only concomitant with the loss of ODA, but also with a substantial modification in the longitudinal distribution of both radial spokes (RS) and inner dynein arms (IDA). Such structures are no longer distributed following the alternation of different repeats as in the 9 + 2 axoneme, but instead share a 32 nm longitudinal repeat: a multiple of the 8 nm repeat observed along the CS wall. Differently from the conventional CPC, the CS and the surrounding RS possess a ninefold symmetry, coherently with the three-dimensional pattern of motility observed in Cloeon free spermatozoa. Biochemical analyses revealed that ultrastructural modifications are concomitant with a reduced complexity of the IDA heavy chain complement. We propose that these structural and molecular modifications might be related to the relief from the evolutionary constraints imposed by the CPC on the basal 9 + 9 + 2 axoneme and could also represent the minimal set compatible with flagellar beating and progressive motility mechanically regulated as suggested by the geometric clutch hypothesis. © 2014 Wiley Periodicals, Inc.

The rectal pads of a species of the controversial polyneopteran order Zoraptera were examined using histological sections and TEM micrographs. Six pads are present along the thin rectal epithelium. Each pad consists of a few large principal cells surrounded by flattened junctional cells, which extend also beneath the principal cells. The cells are lined by a thin apical cuticle. No basal cells and no cavity have been observed beneath the pad. Principal cells have a regular layer of apical microvilli and are joined by intercellular septate junctions, which are interrupted by short dilatations of the intercellular space. At these levels the two adjacent plasma membranes are joined by short zonulae adhaerentes. In the cytoplasm, a rich system of strict associations between lateral plasma membranes and mitochondria forms scalariform junctions. Rectal pads share ultrastructural features with similar excretory organs of several neopteran groups, in particular with Blattodea (roaches and termites) and Thysanoptera, and are involved in fluid reabsorption and ion regulation.

The structural features of eggs of Zorotypus caudelli Karny are described in detail. The egg is elliptic with long and short diameters of 0.6 and 0.3 mm respectively, and creamy white. The egg shows a honeycomb pattern on its surface, without any specialized structures for hatching such as an operculum or a hatching line. The fringe formed by a fibrillar substance secreted after the completion of the chorion encircles the lateral surface. The egg layer is composed of an exochorion, an endochorion, and a vitelline envelope. The exochorion and endochorion are electron-dense and homogeneous in structure. The exochorion shows a perforation of numerous branching aeropyles. The exo- and endochorion are connected by numerous small columnar structures derived from the latter. The vitelline envelope is very thin and more electron-dense than the chorion. A pair of micropyles is present at the equator on the dorsal side of the egg. Originating at the micropyle, the micropylar canal runs through the chorion obliquely. The structural features of the eggs of Zoraptera were compared with those of other polyneopteran and paraneopteran orders.

Endosymbionts of the Cardinium-like genus are described in the testes and other tissues of the proturan Acerella muscorum (Ionescu). Few endosymbionts are present in the large apical cells of functional testes, but they become numerous at the end of the reproductive cycle. They are also found within sperm cells where induce their degeneration. The Gram-negative endosymbionts are characterized by the presence of microtubule-like structures (MLC) in their cytoplasm. It is suggested a possible role of the endosymbionts in the elimination of degenerating sperm cells when the testes activity is ended, thus somewhat playing a role in the timing of the reproductive cycle of the proturan species.

Sperm ultrastructure and spermiogenesis of the dipluran Japygidae (Japyx solifugus, Metajapyx braueri and Occasjapyx japonicus) and Campodeidae (Campodea sp.) were studied with the aim of looking for potential characters for the reconstruction of the phylogenetic relationships of basal hexapods. Both Japygidae and Campodeidae share a common sperm axonemal model 9+9+2, provided with nine accessory microtubules. These microtubules, however, after their formation lose the usual position around the 9+2 and migrate between the two mitochondria. In Japygidae, four of these microtubules are very short and were observed beneath the nucleus after negative staining and serial sections. Accessory microtubules have 13 protofilaments in their tubular wall. Diplura have a sperm morphology which is very different from that of the remaining Entognatha (Protura+Collembola). On the basis of the present results, the presence of accessory microtubules suggests that Diplura are the sister-group of the Insecta s.s.. Moreover, Japygidae and Campodeidae differ with regards to the relative position of the sperm components, the former having the axoneme starting from beneath the nucleus (above which sits the short acrosome), while the latter having a long apical acrosome and a nucleus running parallel with the proximal part of the axoneme. The present study also allowed to redescribe the male genital system of Japyx.

The sperm tail of bug insects has 9 + 9 + 2 flagellar axonemes and two mitochondrial derivatives showing two to three crystalline inclusions in their matrix. During spermiogenesis, the axoneme is surrounded by a membrane cistern which, at sperm maturity, reduces to two short cisterns on the opposite sides of the axoneme adhering to the mitochondrial derivatives. Filamentous bridges connect the intertubular material of the axoneme to these cisterns. Such bridges, which represent a peculiar feature of bug insects, are resistant to detergent treatment, whereas part of the intertubular material and the inner content of microtubular doublets are affected by the treatment. After freeze-fracture replicas, at the insertion of the bridges to the cisternal membrane, the P-face of this membrane shows a characteristic ribbon consisting of four rows of 11 ± 1 nm staggered intramembrane particles, 13 ± 2 nm apart along each row. The bridges could be able to maintain the axoneme in the proper position during flagellar beating avoiding distortion affecting sperm motility. J. Morphol. 2009. © 2009 Wiley-Liss, Inc.

The sperm ultrastructure of a few species of Limoniidae (Limonia nigropunctata; L. nubeculosa; Chionea n. sp.; C. alpina; C. lutescens) was studied. The two species of Limonia have a monolayered acrosome with crystallized material, a three-lobed nucleus in cross section, a ring of centriole adjunct material and a flagellum which consists of a 9 + 9 + 1 axoneme and a single mitochondrial derivative. The central axonemal tubule is provided with 15 protofilaments in its tubular wall, while the accessory tubules have 13 protofilaments and are flanked by the electron-dense intertubular material. The three species of Chionea share a monolayered acrosome, a nucleus with two longitudinal grooves, a centriole adjunct material which surrounds the centriole and the initial part of the axoneme. The axoneme is of conventional type, with 9 + 9 + 2 microtubular pattern, with accessory tubules provided with 13 protofilaments and intertubular material. However, in C. lutescens the accessory tubules start with 15 protofilaments and transform into a tubule with 13 protofilaments. These data are discussed in the light of the phylogenetic relationship between Limoniidae and Tipulidae. For this purpose, the sperm ultrastructure of Nephrotoma appendiculata was also considered comparatively.

Spermatozoa provide an unusual character system, with a limited number of components organized in a single cell. Similar spermatozoa occur in groups widely separated in the phylogenetic tree of Metazoa. Nevertheless, the character system contains phylogenetic information. Hexapoda have acquired spermatophores along with the switch from aquatic to terrestrial habitats, and related to this, a multitude of different sperm types. The aim of this study is a formal evaluation of the phylogenetic information content of spermatozoa. For the first time, sperm characters are coded for formal phylogenetic analyses. Different approaches are used and compared. Mainly due to a high level of homoplasy, the evaluation of sperm characters alone is insufficient for a reconstruction of the phylogeny of the group. Yet, a reliable reconstruction of the evolution of insect sperm is possible when character transformations are assessed using a phylogeny based on extensive molecular data. Important changes took place in the early evolution of Hexapoda. Sperm characters support some major clades (e.g. Hexapoda, Dicondylia, Polyneoptera, Psocodea), but important steps in the evolution are not reflected by transformations of spermatozoa, notably the rise of Pterygota or Holometabola. Important innovations are the formation of mitochondrial derivatives and the acquisition of accessory microtubules. Some features are conservative, whereas others evolved rapidly (e.g. presence or absence of the acrosome vesicle). Some groups are conservative in their sperm features (e.g. Odonata, Heteroptera), whereas the evolution of spermatozoa was distinctly accelerated in others (e.g. Ephemeroptera). The rate of evolution can change drastically in closely related groups. Profound changes in the morphologically uniform Zoraptera underline that sperm evolution can follow a pattern very different from the general somatic morphology. The mode of character reconstruction preferred here will be useful for the evaluation of specialized morphological character systems and strengthen the concept of evolutionary morphology.

The sperm of the heteropteran bug Raphigaster nebulosa (Poda) are of two types, differing in length and size of their flagella. The thicker sperm are shorter than the thinner ones and have large mitochondrial derivatives. The presence of virus particles associated with the plasma membrane of thinner sperm is described for the first time; thicker sperm are immune to virus infection. The fact that virus particles are present on thinner sperm only initiates considerations on the transmission of virus.

The controversial mating of the strepsipteran Xenos vesparum was studied to investigate the possible sperm routes for fertilization. The female, which is a neotenic permanent endoparasite of Polistes wasps, extrudes only its anterior region, the “cephalothorax,” from the host abdomen. This region has an opening where both mating and larval escape occur. Observations with scanning and transmission electron microscopy revealed spermatozoa not only in the hemocoel, but also in the “ventral canal” (an extragenital duct peculiar to strepsipteran females) and in the “genital ducts” (ectodermal invaginations connecting the ventral canal to the hemocoel) of recently mated females. Xenos vesparum spermatozoa can reach the oocytes either through the hemocoel as a result of a hypodermic insemination, or by moving along the extragenital ducts, which are later used by first instar larvae to escape. The hypothesis of hypodermic insemination is reconsidered in the light of behavioral and ultrastructural evidence. J. Morphol. © 2005 Wiley-Liss, Inc.

Nassonow's gland consists of a number of cells with ducts that open on to the ventral surface of the brood canal in the cephalothoracic region of a neotenic female strepsipteran. The structural organization of the gland is reminiscent of the class 3 of the epidermal gland cells as defined by Noirot and Quennedey [Ann. Rev. Entomol. 19 (1974) 61], which consists of secretory and duct forming cells. The ultrastructure of the Nassonow's gland is described in female Xenos vesparum (Rossi) parasitic in the social wasp Polistes dominulus Christ. The large secretory cells are clustered in groups of three to four, rich in smooth endoplasmic reticulum and produce a secretion made up of lipids. In young females, just before mating, the ultrastructure of the cells and their inclusions indicate that they are active. In old-mated females the Nassonow's gland degenerates. Microvilli line an extracellular cavity and there are pores present in the irregularly thick cuticle of the efferent duct. The small duct forming cells, intermingle with epidermal cells, overlap secretory cells and produce a long efferent duct, the cuticle of which becomes thick close to its opening in the brood canal. Nassonow's gland could be the source of a sex pheromone, which might be capable of attracting the free-living male to a permanently endoparasitic female.

Summary Helicobacter pylori is the causative agent of peptic ulcer disease. A major virulence factor of H. pylori is VacA, a toxin that causes massive vacuolization of epithelial cell lines in vitro and gastric epithelial erosion in vivo. Although VacA is exported over the outer membrane and is released from the bacteria, a portion of the toxin remains associated with the bacterial surface. We have found surface-associated toxin to be biologically active and spatially organized into distinct toxin-rich domains on the bacterial surface. Upon bacterial contact with host cells, toxin clusters are transferred directly from the bacterial surface to the host cell surface at the bacteria–cell interface, followed by uptake and intoxication. This contact-dependent transfer of VacA represents a cost-efficient route for delivery of VacA and potentially other bacterial effector molecules to target cells.

The ultrastructure of spermiogenesis in four species of Coccoidea, namely Quadraspidiotus perniciosus and Pseudaulacaspis pentagona (Diaspididae), as well as Planococcus citri and Planococcus ficus (Pseudococcidae), is described. Similarly to other coccids, during spermiogenesis sperm nuclei elongate towards the plasma membrane, forming a conical papilla. The microtubule bundles surrounding the nucleus subsequently elongate and a mature sperm is formed. At the end of spermiogenesis, the motile sperm of all the species consists of a cylindrical axial nucleus surrounded by a spiral (Q. perniciosus) or by concentric rings of microtubules (P. pentagona, P. citri and P. ficus) forming a peculiar flagellum. Other features common to all these species are the lack of centrioles, acrosome and mitochondria in the spermatid and mature sperm. Differences arise in the number of spermatid cells per cyst (32 in Q. perniciosus and 16 in the other three species) and in the number and arrangement of microtubules forming the flagellum. Details on the origin of the flagellum and on the formation of the secondary sheath of the sperm bundle are provided. Lastly, the evolution of the Coccid group is discussed from a phylogenetic perspective based on sperm ultrastructure.

The sperm ultrastructure and the male and female genital apparatus of Zorotypus shannoni were examined and documented in detail, mainly using transmission electron microscopy micrographs. The findings suggest an evolutionary trend shared with Z. hubbardi and Z. impolitus. The three species are characterized by enlarged mitochondrial derivatives and related modifications. Giant sperm are probably a synapomorphy of Z. hubbardi and Z. impolitus, whereas an intermediate condition of this feature is found in Z. shannoni. The monophyletic origin of Z. caudelli, Z. magnicaudelli, Z. huxleyi and Z. weidneri is suggested by characteristically modified axonemes. The presence of extra-acrosomal material is also an unusual feature for Zoraptera, but this condition also occurs in the majority of polyneopteran groups. The long and convoluted female spermathecal duct with secretory and duct-forming cells is a constant feature in Zoraptera. The enlarged seminal receptacle suggests an evolutionary link between the male genital structures and the sperm size on one hand, and the size of the female spermatheca on the other. The small and otherwise uniform group Zoraptera exhibits a remarkable variation of sperm types and genital structures, suggesting the impact of different types of selection. It is likely that cryptic female choice plays a major role in shaping the genital apparatus.

The sperm structure of the jumping bristletail Machilontus sp has been described. The species shares several sperm characteristics with other genera of the same order Archaeognatha. During late spermiogenesis the spermatid bends at half of its length with the two limbs closely apposed within the same plasma membrane. The sperm has a helicoidal bi-layered acrosome with a filamentous perforatorium and a long nucleus. The elongated flagellum consists of an axoneme with 9 accessory microtubules external to the 9+2, two rows of conventional mitochondria and two accessory bodies. The accessory bodies are located lateral to the axoneme and are probably responsible for the shifting of the accessory tubules in two opposite groups of 5 and 4 tubules, respectively. These sperm characteristics represent common traits of all Archaeognatha.

Deep-etching technique was used to investigate the organization of the pellicle complex of Euglena gracilis. The interpretation of the images was further supported by SEM and TEM investigations. Our results mainly validate data obtained by previous freeze-fracture studies on the E and P faces of the outer cortical membrane. At the level of the ridges, the outer E fracture face is highly organized in a regular striated pattern, whereas the P inner face shows a particulate structure. However, our images reveal that this particulate organization of the P face is not limited to the ridges, but it is displayed also by the grooves. Moreover, this face shows two distinct layers, a particulate layer facing the cytoplasm and a striated layer facing the E face; these layers represent different true fracture levels of the same P face.

The male and female reproductive apparatus of Zorotypus magnicaudelli (Malaysia), Zorotypus huxleyi (Ecuador) and Zorotypus weidneri (Brazil) were examined and documented in detail. The genital apparatus and sperm of the three species show only minor differences. The testes are larger in Z. magnicaudelli. Z. huxleyi lacks the helical appendage in the accessory glands. A long cuticular flagellum is present in Z. magnicaudelli and in the previously studied Zorotypus caudelli like in several other species, whereas it is absent in Z. weidneri, Z. huxleyi, Zorotypus hubbardi, Zorotypus impolitus and Zorotypus guineensis. Characteristic features of the very similar sperm are the presence of: a) two dense arches above the axoneme; b) a 9 + 9+2 axoneme with detached subtubules A and B of doublets 1 and 6; c) the axonemal end degenerating with enlarging accessory tubules; d) accessory tubules with 17 protofilaments; e) three accessory bodies beneath the axoneme; and f) two mitochondrial derivatives of equal shape. The first characteristic (a) is unknown outside of Zoraptera and possibly autapomorphic. The sperm structure differs distinctly in Z. impolitus and Z. hubbardi, which produce giant sperm and possess a huge spermatheca. The presence of the same sperm type in species either provided with a sclerotized coiled flagellum in males or lacking this structure indicates that a different organization of the genital apparatus does not necessarily affect the sperm structure. The flagellum and its pouch has probably evolved within Zoraptera, but it cannot be excluded that it is a groundplan feature and was reduced several times. The fossil evidence and our findings suggest that distinct modifications in the genital apparatus occurred before the fragmentation of the Gondwanan landmass in the middle Cretaceous.

The male and female genital apparatus of the recently discovered ground louse Zorotypus impolitus were examined using light and electron microscopy. The rounded testes and a large seminal vesicle are connected with a complex of four accessory glands by a long tapering ejaculatory duct. Two accessory glands have the same whitish coloration, whereas the third one is pale blue, and the elongated and cylindrical fourth one translucent. The sperm are the largest known in Hexapoda, 3 mm long and 3 μm wide, with a volume of ca. 21,000 μm 3 ; the ratio between the diameter of the axoneme and the width of the main body of the sperm ranges between 1:10 and 1:13. The exceptional width of the spermatozoa is due to an extreme enlargement of the mitochondrial derivatives and accessory bodies. A single sperm is contained in a small globular spermatophore (100 μm). The highly unusual external transfer correlates with an atypical mating behavior. The male produces several to many spermatophores during the mating process. As in other zorapterans the ovaries are panoistic and the eggs bear two micropyles. An exceptionally large apical spermathecal receptacle is present; it is connected with the vagina by a long spermathecal duct, which varies structurally along its course. A correlation between the sperm size and the size of the spermatheca is likely. Ultrastructural features of different species support two strikingly different models of male and female reproductive apparatus in the small order Zoraptera. This is in stark contrast to the extreme uniformity of their external morphology. It is likely that sexual selection played a decisive role in the evolution of the reproductive system.

A remarkable external sperm transfer is described for the first time in a species of a group of winged insects (Pterygota), the enigmatic Zoraptera. Mating and sperm transfer of two species of the order were examined in detail, documented, and compared with each other and with patterns described for other species belonging to the order. The behavior differs strikingly in Zorotypus impolitus and Zorotypus magnicaudelli. A copula is performed by males and females of the latter, as it is also the case in other zorapteran species and generally in pterygote insects. In striking contrast to this, males of Z. impolitus do not copulate but deposit small (100 μm in diameter) spermatophores externally on the abdomen of the female. Each spermatophore contains only one giant spermatozoon (3 mm long and 3 μm wide), a unique feature in the entire Hexapoda. External sperm transfer in Pterygota is a highly unusual case of evolutionary reversal. The very small relict group Zoraptera displays a uniform general morphology but exhibits very different reproductive structures and patterns of mating behavior. This may be an extreme form of a more general situation in insects, with a specific form of selection resulting in an accelerated rate of evolution in the reproductive system.

The ultrastructure of spermatogenesis and spermatozoa was studied in Timema poppensis Vickery & Sandoval, 1999, a putative basal taxon of Phasmatodea. The apical portion of testis follicles consists of spermatogonial cells with polymorphic nuclei. Primary spermatocytes display very short primary cilia originating from the peripheral centrosomes. Early spermatids develop a conspicuous “nebenkern” consisting of fused mitochondria. They have a single peripheral centriole with microtubular triplets, which expresses a 3.6-μm-long cilium featuring a 9 + 2 axonemal pattern. In a later stage, the centriole and the ciliary shaft displace toward the inner part of the cytoplasm by an infolding of the plasma membrane. Mature spermatids exhibit a derived centriole with microtubule doublets devoid of dynein arms, which is equipped with a dense arc-like outer structure. Ciliary degeneration was not observed during spermiogenesis. Spermatozoa are short flagellate cells about 55–60 μm in length. They are characterized by a three-layered acrosomal complex. The distinctive bell-shaped morphology of the acrosome vesicle is likely an autapomorphic trait of Timema. The flagellum has a 9 + 9 + 2 axoneme, two accessory bodies, two flattened cisterns, and two elongated mitochondrial derivatives. Results support the hypothesis that Phasmatodea, comprising Timema + Euphasmatodea, form a monophyletic group. The presence of 17 protofilaments in the wall of accessory microtubules and the flattened configuration of the flagellum are potential apomorphic groundplan features of the order. Within Phasmatodea, a key evolutionary divergence was from the conventional insect spermiogenesis and sperm structure of Timema, to the unusual spermiogenetic process and peculiar sperm structure of Euphasmatodea. As a result, Timema retains more sperm character states found in the polyneopteran ground pattern, while Euphasmatodea have evolved outstanding sperm autapomorphies, like the loss of mitochondria and flattened cisterns, and the presence of strongly expanded accessory bodies.

Here we present an ultrastructural study of the male and female reproductive systems of Zorotypus hubbardi and compare the findings to those presented in an earlier study. The male reproductive system consists of small testes and thin and short deferent ducts opening into a huge seminal vesicle. At the end of the deferent duct a wiredrawer structure is present which initiates the spermatophore formation. A long ejaculatory duct, originating from the seminal vesicle, receives the secretions of three accessory glands. The copulatory organ is a relatively stout structure consisting of two cuticular claspers connected to a ventral sclerite. The testes contain very large and few germ cells (32 sperm in each cyst) which give rise to large sperm characterized by two giant mitochondrial derivatives, two large accessory bodies, and an axoneme with accessory tubules with 17 protofilaments in their tubular wall. In the seminal vesicle the sperm are joined by a secretion to form an elongate spermatophore. The female system consists of panoistic ovarioles, two lateral oviducts, and a common oviduct which receives the spermathecal duct of a huge spermathecal sac in the terminal part of the vagina. The duct is an anterior prolongation of the sac. Its distal part turns back twisting around its proximal portion. At this level a conspicuous muscle layer gives rise to a valve. The bent spermatophore is hosted in the spermathecal sac, with the sperm heads placed in the proximal part of the spermathecal duct. The opening of the duct is close to the female genital opening. The reproductive systems of Zorotypus caudelli and Z. hubbardi, apart from a distinctly different general organization, also have a different sperm structure: those of the former species are free long-moving cells, while the sperm of Z. hubbardi are giant cells joined in a spermatophore. This allows to hypothesize and discuss a different reproductive behaviour in the two species: monandric in Z. hubbardi and polyandric in Z. caudelli. Apparently different forms of selection have resulted in a very uniform general morphology in Zoraptera, and in highly divergent features related to the reproductive system. The presence of 17 protofilaments in the accessory microtubules of the flagellar axoneme is a potential synapomorphy of Zoraptera and Phasmatodea.

Considering the overall uniformity of the morphology of Zoraptera, the structural diversity of the male genital system is remarkable. Structures related to the male reproductive system of Zorotypus caudelli differ profoundly from those of Zorotypus hubbardi. The testes are elongated rather than spherical, the seminal vesicle is apparently absent, and the deferent ducts are very long. A feature shared by these two species and other zorapterans examined is that the two accessory glands are closely adherent to each other and form a single large structure, from which the ejaculatory duct originates. This is a potential zorapteran autapomorphy. Another feature possibly present in the groundplan of the order is the strong elongation of the sperm cells. This may be connected with a reproductive strategy of males trying to avoid re-mating of females with other males after the first copulation. The extremely long and coiled spermathecal duct of Z. caudelli and other zorapteran species is possibly correlated with the sperm elongation, and both features combined may result in a sexual isolating mechanism. The short duration of mating of Zorotypus barberi and Zorotypus gurneyi suggests that the male introduces sperm into the female tract up to the opening of the spermathecal duct using their long coiled aedeagus. A thick glycocalyx around the sperm in the distal part of the deferent ducts probably protects the sperm cells during their forward progression towards the long spermathecal duct, and is removed when they reach the apical receptacle. The spermatogenesis of Z. caudelli follows a pattern commonly found in insects, but differs distinctly from that of Z. hubbardi in the number of spermatids in each sperm cyst. An unusual and possibly autapomorphic feature of Z. caudelli is a disconnection of sub-tubules A and B at the level of microtubule doublets 1 and 6 of the mature sperm cells. It is conceivable that this results in a shorter period of sperm motility. The character combination found in different zorapteran species supports the view that the sperm, a very compact functional unit, does not evolve as a unit, but like in other more complex body regions, sperm components can also be modified independently from each other. This results in different mosaic patterns of plesiomorphic and derived features in a very compact entity in different species of the very small and otherwise uniform order Zoraptera. In Z. caudelli, for instance, the bi-layered acrosome and small accessory bodies are plesiomorphic states among several others, whereas the mitochondrial derivatives and the elongate nucleus are apparently derived conditions. Other combinations likely occur in other zorapteran species. Only few but noteworthy sperm characters indicate possible phylogenetic affinities of Zoraptera. A possible synapomorphic feature, the presence of dense laminae radiating in a cartwheel array between neighbouring centriolar triplets, is shared with Phasmatodea and Embioptera. Another potential synapomorphy shared with Phasmatodea is the presence of 17 protofilaments in the tubular wall of the outer accessory microtubules.

The macroparasite Xenos vesparum affects both the behaviour and the physical traits of its host, the social wasp Polistes dominulus. Female wasps, if parasitized, do not perform any social tasks and desert the colony to gather at specific sites, where the parasite mates; at the end of summer they form prehibernating clusters joined by healthy future queens to overwinter. Parasitized wasps become highly gregarious. In April, healthy wasps leave the aggregations to found new colonies, while parasitized wasps remain in overwintering groups and release parasites to infect wasp larvae only later in the season. We studied the prolonged gregarious behaviour of parasitized wasps and analysed the morphology of parasitized and healthy wasps in aggregations collected over a 7-year period to determine whether the parasite affects host size, wing symmetry, ovarian development and lipid stores. All parasitized wasps were smaller and had undeveloped ovaries and more wing fluctuating asymmetry than unparasitized wasps, irrespective of time of year, parasite load and parasite sex. If infected only by one or two X. vesparum females, the wasps had large fat bodies, which could facilitate their overwintering. In contrast, wasps infected by at least one male parasite had little lipid and died at the end of the summer. Thus, X. vesparum, may play a role in the fate of its host, by exploiting wasps' tendency to form aggregations outside the colony and by altering its caste system, nutrient allocation, diapause timing and life span to achieve its own reproduction and dispersal.

Despite their enormous diversity, spermatozoa are only scarcely studied in arachnids. In spiders, harvestmens and mites, it has been shown that spermatozoa are a potential source of characters which can support, contradict or even resolve previous phylogenetic hypotheses. In scorpions, the spermatozoa of most superfamilies (except the taxon-rich Scorpionoidea and the obscure Chaeriloidea) are known in more or less detail revealing considerable differences, especially between buthid and non-buthid scorpions. However, this apparent diversity is based on descriptions of only 12 scorpion species. In the present study, we investigated the spermatozoa of a species of the superfamily Scorpionoidea (Opistophthalmus penrithorum, Scorpionidae) for the first time by means of light and electron microscopy. The scorpionoid spermatozoa are characterized by (1) an asymmetrical, cap-like acrosomal vacuole at the tip of the anterior pole of the nucleus, (2) a short acrosomal filament, (3) a nucleus, which is tapered anteriorly, (4) a midpiece with 5–6 mitochondria and (5) an axoneme with a 9 + 0 pattern with a helical beating movement. Moreover, we provided a detailed description regarding sperm packages, that consist of approximately 250 sperm cells bent in the midpiece region, and lack a secretion sheath. Overall, the organization and general morphology of spermatozoa of the observed species is similar to what is known for non-buthids. To evaluate the evolutionary and phylogenetic implications of our results, we performed a comparative revision of sperm morphology in scorpions for the first time and proposed potential informative characters (six for spermatozoa and six for sperm packages). We concluded so far that sperm structure in scorpions could provide new characters for future comprehensive phylogenetic studies of the order, and that they could even represent synapomorphies not only for the order but for the major scorpion clades as well. Resumen A pesar de su enorme diversidad, la morfologia de los espermatozoides ha sido escasamente estudiada en aracnidos. En aranas, opiliones y acaros, se ha mostrado que los espermatozoides son una fuente potencial de caracteres filogeneticos. En escorpiones, los espermatozoides de la mayoria de las superfamilias (excepto la especiosa superfamilia Scorpionoidea y la enigmatica Chaeriloidea) han sido estudiados en mas o menos el detalle, y revelan diferencias considerables, sobre todo entre buthidos y no-buthidos. Sin embargo, esta diversidad aparente esta basada en descripciones de solo doce especies de escorpiones. En el presente estudio, investigamos por primera vez los espermatozoides de una especie de la superfamilia Scorpionoidea (Opistophthalmus penrithorum, Scorpionidae) por medio de microscopia optica y electronica. Los espermatozoides de O. penrithorum estan caracterizados por (1) una vacuola acrosomica asimetrica, con forma de gorra en el extremo del polo anterior del nucleo, (2) un filamento acrosomal corto, (3) un nucleo ahusado anteriormente, (4) una pieza media con 5–6 mitocondrias y (5) un axonema con un patron 9 + 0 y con movimiento pulsatil helicoidal. Ademas, proporcionamos una descripcion detallada sobre los paquetes de esperma, que consisten en aproximadamente 250 espermatozoides arqueados en la region de la pieza media, y carecen de una vaina de secrecion. En general, la organizacion y la morfologia general del espermatozoide de la especie observada son similares a lo que ha sido reportado para escorpiones no-buthidos. Para evaluar las implicaciones evolutivas y filogeneticas de nuestros resultados, realizamos la primera de la literatura comparada sobre la morfologia del esperma de escorpiones y proponemos caracteres informativos potenciales (seis para el espermatozoide y seis para paquetes de esperma). Concluimos que la estructura del esperma en escorpiones podria proporcionar nuevos caracteres morfologicos para futuros estudios filogeneticos a nivel del orden, y que los mismos podrian representar no solo sinapomorfias para el orden, sino tambien para los principales clados de escorpiones.

In the seminal vesicle of the ‘symphyta’ Arge pagana the spermatozoa are stored in motile spermatodesm bundles, maintained by an anterior cap of extracellular material. This cap consists of a denser cortex and of an internal matrix, where part of the sperm heads are embedded. The number of spermatozoa per bundle is variable. The spermatozoa are short, only 30 μm long, with a head region of about 23 μm, and a very short flagellum of about 7 μm. The head includes the acrosome, with a perforatorium, and the nucleus. The flagellum consists of an axoneme, with a 9 + 9 + 2 microtubule pattern, a centriolar adjunct, two mitochondrial derivatives and two accessory bodies. The mitochondrial derivatives are very slender and of different lengths. The longer begins at the base of the nucleus, while the shorter one starts just below the base of the centriolar adjunct. This latter is asymmetric and appears at the nuclear base, extending parallel to the axoneme up to the anterior end of the smaller mitochondrial derivative. The short spermatodesmata and the small mitochondrial derivatives characterize the A. pagana sperm. In addition, the centriolar adjunct asymmetry and the occurrence of spermatodesm bundles might be considered plesiomorphic states present in the basal Tenthredinoidea.

Various aspects of the reproductive anatomy of the spider crab Inachus phalangium are investigated utilizing light and electron microscopy. Spermatozoal ultrastructure reveals the presence of a glycocalyx in the peripheral region of the periopercular rim, never recorded before in crustacean sperm cells. Sperm cell morphological traits such as semi-lunar acrosome shape, centrally perforate and flat operculum, and absence of a thickened ring, are shared only with Macropodia longirostris, confirming a close phylogenetic relationship of these species and their separation from the other members of the family Majidae. Spermatozoa are transferred to females inside spermatophores of different sizes, but during ejaculate transfer, larger spermatophores might be ruptured by tooth-like structures present on the ejaculatory canal of the male first gonopod, releasing free sperm cells. Such a mechanism could represent the first evidence of a second form of sperm competition in conflict with sperm displacement, the only mechanism of sperm competition known among Brachyura, enabling paternity for both dominant and smaller, non-dominant, males. In addition, we propose several hypotheses concerning the remote and proximal causes of the existence of large seminal receptacles in females of I. phalangium. Among these, genetically diverse progeny, reduction of sexual harassment and phylogenetic retention seem the most plausible, while acquisition of nutrients from seminal fluids, demonstrated in other arthropods, and suggested by previous studies, could be discarded on the basis of the presented data. J. Morphol., 2008. © 2007 Wiley-Liss, Inc.

Until now, the knowledge on pholcid spermatozoa is based on two species, Pholcus phalangioides and, incompletely, Holocnemus pluchei. To complete this knowledge and to reveal more potential phylogenetic characters, we have investigated sperm ultrastructure and spermiogenesis of H. pluchei. We found that the sperm cells of this species are clearly different from those of P. phalangioides with respect to: (1) the lack of specialization in the cylindrical acrosomal vacuole; (2) a nuclear canal which is located in the periphery and not in the center of the nucleus; (3) a more prominent postcentriolar elongation of the nucleus; (4) the presence of "inner microtubules" in the implantation fossa in early and mid-spermatids; (5) the absence of a helical band of nuclear material; (6) the proximal centriole which is not prolonged; (7) the types of secretion in the seminal fluid (only two types in H. pluchei). Similarities in the spermatozoa of both species concern: (1) a large implantation fossa which contains large amounts of glycogen in mature spermatozoa; (2) absence of a centriolar adjunct; (3) an axonemal basis located in the posterior part of the implantation fossa; (4) the formation of the so-called cleistospermia in the vas deferens. Our results strongly support systematic relationships within Pholcidae placing these two species in different subgroups.

International audience; The malaria parasite invades the midgut tissue of its mosquito host as a motile form called the ookinete. We have examined the pellicle of the ookinete of Plasmodium gallinaceum by freeze-fracture and quick-freeze, deep-etch electron microscopy. The general organization is analogous to that of invasive stages of other members of Apicomplexa. The pellicle is composed of three membranes: the plasma membrane, and the two linked intermediate and inner membranes, which in the ookinete form one flattened vacuole that is located beneath the plasma membrane. The edges of this vacuole form a longitudinal suture. Beneath the vacuole is found an array of microtubules that are connected to the inner membrane by intramembranous particles. During freeze-fracture, the membranes can split along their hydrophobic planes, thus yielding six fracture faces, each of which displays a characteristic pattern of intramembranous particles. Additionally, we find that the ookinete pellicle differs from all other apicomplexan motile stages by the presence of large pores. These pores are of unknown function, but clearly might constitute a novel pathway for the transport of molecules to and from the cortex, which is independent of the well-described route through the apical micronemal/rhoptry complex. The pores may be the route by which motor proteins or other non micronemal surface proteins are trafficked, such as P25/P28 and SOAP, some of which are implicated in transmission blocking immunity.