Spernathecal morphology,sperm transfer and a novel mechanism of sperm displacement in the rove beetle,Aleochara curtula (Coleoptera,Staphylinidae)

Summary The mechanism by which sperm are transferred from the male's spermatophore to the female's storing cage is described for the rove beetle Aleochara curtula, emphasizing a novel mechanism of sperm displacement by competing males. The cuticular, U-shaped spermatheca is equipped with a valve structure and two sclerotized teeth. The tube of the spermatophore extends into the spermathecal duct through the guidance of the flagellum of the male endophallus. Further elongation of the spermatophore tube, however, occurs only after separation of the pair. A primary tube bursts at its tip after passing through the valve. Within the lumen of the primary tube, a second tube passes through the valve and continues to extend up to the apical bulb of the spermatheca, doubles back on itself and swells to form a balloon filling most of the spermatheca. The balloon of the spermatophore is pierced within the spermatheca by tooth-like structures pressed against the spermatophore through contraction of the spermathecal muscle. The same process of spermatophore growing and swelling is also observed in mated females. Sperm from previous copulations are backflushed through the valve and the spermathecal duct, indicative of last-male sperm predominance.Abbreviations ad adhesive secretion covering the sperm - sac am amorphous secretion of the spermatophore - as ascending portion of the spermatophore - ds descending portion of the spermatophore - end parts of the male endophallus - ext extended tube - f flagellum - gs genital segment - lt large tooth - m muscle of the spermatheca - nsc non sclerotized cuticle - op opening of the spermathecal gland - pt primary tube - sc sclerotized cuticle - sd spermathecal duct - se secretion of the spermathecal gland - sf secretion flowing out of the primary tube - sg spermathecal gland - sm sperm - smt small tooth - sp spermatheca - ss sperm sac - st secondary tube - vm vaginal muscle     

Coevolution of male and female genitalia in stalk-eyed flies (Diptera: Diopsidae)

The present study investigates the coevolution of a particular male genital process and the female spermathecal ducts in a clade of stalk-eyed flies (Diptera, Diopsidae) and debates the underlying evolutionary mechanisms. The fine morphology and interaction of the male and female genitalic structures are reconstructed from serial sections of mating pairs in one of the species. It is found that the male genital process traverses the common spermathecal duct to enter the base of one of the separate spermathecal ducts during the mating. Spermatozoa and accessory secretions are not transferred through the male genital process but can be discharged only from the male gonopore near its base. A detailed morphometric study reveals low intraspecific variation and hypoallometry of the male genital process. Across 17 species studied comparatively, the lengths of the male genital process and the female common and separate spermathecal ducts are highly variable. The length of the male genital process is correlated significantly with that of the female common spermathecal duct, but not with that of the separate spermathecal ducts. Based on the combined evidence it is concluded that the male genital process and the female common spermathecal duct have coevolved, and that sexual selection by cryptic female choice constitutes a possible and parsimonious explanation for their coevolution. Alternative or additional explanations in terms of sexually antagonistic coevolution cannot be ruled out conclusively, but are not supported by the available evidence.     

Functional morphology of the copulatory organs of a reed beetle and a shining leaf beetle (Coleoptera: Chrysomelidae: Donaciinae,Criocerinae) using X-ray micro-computed tomography

For more than 100 years it has been known that the sclerotised median lobe of beetles harbours a membranous structure (the "internal sac" or "endophallus") which is everted during copula inside the female genital tract. In order to explore the functional role of this structure and those associated with it, we cryofixed copulating pairs of Donacia semicuprea and Lilioceris lilii and studied the relative position of the elements of the copulatory apparatus of males and females by micro-computer-tomography.We found that the everted endophallus fills the lumen of the bursa copulatrix completely. Our data suggest that in Lilioceris lilii the tip of the sclerotised distal part of the ejaculatory duct, the flagellum, is positioned exactly over the opening of the spermathecal duct inside the bursa copulatrix. The mouth of the bursa copulatrix in Donacia semicuprea is armed with a strong muscle ring, and the whole wall of the bursa is covered externally with a layer of muscle fibres. These morphological differences correspond with differences in mating behaviour: In reed beetles (Donaciinae), females seemingly can control mating to a higher degree than in lily beetles (Lilioceris spp.).     

The fine structure of the female reproductive system of Zorotypus caudelli Karny (Zoraptera)

The general structure of the female genital system of Zorotypus caudelli is described. The ovarioles are of the panoistic type. Due to the reduction of the envelope (tunica externa) the ovarioles are in direct contact with the hemolymph like in some other insect groups, Plecoptera included. The calices are much larger in Z. caudelli then in Zorotypus hubbardi and their epithelial cells produce large amounts of secretions, probably protecting the surface of the eggs deposited on the substrate. Eggs taken from the calyx bear a series of long fringes, which are missing in the eggs found in the ovariole, and in other zorapteran species. The long sperm of Z. caudelli and the long spermathecal duct are likely related to a sexual isolating mechanism (cryptic female choice), impeding female re-mating. The apical receptacle and the spermathecal duct - both of ectodermal origin - consist of three cell types. In addition to the cells beneath the cuticle lining the lumen, two other cell types are visible: secretory and canal cells. The cytoplasm of the former is rich in rough endoplasmic reticulum cisterns and Golgi complexes, which produce numerous discrete dense secretory bodies. These products are released into the receiving canal crossing the extracellular cavity of secretory cells, extending over a series of long microvilli. The secretion is transported towards the lumen of the apical receptacle of the spermatheca or to that of the spermathecal duct by a connecting canal formed by the canal cells. It is enriched by material produced by the slender canal cells. Before mating, the sperm cells are enveloped by a thick glycocalyx produced at the level of the male accessory glands, but it is absent when they have reached the apical receptacle, and also in the spermathecal duct lumen. It is likely removed by secretions of the spermatheca. The eggs are fertilized at the level of the common oviduct where the spermathecal duct opens. Two micropyles at the dorsal side of the equator level possibly facilitate fertilization. The presence of these two micropyles is a presumably derived feature shared with Phasmatodea. The fine structure of the female reproductive system of Z. caudelli does not allow to assess the phylogenetic position at the present stage of knowledge. The enlarged calyx and the temporary presence of long fringes on the eggs are potential autapomorphies of Z. caudelli or may indicate relationships with other Zorotypus species.     

'Shouldering' exaggerated genitalia: a unique behavioural adaptation for the retraction of the elongate intromittant organ by the male rove beetle (Aleochara tristis Gravenhorst)

Complex genitalia are ubiquitous among arthropods, but little attention has been given to the fact that the evolution of such elaborate structures may have led to biomechanical constraints that hinder their usage. In the rove beetle, Aleochara tristis, the male's intromittant organ consists of a long flagellum that is more than twice the body length. It is introduced into the spermathecal duct of the female during copulation. The flagellum apparently functions as a guiding rod for a tube growing from the spermatophore that the male deposits in the female's genital chamber. The extraordinary length of the intromittant organ poses a unique physical challenge for the male. During its retraction from the female after mating, the flagellum is under considerable tension. Any sudden release of this tension would result in the flagellum becoming severely entangled, preventing the male from mating again. In response to this novel physical challenge, males have apparently evolved a specialized behavioural adaptation that prevents entanglement after copulation. While retracting the flagellum from the female, the male secures it between a wing shoulder and the pronotum ('shouldering'), holding it taut for about one half of its length. This allows the stepwise retraction of the flagellum from the female and allows it to be retracted back into the male's body in an orderly fashion. This is, to our knowledge, the first demonstration of a behavioural adaptation that has evolved to ameliorate the biomechanical problems caused by exaggerated genital morphology.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 307–312.     

Function of the spermathecal muscle in Chelymorpha alternans Boheman (Coleoptera: Chrysomelidae: Cassidinae)

Abstract. When the spermathecal muscle of a virgin female Chelymorpha alternans Boheman (Coleoptera: Chrysomelidae) was cut, the number of spermatozoa transferred in a single mating to the spermatheca and the spermathecal duct was not affected, but their distribution differed. Cutting the spermathecal muscle also reduced egg fertility. Eggs from females with a cut muscle showed a lower average percentage fertilization. Longer delays in oviposition after removal of the spermathecal muscle were associated with higher proportions of infertile eggs.     

The female postabdomen and genitalia of the basal moth family Heterobathmiidae (Insecta: Lepidoptera): Structure and phylogenetic significance

Female Heterobathmia have the segments behind VIII forming a compact ‘terminal unit’ with a large saddle-shaped dorsal plate and a membranous ventroposterior surface bearing the separate gonopore and anus. While females of most of the nine known species are overall similar, Heterobathmia valvifer is unique amongst lepidopterans in possessing paired ventral appendages (‘ovipositor valves’) arising from the intersegmental groove following segment VIII; evidence from musculature contradicts an interpretation of these appendages structures as ‘true’ ovipositor valves. The ventroposterior wall of the terminal unit in H. valvifer bears paired sclerites, possible homologues of the ‘ventral rods’ in basal Lepidoptera-Glossata. In Heterobathmia megadecella sclerites on paired longitudinal elevations in comparable positions probably are/include homologues of these sclerites. Their similarity with paired sclerotizations in the corresponding region of hydrobiosid caddisflies is noted. A prominent frame-like sclerotization in the genital chamber, located in front of the spermathecal duct origin, is present only in H. megadecella.Putative heterobathmiid autapomorphies include an enlarged ‘subgenital plate’ on venter VIII, absence of apophyses on segment VIII, shortened apophyses on the terminal unit, multilobed accessory glands (but their ‘type 1’ secretory epithelium is plesiomorphic at this level), a conspicuous papilla in the chamber cuticle bearing the opening of the ductus bursae on its apex, and inwards-pointing spines in the ductus bursae. A variably developed thickening of the anterior genital chamber intima is another putative family autapomorphy, while an extreme thickening of the posterior intima seen in Heterobathmia pseuderiocrania is not of general occurrence in heterobathmiids. A sistergroup relationship between Heterobathmiidae and Glossata is supported by their fully developed ‘2-compartment section’ of the spermathecal duct and losses of some likely lepidopteran groundplan muscles.     

Female genital system of the folding-trapdoor spider Antrodiaetus unicolor (Hentz, 1842) (Antrodiaetidae, Araneae): ultrastructural study of form and function with notes on reproductive biology of spiders

The genitalia of the female folding-trapdoor spider Antrodiaetus unicolor are characterized by two pairs of spermathecae that are arranged in a single row and connected to the roof of the bursa copulatrix. Each single spermatheca is divided into three main parts: stalk, bowl, and bulb, which are surrounded by the spermathecal gland. The epithelium of the spermathecal gland is underlain by a muscle meshwork and consists of different types of cells partly belonging to glandular cell units (Class 3 gland cells) that extend into pores in the cuticle of the stalk and bowl. Interestingly, the bulb lacks glandular pores and is characterized by a weakly sclerotized cuticle. This peculiarly structured bulb probably plays an important role in the discharge of the sperm mass. It is suggested that by contraction of the muscle layer the sperm mass may be squeezed out, when the bulb invaginates and expands into the spermathecal lumen, pushing the sperm to the uterus lumen. Each glandular unit consists of usually one or two central secretory cells that are for the most part surrounded by a connecting cell that again is surrounded by a canal cell. The canal cell, finally, is separated from the other epithelial cells (intercalary cells) located between the glandular units by several thin sheath cells that form the outer enveloping layer of the unit. The secretions are released through a cuticular duct that originates proximally between the apical part of the connecting cell and the apical microvilli of the secretory cells and runs into a pore of the spermathecal cuticle. The glandular products of the Class 3 gland cells likely contribute to the conditions allowing long-term storage of the spermatozoa in this species. Details regarding the ovary, the uterus internus, and the uterus externus are reported. Most of the secretion that composes the chorion of the egg is produced in the ovary. Glandular cell units observed in the uterus externus differ structurally from those in the spermathecae and likely play a different role. Finally, we briefly discuss our results on the female genitalia of A. unicolor in the light of knowledge about the reproductive biology of spiders.     

Calleida desenderi, new species from Ecuador (Coleoptera, Carabidae, Lebiinae)

Calleida desenderi Casale, sp. n., is described from Ecuador, Napo Province, surroundings of San Rafael. The new taxon is mostly characterized by the head and appendages rufous, the disc of elytra with marked metallic green reflection, the median lobe of aedeagus ring-like, and the endophallus with a long, twisted flagellum. A key for identification of the closer Neotropical species described so far is also provided.     

Genital feelers: the putative role of parameres and aedeagal sensilla in Coleoptera Phytophaga (Insecta)

The male copulatory organ (aedeagus) of the Curculionoidea and the Chrysomeloidea is originally composed of a median lobe and a tegmen with basal struts and distal parameres. Within the Phytophaga (=Pseudotetramera), the parameres have been reduced several times. Comparison of different types of parameres, median lobes, aedeagi lacking parameres, and investigation of dissected pairs in copula revealed that (1) parameres do not provide mechanical coupling, (2) mechanical footing is provided by the endophallus, (3) median lobes of Phytophaga bear different kinds of sensilla. Mechanical and behavioural interaction between male and female copulatory organs were studied morphologically and by observation of live, copulating pairs. For the first time, copulation of a Sagrinae-species (Chrysomelidae: Sagrinae: Mecynodera coxalgica) was investigated in detail.     

The genitalia of termites (isoptera): Possibilities of using in taxonomy

An attempt has been made to use some structures of the external genitalia in the taxonomy of termites. Twenty-five species of four largest families were examined. Only the female external genitalia appeared to be suitable for identification of species, with some genital structures (medisternite, basivalvae, parasternites, etc.) being most important for these purposes. The taxonomic suitability of these structures is different in different families. In the family Kalotermitidae, the medisternite and spermathecal opening are strongly sclerotized and suitable for the species identification, whereas the basivalvae are reduced or lost. In Hodotermitidae, the basivalvae are well-developed and their shape is different in different species. Structural features of the basivalvae and spermathecal opening are species-specific in Rhinotermitidae, the shape of the basivalvae and position of the spermathecal opening, in Termitidae. In addition, species of Termitidae have a characteristic strigation of the basivalvae. In Macrotermitinae and Nasutitermitinae, the anterior margins of sternite IX are well sclerotized and form parasternites. The structures proposed by us as diagnostic vary only within species.     

Differences in genitalia structure and function between subfamilies of longhorn beetles (Coleoptera: Cerambycidae)

Beetle genitalia are usually described only for taxonomic purposes without considering the possible function of structures. Exceptions are sporadic detailed studies on single species. We studied genital structures in the subfamilies of Cerambycidae and outlined assumptions on the function of these structures and the implications for the phylogeny of the Cerambycidae. We found that male genitalia in particular are taxon-specific on a higher taxonomic level; e.g., the parameres are widely variable in Cerambycinae, while in most Lamiinae species they appear relatively uniform and differ from those of the Cerambycinae. Internal sac structures are very different among the various subfamilies. Small backwards-pointing spines are the most common armature of the internal sac. The female genitalia are less variable, although ovipositor morphology may differ among subfamilies. In most species, the connection between the mates during copulation is achieved by the long internal sac and the ovipositor only, whereas the median lobe and parameres are in contact with the female abdomen only at the beginning of copulation. Cerambycinae and Lepturinae have a basal swelling of the endophallus to prevent it from sliding back into the male abdomen during copulation. The long internal sac functions in connecting the mates and guaranteeing the sperm transfer.     

A newly discovered sperm transport system in the female of Lygaeidae bugs

In the female reproductive system of the relatively large hemipteran, the western conifer seed bug Leptoglossus occidentalis (Heidemann), a cuticle‐lined tube extends medially along the surface of the vagina from the proximal end of the spermathecal complex anteriorly to the base of the common oviduct. This medial tube houses the proximal end of the spermathecal duct, thereby enabling the transport of material from the spermatheca at the distal end of the spermathecal complex, past the vagina (or bursa copulatrix) and directly to the common oviduct. The proximal portion of the spermathecal complex also contains an insemination duct that is separate from the spermathecal duct. The insemination duct allows the male intromittent organ to extend from the vagina to the spermatheca without navigating through the spermathecal duct. The reproductive systems of two previously studied Hemiptera, the milkweed bug Oncopeltus fasciatus (Dallas) and the box elder bug Leptocoris trivittatus (Say), possess a similar cuticle‐lined medial tube housing the spermathecal duct. This new information provides a clearer understanding of sperm transport in the female reproductive system of Lygaeidae bugs, and helps to clarify the path of the male organ during copulation, as well as the movement of sperm during egg laying.     

Spermatogenesis, changes in reproductive structures, and time constraint associated with insemination in Podisus nigrispinus

Males of the predatory stinkbug, Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae), accomplish long and multiple matings. We hypothesize that this behavior is due to time requirement for spermatozoa production and their transference to the females. Thus, this work investigated the effect of mating status of males and mating duration on spermatozoa transference to the females and the location of spermatozoa in the male reproductive tract during mating. On females, morphological alterations on female spermatheca and associated structures during a mating were investigated. Analyses of male reproductive tract showed presence of spermatozoa in the lumen of vas deferens was independent of mating status (ca. virgin, 0, 12 and 24 h after having a full mating), indicating continuous spermatogenesis which is supported by the absence of a seminal vesicle for spermatozoa storage. Female spermatheca had no changes associated with the duration of mating. However, females exhibited spermathecal elastic duct swelling by 30 min of mating duration. The success of males in filling the female spermatheca with spermatozoa depends on duration of mating. Thus, the results indicate that multiple mating is a requirement for reproductive success in the species by transference of spermatozoa and accessory substances stored in the female spermathecal duct. Likewise, the long mating is a male requirement to transfer materials in appropriate amount to the female but it is not dependent on spermatozoa alone.     

Diagnosis, classification, and phylogenetic relationships of the orphnine scarab beetles (Coleoptera, Scarabaeidae: Orphninae)

Orphnine scarab beetles (Orphninae) are widely distributed in the tropical and subtropical regions of the southern continents except for Australia. The catalogue of nominal taxa of orphnines includes 2 tribes, 15 genera, and 195 species. Diagnosis of the group, based on adult morphological characters, is as follows: antennae 10-segmented with 3-segmented club; mandibles with 2?C4 scissorial teeth and well developed mola; labrum and mandibles protruding past clypeus and visible from above; scutellum well developed in winged species, reduced but distinct in wingless species; wings with distinct anal area; apices of anterior tibia in males without spur but normally with a few robust setae; anterior coxa with longitudinal hollow on anterior surface; tarsi with 2 similar claws; middle and hind tibiae with 2 apical spurs; abdominal sternite 2 with sub-triangular to rounded plectrum; dorsal surface of hind coxae with oval flat stridulatory file; pygidium partly hidden under elytra; parameres symmetrical; bursa copulatrix sacciform, membranous; spermatheca C-shaped, not sclerotized; accessory vaginal glands developed; abdomen with 2 sclerotized tergites (VII?CVIII) and 6 visible sternites (III?CVIII). Preliminary phylogenetic analysis based on 47 characters of adult morphology shows that the tribe Aegidiini Paulian is a natural, monophyletic group. The genus Stenosternus Karsch described from a single specimen from S?o Tomé Island (Gulf of Guinea), is morphologically more similar to the New World taxa than to the Old World ones and is provisionally placed in Aegidiini. The tribe Orphnini Erichson seems non-monophyletic and has no synapomorphies. The genus Orphnus is apparently a polyphyletic group and it needs taxonomic revision. The hypothesis on sister-group relationship of Orphninae and Allidiostomatinae, based on molecular data, is not supported by the morphological characters. The stridulatory organs (the putative synapomorphy of Orphninae + Allidiostomatinae) are not identical in these groups; the mouthparts and female genitalia are essentially different. Orphninae have chewing mouthparts with large scissorial teeth and well developed mola, which is characteristic of generalist saprophagous species. Allidiostomatinae have mandibles with scissorial teeth and mola reduced; they also have sclerotized bursa copulatrix and sclerotized mandibular duct which opens on the dorsal side near condyle. Considering the present day development of alpha-taxonomy of most orphnine taxa, especially the speciose genus Orphnus, it seems premature to propose changes in higher classification of the subfamily. To clarify the phylogenetic position of the Orphninae among scarab beetles it is essential to include representative members of all taxa of orphnine lineage (sensu Browne, Scholtz, 1998) into the analysis.     

三种蚤生殖系统的细微结构:雄性外生殖器的发育

本文研究了缓慢细蚤Leptopsylla segnis(Schonherr),不等单蚤Monopsyllus anisus(Rothschild)和猫栉首蚤指名亚种Ctenocephalides felis felis(Bouche)雄性外生殖器的结构,观察了从幼虫、前蛹、蛹至成虫各发育时期的雄性外生殖器的内部结构变化.对有争议的雄蚤上抱器的起源,雄蚤生殖孔的位置,雄性外生殖器芽内陷的腹节以及射精管横切面的细胞数目和阳茎背、腹杆的结构等问题进行了详细的观察和探讨.     

Morphology of eggs and spermatheca of <Emphasis Type="Italic">Odontotarsus purpureolineatus</Emphasis> (Heteroptera,Scutelleridae)

The morphology of the spermatheca and eggs of Odontotarsus purpureolineatus were studied by optical microscopy and scanning electron microscopy. The spherical eggs were about 1.35 mm long and 1.09 mm wide. The egg batches generally consist of 13–14 eggs. The egg surface is covered by polygonal (hexagonal and pentagonal shapes prevail) ridges and tiny chorionic tubercles. There were 8–10 aero-micropylar processes between the polygons. The spermatheca of O. purpureolineatus is characterized by a spherical spermathecal bulb, a pumping region, a flange of pump and dilation of spermathecal duct. Spermathecal processes and a median spermathecal dilation with sclerotized rod are missing. The spermathecal bulb and the pumping region possess many pores.     

Mating behavior and genital damage during copulation in the leaf beetle Lema coronata (Chrysomelidae: Criocerinae)

The criocerine leaf beetle Lema coronata Baly has extremely long genitalia that reach more than twice the body length in both sexes. We observed mating behavior of this species in the laboratory and inspected the male genital morphology using a scanning electron microscope. The males did not perform pre-copulatory courtship and post-copulatory guarding of the mates, and copulation lasted only for about 30 min. The surface of male genitalia is smooth without any special structures at the tip. A fragment of broken male genitalia was detected in the spermathecal duct of one female. We discuss the adaptive significance of male genital damage and the selective factor of elongated genitalia.     

Co-Evolution of the Mating Position and Male Genitalia in Insects: A Case Study of a Hangingfly

Hangingflies are unique for the male providing a nuptial gift to the female during mating and taking a face-to-face hanging copulation with the female. Their male genitalia are peculiar for an extremely elongated penisfilum, a pair of well-developed epandrial lobes (9th tergum), and a pair of degenerated gonostyli. However, the co-evolution of their face-to-face copulation behavior and the male genitalia has rarely been studied hitherto. In this paper the mating behavior of the hangingfly Bittacus planus Cheng, 1949 was observed under laboratory conditions, and the morphology of the male and female external genitalia was investigated using light and scanning electron microscopy. The male provides an insect prey as a nuptial gift to the female in courtship and mating process, and commits a face-to-face copulation. During copulation, the male abdomen twists temporarily about 180° to accommodate their face-to-face mating position. The aedeagal complex has an extremely elongated penisfilum, corresponding to the elongated spermathecal duct of the female. The well-developed epandrial lobes serve as claspers to grasp the female subgenital plate during copulation, replacing the function of gonostyli, which are greatly reduced in Bittacidae. The modified proctiger assists the penisfilum to stretch and to enter into the female spermathecal duct. The possible reasons why this species might mate face-to-face are briefly discussed.