Copulation reduces male but not female longevity in Saltella sphondylli (Diptera: Sepsidae)

Mating more than once is extremely costly for females in many species, making the near ubiquity of polyandry difficult to understand. However, evidence of mating costs for males is much rarer. We investigated the effects of copulation on longevity of male and female flies (Saltella sphondylli). We also scrutinized potential fecundity and fertility benefits to females with differing mating history. Copulation per se was found to decrease the longevity of males but not that of females. However, when females were allowed to lay eggs, females that mated died earlier than virgin females, indicating costs of egg production and/or oviposition. Thus, although longevity costs of copulation are higher for males, reproduction is nevertheless costly for females. We also found no differences in fecundity or fertility relative to female mating history. Results suggest that polyandry may be driven by minor costs rather than by major benefits in this species.     

The internal female genitalia of Aulacigaster (Diptera: Aulacigastridae)—description and phylogenetic analysis

The internal female genitalia of 22 species of Aulacigaster are studied, covering all species groups as defined by Rung and Mathis (Smithson. Contrib. Zool     

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.     

Lack of morphological coevolution between male forelegs and female wings in Themira (Sepsidae: Diptera: Insecta)

The complex, species-specific foreleg armature in males of the genus Themira (Diptera: Sepsidae) provides an ideal system for testing competing hypotheses for the evolution of sexually dimorphic character divergence. In sepsid flies, the male holds onto the female by clasping her wing base with his modified forelegs. In the present study, we document the male leg and the female wing morphology using scanning electron microscopy and confocal microscopy. We use a phylogenetic tree for Themira to reconstruct male foreleg and female wing evolution and demonstrate that the male legs have evolved elaborate structures with little or no corresponding changes in wing morphology. This lack of interspecific variation in female wings is not in agreement with the hypothesis of a morphological 'evolutionary arms race' between males and females. However, there is also no evidence for sex-specific wing differences in sensory organs on the wing base that may explain how females could assess males according to Eberhard's 'cryptic female choice' hypothesis. Finally, our study reveals the function of several novel morphological clasping structures and documents that the male foreleg characters in Themira are highly homoplastic. Male forelegs in two clades evolve considerably faster than in other species or clades. These two clades include Themira superba and Themira leachi , species that have some of the most dramatically modified forelegs known in Diptera.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 227–238.     

鼓翅蝇科(双翅目:沼蝇总科)的分类研究进展

对双翅目鼓翅蝇科分类沿革,分类地位,分类系统,系统发育的研究进展作了详细的介绍,同时提出了在该科昆虫研究中存在的一些主要问题。     

Cryptic female exaggeration: the asymmetric female internal genitalia of Kaliana yuruani (Araneae: Pholcidae)

Males of the Venezuelan pholcid spider Kaliana yuruani have unique genitalia, with the procursi about six times as long as usual in the family. The present article describes the previously unknown female, searching for a morphological correlate in the female genitalia to the male's exaggeration. Reconstruction of histological serial sections reveals an internal female complexity that is unequalled in pholcid spiders. An intricate system of ducts and folds is arranged in an asymmetric way, making this the third known case of genital asymmetry in spiders. The term "cryptic female exaggeration" is used in analogy to cryptic female choice, pointing to the fact that from the outside, the female genitalia do not appear unusual. I propose that cryptic female exaggeration may be relatively common in copulatory structures if male exaggerations need to be evaluated according to the female choice by mechanical fit model. Finally, the evolution of genital asymmetry in spiders is contrasted with that in insects.     

The function of female resistance behavior: intromission by male coercion vs. female cooperation in sepsis flies (Diptera: Sepsidae)

Female resistance behavior that occurs prior to intromission does not by itself imply forced copulation. Such behavior may function instead as a test of the male in order to favor some males over others, or to induce the male to desist. Thus, male persistence and forcefullness may sometimes be better described as persuasion rather than coercion. Under the persuasion hypothesis, the male only gains intromission due to an active response of the female. Under the coercion hypothesis, male and female are opposed in a physical battle which the female loses if copulation occurs. In species in which males are morphologically incapable of forcing intromission without active female cooperation (I argue here that this is probably a very common situation), data on the behavioral and ecological context in which resistance occurs can distinguish between the two possibilities. Partially congruent functions of resistance, seen from the female point of view, are female resistance to screen (male persuasion), and female resistance to avoid males non-selectively (male coercion). Sepsis flies illustrate these ideas. Females often struggle energetically in apparent attempts to dislodge mounted males and to prevent intromission, and males grasp females with powerful species-specific structures on their front legs and genitalia. This suggests the possibility of coerced intromission. But behavioral and morphological evidence demonstrate that active female cooperation occurs at the moment of intromission, and that males are probably dependent on this cooperation because they are not morphologically equipped to force their genitalia into those of an uncooperative female. Despite the impression from previous publications, male insects in general may seldom be able to achieve intromission by genitalic force. The species-specific forms of the grasping genitalia of male sepsis are probably not the result of an evolutionary arms race between coercive males and unselectively resistant females.     

The functional morphology of species-specific clasping structures on the front legs of male Archisepsis and Palaeosepsis flies (Diptera, Sepsidae)

Several possible explanations for the elaborate species-specific morphology of male front leg clasping organs were tested by comparing six species of Archisepsis, Palaeosepsis and Microsepsis flies. The only previously published hypothesis regarding these clasping organs was refuted by the finding that species-specific portions of the male femur and tibia consistently meshed tightly with prominent veins and folds in the female's wing, rather than meshing with each other. Female wing morphology in the region grasped by the male was relatively uniform and in general did not vary in ways that would prevent non-conspecific males from grasping them, arguing in all but one species against both simple lock-and-key and male-female conflict of interests hypotheses based on morphology. Interspecific differences in male front leg morphology generally represent alternative ways to accomplish the same basic mechanical function of holding tightly onto the relatively invariant female. Despite the fact that female resistance behaviour indicates that male-female conflict over male mounting is common, only one female wing structure in one species resembled an anti-clasper device, giving a second reason to doubt the morphological male-female conflict of interest hypothesis, at least for five of the six species. The positions of probable sensory structures on the wings of females were relatively similar in different species and did not correspond in any obvious way to species-specific features of male clasping structures. This, plus the intraspecific variation in both the positions of these sensilla and the exact site where the male grasped the female's wing, argued against simple 'sensory lock-and-key' ideas about male front leg function. By a process of elimination, it appears that generalized female receptors are able to sense species-specific differences in male front legs. This idea was supported by increased female rejection behaviour in cross-specific pairs.     

Musculature of the male genitalia in Rivellia (Diptera: Platystomatidae)

The musculature of male genitalia was studied hitherto only in two species of Tephritidae, one species of Platystomatidae, one species of Pallopteridae, and three species of Ulidiidae of the superfamily Tephritoidea. The split of the hypandrium from one structure into three (the hypandrium and two lateral sclerites) is traced. The hypandrial origin of the lateral sclerites of the hypandrial complex is shown based on the localization of muscle attachment sites. The subepandrial origin of the inner lobes of the surstyli is also confirmed.     

日本北海道虻类雌性外生殖器形态(双翅目：虻科)(英文)

【目的】利用日本北海道虻类评估和验证外生殖器在分类学上的意义。【方法】将虻类成虫标本浸渍在生理盐水中并置于双目显微镜下通过针和镊子在培养皿中进行解剖并绘图,观察第9背板、第10背板、尾叶、第8腹板、受精囊、受精囊管及生殖叉器的形态特征。【结果】在日本北海道共记录了虻科(Tabanidae) 3亚科7属38种。我们观察并描述了3亚科其中的6属24种的雌性外生殖器的主要特征。亚科之间存在明显差异;然而在一般情况下属之间很难建立一种方法来确定共同点;种之间只有在斑虻属Chrysops中有相似之处,其他属中则比较多样化。因此,亚科鉴定根据第9背板、第8腹板及受精囊足以进行区分,属及种鉴定需要结合第9背板、第10背板、尾叶、第8腹板、受精囊、受精囊管及生殖叉器各自的特征组合在一起才能区分开来。我们也制作了虻类外生殖器的检索表。【结论】和许多其他昆虫一样,外生殖器是虻科的重要分类特征,对于促进分类学和系统学的发展具有重要意义。本研究首次对分布在日本北海道的虻科雌性外生殖器进行了系统研究。     

Malformations of the genitalia in male Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae)

Phlebotomus papatasi ( Scopoli, 1786 ) (Diptera: Psychodidae) is a major vector of Leishmania major (Kinetoplastida: Trypanosomatidae), a causative agent of zoonotic cutaneous leishmaniasis. Morphological characters of sand fly genitalia are key indicators for species identification. Various anomalies affecting male genitalia have been previously described. We take advantage of a large sand flies survey conducted in 32 stations in Central and Southern Morocco to systematically quantify the prevalence and spatial distribution of malformations affecting the genitalia of P. papatasi. Among 597 examined males, 122 were abnormal (20.4%). Malformations were widespread and largely concerned the number of spines in the lateral lobes and in the styles. Asymmetrical anomalies in lateral lobes were common. Correspondence analysis of our results highlighted the symmetrical anomalies observed in the lateral lobes, and abnormal styles of the male genitalia were found to be associated with environmental disturbances since they were prevalent in sewage dumps.     

The distribution and biology of Sepsidae (Diptera) in upland regions of northern England

Abstract. 1. A survey of the distribution of Sepsidae was made over 2 years at forty-two sites in northern England. Material was collected by pitfall trapping and in sweep-net samples.
2. With the exception of a single specimen taken in a pasture, only members of the genus Sepsis were found and three species, S.cynipsea, S.orthocnemis and S.neocynipsea , occurred at most sites. The numbers of S.cynipsea were greater than S.orthocnemis at the great majority of sites. S.neocynipsea was the least abundant of the three species but occurred over the whole altitudinal range and formed a greater proportion of the catch at higher sites.
3. It is suggested that the three commonest species use sheep dung as their main larval habitat in upland areas. Cow dung (the commonest reported larval habitat of Sepsis spp.) did not occur on any of the main sites studied. No sepsids were reared from red grouse droppings.
4. There was no difference in the species composition on peat and grassland sites but almost 4 times as many sepsids were caught on the peat moor than on the neighbouring grasslands.
5. There was a marked bimodal distribution of adults with a trough of captures in June and July. This is in contrast to data from other studies, at low altitudes, and is probably the result of there being only two generations per year in upland areas rather than four (or more) in warmer conditions.     

Bending for love: losses and gains of sexual dimorphisms are strictly correlated with changes in the mounting position of sepsid flies (Sepsidae: Diptera)

Background  

Sexually dimorphic structures ntribute the largest number of morphological differences between closely related insect species thus implying that these structures evolve fast and are involved in speciation. The current literature focuses on the selective forces that drive these changes, be it 'sexual conflict' or 'female choice'. However, there are only few studies examining the function of sexual dimorphisms and even fewer that investigate how functional changes influence dimorphisms. This is largely due to the paucity of taxa for which the morphology, behavior, and phylogenetic relationships for multiple species are known. Here we present such data for sepsid flies. Sepsids have starkly dimorphic forelegs whose function can be documented under laboratory conditions. We use data from 10 genes to reconstruct the phylogenetic relationships for 33 species and test whether mounting positions are correlated with the presence and absence of sexual dimorphisms in the forelegs.     

Complex asymmetric male genitalia of Anevrina Lioy (Diptera: Phoridae)

Detailed structure of the male genitalia of Anevrina is described. Hitherto unknown morphological characters of the internal sclerites relating to the epandrium and hypandrium are illustrated and elucidated. The subepandrial sclerite + bacilliform sclerites are distinctly modified, and the typical subepandrial sclerite is not recognizable. The right base of the medially shifted right surstylus is not connected to the posterior margin of the epandrium, and is directly supported by a robust bacilliform sclerite. The robust bacilliform sclerites are greatly developed inside the epandrium, and extended to three clasping components, the left surstylus, the medially shifted right surstylus and a pair of clasping lobes on the posteroventral margin of the right side of the epandrium. The upper lobe of a pair of clasping lobes on the right side of the epandrium is considered to originally have been situated on the left side and subsequently shifted to the right side. The plesiomorphic state of the clasping components relative to Anevrina is thought to be symmetrically four, comprising both the left and right surstyli and the posterior edge of both sides of the epandrium, indicating that the amazing phenomenon of cross-shifting of the clasping components has occurred in Anevrina. A cladogram generated based on the genitalic characters observed in this study shows sister groups within Anevrina, namely an Anevrina urbana-group comprised of A. urbana, A. setigera, A. olympiae, A. variabilis, A. thoracica, and an Anevrina unispinosa-group comprised of A. unispinosa, A. curvinervis, A. luggeri and A. macateei.     

Skeleton and musculature of the male genitalia in the family Nothybidae (Diptera)

Sclerites and musculature of the male genitalia of Nothybidae (Diptera) were studied for the first time. Symmetry of the genital and pregenital sclerites, similar to that in Psilidae, was revealed. The muscles of the male genitalia of Nothybus resemble the apomorphic plan of Cyclorrhapha (Sciomyzidae, Scathophagidae and Calliphoridae) due to the splitting of the hypandrium and hypandrial muscles.     

Revisional notes on the genus Toxopoda Macquart (Diptera,Sepsidae) in the Oriental and Australasian regions

I herein revise the genus Toxopoda Macquart of the Oriental and Australasian regions. A total of 16 species is discussed. Six new species are described: T. cavata sp. nov., T. angulata sp. nov., T. elephantina sp. nov., T. zuskai sp. nov., T. malayana sp. nov., and T. ozerovi sp. nov. The species T. contracta (Walker), T. viduata (Thomson) and T. simplex Iwasa, which can be easily confused with other species, are correctly redescribed and illustrated. Distributional notes and a key to the species of the Oriental and Australasian regions are provided.     

丝状鼓翅蝇属二中国新记录种

Nemopoda nitidula (Fallén) and N. mamaevi Ozerov were redescribed and found to be new record species of Sepsidae from China. The specimens were deposited in the Institute of Applied Entomology of Yangzhou University.     

The female postabdomen and internal genitalia of the basal moth genus Agathiphaga (Insecta: Lepidoptera: Agathiphagidae): morphology and phylogenetic implications

The female postabdomen of Agathiphaga vitiensis terminates in a telescope‐type extensible oviscapt with an apial ‘oviscapt probe’ composed of fused segments behind VIII. Exceptionally within the Lepidoptera two pairs of long ‘anterior apophyses’ arise from segment VIII, from the dorsum and venter. Agathiphaga has the most elaborate postabdominal musculature recorded from female Lepidoptera, comprising 24 muscle sets of which nine may be family autapomorphies. Apophysis musculature does not permit unambiguous homologizing of the single anterior apophysis in Lepidoptera–Glossata with either the dorsal or ventral pair in Agathiphaga, but is compatible with an interpretation of the glossatan anterior apophyses as a composite formation. Nine muscle sets shared with rhyacophilid caddisflies are ascribed to the amphiesmenopteran ground plan. The spermathecal duct represents an intermediate stage between the simple type present in Micropterigidae and the ‘two‐compartment type’ characteristic of almost all other Lepidoptera. The spermatheca has no lagena. The bursa copulatrix is small and simple. Accessory glands are very large, simple sacs. There are 40 + ovarioles per ovary. A terminal cloaca is extremely short. The numerous ovarioles potentially support a sister‐group relationship between Agathiphagidae and all other Lepidoptera, whereas the spermathecal duct histology supports the alternative conservative placement of the family as sister group of all nonmicropterigid Lepidoptera. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 905–920.