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Brazilian sex-role reversed cave insects (genus Neotrogla) have a striking structure called the gynosome (or female penis), which deeply penetrates male vagina-like genitalia during copulation to receive nutritious semen. However, the protruding and retracting mechanisms of the female penis, including their evolutionary origin, are poorly understood. By using micro-computed tomography (mu CT), we compared the genital morphology and musculature between species with a gynosome and others lacking this structure. As a result, we discovered two groups of muscles related to the protrusion and retraction of gynosomes. These muscles were also observed in species with non-protrusible prepenis. This suggests that evolution of these muscles preceded the acquisition of the protruding function of the gynosome, originally having a putative stimulatory function to receive nutritious semen. This intermediate stage probably allowed for the reversal of genital functions.

Brazilian sex-role reversed cave insects (genus Neotrogla) have a striking structure called the gynosome (or female penis), which deeply penetrates male vagina-like genitalia during copulation to receive nutritious semen. However, the protruding and retracting mechanisms of the female penis, including their evolutionary origin, are poorly understood. By using micro-computed tomography (mu CT), we compared the genital morphology and musculature between species with a gynosome and others lacking this structure. As a result, we discovered two groups of muscles related to the protrusion and retraction of gynosomes. These muscles were also observed in species with non-protrusible prepenis. This suggests that evolution of these muscles preceded the acquisition of the protruding function of the gynosome, originally having a putative stimulatory function to receive nutritious semen. This intermediate stage probably allowed for the reversal of genital functions.

A new species of the genus Trichadenotecnum (Psocodea: Psocidae) belonging to the corniculum species group,Trichadenotecnum okuyamai, was described from Awajishima Island, Japan. This is the 25th species of the genus and the third species of the corniculum group recorded from Japan.

The widely distributed tropical species Psyllipsocus yucatan Gurney is recorded from several localities in Thailand. P. yongi New & Lee, previously only known from Peninsular Malaysia, is recorded from Thailand and its male is described for the first time. Four new species are described and illustrated: P. formosus Lienhard & Yoshizawa n. sp. (Peninsular Malaysia), P. sarawakensis Lienhard & Yoshizawa n. sp. (East Malaysia:Sarawak), P. siamensis Lienhard & Yoshizawa n. sp. (Thailand), P. hyalomarginatus Lienhard & Yoshizawa n. sp. (Thailand). A checklist of the 17 species of Psyllipsocus known from the Oriental Region is provided. The name of the Chinese species P. maculatus Li Fasheng, a junior homonym of the American P. maculatus Garcia Aldrete, is replaced by the new name P. apicosectus Lienhard & Yoshizawa n. nom.

By using mu CT technology, we reconstructed 3D models of the female genital structures and associated muscles of seven species from three suborders of Psocodea (free-living species only, formerly known as independent insect order "Psocoptera"). The homology of the female genital structures and associated muscles of different species is discussed. A total of 21 muscle groups were observed, and except for one muscle, all were homologized throughout the order. Moreover, some of the homologous muscles could be identified confidently in holometabolan insects. Using the muscles as landmarks, we discuss the homology of the ovipositor valves between Psocodea and other neopteran insects. Most importantly, the ovipositor of the suborder Trogiomorpha was identified to consist of the well-developed external valve (V3) plus a remnant of the dorsal valve (V2). We also examined the phylogenetic information included in the female genital muscles and found that certain muscles provide useful information and support deeper nodes (e.g., monophyly of the suborder Psocomorpha). The present study of female genital muscles not only helps us to better understand the phylogeny of Psocodea but also provides a solid foundation for research on muscle evolution. (C) 2022 Elsevier Ltd. All rights reserved.

The thoracic musculature of the insect order Psocodea has been examined in only a few species of a single suborder to date. In the present study, we examined the thoracic musculature of species selected from all three suborders of Psocodea to elucidate the ground plan of the order and to examine the phylogenetic utility of the character system. The sister-group relationship between the suborders Troctomorpha and Psocomorpha received support from two novel nonhomoplasious synapomorphies, although the support from other morphological characters for this relationship is ambiguous. The sister-group relationship between the infraorders Epipsocetae and Psocetae also received support from one nonhomoplasious synapomorphy, although no other morphological characters supporting this relationship have been identified to date. The present examination revealed the potential of thoracic muscle characters for estimating deep phylogeny, possibly including interordinal relationships.

A new species of the genus Trichadenotecnum (Psocodea: Psocidae) belonging to the corniculum species group,Trichadenotecnum okuyamai, was described from Awajishima Island, Japan. This is the 25th species of the genus and the third species of the corniculum group recorded from Japan.

The widely distributed tropical species Psyllipsocus yucatan Gurney is recorded from several localities in Thailand. P. yongi New & Lee, previously only known from Peninsular Malaysia, is recorded from Thailand and its male is described for the first time. Four new species are described and illustrated: P. formosus Lienhard & Yoshizawa n. sp. (Peninsular Malaysia), P. sarawakensis Lienhard & Yoshizawa n. sp. (East Malaysia:Sarawak), P. siamensis Lienhard & Yoshizawa n. sp. (Thailand), P. hyalomarginatus Lienhard & Yoshizawa n. sp. (Thailand). A checklist of the 17 species of Psyllipsocus known from the Oriental Region is provided. The name of the Chinese species P. maculatus Li Fasheng, a junior homonym of the American P. maculatus Garcia Aldrete, is replaced by the new name P. apicosectus Lienhard & Yoshizawa n. nom.

By using mu CT technology, we reconstructed 3D models of the female genital structures and associated muscles of seven species from three suborders of Psocodea (free-living species only, formerly known as independent insect order "Psocoptera"). The homology of the female genital structures and associated muscles of different species is discussed. A total of 21 muscle groups were observed, and except for one muscle, all were homologized throughout the order. Moreover, some of the homologous muscles could be identified confidently in holometabolan insects. Using the muscles as landmarks, we discuss the homology of the ovipositor valves between Psocodea and other neopteran insects. Most importantly, the ovipositor of the suborder Trogiomorpha was identified to consist of the well-developed external valve (V3) plus a remnant of the dorsal valve (V2). We also examined the phylogenetic information included in the female genital muscles and found that certain muscles provide useful information and support deeper nodes (e.g., monophyly of the suborder Psocomorpha). The present study of female genital muscles not only helps us to better understand the phylogeny of Psocodea but also provides a solid foundation for research on muscle evolution. (C) 2022 Elsevier Ltd. All rights reserved.

The thoracic musculature of the insect order Psocodea has been examined in only a few species of a single suborder to date. In the present study, we examined the thoracic musculature of species selected from all three suborders of Psocodea to elucidate the ground plan of the order and to examine the phylogenetic utility of the character system. The sister-group relationship between the suborders Troctomorpha and Psocomorpha received support from two novel nonhomoplasious synapomorphies, although the support from other morphological characters for this relationship is ambiguous. The sister-group relationship between the infraorders Epipsocetae and Psocetae also received support from one nonhomoplasious synapomorphy, although no other morphological characters supporting this relationship have been identified to date. The present examination revealed the potential of thoracic muscle characters for estimating deep phylogeny, possibly including interordinal relationships.

Background Caenis rivulorum Eaton, 1884 is widely distributed and has been reported from a wide range in the Palearctic Region. New information We report this species from Japan for the first time, from five localities of Hokkaido, based on morphology and molecular data.

We describe a new psocid genus and species, Burmesopsocus lienhardi Yoshizawa, based on a fossil specimen embedded in mid-Cretaceous Burmese (Kachin) amber. Phylogenetic analysis based on the morphological data strongly suggest that the species is a member of the suborder Psocomorpha and may belong to the infraorder Homilopsocidea. However, its familial placement could not be determined. Therefore, this species is treated here as incertae sedis within Homilopsocidea without assigning it to any known family. This is the oldest fossil record of Psocomorpha and represents the first occurrence of the suborder from Kachin amber. The present discovery of a mid-Cretaceous homilopsocid species will contribute greatly to calibrating the time tree of Psocodea.

To elucidate the effect of Pleistocene climatic fluctuations on the historical distribution and geographical genetic structure of temperate Japanese species, we performed phylogeographical and demographic analyses using mitochondrial gene sequences obtained from the stonefly species Kamimuria tibialis, sampled from four main islands of the Japanese Archipelago (i.e. Hokkaido, Honshu, Shikoku and Kyushu) and Tsushima Island. We detected three main clades with distinct geographical distributions, including the Tsushima, Kyushu and Hokkaido-Honshu-Shikoku phylogroups. These groups were estimated to have diverged from one another 0.54-2.02 Mya, suggesting they have undergone several glacial cycles in different refugia. Our results showed that during the glacial epochs and with a fall in sea-level, gene flow was limited among Tsushima and Kyushu, and among Hokkaido and Honshu, probably because the straits between these islands are deep. The population in Kyushu and Shikoku, the southernmost islands, exhibited high genetic diversity, with two distinct haplotype lineages occurring sympatrically. These results suggest that the population division into multiple refugia and the existence of stable southern refugia have contributed to the high genetic diversity of the species in this region.

To elucidate the effect of Pleistocene climatic fluctuations on the historical distribution and geographical genetic structure of temperate Japanese species, we performed phylogeographical and demographic analyses using mitochondrial gene sequences obtained from the stonefly species Kamimuria tibialis, sampled from four main islands of the Japanese Archipelago (i.e. Hokkaido, Honshu, Shikoku and Kyushu) and Tsushima Island. We detected three main clades with distinct geographical distributions, including the Tsushima, Kyushu and Hokkaido-Honshu-Shikoku phylogroups. These groups were estimated to have diverged from one another 0.54-2.02 Mya, suggesting they have undergone several glacial cycles in different refugia. Our results showed that during the glacial epochs and with a fall in sea-level, gene flow was limited among Tsushima and Kyushu, and among Hokkaido and Honshu, probably because the straits between these islands are deep. The population in Kyushu and Shikoku, the southernmost islands, exhibited high genetic diversity, with two distinct haplotype lineages occurring sympatrically. These results suggest that the population division into multiple refugia and the existence of stable southern refugia have contributed to the high genetic diversity of the species in this region.

Zoraptera is one of the most enigmatic and least understood orders in insects. Based on a wide taxon sampling from all continents where the group is known, we applied a phylogenetic approach using multiple DNA sequences to elucidate species-level relationships. The resulting phylogeny shows that Zoraptera is divided into three major clades, and that two comprise species distributed on different continents. The monophyly of these clades is at least partly supported by shared derived morphological features. The divergence age estimation and ancestral distribution area reconstruction suggest an ancient origin and early radiation initiated in the Permian. Plate tectonics theory suggests that the present distribution of Zoraptera was mainly established by vicariance, rather than dispersal. The three major clades probably originated on the Pangaea supercontinent, or alternatively on the linked Gondwana and Laurasia supercontinents. Their ancient origin explains previously found conspicuous interspecific variation of the genital apparatus, sperm structure and mating behaviour, in striking contrast to a highly conserved general body morphology. We compiled data of available reproductive features and reconstructed the character evolution. Our analyses revealed repeated acquisitions and/or losses of a hyperelongated intromittent organ, mating hooks and tergal protuberances.

The Japanese species of the genus Strigiphilus Mjoberg, 1910 (Insecta: Phthiraptera: Philopteridae) are revised. Six species are recorded, including a new species belonging to the cursitans species-group: Strigiphilus stenocephalus new species, described from the type host Otus bakkamoena semitorques and based on specimens originally identified and reported by Uchida (1949) as Strigiphilus rostratus (Burmeister, 1838). A lectotype for Strigiphilus laticephalus (Uchida, 1949) (type host: Strix aluco yamadae) is designated and redescribed, and this louse species is synonymized under Strigiphilus cursor (Burmeister, 1838). Strigiphilus ceblebrachys (Denny, 1842), S. heterogenitalis Emerson & Elbel, 1957 and S. tuleskovi Balat, 1958 are recorded for the first time in Japan. Also, Strix uralensis and Otus sunia japonicus are recorded as new hosts for Strigiphilus heterogenitalis and S. tuleskovi respectively.

The systematic placement of an enigmatic psocid family restricted to Africa, Lesneiidae, was estimated by using a multiple gene data set. The candidates for its close relatives are now classified under two different infraorders, the family Archipsocidae of the infraorder Archipsocetae or the families Elipsocidae/Mesopsocidae of the infraorder Homilopsocidea. The maximum likelihood and Bayesian analyses of the molecular data set strongly suggested that the Lesneiidae belongs to Homilopsocidea and forms a Glade with Elipsocidae/ Mesopsocidae/Eolachesillinae (Lachesillidae). However, the relationships among these (sub)families and Lesneiidae, including the monophyly of Elipsocidae and Mesopsocidae, were ambiguous or questionable, showing the necessity of further investigations for elucidating their relationships and validating the status of these families. Two species, L. johnsoniYoshizawa & Lienhard, n. sp. and L. testudinataYoshizawa & Lienhard, n. sp. (Psocodea: Lesneiidae), were described from South Africa. There appears to be a tight association between the reproductive biology and morphological specialization of this group.

The genus Neotrogla (Psocodea: Prinoglarididae) comprises four named species from Brazil. Females of this cave‐dwelling insect are characterized by a conspicuous penis‐like intromittent organ, termed a gynosome, which is inserted into the vagina‐like male genitalia during copulation. Another evolutionarily novel structure, the spermathecal plate, enables a female to simultaneously store two freshly deposited spermatophores (consisting of sperm and possibly nutritious substances) in her sperm storage organ (spermatheca). It is unknown whether the two spermatophores are derived from two different males. To investigate the mating ecology and population genetic structures of these insects with sex‐reversed genitalia, 16 novel highly polymorphic microsatellite loci were isolated and characterized based on ～2,275 Mbp genomic sequences from an undescribed Neotrogla species. Our first screening detected 99,888 candidate loci. Similar to other hemipteroid insects studied thus far, AAT motif microsatellites were conspicuously dominant. We further screened 99 sequences, for which 50 pairs of polymerase chain reaction primers were successfully designed. Sixteen of these primers successfully amplified products of the expected size in the 11 Neotrogla sp. individuals collected from two caves. The number of alleles per loci varied from two to nine, with no significant deviation from the Hardy–Weinberg equilibrium in either population. Although the caves sampled were only approximately 1 km apart, significant genetic differentiation was detected between the two populations. In total, 13, 12, 13 and 11 loci were cross‐amplified in N. aurora, N. brasiliensis, N. curvata and N. truncata, respectively, indicating the applicability of these microsatellite loci for metapopulation genetic studies in multiple Neotrogla species.

The evolution of a female penis is an extremely rare event and is only known to have occurred in a tribe of small cave insects, Sensitibillini (Psocodea: Trogiomorpha: Prionoglarididae). The female penis, which is protrudable and inserted into the male vagina-like cavity during copulation to receive semen, is thought to have evolved independently twice in this tribe, in the Brazilian Neotrogla and the African Afrotrogla. These findings strongly suggest that there are some factors unique to Sensitibillini that have facilitated female penis evolution. Here, several hypothetical factors are presented that may have enabled the evolution of the female penis in Sensitibillini. The female-female competition for nutritious semen, the oligotrophic environment, and the twin insemination slots with switching valve are considered to be the driving factors for female penis evolution. Additionally, the following factors are considered responsible for relaxing the constraint against female penis evolution: preexistence of the female-above mating position, the elongated duct connecting the female pre-penis with the sperm storage organ, and the small male genital cavity accepting the female genital tubercle bearing the opening of this duct. Understanding the factors enabling female penis evolution may also shed light on the evolution of the male penis.

The divergence date and ancestral distributional area of the psocid subfamily Speleketorinae, which includes taxa with reversed genitalia (female penis and male vagina of Afrotrogla and Neotrogla, tribe Sensitibillini), were estimated. The most basal divergence of the subfamily (between the North American Speleketor and the tribe Sensitibillini) was estimated to have occurred according to the separation between the North American continent and Gondwana, ca. 175 Ma. The most basal divergence of Sensitibillini (between African Afrotrogla + Sensitibilla and Brazilian Neotrogla) was estimated to have occurred according to the split of West Gondwana (separation between the African and South American continents), ca. 127 Ma. The biome of the ancestral distributional area of Sensitibillini (inland of West Gondwana) is believed to be arid to semi-arid, which might strengthen the reversed sexual selection and then facilitate the origin of preadaptive features related to the evolution of a female penis. All extant Sensitibillini species inhabit carbonatic caves, but geological evidence suggested independent shifts of these genera to the carbonatic cave habitat in the Tertiary/Quaternary.

Many four‐winged insects have mechanisms that unite the forewings and hindwings in a single plane. Such an in‐flight wing coupling apparatus may improve flight performance in four‐winged insects, but its structure is variable among different insect groups. The wings of bark lice (Insecta: Psocodea: "Psocoptera") also have an in‐flight wing coupling apparatus, but to date, its morphology has not been studied in detail. In this study, we examined the wing‐coupling structure in representative species of the three suborders of bark lice (Trogiomorpha, Troctomorpha, and Psocomorpha) and inferred its origin and transformation. We conclude that the main component of the psocodean wing coupling apparatus evolved once in the common ancestor via modification of cuticular structures at the apex of the forewing CuP vein. Morphological differences in components of the coupling structures are phylogenetically informative at the intraorder level and include an autapomorphy that characterizes Troctomorpha and a synapomorphy that supports a sister relationship between Troctomorpha and Psocomorpha.

The gain of foldable wings is regarded as one of the key innovations enabling the present-day diversity of neopteran insects. Wing folding allows compact housing of the wings and shields the insect body from damage. Wing-fixing systems have evolved in some insects, probably to increase the durability of the shielding function by the wings. Bark lice (Psocodea) are known to possess a unique wing-to-wing repose coupling system, but a detailed morphological and evolutionary study of this system is lacking. In this study, we examined this repose coupling structure by SEM in 32 species including representatives of all three suborders of bark lice (Trogiomorpha, Troctomorpha and Psocomorpha). We concluded that the repose wing-coupling apparatus independently evolved twice within Psocodea. In Trogiomorpha, the apparatus is located on the subcostal vein of the forewing and is composed of elongated rib-like structures. In Troctomorpha and Psocomorpha, in contrast, the repose coupling structure is located on the radius vein of the forewing and is formed by a swollen vein. These morphological and developmental differences in the repose coupling structures also provide phylogenetic information at different systematic levels.

The elytral base sclerites (= sclerites located at the articular region between the forewing and thorax in Coleoptera) of selected taxa were examined and homologized. Although the elytral base sclerites are highly modified compared to the wing base sclerites of the other neopterans, they can be homologized by using the conservative wing flapping and folding lines as landmarks. A reduction of the first axillary sclerite was identified as a general trend of the elytral base sclerites, although the sclerite usually has a very important function to mediate flight power from the notum to the wing. This result indicates that the functional constraint against the basal sclerites is relaxed because of the lack of an ability to produce flight power by elytra. In contrast, the elytral folding system formed by the basal sclerites is well retained, which probably occurs because proper wing folding is a key for the shelter function of the elytra. The elytral base sclerites apparently contain more homoplasies than the serially homologous hindwing base sclerites of Coleoptera, which suggests that the structure is less useful for higher-level systematics. However, the faster evolutionary rate of the elytral base sclerites suggests there is potential for studying the lower-level phylogeny of Coleoptera.

We report a functional switching valve within the female genitalia of the Brazilian cave insect Neotrogla. The valve complex is composed of two plate-like sclerites, a closure element, and in-and-outflow canals. Females have a penis-like intromittent organ to coercively anchor males and obtain voluminous semen. The semen is packed in a capsule, whose formation is initiated by seminal injection. It is not only used for fertilization but also consumed by the female as nutrition. The valve complex has two slots for insemination so that Neotrogla can continue mating while the first slot is occupied. In conjunction with the female penis, this switching valve is a morphological novelty enabling females to compete for seminal gifts in their nutrient-poor cave habitats through long copulation times and multiple seminal injections. The evolution of this switching valve may have been a prerequisite for the reversal of the intromittent organ in Neotrogla.

The cave-dwelling psocid tribe Sensitibillini (Afrotrogla, Neotrogla and Sensitibilla) is of special morphological and evolutionary interest because of its possession of reversed copulatory organs: i.e. females of Afrotrogla and Neotrogla have a penis-like organ. The female penis structure is highly variable among taxa, as is the case of the male penis in animals with normal copulatory organs. Here, we present the first molecular phylogeny of Sensitibillini and analyse the evolutionary pattern of their genitalia. Afrotrogla and Neotrogla did not form a monophyletic clade, and their female penis structures are significantly different, suggesting two independent origins of the female penis within Sensitibillini. In Neotrogla, the species that has a simple female penis is embedded among species that have an elaborate penis, and detailed structures of the female penis elaborations are in exact agreement among species, suggesting a secondary simplification of the female penis. A correlated evolutionary pattern between male and female genitalia was also detected. This coevolution of genitalia may suggest that sexual conflict or cryptic 'male' choice drove the diversity of the female penis, as is the case of male penile diversity in animals with conventional genitalia.

Two new oversize troglobitic species of diplurans campodeids, Pacificampa daidarabotchi Sendra, sp. n. and Pacificampa nipponica Sendra, sp. n., found in three caves in two southern Japanese islands are described. It is the first record of cave-dwelling Diplurans from Japan and more specifically these are two Campodeinae of Pacificampa Chevrizov, 1978 formally known in continental Asia with three cave-dwelling species described in Russia and China near the north of the Korean peninsula. In P. daidarabotchi sp. n., in addition to its oversized body, the longest ever known in campodeids family, it shows as its main differential taxonomical feature the absence of lp metanotal macrosetae. P. nipponica sp. n. is much closer to continental Pacificampa species but it shows differences in the urotergal macrosetae formula. Both Japanese species have clear troglomorphic features related with their elongated body and appendages and an increase in number and complexity of the sensorial antennal equipment with unique olfactory chemoreceptors. Two biogeographical remarks are inferred: P. nipponica sp. n., has been found in two islands that were connected during the glacial age and P. daidarabotchi sp. n. lives in a single cave near another where P. nipponica sp. n. dwells which allowing to suggest a sympatric distribution; Pacificampa seems to be related with Eumesocampa, a genus from North-America, as a consequence of the Holarctic connection between Asia and America. The interests of P. daidarabotchi sp. n. and P. nipponica sp. n. as endemic species in addition to their biogeographical importance should be taken into consideration to ensure better management of the three touristic caves where they dwell and especially the protection of Mejido-do cave, the only location of the large P. daidarabotchi sp. n. near to an active quarry.

Hemipteroid insects (Paraneoptera), with over 10% of all known insect diversity, are a major component of terrestrial and aquatic ecosystems. Previous phylogenetic analyses have not consistently resolved the relationships among major hemipteroid lineages. We provide maximum likelihood-based phylogenomic analyses of a taxonomically comprehensive dataset comprising sequences of 2,395 single-copy, protein-coding genes for 193 samples of hemipteroid insects and outgroups. These analyses yield a well-supported phylogeny for hemipteroid insects. Monophyly of each of the three hemipteroid orders (Psocodea, Thysanoptera, and Hemiptera) is strongly supported, as are most relationships among suborders and families. Thysanoptera (thrips) is strongly supported as sister to Hemiptera. However, as in a recent large-scale analysis sampling all insect orders, trees from our data matrices support Psocodea (bark lice and parasitic lice) as the sister group to the holometabolous insects (those with complete metamorphosis). In contrast, four-cluster likelihood mapping of these data does not support this result. A molecular dating analysis using 23 fossil calibration points suggests hemipteroid insects began diversifying before the Carboniferous, over 365 million years ago. We also explore implications for understanding the timing of diversification, the evolution of morphological traits, and the evolution of mitochondrial genome organization. These results provide a phylogenetic framework for future studies of the group.

The phylogenetic placement of the moss bugs (Insecta: Hemiptera: Coleorrhyncha) has been highly controversial. Many apparent morphological apomorphies support the close relationship between Coleorrhyncha and Heteroptera (=true bugs). However, a recent phylogenomic study strongly supported a sister group relationship between Coleorrhyncha and Auchenorrhyncha (planthoppers, leafhoppers, treehoppers, spittlebugs, and cicadas). To test these two alternative hypotheses, we examined the fore- and hindwing base structure of the only known extant macropterous species of Coleorrhyncha using binocular and confocal laser scanning microscopes and analyzed the data selected from the wing base phylogenetically. When full morphological data including the wing base characters were analyzed, the sister group relationship between Coleorrhyncha+Heteroptera was supported, agreeing with previous consensus based on morphology. In contrast, when only wing base characters were analyzed separately, the clade Coleorrhyncha+Auchenorrhyncha was recovered, in agreement with the result from the phylogenomic study. The membranous condition of the proximal median plate in the forewing was identified as a potential synapomorphy of the latter grouping, and the absence of the tegula was excluded as a potential synapomorphy of Coleorrhyncha and Heteroptera.

Morphological and behavioral characters are frequently examined for comparative studies. Unlike morphology, a single behavioral trait is difficult to subdivide as multiple characters, even when achieved by many evolutionary changes. Therefore, when similar behavioral traits evolved independently among closely related taxa, their distinction is difficult. Almost all members of the suborder Auchenorrhyncha (Insecta: Hemiptera) possess a jumping ability that uses metathoracic muscles, and this behavioral trait has been regarded as a synapomorphy. In this study, the anatomical observations of metathoracic muscles revealed that highly elaborated jumping ability was gained independently within the suborder, although the evolution of jumping ability might have been initiated at their common ancestor. Our results provide an example of identifying a true evolutionary pathway by dissecting a behavioral character into mechanical elements.

Trichadenotecnum is one of the most diverse genera among the non-parasitic members of Psocodea (Insecta: "Psocoptera"). The genus shows a world-wide distribution (excluding the Australian Region, where only one introduced species is known) with its center of diversity in southern to eastern Asia. Several species groups had been proposed for this large genus based on morphology, but their validity and phylogenetic relationships are still unclear because of great morphological diversity in the genitalia, systematically the most relevant character. In this study, we estimated the molecular phylogeny of the Old World species of Trichadenotecnum based on extensive taxon sampling. As a result, the monophyly of morphology-based species groups was very strongly supported in most cases. However, two groups were recovered as non-monophyletic, which had been inadequately defined on the basis of plesiomorphies or convergences of genital characters. First, the monophyly of the sexpunctatum group was not supported because the medium group was found to be embedded within this group. The simpler genitalia observed in the medium group were considered to be derived from the more complicated genitalia present in the sexpunctatum group. Second, the monophyly of the majus group was not supported for two reasons: (1) It was divided into two distant clades which initially had been united on the basis of convergent similarities of the male genitalia. (2) Two species groups were revealed to be embedded within the main clade of the majus group; the initial separation of these groups had been based on reversals to the ancestral genital condition.

The diversity of feeding apparatuses in insects far exceeds that observed in any other animal group. Consequently, tracking mouthpart innovation in insects is one of the keys toward understanding their diversification. In hemipteroid insects (clade Paraneoptera or Acercaria: lice, thrips, aphids, cicadas, bugs, etc.), the transition from chewing to piercing-and-sucking mouthparts is widely regarded as the turning point that enabled hyperdiversification of the Hemiptera, the fifth largest insect order. However, the transitional process from chewing to piercing-and-sucking in the Paraneoptera was hitherto completely unknown. In this paper, we report a well preserved mid Cretaceous amber fossil of the paraneopteran insect family Archipsyllidae and describe it as Mydiognathus eviohlhoffae gen. et sp. n. This species has elongate mandibles and styliform laciniae similar to Hemiptera but retains functional chewing mouthparts. A number of morphological characters place the Archipsyllidae as the sister group of the thrips plus hemipterans, which strongly suggests that the mouthparts of M. eviohlhoffae represent a transitional condition from primitive chewing to derived piercing-and-sucking mouthparts. The clade composed of Archipsyllidae, thrips, and hemipterans is here named Pancondylognatha, a new supra-ordinal taxon. Based on newly obtained information, we also assess the monophyly of the Paraneoptera, which was called into question by recent phylogenomic analyses. A phylogenetic analysis that includes Mydiognathus strongly supports the monophyly of the Paraneoptera.

The male of Manicapsocus alettae Smithers was recorded for the first time and its genital morphology was described and illustrated. This also represented the first report of the male of the genus. The highly specialized phallosome of M. alettae supported its close relationship with Epitroctes Mockford and Nothoentomum Badonnel, as previously suggested from general and female genital characters.

The Aetalionidae is a small family belonging to the treehopper superfamily Membracoidea (Hemiptera: Cicadomorpha). Although the wing-base morphology of Cicadomorpha was examined in detail recently, the wing base of this family has not been investigated to date. We examined morphology of the wing-base structure of Aetalionidae. Using the characters selected from the wing base, we inferred the phylogenetic placement of this family and confirmed that it belongs to the superfamily Membracoidea and is likely a sister group of the Membracidae.

The genus Cryptopsocus Li, 2002 is synonymized with Trichadenotecnum Enderlein, 1909. The type species of Cryptopsocus, T. cynostigmus (Li, 2002) n. comb., is considered to be a close relative of T. marginatum New & Thornton, 1976. These species cannot be assigned to any species group previously established in Trichadenotecnum so that the marginatum species group is here proposed for them. Three new species belonging to this species group are described: T. tigrinum and T. sharkeyi from Thailand and T. sabahense from Sabah, Malaysia. The phylogenetic position of the marginatum group is discussed using morphological data.

Background: Maternal care (egg-nymph guarding behavior) has been recorded in some genera of Acanthosomatidae. However, the origin of the maternal care in the family has remained unclear due to the lack of phylogenetic hypotheses. Another reproductive mode is found in non-caring species whose females smear their eggs before leaving them. They possess pairs of complex organs on the abdominal venter called Pendergrast’s organ (PO) and spread the secretion of this organ onto each egg with their hind legs, which is supposed to provide a protective function against enemies. Some authors claim that the absence of PO may be associated with the presence of maternal care. No study, however, has tested this hypothesis of a correlated evolution between the two traits. Results: We reconstructed the molecular phylogeny of the subfamily Acanthosomatinae using five genetic markers sequenced from 44 species and one subspecies with and without maternal care. Eight additional species from the other two acanthosomatid subfamilies were included as outgroups. Our results indicated that maternal care has evolved independently at least three times within Acanthosomatinae and once in the outgroup species. Statistical tests for correlated evolution showed that the presence of maternal care is significantly correlated with the secondary loss or reduction of PO. Ancestral state reconstruction for the node of Acanthosoma denticaudum (a non-caring species in which egg smearing with developed POs occurs) and A. firmatum (a caring species with reduced POs) suggested egg smearing was still present in their most recent common ancestor and that maternal care in A. firmatum has evolved relatively recently. Conclusions: We showed that maternal care is an apomorphic trait that has arisen multiple times from the presence of PO within the subfamily Acanthosomatinae. The acquisition of maternal care is correlated with the reduction or loss of PO, which suggests an evolutionary trade-off between the two tra

Data from gene sequences and morphological structures were collected for the gull feather lice, Saemundssonia lari, Quadraceps punctatus, and Q. ornatus, parasitizing Larus crassirostris and L. schistisagus. Saemundssonia lari was collected from both gull species, and no detectable morphological and genetic differences were found between lice collected from the two different hosts. In contrast, Q. punctatus was only collected from L. crassirostris, whereas Q. ornatus was only collected from L. schistisagus. The two Quadraceps species were genetically highly divergent, and body-size differences corresponding to the gull's body size (Harrison's rule) were also detected between them. Both Quadraceps species were collected from the interbarb of the remex or rectrix, and a match in body size between the louse and the interbarb space may be important in escape from host preening defenses. In contrast, Saemundssonia is a head louse, inhabiting the finer feathers of the head and neck, which the bird cannot preen. A close match to host body size may be less important for lice in the head microhabitat. The differences in the pattern of host-specificity between Saemundssonia and Quadraceps on the two focal host species of this study were probably due to their different microhabitat preferences. More broadly, comparisons of the gene sequences of S. lari and Q. punctatus to those from other gull hosts showed that genetically almost undifferentiated populations of both species were distributed on wide range of gull species. Frequent interspecific hybridization of gulls is one possible factor that may allow these lice to maintain gene flow across multiple host species.

Zoraptera are a cryptic and enigmatic group of insects. The species diversity is lower than in almost all other groups of Hexapoda, but may be distinctly higher than presently known. Several new species were described from different regions recently. The systematic placement was discussed controversially since the group was discovered 100 years ago. Affinities with Isoptera and Psocoptera were discussed in earlier studies. A sister group relationship with Acercaria (Psocodea, Thysanoptera, Hemiptera) was proposed by W. Hennig, for the first time based on a strictly phylogenetic argumentation. More recent studies consistently suggest a placement among the “lower neopteran orders” (Polyneoptera). Close affinities to Dictyoptera were proposed and alternatively a sister group relationship with Embioptera or with Embioptera + Phasmatodea (Eukinolabia), respectively. The precise placement is still controversial and the intraordinal relationships are largely unclear. Recent transcriptome analyses tentatively suggest a clade Zoraptera + Dermaptera as sister group of all other polyneopteran orders. The oldest fossils are from Cretaceous amber. An extinct genus from this era may be the sister group of all the remaining zorapterans. The knowledge of the morphology, development and features related to the reproductive system greatly increased in recent years. The general body morphology is very uniform, whereas the genitalia differ strongly between species. This is likely due to different kinds of selection, i.e. sexual selection in the case of the genital organs. The mating pattern also differs profoundly within the order. A unique external sperm transfer occurs in Zorotypus impolitus. A species-level phylogeny and more investigations of the reproductive system should have high priority.

The largest suborder of bark lice (Insecta: Psocodea: ‘Psocoptera’) is Psocomorpha, which includes over 3600 described species. We estimated the phylogeny of this major group with family-level taxon sampling using multiple gene markers, including both nuclear and mitochondrial ribosomal RNA and protein-coding genes. Monophyly of the suborder was strongly supported, and monophyly of three of four previously recognized infraorders (Caeciliusetae, Epipsocetae, and Psocetae) was also strongly supported. In contrast, monophyly of the infraorder Homilopsocidea was not supported. Based on the phylogeny, we divided Homilopsocidea into three independent infraorders: Archipsocetae, Philotarsetae, and Homilopsocidea. Except for a few cases, previously recognized families were recovered as monophyletic. To establish a classification more congruent with the phylogeny, we synonymized the families Bryopsocidae (with Zelandopsocinae of Pseudocaeciliidae), Calopsocidae (with Pseudocaeciliidae), and Neurostigmatidae (with Epipsocidae). Monophyly of Elipsocidae, Lachesillidae, and Mesopsocidae was not supported, but the monophyly of these families could not be rejected statistically, so they are tentatively maintained as valid families. The molecular tree was compared with a morphological phylogeny estimated previously. Sources of congruence and incongruence exist and the utility of the morphological data for phylogenetic estimation is evaluated.

Phylogenetic relationships among major groups of Criocerinae were reconstructed using molecular data (mitochondrial cytochrome oxidase I and 12S rDNA, and nuclear histone 3). The monophyly of Criocerinae was consistently and robustly supported. The Lema group including Lema, Oulema and Neolema was recovered as a clade, with the latter two genera imbedded within Lema. The Lilioceris group was placed as the sister taxon of the Lema group, and the genus Crioceris was identified as the sister taxon of the Lilioceris + Lema groups. The monophyly and/or validity of Mecoprosopus Chûjô, 1951 and the subgenera Lema, Petauristes Latreille, 1829, Quasilema Monrós, 1960, Microlema Pic, 1932, and Bradyceris Chûjô, 1951 were not confirmed. The monophyly of the subgenus Lema except for the type species L. cyanea was supported by molecular and morphological data, and we termed it the cyanella clade. The present molecular phylogeny was compared with previous concepts with respect to the validity of each genus/subgenus. A revision of several genera is necessary. Based on the phylogenic result, the character evolution of the reproductive organs was analyzed. The ancestral states of this character system were parsimoniously reconstructed. Various shapes of the spermatheca were observed in the subfamily. A convoluted spermatheca evolved once, and reversals to the ancestral state took place several times independently. An elongation of a part of the intromittent organ also occurred several times independently. The length of the male and female reproductive ducts, which are in physical contact during copulation, showed a tight positive correlation even after removing phylogenetic effects. This strongly suggests coevolution between the male and female genital length.

Sex-specific elaborations are common in animals and have attracted the attention of many biologists, including Darwin [1]. It is accepted that sexual selection promotes the evolution of sex-specific elaborations. Due to the faster replenishment rate of gametes, males generally have higher potential reproductive and optimal mating rates than females. Therefore, sexual selection acts strongly on males [2], leading to the rapid evolution and diversification of male genitalia [3]. Male genitalia are sometimes used as devices for coercive holding of females as a result of sexual conflict over mating [4 and 5]. In contrast, female genitalia are usually simple. Here we report the reversal of intromittent organs in the insect genus Neotrogla (Psocodea: Prionoglarididae) from Brazilian caves. Females have a highly elaborate, penis-like structure, the gynosome, while males lack an intromittent organ. The gynosome has species-specific elaborations, such as numerous spines that fit species-specific pouches in the simple male genital chamber. During prolonged copulation (∼40–70 hr), a large and potentially nutritious ejaculate is transferred from the male via the gynosome. The correlated genital evolution in Neotrogla is probably driven by reversed sexual selection with females competing for seminal gifts. Nothing similar is known among sex-role reversed animals.

Species of the bark louse genus Trichadenotecnum Enderlein (Insecta: Psocodea) from Peninsular Malaysia and Singapore are revised with illustrations and identification keys. Twenty species are here recognised, with four new species and ten recorded for the first time from this region, together with an unnamed species represented by a single female. The previously described species T. marginatum New & Thornton is not included because its generic assignment is questionable. Females of T. cinnamonum Endang & New, T. imrum New & Thornton and T. sibolangitense Endang, Thornton & New, and the male of T. kerinciense Endang & New are described for the first time. A new species group is defined for T. krucilense Endang, Thornton & New.

Very unusual genitalia of the species Zorotypus caudelli are described. It contains the unique configuration of two different intromittent organs, one of them strongly elongated. Hyper elongated genitalia are known in different groups of insects. Males have to accommodate these unwieldy structures in the limited spaces of the abdomen and manipulate them acutely during copulation. A crucial question is how do species with elongated genitalia cope with these requirements? To investigate this, we studied key features enabling storage, insertion, and withdrawal of the elongated genitalia. The co-existence of an elongated narrow tube and a bulky spermatophore is a highly unusual and apparently paradoxical condition. However, we demonstrate that the tube is not involved in sperm transmission, whereas the large spermatophore is transferred to females by a membranous fold of the genitalia. The movement of the spermatophore is caused by haemolymph pressure, which likely also promotes the insertion of both intromittent organs. A comparison with the genital anatomy and reproductive mode in related groups suggests that the elongated tube and its accommodating pouch is a de novo structure, and that the ancestral sperm transport via spermatophore is a preadaptive condition for the acquisition of this unusual structure.

The phylogenetic relationships of bark lice and parasitic lice (Insecta: Psocodea) have been studied in a number of recent molecular phylogenetic analyses based on DNA sequences. Many of these studies have focused on the position of parasitic lice within the free-living bark lice. However, fewer such studies have examined the relationships among major groups of free-living bark lice and their implications for classification. In this study we focus on the infraorder Caeciliusetae, a large group of bark lice (˜1000 species) within the suborder Psocomorpha. Using sequences of two mitochondrial and two nuclear genes, we estimated the phylogeny for relationships among the five recognized families within the infraorder Caeciliusetae. Based on the results, the sister-group relationship and respective monophyly of Stenopsocidae and Dasydemellidae is strongly supported. Monophyly of the larger families Amphipsocidae and Caeciliusidae was not supported, although the causes of this were the placement of two distinct subfamilies (Paracaeciliinae and Calocaeciliinae). The monophyly of Asiopsocidae could not be tested because it was sampled only by one species. Based on these results and consideration of morphological characters, we propose a new classification for Caeciliusetae, recognizing six families: Amphipsocidae, Stenopsocidae, Dasydemellidae, Asiopsocidae, Paracaeciliidae and Caeciliusidae. We expect that this new classification will stabilize the higher-level taxonomy of this group and help to identify groups in need of further work among these insects.

Atrichadenotecnum multispinosus sp. n. is described from southwestern China. Psocomesites and Clematostigma from China are discussed, with five species transferred to Atrichadenotecnum and four species placed as new synonyms. Keys to adult males and females of Atrichadenotecnum species are presented.

Extreme elongation of a part of the intromittent organ, the flagellum, has occurred several times in Criocerinae (Chrysomelidae). These leaf beetles have acquired a specialized pocket to store the flagellum in the abdominal cavity, at the same time allowing a quick control of movements of this structure during copulation. We investigated the morphogenesis of the intromittent organs of species with and without a flagellum to discuss the evolutionary background of parallel evolution of novel structures. We found that the specialized pocket is formed by the invagination of an epidermal layer and a resultant rotation of the primary gonopore. Invagination itself is a well-known phenomenon in morphogenetic processes, which leads us to hypothesize that the novelty is formed by co-opting a previously acquired genetic system. A large open-space is present within the intromittent organ during the entire morphogenesis in species without a flagellum, and the invagination in the species with a flagellum grows in the corresponding area. This means that there are no physical impediments for the growth of a large pocket. In addition the sites of muscular attachments in the species with a flagellum are also different from those without it. The differentiation of muscles is completed immediately before adult emergence, which means the muscles are adjustable during the entire morphogenesis in this group. Simple modifications probably based on a co-option of previously acquired genetic systems, the potential space for adding a new element, and an adjustable factor in morphogenesis of the intromittent organ facilitate the parallel evolution of the extreme elongation.

All fossil psocid species ('Psocoptera', i. e. free living, mostly bark-dwelling members of the insect order Psocodea) known from Cretaceous amber are listed and their systematic placement is discussed. This critical evaluation of published data resulted in a list of 32 species assignable to 27 genera and 11 families. Each genus could be assigned to one of the three suborders Trogiomorpha, Troctomorpha and Psocomorpha, but five genera could not clearly be assigned to a family. No extant genus is represented in Cretaceous amber. Several systematic misallocations, a few at subordinal level, have been identified. Suborder transfers are proposed for the genera Paramesopsocus, Arcantipsocus and Libanopsyllipsocus; an infraorder transfer within Troctomorpha is proposed for Globopsacus. The extant troctomorph family Pachytroctidae is recorded for the first time from the Cretaceous. Two family-group names of Psocomorpha (Paramesopsocidae and Arcantipsocidae), based on extinct taxa, are considered as synonyms of two extant families of Troctomorpha (Electrentomidae and Amphientomidae respectively). The extant family Lachesillidae is the only family of Psocomorpha represented in Cretaceous amber. 53% of the species from Cretaceous amber belong to the Trogiomorpha, representing the basal clade of Psocoptera; 41% belong to Troctomorpha and only 6% to Psocomorpha, while the latter comprises 69% of the species known from Baltic amber (Eocene) and 82% of the extant species. The presence of the family Lachesillidae shows that the deepest divergences of the psocomorphan phylogeny date back at least to the Cretaceous, but the main radiation of Psocomorpha at generic or species level probably happened in the Cenozoic. This critical review of published information about the oldest known fossils clearly assignable to the order Psocodea (as this group is defined by taxonomists working on the extant fauna) aims to refine the data which could provide some fossil evidence for calibration of mol

Three new species of the uncommonly encountered insect order Zoraptera are described and figured from Peninsular Malaysia—Zorotypus magnicaudelli sp. n., Zorotypus cervicornis sp. n., and Zorotypus impolitus sp. n. Another species from the region, identified as Zorotypus caudelli Karny, 1927, was also collected and is reevaluated herein based on new material. A brief discussion of characters used in zorapteran systematics is provided, and a key to the species of Peninsular Malaysia provided. This is the first report for the order Zoraptera from Peninsular Malaysia.

The infraorder Cicadomorpha is a monophyletic group of the order Hemiptera, suborder Auchenorrhyncha, and is composed of three superfamilies: Cercopoidea (spittle bugs), Cicadoidea (cicadas) and Membracoidea (leafhoppers and treehoppers). Phylogenetic relationships among the superfamilies have been highly controversial morphologically and molecularly, but recent molecular phylogenetic analyses provided support for Cercopoidea + Cicadoidea. In this study, we examined morphology of the wing base structure in Cicadomorpha and tested the previous phylogenetic hypotheses using the characters selected from the wing base. As a result, a sister-group relationship between Cicadoidea and Cercopoidea was supported by three synapomorphies (presence of a projection posterior to the anterior notal wing process, presence of a novel notal process anterior to the posterior notal wing process, presence of a novel sclerite between the distal median plate and the base of anal vein). The present study provides the first unambiguous and prominent morphological support for Cicadoidea + Cercopoidea.

Unusual biogeographic patterns of closely related groups reflect events in the past, and molecular analyses can help to elucidate these events. While ample research on the origin of disjunct distributions of different organism groups in the Western Paleartic has been conducted, such studies are rare for Eastern Palearctic organisms. In this paper we present a phylogeographic analysis of the disjunct distribution pattern of the extant species of the strongly cool-adapted Epiophlebia dragonflies from Asia. We investigated sequences of the usually more conserved 18 S rDNA and 28 S rDNA genes and the more variable sequences of ITS1, ITS2 and CO2 of all three currently recognised Epiophlebia species and of a sample of other odonatan species. In all genes investigated the degrees of similarity between species of Epiophlebia are very high and resemble those otherwise found between different populations of the same species in Odonata. This indicates that substantial gene transfer between these populations occurred in the comparatively recent past. Our analyses imply a wide distribution of the ancestor of extant Epiophlebia in Southeast Asia during the last ice age, when suitable habitats were more common. During the following warming phase, its range contracted, resulting in the current disjunct distribution. Given the strong sensitivity of these species to climatic parameters, the current trend to increasing global temperatures will further reduce acceptable habitats and seriously threaten the existences of these last representatives of an ancient group of Odonata.