B chromosomes in Sternorrhyncha (Hemiptera, Insecta)

In the hemipteroid insects of the suborder Sternorrhyncha, B chromosomes are relatively common in comparison with other suborders of Hemiptera. However, the occurrence of supernumerary chromosomes is restricted, in most cases, to several genera or closely related species. At least in some species of Psylloidea with the XY sex determination system, a mitotically stable B chromosome integrated into an achiasmatic segregation system with the X, and became fixed as a Y chromosome. In some Aphidoidea with a multiple X system of sex determination, B chromosomes appear to be in fact non-functional X chromosomes. Supernumerary chromosomes thus probably play an important role in the evolution of sex determination systems in Sternorrhyncha.     

Ehrendorferiana, a new genus of Neotropical jumping plant lice (Insecta: Hemiptera: Psylloidea) associated with conifers (Cupressaceae)

Ehrendorferiana and its two included new species, E. austrocedri (the type species) and E. fitzroyae, are diagnosed. The new genus is a member of the predominantly temperate Neotropical subfamily Aphalaroidinae (Psyllidae). Based on the absence of metabasitarsal spurs it forms a likely monophyletic group with Baccharopelma, Panisopelma and Russelliana. The absence or paucity of long dorsal or marginal setae on the wing pads and caudal plate suggests a probable sister-taxon relationship with Russelliana. Apart from two species of Triozidae from New Zealand on Podocarpaceae, Ehrendorferiana is unique within Psylloidea in its host association with conifers, viz. Austrocedrus and Fitzroya (both Cupressaceae).

See also Electronic Supplement at: http://www.senckenberg.de/odes/05-12.htm     

A review of karyotype variation in jumping plant-lice (Psylloidea,Sternorrhyncha, Hemiptera) and checklist of chromosome numbers

Karyotype variation in Psylloidea (Hemiptera) was analysed. Chromosome numbers and type of chromosome sex determination of 153 species belonging to 51 genera and five out of six families (except tropical Phacopteronidae) are listed. Some important cytological characteristics, such as chromosome type, structure of karyotypes, sex determination type, pattern of male meiosis, type of chromosome rearrangements, and B chromosome occurrence, as well as the C-heterochromatin and NOR localization, are discussed. In addition, a comparison of chromosome systems between Psylloidea and other superfamilies of Sternorrhyncha (Aphidoidea, Coccoidea, and Aleyrodoidea) was undertaken.     

The function and phylogenetic implications of the tentorium in adult Neuroptera (Insecta)

Despite several recent analyses on the phylogeny of Neuroptera some questions still remain to be answered. In the present analysis we address these questions by exploring a hitherto unexplored character complex: the tentorium, the internal cuticular support structure of the insect head. We described in detail the tentoria of representatives of all extant neuropteran families and the muscles originating on the tentorium using 3D microCT images and analyzed differences in combination with a large published matrix based on larval characters. We find that the tentorium and associated musculature are a source of phylogenetically informative characters. The addition of the tentorial characters to the larval matrix causes a basad shift of the Sisyridae and clearly supports a clade of all Neuroptera except Sisyridae and Nevrorthidae. A sister group relationship of Coniopterygidae and the dilarid clade is further corroborated. A general trend toward a reduction of the dorsal tentorial arms and the development of laminatentoria is observed. In addition to the phylogenetic analysis, a correlation among the feeding habits, the development of the maxillary muscles, and the laminatentoria is demonstrated.     

First evidence of polyploidy in Psylloidea (Homoptera,Sternorrhyncha): a parthenogenetic population of <Emphasis Type="Italic">Cacopsylla myrtilli</Emphasis> (W. Wagner, 1947) from northeast Finland is apomictic and triploid

This paper reports results of the first cytogenetic study of parthenogenetic psyllids, carried out on an asexual population of the holarctic species Cacopsylla myrtilli W. Wagner from northeast Finland. Preparations of mature eggs extracted from females revealed 39 univalent chromosomes in prophase and metaphase cells. Hence, female meiosis is of apomictic type and replaced by a modified mitosis. The karyotype consists of 3n = 39 (36 + XXX). Clearly, the population is triploid, the haploid number being n = 12 + X as characteristic of the genus Cacopsylla as a whole. As typical for Psylloidea, the chromosomes are holokinetic, only slightly varying in size and without any visible markers, rendering impossible the precise identification of triplets of homologous chromosomes in the triploid complement. The distribution of bisexual and parthenogenetic populations of C. myrtilli throughout the world is briefly given, and a possible origin of the triploid parthenogenetic population is discussed.     

Preliminary study of wing interference patterns (WIPs) in some species of soft scale (Hemiptera,Sternorrhyncha, Coccoidea,Coccidae)

The fore wings of scale insect males possess reduced venation compared with other insects and the homologies of remaining veins are controversial. The hind wings are reduced to hamulohalterae. When adult males are prepared using the standard methods adopted to females and nymphs, i.e. using KOH to clear the specimens, the wings become damaged or deformed, an so these structures are not usually described or illustrated in publications. The present study used dry males belonging to seven species of the family Coccidae to check the presence of stable, structural colour patterns of the wings. The visibility of the wing interference patterns (WIP), discovered in Hymenoptera and Diptera species, is affected by the way the insects display their wings against various backgrounds with different light properties. This frequently occurring taxonomically specific pattern is caused by uneven membrane thickness and hair placement, and also is stabilized and reinforced by microstructures of the wing, such as membrane corrugations and the shape of cells. The semitransparent scale insect’s fore wings possess WIPs and they are taxonomically specific. It is very possible that WIPs will be an additional and helpful trait for the identification of species, which in case of males specimens is quite difficult, because recent coccidology is based almost entirely on the morphology of adult females.     

Achiasmate Segregation of a B Chromosome from the X Chromosome in Two Species of Psyllids (Psylloidea, Homoptera)

The segregation of a B chromosome from the X chromosome was studied in male meiosis in two psyllid species, Rhinocola aceris (L.) and Psylla foersteri (Flor.) (Psylloidea, Homoptera). The frequency of segregation was determined from cells at metaphase II. In R. aceris, the B chromosome was mitotically stable and segregated quite regularly from the X chromosome in four geographically distant populations, while it showed less regular, but preferential segregation in one population. This was attributed to the presence of B chromosome variants that differ in their ability to interact with the X chromosome in segregation. In P. foersteri, the B chromosome was mitotically unstable and segregated preferentially from the X chromosome in spermatocyte cysts, which displayed one B chromosome in every cell. Behaviour of the B chromosome and X chromosome univalents during meiotic prophase and at metaphase I in R. aceris, and during anaphase I in P. foersteri suggested that the regular segregation resulted from the incorporation of B chromosomes in achiasmate segregation mechanisms with the X chromosome in the place occupied by the Y chromosome in species with XY system. The regular segregation of a B chromosome from the X chromosome may obscure the distinction of a B chromosome and an achiasmate Y chromosome in some cases. This revised version was published online in August 2006 with corrections to the Cover Date.     

The Origin of the Achiasmatic XY Sex Chromosome System in Cacopsylla peregrina (Frst.) (Psylloidea, Homoptera)

The status of an extra univalent, if it is a B chromosome or an achiasmatic Y chromosome, associating with the X chromosome in male meiosis of Cacopsylla peregrina (Frst.) (Homoptera, Psylloidea) was analysed. One extra univalent was present in all males collected from three geographically well separated populations, it was mitotically stable, and showed precise segregation from the X chromosome. These findings led us to propose that the univalent represents in fact a Y chromosome. The behaviour of the X and Y chromosomes during meiotic prophase suggested that their regular segregation was based on an achiasmatic segregation mechanism characterised by a 'touch and go' pairing of segregating chromosomes at metaphase I. To explain the formation of the achiasmatic Y within an insect group with X0 sex chromosome system, it was suggested that the Y chromosome has evolved from a mitotically stable B chromosome that was first integrated into an achiasmatic segregation system with the X chromosome, and has later become fixed in the karyotype as a Y chromosome.     

Entomologically famous, evolutionarily unexplored: The first phylogeny of the lanternfly family Fulgoridae (Insecta: Hemiptera: Fulgoroidea)

Lanternflies (Insecta: Hemiptera: Fulgoridae) are frequently used as examples of unusual morphological evolution, with some species (such as the peanut-headed bug, Fulgora laternaria Linnaeus) also ubiquitously cited as icons of tropical insect biodiversity. Despite that entomological notoriety, the phylogeny of this charismatic planthopper family has never before been studied. Presented here are the results of a phylogenetic investigation of Fulgoridae based on DNA nucleotide sequence data from five genetic loci (18S rDNA, 28S rDNA, histone 3, wingless, and cytochrome oxidase I). The resulting topologies are used to test the higher classification of Fulgoridae, which is based primarily on characters associated with the curious head morphology of many included species. Analyses include a taxonomic sample of 69 fulgorid species representing 46 (of 110) genera, 10 (of 11) tribes, and all 8 currently recognized subfamilies. Results of this study: (1) demonstrate the need for a revised classification of Fulgoridae, particularly at the higher taxonomic levels; (2) suggest that the genus Zanna is excluded from a monophyletic Fulgoridae; (3) indicate that there have been multiple losses of the extended head process across fulgorid evolution, with what appears to be convergence (in shape and/or loss) in distantly related lineages; and (4) suggest two alternative biogeographic hypotheses to explain the distribution of extant Fulgoridae, with either an Old World origin and a single subsequent colonization of the New World, or a contemporaneous diversification of Old and New World lineages.     

The larval head of Raphidia (Raphidioptera, Insecta) and its phylogenetic significance

External and internal head structures of larval representatives of Raphidiidae are described. The obtained data were compared to characters of other neuropterid larvae and to larval characters of representatives of other endopterygote lineages. Characters potentially relevant for phylogenetic reconstruction are listed and discussed. The larvae of Raphidioptera differ distinctly from other neuropterid larvae in their morphology. They are mainly characterised by autapomorphic and plesiomorphic character states and few features indicate systematic affinities with other groups. Endopterygote groundplan features maintained in Raphidioptera are the complete tentorium, the free labrum, the full set of labral muscles, the presence of four extrinsic antennal muscles, the three-segmented labial palpi, the presence of a full set of extrinsic maxillary and labial muscles, the presence of a salivarium, and possibly the high number of stemmata. Apomorphies likely correlated with predaceous habits are the long gula, the protracted maxillae, the longitudinal arrangement of extrinsic maxillary muscles, and the elongated prepharyngeal tube. Highly unusual, potentially autapomorphic features are the presence of a dorsal ligament of the tentorium and paired gland-like structures below the pharynx. A prognathous or very slightly inclined head and slender mandibles without mola are features shared by larvae of all orders of Neuropterida. The parallel-sided head is a potential synapomorphy of Raphidioptera and Megaloptera. A fully prognathous head with anteriorly shifted posterior tentorial grooves and the presence of a parietal ridge and a distinct neck region are features shared with Corydalidae. Characters of the larval head are not sufficient for a reliable placement of Raphidioptera.     

Organization of the mitochondrial genomes of whiteflies,aphids, and psyllids (Hemiptera,Sternorrhyncha)

Background  

With some exceptions, mitochondria within the class Insecta have the same gene content, and generally, a similar gene order allowing the proposal of an ancestral gene order. The principal exceptions are several orders within the Hemipteroid assemblage including the order Thysanoptera, a sister group of the order Hemiptera. Within the Hemiptera, there are available a number of completely sequenced mitochondrial genomes that have a gene order similar to that of the proposed ancestor. None, however, are available from the suborder Sternorryncha that includes whiteflies, psyllids and aphids.     

A phylogenetic hypothesis for Asilidae based on a total evidence analysis of morphological and DNA sequence data (Insecta: Diptera: Brachycera: Asiloidea)

An hypothesis of phylogenetic relationships of Asilidae and its constituent taxa is presented, combining morphological and DNA sequence data in a total evidence framework. It is based on 77 robber fly species, 11 Asiloidea outgroup species, 211 morphological characters of the adult fly, and approximately 7300 bp of nuclear DNA from five genes (18S and 28S rDNA, AATS, CAD, and EF-1α protein-encoding DNA). The equally weighted, simultaneous parsimony analysis under dynamic homology in POY resulted in a single most parsimonious cladogram with a cost of 27,582 (iterative pass optimization; 27,703 under regular direct optimization). Six of the 12 included subfamily taxa are recovered as monophyletic. Trigonomiminae, previously always considered as monophyletic based on morphology, is shown to be non-monophyletic. Two of the three Trigonomiminae genera, Holcocephala Jaennicke, 1867 and Rhipidocephala Hermann, 1926, group unexpectedly as the sister taxon to all other Asilidae. Laphriinae, previously seen in the latter position, is the sister group of the remaining Asilidae. Five other subfamily taxa, i.e. Brachyrhopalinae, Dasypogoninae, Stenopogoninae, Tillobromatinae, and Willistonininae, are also shown to be non-monophyletic. The phylogenetic relationships among the higher-level taxa are partly at odds with findings of a recently published morphological study based on more extensive taxon sampling. The total evidence hypothesis is considered as the most informative one, but the respective topologies from the total-evidence, morphology-only, and molecular-only analyses are compared and contrasted in order to discuss the signals from morphological versus molecular data, and to analyze whether the molecular data outcompete the fewer morphological characters. A clade Apioceridae+Mydidae is corroborated as the sister taxon to Asilidae.     

Jumping plant lice (Homoptera: Psylloidea) of the temperate neotropical region. Part 1: Psyllidae (subfamilies Aphalarinae, Rhinocolinae and Aphalaroidinae)

The psyllid-fauna of temperate and subantarctic South America comprises members of three families: Calophyidae, Triozidae and Psyllidae. Three subfamilies of the Psyllidae are revised in this paper: the Aphalarinae are represented by two species in two genera, one of which develops on Aquifoliaceae; the Rhinocolinae are represented by two congeneric species on Anacardiaceae while the Aphalaroidinae contain 38 species in seven genera trophically linked to the Compositae, Euphorbiaceae, Leguminosae, Myzodendraceae, Rhamnaceae, Solanaceae and Zygophyllaceae. The family Psyllidae (= Aphalaridae syn. nov. , =Spondyliaspididae syn. nov. ) and the constituent subfamily Aphalaroidinae (= Arepuninae syn nov. , = Ciriacreminae auct. pp) are redefined. Three genera and 30 species are described as new and two new generic, two new specific synonyms, and five new combinations are proposed. Information on larvae and host plant relationships is also given. Lectotypes are designated for eight species and a type-species is fixed for one genus. Keys are provided for the identification to species.     

Comparative morphology of the male genitalia of Aphididae (Insecta,Hemiptera): part 1

The present study provides new data concerning the morphology of the male genitalia of Aphididae and unifies their nomenclature. The structure of the male genitalia of 31 species from 26 genera of Aphididae was studied with light and scanning electron microscopy. In the studied species, the genitalia of males consist of a phallus composed of the sclerotized basal part with its articulation and a membranous apical part—an aedeagus. Laterally of the phallus, there is a pair of setose parameres. The shape of the aedeagus, the shape and length of the sclerotized basal part and its articulation as well as the variability of parameres in their form and the number of setae are recognized as important systematic signs of the genitalia. These characters are considered in conjunction with the phylogenetic relationships among the studied taxa.     

Male-specific flight apparatus development in Acyrthosiphon pisum (Aphididae, Hemiptera, Insecta): comparison with female wing polyphenism

Wing polymorphisms observed in many Insecta are important topics in developmental biology and ecology; these polymorphisms are a consequence of trade-offs between flight and other abilities. The pea aphid, Acyrthosiphon pisum, possesses 2 types of wing polymorphisms: One is a genetic wing polymorphism occurring in males, and the other is an environmental wing polyphenism seen in viviparous females. Although genetic and environmental cues for the 2 wing polymorphisms have been studied, differences in their developmental regulation have not been elucidated. In particular, there is little knowledge regarding the developmental processes in male wing polymorphism. Therefore, in this study, the development of flight apparatuses and external morphologies was compared among 3 male wing morphs (winged, wingless, and intermediate). These male developmental processes were subsequently compared with those of female wing morphs. Developmental differences between the male and female polymorphisms were identified in flight muscle development and degeneration but not in wing bud development. Furthermore, the nymphal periods of wingless and intermediate males were significantly shorter than that of winged males, indicating the adaptive significance of male winglessness. Overall, this study indicates that the male and female wing polymorphisms are based on different regulatory systems for flight apparatus development, which are probably the result of different adaptations under different selection pressures.