Scale insects (Hemiptera: Coccoidea) are small herbivorous insects found on all continents except Antarctica. They are extremely invasive, and many species are serious agricultural pests. They are also emerging models for studies of the evolution of genetic systems, endosymbiosis and plant-insect interactions. ScaleNet was launched in 1995 to provide insect identifiers, pest managers, insect systematists, evolutionary biologists and ecologists efficient access to information about scale insect biological diversity. It provides comprehensive information on scale insects taken directly from the primary literature. Currently, it draws from 23 477 articles and describes the systematics and biology of 8194 valid species. For 20 years, ScaleNet ran on the same software platform. That platform is no longer viable. Here, we present a new, open-source implementation of ScaleNet. We have normalized the data model, begun the process of correcting invalid data, upgraded the user interface, and added online administrative tools. These improvements make ScaleNet easier to use and maintain and make the ScaleNet data more accurate and extendable.Database URL: http://scalenet.info
Neuropterida comprise the holometabolan orders Neuroptera (lacewings, antlions and relatives), Megaloptera (alderflies, dobsonflies) and Raphidioptera (snakeflies) as a monophyletic group sister to Coleoptera (beetles). The higher‐level phylogenetic relationships among these groups, as well as the family‐level hierarchy of Neuroptera, have to date proved difficult to reconstruct. We used morphological data and multi‐locus DNA sequence data to infer Neuropterida relationships. Nucleotide sequences were obtained for fragments of two nuclear genes (CAD, 18S rDNA) and two mitochondrial genes (COI, 16S rDNA) for 69 exemplars representing all recently recognized families of Neuropterida as well as outgroup exemplars from Coleoptera. The joint posterior probability of phylogeny and divergence times was estimated using a Bayesian relaxed‐clock inference method to establish a temporal sequence of cladogenesis for the group over geological time. Megaloptera were found to be paraphyletic with respect to the rest of Neuropterida, calling into question the validity of the ordinal status for Megaloptera as presently defined. Ordinal relationships were weakly supported, and monophyly of Megaloptera was not recovered in any total‐evidence analysis; Corydalidae were frequently recovered as sister to Raphidioptera. Only in relaxed‐clock inferences were Raphidioptera and a paraphyletic Megaloptera recovered with strong support as a monophyletic group sister to Neuroptera. A monophyletic Neuroptera diverged from a common Raphidioptera + ‘Megaloptera’ ancestor during the Late Carboniferous. Contrary to some previous hypotheses, Coniopterygidae, not Nevrorthidae, were recovered as sister to the rest of Neuroptera, with Nevrorthidae recovered with Osmylidae and Sisyridae. The monophyly of the universally recognized Myrmeleontiformia was confirmed, with an origin in the mid‐Triassic, but a monophyletic Hemerobiiformia was not recovered in any analysis. Dilaridae were not closely related to the clade comprising Mantispidae and Berothidae, and diverged earlier than proposed previously. The phylogenetic status and taxonomic composition of Polystoechotidae and Ithonidae are in need of re‐evaluation, as Oliarces Carpenter (presently Ithonidae) was placed well within the present circumscription of Polystoechotidae.
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.
Evolutionary biologists have often assumed that ecological generalism comes at the expense of less intense exploitation of specific resources and that this trade-off will promote the evolution of ecologically specialized daughter species. Using a phylogenetic comparative approach with butterflies as a model system, we test hypotheses that incorporate changes in niche breadth and location into explanations of the taxonomic diversification of insect herbivores. Specifically, we compare the oscillation hypothesis, where speciation is driven by host-plant generalists giving rise to specialist daughter species, to the musical chairs hypothesis, where speciation is driven by host-plant switching, without changes in niche breadth. Contrary to the predictions of the oscillation hypothesis, we recover a negative relationship between host-plant breadth and diversification rate and find that changes in host breadth are seldom coupled to speciation events. By contrast, we present evidence for a positive relationship between rates of host switching and butterfly diversification, consonant with the musical chairs hypothesis. These results suggest that the costs of trophic generalism in plant-feeding insects may have been overvalued and that transitions from generalists to ecological specialists may not be an important driver of speciation in general.
We provide the first highly sampled phylogeny estimate for the dipteran family Chironomidae using molecular data from fragments of two ribosomal genes (18S and 28S), one nuclear protein‐coding gene (CAD), and one mitochondrial protein‐coding gene (COI), analysed using mixed‐model Bayesian and maximum likelihood inference methods. The most recently described subfamilies Chilenomyiinae and Usambaromyiinae proved elusive, and are unsampled. We confirm monophyly of all sampled subfamilies except Prodiamesinae, which contains Propsilocerus Kieffer, previously in Orthocladiinae. The semifamily Chironomoinae is confirmed only if Telmatogetoninae is included, which is closer to Brundin's original suggestion. Buchonomyiinae is excluded from Chironomoinae: it is a sister group to all remaining Chironomidae, conforming more to Murray and Ashe's argumentation. Semifamily Tanypodoinae is a grade and unsupported as monophyletic: the austral Aphroteniinae alone is sister to all Chironomidae (less Buchonomyiinae). Podonominae is weakly supported as the next sister group, in contrast to some estimates that place this subfamily as sister group to Tanypodinae alone. In Diamesinae, the southern African Harrisonini is confirmed as a member, but embedded within austral tribe Heptagiini, which is confirmed as sister to the undersampled Diamesini. Tribe Pentaneurini and ‘non‐Pentaneurini’ taxa are reciprocally monophyletic in Tanypodinae. Recent molecular findings concerning Podonominae are substantiated, with a monophyletic tribe Podonomini, Boreochlini forming a grade and Lasiodiamesa Kieffer placed as sister to all other Podonominae, but with uncertainty. In Orthocladiinae, a postulated two‐tribe system of Orthocladiini and Metriocnemini can be supported after exclusion of a Corynoneura group and a Brillia group, which is revealed as sister to Stictocladius Edwards. The marine Clunio Haliday and Thalassosmittia Strenzke & Remmert (given high rank in the past) are clearly embedded deep in Orthocladiinae. The finding of Shangomyia Sæther & Wang + Xyiaomyia Sæther & Wang as sister group to all other Chironominae justifies high rank, as their authors suggested. Pseudochironomini (untested by sampling shortfall) is sister to a monophyletic Tanytarsini (with a weakly supported inclusion of the enigmatic Nandeva Wiedenbrug, Reiss & Fittkau). The tribe Chironomini can be supported only by excluding Shangomyia + Xyiaomyia, and a postulated monophyletic clade comprising several taxa such as Microtendipes Kieffer, with six‐segmented larval antennae and alternate Lauterborn organs, that is sister group to Pseudochironomini + Tanytarsini. The tempo of diversification of the family, deduced by divergence time analysis (beast), shows Permian origination with subfamily stem‐group origination from the mid–late Triassic to the early Cretaceous. Crown‐group origination ranged from Podonominae on a short stem originating in the mid Jurassic to long‐stemmed Aphroteninae from the late Cretaceous. Node dates allow inference of some vicariance via Gondwanan...
The mealybugs (Hemiptera: Coccoidea: Pseudococcidae) are a speciose and ubiquitous group of sap‐sucking plant parasites, many of which are very serious agricultural pests. There has been much work on the alpha‐level taxonomy, amounting to the description of more than 2000 species, but suprageneric relationships remain poorly known. Downie & Gullan reviewed proposed schemes for a mealybug subfamily‐level classification and used DNA sequence data from three nuclear genes to infer the mealybug phylogeny. They recognized three subfamilies: the Rhizoecinae, the Phenacoccinae, and the Pseudococcinae; and within the Pseudococcinae, recognized the tribes Pseudococcini, Trabutinini, and Planococcini. Excepting the Trabutinini, none of these groupings was well‐supported. We improve our estimation of the mealybug phylogeny by: (i) increasing the taxon sampling by 50%; (ii) adding a morphological character matrix; and (iii) performing mixed model Bayesian and maximum likelihood inference procedures. We recover two primary clades within the Pseudococcidae, to which we apply the subfamily names Phenacoccinae and Pseudococcinae. Within the Phenacoccinae, we recover support for the monophyly of the hypogaeic mealybugs (Rhizoecini), and within the Pseudococcinae, we find support for the tribes Pseudococcini, Trabutinini, and Planococcini. Our results suggest a clear sequence of (i) β‐Proteobacteria primary endosymbionts infecting the mycetome of the most recent common ancestor of the Pseudococcinae, followed by (ii) γ‐Proteobacteria secondary endosymbionts infecting the primary β‐Proteobacteria endosymbionts. For each subfamily, we provide a morphological diagnosis and a comprehensive list of included genera. We resurrect the genus Ceroputo Šulc, currently under synonymy with the genus Puto Signoret (Putoidae), and place it in the mealybug subfamily Phenacoccinae. Greenoripersia kaiseri Bodenheimer is transferred from the Pseudococcidae to the Eriococcidae.
Abstract. Despite the widespread and common use of DNA-sequence data to estimate phylogenies, support or contest classifications, and identify species using barcodes, they are not commonly used as the primary or sole source of data for describing species. This is possibly due to actual or perceived pressure from peers to include morphology as the primary source of data for species descriptions. We find no compelling evidence to exclude DNA-only descriptions, or to insist that morphology always be included in a species description. It is not the data type per se that is important, but the science behind the taxonomic conclusions. Using alternative kinds of data for descriptions should not cause problems for taxonomy if links are kept with type specimens.
Mealybugs (Coccoidea: Pseudococcidae) are sap-sucking plant parasites that harbor bacterial endosymbionts within specialized organs. Previous studies have identified two subfamilies, Pseudococcinae and Phenacoccinae, within mealybugs and determined the primary endosymbionts (P-endosymbionts) of the Pseudococcinae to be Betaproteobacteria ("Candidatus Tremblaya princeps") containing Gammaproteobacteria secondary symbionts. Here, the P-endosymbionts of phenacoccine mealybugs are characterized based on 16S rRNA from the bacteria of 20 species of phenacoccine mealybugs and four outgroup Puto species (Coccoidea: Putoidae) and aligned to more than 100 published 16S rRNA sequences from symbiotic and free-living bacteria. Phylogenetic analyses recovered three separate lineages of bacteria from the Phenacoccinae, and these are considered to be the P-endosymbionts of their respective mealybug hosts, with those from (i) the mealybug genus Rastrococcus belonging to the Bacteroidetes, (ii) the subterranean mealybugs, tribe Rhizoecini, also within Bacteroidetes, in a clade sister to cockroach endosymbionts (Blattabacterium), and (iii) the remaining Phenacoccinae within the Betaproteobacteria, forming a well-supported sister group to "Candidatus Tremblaya princeps." Names are proposed for two strongly supported lineages: "Candidatus Brownia rhizoecola" for P-endosymbionts of Rhizoecini and "Candidatus Tremblaya phenacola" for P-endosymbionts of Phenacoccinae excluding Rastrococcus and Rhizoecini. Rates of nucleotide substitution among lineages of Tremblaya were inferred to be significantly faster than those of free-living Betaproteobacteria. Analyses also recovered a clade of Gammaproteobacteria, sister to the P-endosymbiont lineage of aphids ("Candidatus Buchnera aphidicola"), containing the endosymbionts of Putoidae, the secondary endosymbionts of pseudococcine mealybugs, and the endosymbionts of several other insect groups.Many insect species possess specialized cells that contain obligate mutualist bacteria, primary endosymbionts (P-endosymbionts). P-endosymbionts usually show an evolutionary history of codiversification with an insect host and are thought to be essential to the survival of host species (4, 27). Insects with P-endosymbionts are phylogenetically and ecologically heterogeneous but commonly have a nutritionally unbalanced diet. Endosymbiotic bacteria can provide nutritional supplements to their host, permitting exploitation of otherwise inadequate food sources. For example, tsetse fly P-endosymbionts (Wigglesworthia glossinidia) synthesize B vitamins that are lacking in vertebrate blood (1,3,32,33). Several additional examples of blood-feeding insect groups that depend upon P-endosymbionts are known, but the greatest diversity of P-endosymbionts is found in insects that feed on plant sap, a food source poor in amino acids. More than 80% of the approximately 63,000 described insect species with P-endosymbionts feed on plant sap and depend on P-endosymbionts to enrich their diet with amino acids (4,34,35,45,46)...
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