Psyllids are plant sap-feeding insects that harbor prokaryotic endosymbionts in specialized cells within the body cavity. Four-kilobase DNA fragments containing 16S and 23S ribosomal DNA (rDNA) were amplified from the primary (P) endosymbiont of 32 species of psyllids representing three psyllid families and eight subfamilies. In addition, 0.54-kb fragments of the psyllid nuclear gene wingless were also amplified from 26 species. Phylogenetic trees derived from 16S-23S rDNA and from the host wingless gene are very similar, and tests of compatibility of the data sets show no significant conflict between host and endosymbiont phylogenies. This result is consistent with a single infection of a shared psyllid ancestor and subsequent cospeciation of the host and the endosymbiont. In addition, the phylogenies based on DNA sequences generally agreed with psyllid taxonomy based on morphology. The 3 end of the 16S rDNA of the P endosymbionts differs from that of other members of the domain Bacteria in the lack of a sequence complementary to the mRNA ribosome binding site. The rate of sequence change in the 16S-23S rDNA of the psyllid P endosymbiont was considerably higher than that of other bacteria, including other fast-evolving insect endosymbionts. The lineage consisting of the P endosymbionts of psyllids was given the designation Candidatus Carsonella (gen. nov.) with a single species, Candidatus Carsonella ruddii (sp. nov.).Insects within the families Aphididae (aphids), Psyllidae (psyllids), Aleyrodidae (whiteflies), and Pseudococcidae (mealybugs) feed predominantly or exclusively on plant phloem sap. These insects have a number of common structural properties (8) and constitute separate lineages within the suborder Sternorrhyncha (15, 54). The utilization of plant sap necessitates the penetration of tissue by flexible mouth parts (stylets) and the ingestion of the fluid. This mode of feeding is conducive to the transmission of viruses and other infectious agents, and members of these families are vectors of pathogens of agriculturally important plants (7,28,51). In addition, these insects may reach enormous populations, causing plant nutrient deprivation, leaf curling, and gall formation (8). Plant phloem sap, the diet of these insects, is rich in carbohydrates but deficient in nitrogenous compounds (21,46). Due to this deficiency, a large amount of plant sap is consumed and is excreted as honeydew. This sticky material may cover the plant and serve as a substrate for fungal growth (8).A common feature of organisms that live on diets containing an excess of one class of compounds and a deficiency in essential nutrients is the presence of prokaryotic intracellular symbionts (endosymbionts) that may provide the missing essential nutrients (6, 21, 37). Early histological studies indicated that these endosymbionts are housed within specialized cells (bacteriocytes) that form an aggregate (bacteriome) found within the body cavity (5, 10, 37). Typically, insects of a particular family or superfamily were found to have a ...

A revised classification for the world jumping plant-lice (Hemiptera: Psylloidea) is presented comprising all published family and genus-group names. The new classification consists of eight families: Aphalaridae, Carsidaridae, Calophyidae, Homotomidae, Liviidae, Phacopteronidae, Psyllidae and Triozidae. The Aphalaridae, Liviidae and Psyllidae are redefined, 20 family-group names as well as 28 genus-group names are synonymised, and one replacement name is proposed [Sureaca nomen nov., for Acaerus Loginova, 1976]. Forty two new species combinations are proposed resulting from new genus-group synonymies and a replacement name. One subfamily and three genera are considered taxa incertae sedis, and one genus a nomen dubium. Finally eight unavailable names are listed ( one family-group and seven genus-group names).

Understanding evolutionary relationships in the superfamily Psylloidea is challenging due to the lack of clear morphological synapomorphies for many groups. Some families and many of the genera, including the two largest, Cacopsylla Ossiannilsson and Trioza Foerster, have long been acknowledged as nonmonophyletic and the circumscription of natural groups has remained fluid. We present the best phylogenetic hypothesis to date for Psylloidea and provide a working systematic framework to better reflect evolutionary relationships. A shotgun sequencing approach using mixed pool DNAs for more than 400 species resulted in recovery from de novo assemblies of near-complete mitogenomes (≥10 kb) for 359 species, and partial genomes (5-10 kb) for an additional 40 species. The resulting phylogeny improves and clarifies the family classification and resolves some of the longstanding uncertainties in relationships within and between genera. A whole-nuclear-genome scan approach (yielding data from an estimated 373 nuclear genes) using the anchored hybrid enrichment method for a representative subset of taxa confirms the placement of major groupings and overall tree topology recovered with the mitochondrial data. The data generated represent a major increase in molecular resources for this superfamily. In addition, we highlight areas of remaining uncertainty that require further sampling and/or additional sources of data. The phylogeny provides new insights for both evolutionary and applied research, and a backbone constraint tree allows the placement of taxa of particular interest or concern (e.g. pest taxa) with only small fragments of sequence available (e.g. DNA barcodes).

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The number of described species on the planet is about 1.9 million, with ca. 17,000 new species described annually, mostly from the tropics. However, taxonomy is usually described as a science in crisis, lacking manpower and funding, a politically acknowledged problem known as the Taxonomic Impediment. Using data from the Fauna Europaea database and the Zoological Record, we show that contrary to general belief, developed and heavily-studied parts of the world are important reservoirs of unknown species. In Europe, new species of multicellular terrestrial and freshwater animals are being discovered and named at an unprecedented rate: since the 1950s, more than 770 new species are on average described each year from Europe, which add to the 125,000 terrestrial and freshwater multicellular species already known in this region. There is no sign of having reached a plateau that would allow for the assessment of the magnitude of European biodiversity. More remarkably, over 60% of these new species are described by non-professional taxonomists. Amateurs are recognized as an essential part of the workforce in ecology and astronomy, but the magnitude of non-professional taxonomist contributions to alpha-taxonomy has not been fully realized until now. Our results stress the importance of developing a system that better supports and guides this formidable workforce, as we seek to overcome the Taxonomic Impediment and speed up the process of describing the planetary biodiversity before it is too late.