Disparity of metatibial and metatarsal cuticular and sensory structures in Cixiidae (Hemiptera: Fulgoromorpha) with a metatibiotarsal diagnosis for the tribes.

A review of the cuticular and sensory metatibial and metatarsal structures in cixiid planthoppers (Hemiptera: Fulgoromorpha) is proposed, depicting both their strong disparity and the great diversity of the patterns observed. Terminology and definitions for these structures are provided. The so-called lateral teeth of the metatibia in fact are particular styloconic sensory structures, called spiniform sensilla in Cixiidae. The apical metatibiotarsal teeth are non-sensory cuticular expansions, often bearing one or several chaetic sensilla ventrally, generally distributed in an internal and an external group of three teeth each, in some instances separated by a diastema; innermost and outermost teeth are generally larger. On the first tarsomere seven to eight teeth generally occur in one row, although two rows are observed in Brixidiini. A strong diversity of conformations and patterns is observed in the second metatarsomere. A specific subdorsal sensillum, of platellar type, may be present in the first metatarsomere teeth for a few taxa. It is generally present in the second metatarsomere, either as a narrow-based acutellar sensillum or as a broad-based platellar sensillum according to the taxon. Scanning electron microscope (SEM) analyses of 54 species of cixiids from all described tribes of the family, supplemented by data from the literature, are used to provide a metatibiotarsal diagnosis for each of the tribes of Cixiidae. In the state of our knowledge of the sufficiently precise observations of metatibiotarsal structures in the Cixiidae which are available, and of the phylogeny of the group as a frame of reference for their interpretations, we note that the observed patterns are probably the result of multiple and independent convergences and evolutionary regressions. These occurred at all levels of cixiid classification. Although these patterns can be useful in the identification of taxa at a low taxonomic level, they would be less useful for phylogenetic approaches.

Functional Morphology and Ultrastructure of the Peripheral Antennal Sensillar System of Graphosoma italicum (Müller, 1766) (Insecta: Hemiptera: Pentatomidae).

The antennae of the shield bug Graphosoma italicum (Müller, 1766) were examined through scanning and transmission electron microscopy to reveal their general morphology, as well as the antennal sensilla's distribution, size, and ultrastructure of their dendrites and function. The antennae comprise five antennomeres (one scape, two pedicels, and two flagellomeres). Different lengths of chaetic mechanosensilla (Ch1-Ch4) exist on all antennomeres, and several highly sensitive campaniform sensilla are embedded in the exoskeleton and measure cuticular strain. One pair of peg sensilla, the typical proprioceptive, is only on the proximal edge of the first pedicel and directed to the distal edge of the scapus. The antennal flagellum possesses two subtypes of trichoid and basiconic sensilla, each with one type of coeloconic olfactory sensilla. The distinctive characteristics of G. italicum are also apparent in two subtypes of coeloconic sensilla embedded in different cavities on both antennomeres of the flagellum, probably with a thermo-hypersensitive function. All studied morphological types of the sensilla and their function were supported by ultrastructural elements. The long and thin trichoid sensilla type 2 (TrS2) with an olfactive function was the most abundant sensilla localized on both flagellomeres. The peripheral antennal sensilla system consists of six main types of sensilla divided into twelve subtypes.

Facultatively intrabacterial localization of a planthopper endosymbiont as an adaptation to its vertical transmission.

Transovarial transmission is the most reliable way of passing on essential nutrient-providing endosymbionts from mothers to offspring. However, not all endosymbiotic microbes follow the complex path through the female host tissues to oocytes on their own. Here, we demonstrate an unusual transmission strategy adopted by one of the endosymbionts of the planthopper Trypetimorpha occidentalis (Hemiptera: Tropiduchidae) from Bulgaria. In this species, an Acetobacteraceae endosymbiont is transmitted transovarially within deep invaginations of cellular membranes of an ancient endosymbiont Sulcia-strikingly resembling recently described plant virus transmission. However, in males, Acetobacteraceae colonizes the same bacteriocytes as Sulcia but remains unenveloped. Then, the unusual endobacterial localization of Acetobacteraceae observed in females appears to be a unique adaptation to maternal transmission. Further, the symbiont's genomic features, including encoding essential amino acid biosynthetic pathways and its similarity to a recently described psyllid symbiont, suggest a unique combination of the ability to horizontally transmit among species and confer nutritional benefits. The close association with Acetobacteraceae symbiont correlates with the so-far-unreported level of genomic erosion of ancient nutritional symbionts of this planthopper. In Sulcia, this is reflected in substantial changes in genomic organization, reported for the first time in the symbiont renowned for its genomic stability. In Vidania, substantial gene loss resulted in one of the smallest genomes known, at 108.6 kb. Thus, the symbionts of T. occidentalis display a combination of unusual adaptations and genomic features that expand our understanding of how insect-microbe symbioses may transmit and evolve.IMPORTANCEReliable transmission across host generations is a major challenge for bacteria that associate with insects, and independently established symbionts have addressed this challenge in different ways. The facultatively endobacterial localization of Acetobacteraceae symbiont, enveloped by cells of ancient nutritional endosymbiont Sulcia in females but not males of the planthopper Trypetimorpha occidentalis, appears to be a unique adaptation to maternal transmission. Acetobacteraceae's genomic features indicate its unusual evolutionary history, and the genomic erosion experienced by ancient nutritional symbionts demonstrates the apparent consequences of such close association. Combined, this multi-partite symbiosis expands our understanding of the diversity of strategies that insect symbioses form and some of their evolutionary consequences.

Genome Comparison Reveals Inversions and Alternative Evolutionary History of Nutritional Endosymbionts in Planthoppers (Hemiptera: Fulgoromorpha).

The evolutionary success of sap-feeding hemipteran insects in the suborder Auchenorrhyncha was enabled by nutritional contributions from their heritable endosymbiotic bacteria. However, the symbiont diversity, functions, and evolutionary origins in this large insect group have not been broadly characterized using genomic tools. In particular, the origins and relationships among ancient betaproteobacterial symbionts Vidania (in Fulgoromorpha) and Nasuia/Zinderia (in Cicadomorpha) are uncertain. Here, we characterized the genomes of Vidania and Sulcia from three Pyrops planthoppers (family Fulgoridae) to understand their metabolic functions and evolutionary histories. We find that, like in previously characterized planthoppers, these symbionts share nutritional responsibilities, with Vidania providing seven out of ten essential amino acids. Sulcia lineages across the Auchenorrhyncha have a highly conserved genome but with multiple independent rearrangements occurring in an early ancestor of Cicadomorpha or Fulgoromorpha and in a few succeeding lineages. Genomic synteny was also observed within each of the betaproteobacterial symbiont genera Nasuia, Zinderia, and Vidania, but not across them, which challenges the expectation of a shared ancestry for these symbionts. The further comparison of other biological traits strongly suggests an independent origin of Vidania early in the planthopper evolution and possibly of Nasuia and Zinderia in their respective host lineages. This hypothesis further links the potential acquisition of novel nutritional endosymbiont lineages with the emergence of auchenorrhynchan superfamilies.

Variable organization of symbiont-containing tissue across planthoppers hosting different heritable endosymbionts.

Sap-feeding hemipteran insects live in associations with diverse heritable symbiotic microorganisms (bacteria and fungi) that provide essential nutrients deficient in their hosts' diets. These symbionts typically reside in highly specialized organs called bacteriomes (with bacterial symbionts) or mycetomes (with fungal symbionts). The organization of these organs varies between insect clades that are ancestrally associated with different microbes. As these symbioses evolve and additional microorganisms complement or replace the ancient associates, the organization of the symbiont-containing tissue becomes even more variable. Planthoppers (Hemiptera: Fulgoromorpha) are ancestrally associated with bacterial symbionts Sulcia and Vidania, but in many of the planthopper lineages, these symbionts are now accompanied or have been replaced by other heritable bacteria (e.g., Sodalis, Arsenophonus, Purcelliella) or fungi. We know the identity of many of these microbes, but the symbiont distribution within the host tissues and the bacteriome organization have not been systematically studied using modern microscopy techniques. Here, we combine light, fluorescence, and transmission electron microscopy with phylogenomic data to compare symbiont tissue distributions and the bacteriome organization across planthoppers representing 15 families. We identify and describe seven primary types of symbiont localization and seven types of the organization of the bacteriome. We show that Sulcia and Vidania, when present, usually occupy distinct bacteriomes distributed within the body cavity. The more recently acquired gammaproteobacterial and fungal symbionts generally occupy separate groups of cells organized into distinct bacteriomes or mycetomes, distinct from those with Sulcia and Vidania. They can also be localized in the cytoplasm of fat body cells. Alphaproteobacterial symbionts colonize a wider range of host body habitats: Asaia-like symbionts often colonize the host gut lumen, whereas Wolbachia and Rickettsia are usually scattered across insect tissues and cell types, including cells containing other symbionts, bacteriome sheath, fat body cells, gut epithelium, as well as hemolymph. However, there are exceptions, including Gammaproteobacteria that share bacteriome with Vidania, or Alphaproteobacteria that colonize Sulcia cells. We discuss how planthopper symbiont localization correlates with their acquisition and replacement patterns and the symbionts' likely functions. We also discuss the evolutionary consequences, constraints, and significance of these findings.

Comparative Analysis of the Complete Mitochondrial Genomes of Five Species of Ricaniidae (Hemiptera: Fulgoromorpha) and Phylogenetic Implications.

Ricaniidae is a relatively small planthopper family with about 69 genera and 442 species worldwide. Members of this family occur throughout the warm temperate and tropical regions. Some species cause devastating damage to major agricultural and economic plants. However, the relationship between Ricaniidae and other families of Fulgoroidea needs to be further explored. The morphological definitions of the two biggest genera, Pochazia Amyot & Serville, 1843 and Ricania Germar, 1818 (the type genus of Ricaniidae) remain controversial. In this study, mitogenomes of five representatives in these two genera were decoded using the next-generation sequence method and genome assembly. Results showed that their complete mitogenomes are circular DNA molecules with 15,457 to 16,411 bp. All protein-coding genes (PCGs) begin with the start codon ATN, GTG or TTG and end with TAA, TAG, an incomplete stop codon single T or an incomplete stop codon single A. A lost DHU arm was discovered in the trnS gene of the five mitogenomes and the trnV gene within Pochaziaconfusa, Pochazia guttifera and Ricania simulans. The remnant tRNAs folded into clover-leaf structures. The sliding window, genetic distance, and Ka/Ks analyses indicated that the cox1 gene is the slowest evolving and is relatively conserved. The phylogenetic tree topologies support (Delphacidae + (((Issidae + (Lophopidae + Caliscelidae)) + (Flatidae + Ricaniidae)) + (Achilidae + (Dictyopharidae + Fulgoridae)))) as the best topology, as recognized by both PhyloBayes, RAxML and MrBayes based on four data sets (PCG, PCGRNA, PCG12, PCG12RNA). The monophyly of Ricaniidae and the sister group status of two families Flatidae and Ricaniidae are supported, but all analyses failed to support the monophyly of Pochazia and Ricania. The diagnoses between these two genera cannot be resolved until more evidence is acquired.

First records of Pochazia shantungensis (Chou & Lu, 1977) (Hemiptera: Fulgoromorpha: Ricaniidae) in Italy.

The invasive ricaniid species Pochazia shantungensis (Chou & Lu, 1977), an Asiatic pest in China and Korea, is reported for the first time in Italy. This is the fourth confirmed record from Europe after Turkey, France, and Germany. The list of the host plants recorded in Europe is given. Illustrations of male and female genital structures (external and internal) are also presented.

Alternative Transmission Patterns in Independently Acquired Nutritional Cosymbionts of Dictyopharidae Planthoppers.

Sap-sucking hemipterans host specialized, heritable microorganisms that supplement their diet with essential nutrients. These microbes show unusual features that provide a unique perspective on the coevolution of host-symbiont systems but are still poorly understood. Here, we combine microscopy with high-throughput sequencing to revisit 80-year-old reports on the diversity of symbiont transmission modes in a broadly distributed planthopper family, Dictyopharidae. We show that in seven species examined, the ancestral nutritional symbionts Sulcia and Vidania producing essential amino acids are complemented by co-primary symbionts, either Arsenophonus or Sodalis, acquired several times independently by different host lineages and contributing to the biosynthesis of B vitamins. These symbionts reside within separate bacteriomes within the abdominal cavity, although in females Vidania also occupies bacteriocytes in the rectal organ. Notably, the symbionts are transovarially transmitted from mothers to offspring in two alternative ways. In most examined species, all nutritional symbionts simultaneously infect the posterior end of the full-grown oocytes and next gather in their perivitelline space. In contrast, in other species, Sodalis colonizes the cytoplasm of the anterior pole of young oocytes, forming a cluster separate from the "symbiont ball" formed by late-invading Sulcia and Vidania. Our results show how newly arriving microbes may utilize different strategies to establish long-term heritable symbiosis. IMPORTANCE Sup-sucking hemipterans host ancient heritable microorganisms that supplement their unbalanced diet with essential nutrients and have repeatedly been complemented or replaced by other microorganisms. These symbionts need to be reliably transmitted to subsequent generations through the reproductive system, and often they end up using the same route as the most ancient ones. We show for the first time that in a single family of planthoppers, the complementing symbionts that have established infections independently utilize different transmission strategies, one of them novel, with the transmission of different microbes separated spatially and temporally. These data show how newly arriving microbes may utilize different strategies to establish long-term heritable symbioses.

Hagneia kallea gen. and sp. nov. (Hemiptera: Fulgoromorpha: Ricaniidae) from North Vietnam.

A new monotypic genus of ricaniid planthoppers (Hemiptera: Fulgoromorpha: Ricaniidae), Hagneia gen. nov., is described for Hagneia kallea sp. nov. (type species). Habitus, male and female external and internal genital structures of the new species are illustrated.

Kelyflata gen. nov. adds to Selizini flatids in Madagascar (Hemiptera: Fulgoromorpha: Flatidae).

A new genus of flatid planthoppers (Hemiptera: Fulgoromorpha: Flatidae), Kelyflata gen. nov., is described for Kelyflata capensis sp. nov. (type species) and Kelyflata ilakakae sp. nov. from the island of Madagascar. Habitus, male external and internal genital structures of the new species are illustrated. Kelyflata is probably endemic to Madagascar where it is known to date, only from a southern part of the island.

Socoflata gen. nov., described for two new planthopper species from the mountains in Socotra island (Hemiptera: Fulgoromorpha: Flatidae).

A new genus of flatid planthoppers (Hemiptera: Fulgoromorpha: Flatidae) is described from the island of Socotra (Yemen): Socoflata gen. nov., for S. aurolineata sp. nov. and S. histrionica sp. nov. (type species). Habitus, male and female external and internal genital structures of the new species are illustrated and diagnosed. Both Socoflata species are abundant and syntopic in the evergreen montane woodland and dwarf shrubland at high elevations in the Hagher mountains in central Socotra and are likely endemics of this area.

Symbiotic cornucopia of the monophagous planthopper Ommatidiotus dissimilis (Fallén, 1806) (Hemiptera: Fulgoromorpha: Caliscelidae).

In contrast to Cicadomorpha, in which numerous symbiotic bacteria have been identified and characterized, the symbionts of fulgoromorphans are poorly known. Here, we present the results of histological, ultrastructural, and molecular analyses of the symbiotic system of the planthopper Ommatidiotus dissimilis. Amplification, cloning, and sequencing of bacterial 16S RNA genes have revealed that O. dissimilis is host to five types of bacteria. Apart from bacteria Sulcia and Vidania, which are regarded as ancestral symbionts of Fulgoromorpha, three additional types of bacteria belonging to the genera Sodalis, Wolbachia, and Rickettsia have been detected. Histological and ultrastructural investigations have shown that bacteria Sulcia, Vidania, and Sodalis house separate bacteriocytes, whereas bacteria Wolbachia and Rickettsia are dispersed within various insect tissue. Additionally, bacteria belonging to the genus Vidania occupy the bacteriome localized in the lumen of the hindgut. Both molecular and microscopic analyses have revealed that all the symbionts are transovarially transmitted between generations.

Three new species of the genus Ricanula Melichar, 1898 (Hemiptera: Fulgoromorpha: Ricaniidae) from China.

Three new species of the genus Ricanula Melichar, 1898: R. unica sp. nov., R. fujianensis sp. nov. and R. hainanensis sp. nov. are described from south China. An identification key to Ricanula species in Chinese fauna is provided. Photographs of the adults and illustrations of genital structures of the new species are also given.

A new lophopid genus as another piece in the biogeographical history puzzle of the family in the Sunda Shelf (Hemiptera: Fulgoromorpha: Lophopidae).

A new Lophopidae genus Binaluana gen. nov. and species B. emarginata sp. nov. from Palawan are described. Characters are given in order to distinguish this new genus from Bisma and Zeleja that share general figure with it. The morphological characters are coded for the genus and a new phylogenetic analysis using parsimony is performed. The Lophopidae remain monophyletic and Binaluana is placed as sister group of the genus Bisma. (Zeleja (Binaluana+Bisma)) is monophyletic and emerges at the base of the Zeleja+ group. The place of Binaluana within the Lophopidae is discussed along with its historical biogeographic origin.

A new Asian genus of the tribe Elicini (Hemiptera: Fulgoromorpha: Tropiduchidae) with two new species from Vietnam.

A new genus Connelicita gen. nov. with 2 new species (C. backyensis sp. nov. and C. haiphongensis sp. nov.) of Tropiduchidae Elicini from Vietnam are described and illustrated. The Chinese species C. lungchowensis (Chou et Lu, 1977) comb. nov. is transferred into this new genus from the genus Sassula (Nogodinidae). A key to species of the new genus distributed in North Vietnam and China (Guangxi) is provided.

A new species of the genus Euricania Melichar, 1898 (Hemiptera: Fulgoromorpha: Ricaniidae) from China, with a world checklist and a key to all species recorded for the country.

One new species of the planthopper genus Euricania Melichar, 1898 - E. paraclara sp. nov. is described from Guizhou (southwest China). A checklist of all Euricania species and an identification key to the species of the Chinese fauna are provided. Photographs of the adult and illustrations of male and female genitalia of the new species are also given.

Why so scarce? Dictyopharidae from Madagascar (Hemiptera: Fulgoromorpha).

A new genus and species of Dictyopharidae from Madagascar-Tupala occulta gen. et sp. nov. is described and illustrated. It is the third known dictyopharid and the second representing tribe Dictyopharini. Two other taxa with taxonomic problems ascribed to Dictyopharidae are discussed. The question of paucity of Dictyopharidae of Madagascar is raised and several possible explanations are presented.

Egg morphology, laying behavior and record of the host plants of Ricania speculum (Walker, 1851), a new alien species for Europe (Hemiptera: Ricaniidae).

The exotic planthopper, Ricania speculum (Ricaniidae) was recently detected in Liguria, in northern Italy, and recorded as a first alert for Europe. The first morphological description of eggs and laying behavior are given. Eggs are inserted into the woody tissue of a wide range of different host plants in such a unique manner among native and alien planthoppers of Italy that it can be used to describe the prevalence and diffusion of the species in new environments, though in the absence of juveniles and/or adults. In addition, the paper lists the host plants utilized for egg laying and describes the eggs.

Tip of the clade on the top of the World--the first fossil Lophopidae (Hemiptera: Fulgoromorpha) from the Palaeocene of Tibet.

Lophopidae is a family of planthoppers (Hemiptera: Fulgoromorpha) present today in tropical and subtropical zones of the Old World. The most recent taxonomic studies and phylogeny of these insects do not include the extinct representatives. Therefore, each new discovery of a fossil lophopid is of high interest, giving new insights to their evolutionary history and enabling to test the proposed relationships. The recent findings of extinct Lophopidae in Europe, in various Palaeogene deposits, put in doubts their proposed evolutionary and biogeographic scenario. The new fossil from the Palaeocene of Northern Tibet is related to one of the Lophopidae clades, Apia(+) group, believed to be the most advanced one, and recently distributed in the recent Sundaland-New Guinea-Queensland area. A new genus and species Gesaris gnapo gen. et sp. n. provide information on early lophopids diversity and relationships and demonstrates the necessity for a revision of the existing hypotheses for the initial diversification and distributional pattern of the Lophopidae.

From micropterism to hyperpterism: recognition strategy and standardized homology-driven terminology of the forewing venation patterns in planthoppers (Hemiptera: Fulgoromorpha).

Following recent advances in the morphological interpretations of the tegmen basal cell margins in the Paraneoptera, a standardized and homology-driven groundplan terminology for tegmina types, structures and vein patterns in Hemiptera Fulgoromorpha, including fossils, is proposed. Each term is listed with a morphological definition, compared and linked to the main systems of planthopper forewing description that have been reviewed. The importance of a standardized and homology-driven terminology is stressed to enhance the quality of data in taxonomic descriptions and to strengthen phylogenetic morphological analysis results. When the interpretation of the origin of vein branches is render difficult, a three-step strategy for pattern recognition of the vein is proposed based on two principles: (1) vein forks are more informative than topology of the vein branches: a search for homologous areas, the nodal cells in particular, must first guide the recognition rather the number of branches of a vein, and (2) minimum of ad hoc evolutionary events should be invoked in the understanding of a modified vein pattern. Examples of some conflicting interpretations of venation patterns in planthoppers are discussed within different families for both extant and extinct taxa. For the first time, the concept of brachypterism is defined in a non-relative way independently from other structures, and the new one of hyperpterism is proposed; a reporting system is proposed for each of them.