Higher level phylogeny and the first divergence time estimation of Heteroptera (Insecta: Hemiptera) based on multiple genes

Heteroptera, or true bugs, are the largest, morphologically diverse and economically important group of insects with incomplete metamorphosis. However, the phylogenetic relationships within Heteroptera are still in dispute and most of the previous studies were based on morphological characters or with single gene (partial or whole 18S rDNA). Besides, so far, divergence time estimates for Heteroptera totally rely on the fossil record, while no studies have been performed on molecular divergence rates. Here, for the first time, we used maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI) with multiple genes (18S rDNA, 28S rDNA, 16S rDNA and COI) to estimate phylogenetic relationships among the infraorders, and meanwhile, the Penalized Likelihood (r8s) and Bayesian (BEAST) molecular dating methods were employed to estimate divergence time of higher taxa of this suborder. Major results of the present study included: Nepomorpha was placed as the most basal clade in all six trees (MP trees, ML trees and Bayesian trees of nuclear gene data and four-gene combined data, respectively) with full support values. The sister-group relationship of Cimicomorpha and Pentatomomorpha was also strongly supported. Nepomorpha originated in early Triassic and the other six infraorders originated in a very short period of time in middle Triassic. Cimicomorpha and Pentatomomorpha underwent a radiation at family level in Cretaceous, paralleling the proliferation of the flowering plants. Our results indicated that the higher-group radiations within hemimetabolous Heteroptera were simultaneously with those of holometabolous Coleoptera and Diptera which took place in the Triassic. While the aquatic habitat was colonized by Nepomorpha already in the Triassic, the Gerromorpha independently adapted to the semi-aquatic habitat in the Early Jurassic.     

Phylogeny of Eunicida (Annelida) and exploring data congruence using a partition addition bootstrap alteration (PABA) approach

Even though relationships within Annelida are poorly understood, Eunicida is one of only a few major annelid lineages well supported by morphology. The seven recognized eunicid families possess sclerotized jaws that include mandibles and a maxillary apparatus. The maxillary apparatuses vary in shape and number of elements, and three main types are recognized in extant taxa: ctenognath, labidognath, and prionognath. Ctenognath jaws are usually considered to represent the plesiomorphic state of Eunicida, whereas taxa with labidognath and prionognath are thought to form a derived monophyletic assemblage. However, this hypothesis has never been tested in a statistical framework even though it holds considerable importance for understanding annelid phylogeny and possibly lophotrochozoan evolution because Eunicida has the best annelid fossil record. Therefore, we used maximum likelihood and Bayesian inference approaches to reconstruct Eunicida phylogeny using sequence data from nuclear 18S and 28S rDNA genes and mitochondrial 16S rDNA and cytochrome c oxidase subunit I genes. Additionally, we conducted three different tests to investigate suitability of combining data sets. Incongruence length difference (ILD) and Shimodaira-Hasegawa (SH) test comparisons of resultant trees under different data partitions have been widely used previously but do not give a good indication as to which nodes may be causing the conflict. Thus, we developed a partition addition bootstrap alteration (PABA) approach that evaluates congruence or conflict for any given node by determining how bootstrap scores are altered when different data partitions are added. PABA shows the contribution of each partition to the phylogeny obtained in the combined analysis. Generally, the ILD test performed worse than the other approaches in detecting incongruence. Both PABA and the SH approach indicated the 28S and COI data sets add conflicting signal, but PABA is more informative for elucidating which data partition may be misleading at a given node. All our analyses indicate that the monophyly of the labidognath/prionognath taxa and even a labidognath clade (i.e., a "Eunicidae"/Onuphidae/Lumbrineridae clade) is significantly rejected. We show that the definition of both the labidognath and ctenognath jaw type does not address adequately the variation within Eunicida and thus misleads our current evolutionary understanding. Based on the presented results a symmetric maxillary apparatus with a carrier and four to six maxillae is most likely the plesiomorphic condition for Eunicida. [COI; conflicting data; fossil record; ILD; Jaw Evolution; molecular phylogeny; rDNA; SH test.].     

Affinities among anostracan (Crustacea: Branchiopoda) families inferred from phylogenetic analyses of multiple gene sequences

To gain insights into the relationships among anostracan families, molecular phylogenetic analyses were performed on nuclear (28S D1-D3 ribosomal DNA) and mitochondrial (16S rDNA, COI) gene regions for representatives of seven families and an outgroup. Data matrices used in the analyses included 951 base pairs (bp) of aligned sequences for 28S, 465 bp for 16S, and 658 bp (219 amino acids) for COI. Maximum-parsimony and maximum-likelihood methods were used to construct phylogenetic trees, enabling the evaluation of both previous hypotheses of taxonomic relationships among families based on morphology, and of the relative merits of independent versus simultaneous analyses of multiple data sets for phylogeny construction. Data from various combinations of the gene regions produced relatively congruent patterns of phylogenetic affinity. In most analyses, two monophyletic groups were resolved: one cluster included the families Polyartemiidae, Chirocephalidae, Branchinectidae, Streptocephalidae, and Thamnocephalidae, while the other contained the Artemiidae and Branchipodidae. Comparative analyses showed that combining gene regions in a single matrix generally resulted in increased resolution and support for each cluster relative to those obtained from single-gene analyses. Statistical tests demonstrated that morphology-based hypotheses of relationships among families had poorer support than those determined from molecular data, reflecting the homoplasy in characters used to differentiate families.     

Revisiting habitat and lifestyle transitions in Heteroptera (Insecta: Hemiptera): insights from a combined morphological and molecular phylogeny

Heteroptera, the true bugs, are part of the largest clade of non-holometabolous insects, the Hemiptera, and include > 42 000 described species in about 90 families. Despite progress in resolving phylogenetic relationships between and within infraorders since the first combined morphological and molecular analysis published in 1993 (29 taxa, 669 bp, 31 morphological characters), recent hypotheses have relied entirely on molecular data. Weakly supported nodes along the backbone of Heteroptera made these published phylogenies unsuitable for investigations into the evolution of habitats and lifestyles across true bugs. Here we present the first combined morphological and molecular analyses of Heteroptera since 1993, using 135 taxa in 60 families, 4018 aligned bp of ribosomal DNA and 81 morphological characters, and various analytical approaches. The sister-group relationship of the predominantly aquatic Nepomorpha with all remaining Heteroptera is supported in all analyses, and a clade formed by Enicocephalomorpha, Dipsocoromorpha and Gerromorpha in some. All analyses recover Leptopodomorpha + (Cimicomorpha + Pentatomomorpha), mostly with high support. Parsimony- and likelihood-based ancestral state reconstructions of habitats and lifestyles on the combined likelihood phylogeny provide new insights into the evolution of true bugs. The results indicate that aquatic and semi-aquatic true bugs invaded these habitats three times independently from terrestrial habitats in contrast to a recent hypothesis. They further suggest that the most recent common ancestor of Heteroptera was predacious, and that the two large predominantly phytophagous clades (Trichophora and Miroidea) are likely to have derived independently from predatory ancestors. We conclude that by combining morphological and molecular data and employing various analytical methods our analyses have converged on a relatively well-supported hypothesis of heteropteran infraordinal relationships that now requires further testing using phylogenomic and more extensive morphological datasets.     

山地原花蝽核型研究(半翅目,花蝽科)

采用姬姆萨染色压片法,对花蝽科山地原花蝽性细胞进行了核型研究.结果表明该种单倍染色体组成为n=14A+XY,为无交叉减数分裂,性染色体经历后减数分裂,上述核型特征为阐明臭虫型内不同科的系统发育关系具有重要意义.     

A Molecular Phylogeny of Hemiptera Inferred from Mitochondrial Genome Sequences

Classically, Hemiptera is comprised of two suborders: Homoptera and Heteroptera. Homoptera includes Cicadomorpha, Fulgoromorpha and Sternorrhyncha. However, according to previous molecular phylogenetic studies based on 18S rDNA, Fulgoromorpha has a closer relationship to Heteroptera than to other hemipterans, leaving Homoptera as paraphyletic. Therefore, the position of Fulgoromorpha is important for studying phylogenetic structure of Hemiptera. We inferred the evolutionary affiliations of twenty-five superfamilies of Hemiptera using mitochondrial protein-coding genes and rRNAs. We sequenced three mitogenomes, from Pyrops candelaria, Lycorma delicatula and Ricania marginalis, representing two additional families in Fulgoromorpha. Pyrops and Lycorma are representatives of an additional major family Fulgoridae in Fulgoromorpha, whereas Ricania is a second representative of the highly derived clade Ricaniidae. The organization and size of these mitogenomes are similar to those of the sequenced fulgoroid species. Our consensus phylogeny of Hemiptera largely supported the relationships (((Fulgoromorpha,Sternorrhyncha),Cicadomorpha),Heteroptera), and thus supported the classic phylogeny of Hemiptera. Selection of optimal evolutionary models (exclusion and inclusion of two rRNA genes or of third codon positions of protein-coding genes) demonstrated that rapidly evolving and saturated sites should be removed from the analyses.     

Phylogeny of the true water bugs (Nepomorpha: Hemiptera–Heteroptera) based on 16S and 28S rDNA and morphology

Abstract. Morphological characters and molecular sequence data were for the first time analysed separately and combined for the true water bugs (Hemiptera–Heteroptera, infraorder Nepomorpha). Data from forty species representing all families were included, together with two outgroup species representing the infraorders Gerromorpha and Leptopodomorpha. The morphological data matrix consisted of sixty‐five characters obtained from literature sources. Molecular data included approximately 960 bp from the mitochondrial gene 16S and the nuclear gene 28S for all forty‐two terminal taxa. The morphological dataset was analysed using maximum parsimony and the combined morphological and molecular (16S + 28S rDNA) dataset was analysed using direct optimization. A sensitivity analysis of sixteen different sets of parameters (various combinations of insertion–deletion cost and transversion costs) was undertaken. Character congruence was used as an optimality criterion to choose among competing phylogenetic hypotheses. The final hypothesis was obtained from the analysis of the combined molecular and mor phological dataset with the most congruent parameter set. This hypothesis supports the monophyly of all currently recognized families of Nepomorpha, and of the superfamilies Nepoidea (Nepidae + Belostomatidae), Corixoidea (Corixidae), Ochteroidea Ochteridae + Gelastocoridae), Notonectoidea (Notonectidae), and Pleoidea (Pleidae + Helotrephidae), but not the monophyly of the Naucoroidea (Naucoridae + Aphelocheiridae + Potamocoridae). The close relationship between the Notonectidae and Pleoidea is also supported. Our hypothesis concurs with Mahner in the placement of the Corixidae as a sister group to the remaining nepomorphan superfamilies except the Nepoidea, but differs in the placement of the Ochteroidea as a sister group to the Notonectoidea + Pleoidea. The superfamily Naucoroidea should be limited to only including the family Naucoridae and not the families Aphelocheiridae and Potamocoridae. The present analysis strongly supports a sister group relationship between the families Aphelocheiridae and Potamocoridae, a monophylum for which we propose a new superfamily, Aphelocheiroidea.     

Is a robust phylogeny of the enterobacterial plant pathogens attainable?

Sequences from gapA, gyrA and ompA were used to evaluate the relationships of the enterobacterial plant pathogens, and assess whether a robust phylogeny can be ascertained using this group of housekeeping genes. Up to 48 taxa were included in a combined phylogenetic analysis to explore the evolutionary distribution of plant pathogenic species across the family Enterobacteriaceae. Phylogenies were reconstructed from gapA, gyrA and ompA gene sequences using maximum parsimony and maximum likelihood algorithms, and phylogenetic congruence was evaluated by the incongruence length difference test and the partition addition bootstrap alteration approach. The resulting gene trees were found to be incongruent, with gapA supporting a monophyletic origin for the plant pathogenic species. In contrast, gyrA and ompA supported multiple polyphyletic origins of Erwinia, Brenneria, Pectobacterium and Pantoea in conjunction with a previously published 16S rDNA phylogeny. However, none of the trees (not even the published 16S rDNA gene tree) supports the current taxonomic classification of these genera into four clades, with Pantoea forming the only monophyletic group in the gapA, gyrA and 16S rDNA trees. Finally, the gapA, gyrA and previously published 16S rDNA phylogenies differ in the taxonomic placement of several bacterial strains which are separated in the three trees. The observed incongruence among the four gene histories is likely to be the result of horizontal transfer events, confounding the search for a robust set of housekeeping genes with a shared evolutionary history that could be used to confidently characterize the relationships of the plant pathogenic enterobacteria. © The Willi Hennig Society 2010.     

Combining molecular and morphological analyses of water strider phylogeny (Hemiptera–Heteroptera, Gerromorpha): effects of alignment and taxon sampling

Abstract. The semiaquatic bugs (Hemiptera–Heteroptera, infraorder Gerromorpha), comprising water striders and their allies (c. 1900 described species), are familiar inhabitants of water surfaces in all continents. Recent fossil evidence indicates that the evolutionary history of semiaquatic bugs spans more than 120 million years of geological time. At present, our insight into the phylogeny of higher taxa is based upon Andersen's manual cladistic analysis of a suite of morphological characters. The present work expands the phylogenetic insight with numerical cladistic analyses of morphological and molecular datasets (partial sequences of 16S and 28S rDNA) for forty species of Gerromorpha covering most higher taxa (families, subfamilies), estimates of branch support, character incongruence, and topological congruence (nodal stability). For the molecular data we apply different alignment options (manual vs numerical alignment; multiple alignment vs direct optimization), treat insertion–deletion events (indels) as either missing data or as a fifth character state, subject the data to a sensitivity analysis, and estimate topological congruence between different analysis trees. Relationships change considerably under different analysis conditions, which means that there is little node stability, and for selecting preferred analysis conditions there is conflicting evidence from rescaled incongruence length difference and the key node criterion. Based on the analysis of the combined morphological and molecular datasets, this study supports the close relationship between the families Gerridae, Hermatobatidae and Veliidae (superfamily Gerroidea), but not the monophyly of the family Veliidae. The results suggest that the genus Ocellovelia (Ocelloveliinae) should be excluded from this family and placed as a sister group to Gerridae + the remaining species of Veliidae. Our study also supports a close relationship between the subfamilies Halobatinae and Ptilomerinae (Gerridae), and that the subfamily Veliinae is probably nonmonophyletic.     

Phylogenetic analyses of Cornales based on 26S rRNA and combined 26S rDNA-MATK-RBCL sequence data

Nuclear 26S rDNA sequences were used to corroborate and test previously published matK-rbcL-based hypotheses of phylogenetic relationships in Cornales. Sequences were generated for 53 taxa including Alangium, Camptotheca, Cornus, Curtisia, Davidia, Diplopanax, Mastixia, Nyssa, and four families: Grubbiaceae, Hydrangeaceae, Hydrostachyaceae, and Loasaceae. Fifteen taxa from asterids were used as outgroups. The 26S rDNA sequences were initially analyzed separately and then combined with matK-rbcL sequences, using both parsimony and maximum likelihood methods. Eight strongly supported major clades were identified within Cornales by all analyses: Cornus, Alangium, nyssoids (Nyssa, Davidia, and Camptotheca), mastixioids (Mastixia and Diplopanax), Hydrangeaceae, Loasaceae, Grubbia-Curtisia, and Hydrostachys. However, relationships among the major lineages are not strongly supported in either 26S rDNA or combined 26S rDNA-matK-rbcL topologies, except for the sister relationships between Cornus and Alangium and between nyssoids and mastixioids in the tree from combined data. Discrepancies in relationships among major lineages, especially the placement of the long-branched Hydrostachys, were found between parsimony and maximum likelihood trees in all analyses. Incongruence between the 26S rDNA and matK-rbcL data sets was suggested, where Hydrangeaceae was found to be largely responsible for the incongruence. The long branch of Hydrostachys revealed in previous analyses was reduced significantly with more sampling. Maximum likelihood analysis of combined 26S rDNA-matK-rbcL sequences suggested that Hydrostachys might be sister to the remainder of Cornales, that Cornus-Alangium are sisters, that nyssoids-mastixioids are sisters, and that Hydrangeaceae-Loasaceae are sisters, consistent with previous analyses of matK-rbcL sequence data.     

Molecular systematics of the suborder Trogiomorpha (Insecta: Psocodea: 'Psocoptera')

Phylogenetic relationships among extant families in the suborder Trogiomorpha (Insecta: Psocodea: 'Psocoptera') were inferred from partial sequences of the nuclear 18S rDNA and Histone 3 and mitochondrial 16S rDNA genes. Analyses of these data produced trees that largely supported the traditional classification; however, monophyly of the infraorder Psocathropetae (= Psyllipsocidae + Prionoglarididae) was not recovered. Instead, the family Psyllipsocidae was recovered as the sister taxon to the infraorder Atropetae (= Lepidopsocidae + Trogiidae + Psoquillidae), and the Prionoglarididae was recovered as sister to all other families in the suborder. Character states previously used to diagnose Psocathropetae are shown to be plesiomorphic. The sister group relationship between Psyllipsocidae and Atropetae was supported by two morphological apomorphies: the presence of a paraproctal anal spine and an anteriorly opened phallosome. Based on these sequence data and morphological observations, we propose a new classification scheme for the Trogiomorpha as follows: infraorder Prionoglaridetae (Prionoglarididae), infraorder Psyllipsocetae (Psyllipsocidae), infraorder Atropetae (Lepidopsocidae, Trogiidae, Psoquillidae).  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 146 , 287–299.     

Molecular phylogeny of the Rhinotermitidae

Summary. Relationships among genera in the termite family Rhinotermitidae and their relationship to the families Termitidae and Serritermitidae were investigated based on analysis of three mitochondrial genes: COI, COII and 16S rDNA. Maximum Parsimony (MP) bootstrap analysis of each of these genes indicated a low level of phylogenetic incongruence between them, and thus they were combined and analysed by MP and Bayesian analysis. Six main lineages were clearly identified, however relationships among these were not well defined. Tentative support was found for the Rhinotermitid genera Coptotermes, Heterotermes and Reticulitermes being the sister group to the Termitidae, rendering the Rhinotermitidae paraphyletic. The species Serritermes serrifer and Glossotermes oculatus were found to group with strong support, in agreement with the recent transfer of the latter species to the family Serritermitidae based on morphological characteristics. No support was found for the Rhinotermitidae being paraphyletic with respect to the Serritermitidae. A number of disagreements were found between the molecular tree and traditional classifications of genera within subfamilies.Received 20 February 2004; revised 2 April 2004; accepted 19 April 2004.     

Mitochondrial DNA,morphology, and the phylogenetic relationships of Antarctic icefishes (Notothenioidei: Channichthyidae)

The Channichthyidae is a lineage of 16 species in the Notothenioidei, a clade of fishes that dominate Antarctic near-shore marine ecosystems with respect to both diversity and biomass. Among four published studies investigating channichthyid phylogeny, no two have produced the same tree topology, and no published study has investigated the degree of phylogenetic incongruence between existing molecular and morphological datasets. In this investigation we present an analysis of channichthyid phylogeny using complete gene sequences from two mitochondrial genes (ND2 and 16S) sampled from all recognized species in the clade. In addition, we have scored all 58 unique morphological characters used in three previous analyses of channichthyid phylogenetic relationships. Data partitions were analyzed separately to assess the amount of phylogenetic resolution provided by each dataset, and phylogenetic incongruence among data partitions was investigated using incongruence length difference (ILD) tests. We utilized a parsimony-based version of the Shimodaira-Hasegawa test to determine if alternative tree topologies are significantly different from trees resulting from maximum parsimony analysis of the combined partition dataset. Our results demonstrate that the greatest phylogenetic resolution is achieved when all molecular and morphological data partitions are combined into a single maximum parsimony analysis. Also, marginal to insignificant incongruence was detected among data partitions using the ILD. Maximum parsimony analysis of all data partitions combined results in a single tree, and is a unique hypothesis of phylogenetic relationships in the Channichthyidae. In particular, this hypothesis resolves the phylogenetic relationships of at least two species (Channichthys rhinoceratus and Chaenocephalus aceratus), for which there was no consensus among the previous phylogenetic hypotheses. The combined data partition dataset provides substantial statistical power to discriminate among alternative hypotheses of channichthyid relationships. These findings suggest the optimal strategy for investigating the phylogenetic relationships of channichthyids is one that uses all available phylogenetic data in analyses of combined data partitions.     

Performance of 18S rDNA helix E23 for phylogenetic relationships within and between the Rotifera-Acanthocephala clades

The species diversity of the phylum Rotifera has been largely studied on the basis of morphological characters. However, cladistic relationships within this group are poorly resolved due to extensive homoplasy in morphological traits, substantial phenotypic plasticity and a poor fossil record. We undertook this study to determine if a phylogeny based on partial 18S rDNA, which included the helix E23 of 18S rDNA sequence, was concordant with established taxonomic relationships within the order Ploimida (class: Monogononta). We also estimated the level of polymorphism within clones and populations of Ploimida 'species'. Finally, we included the Cycliophora Symbion pandora as outgroup and the variable helix E23 region to examine the influence of their signal on the evolutionary relationships among Acanthocephala, Bdelloidea and Ploimida. Phylogenetic reconstruction was performed using maximum parsimony, neighbour joining and maximum likelihood methods. We found 1) that morphologically similar Ploimida 'species' show vastly different 18S E23 rDNA sequences; 2) inclusion of the helix E23 of 18S rDNA and its secondary structure analysis results in better resolution of family level relationships within the Ploimida; 3) an impact of Symbion pandora as an outgroup with inclusion of the helix E23 on the relationships between the Rotifera and the Acanthocephala; and 4) partial incongruence and differential substitution rate between conserved region and helix E23 region of the 18S rDNA gene depending on the taxomic group studied.     

Phylogenetic study of Baylisascaris schroederi isolated from Qinling subspecies of giant panda in China based on combined nuclear 5.8S and the second internal transcribed spacer (ITS-2) ribosomal DNA sequences

The nuclear ribosomal DNA (rDNA) region spanning 5.8S rDNA and the second internal transcribed spacer (ITS-2) of Baylisascaris schroederi isolated from the Qinling subspecies of giant panda in Shaanxi Province, China were amplified and sequenced. Sequence variations in the two rDNA regions within B. schroederi and among species in the family Ascarididae were examined. The lengths of B. schroederi 5.8S and ITS-2 rDNA sequences were 156 bp and 327 bp, respectively, and no nucleotide variation was found in these two rDNA regions among the 20 B. schroederi samples examined, and these ITS-2 sequences were identical to that of B. schroederi isolated from giant panda in Sichuan province, China. The inter-species differences in 5.8S and ITS-2 rDNA sequences among members of the family Ascarididae were 0-1.3% and 0-17.7%, respectively. Phylogenetic relationships among species in the Ascarididae were re-constructed by Bayesian inference (Bayes), maximum parsimony (MP), and maximum likelihood (ML) analyses, based on combined sequences of 5.8S and ITS-2 rDNA. All B. schroederi samples clustered together and sistered to B. transfuga with high posterior probabilities/bootstrap values, which further confirmed that nematodes isolated from the Qinling subspecies of giant panda in Shaanxi Province, China represent B. schroederi. Because of the large number of ambiguously aligned sequence positions (difficulty of inferring homology by positions), ITS-2 sequence alone is likely unsuitable for phylogenetic analyses at the family level, but the combined 5.8S and ITS-2 rDNA sequences provide alternative genetic markers for the identification of B. schroederi and for phylogenetic analysis of parasites in the family Ascarididae.     

基于核内核糖体小亚基序列的蝗总科系统发育关系分析

用核糖体SSURdna全序列对蝗总科（Acridoidea）进行了分子系统学研究。依据测定的8种蝗虫的SSU Rdna全序列 (平均 1.844 bp),并从GenBank中选取了6种内群种类和2种外群种类的SSU Rdna同源序列,进行序列分析。利用Clustal、MEGA 和 PHYLIP 软件构建分子系统树（距离邻接法Neighbor-Joining,NJ;最小进化法 Minimum Evolution）。结果显示： (1) 蝗总科是一个单系类群;(2) 锥头蝗科（Chrotogonidae）和瘤锥蝗科（Pyrgomorphidea）亲缘关系较近,为蝗总科最原始的类群;(3) 网翅蝗科（Arcypteridae）和槌角蝗科（Gomphoceridae）有较近的亲缘关系; (4) 斑翅蝗科 （Oedipodidae）为最进化的类群; (5) SSU Rdna序列保守性强,转换transition）取代的速率大于或接近颠换（transversion）取代的速率;(6) 在系统树中,总科首先分离,大多数同科不同属的类群以高置信度聚合在一起,说明SSU Rdna序列适合用于蝗总科的系统发育关系分析。     

Paraphyly of Homoptera and Auchenorrhyncha inferred from 18S rDNA nucleotide sequences

Evolutionary affiliations of eighteen families of Hemiptera (s.l.) are inferred using molecular phylogenetic analysis of nucleotide (nt) sequences of 18S rDNAs. Exemplar taxa include: Archaeorrhyncha (=Fulgoromorpha): flatid, issid, dictyopharid, cixiid and delphacid; Prosorrhyncha (=Heteropterodea): Peloridiomorpha (=Coleorhyncha) -peloridiid, Heteroptera gerrid, lygaeid and mirid; Clypeorrhyncha [=extant (monophyletic) cicadomorphs]: cicadid, cercopoids (cercopid, aphrophorid), membracid and cicadellids (deltocephaline and cicadelline); and Sternorrhyncha: psyllid, aleyrodid, diaspidid and aphid. Analysed sequences encompass a region beginning ?550 nucleotides (nts) from the 5'-end to ?200 nts upstream from the 3'-end of the gene [?1150 base pairs (bp) in euhemipteran to >1400 bp in sternorrhynchan taxa]. Maximum parsimony and bootstrap analyses (PAUP) identify four principal hemipteran clades, Stenorrhyncha, Clypeorrhyncha, Archaeorrhyncha and Prosorrhyncha. These lineages are identified by synapomorphies distributed throughout the gene. Sternorrhyncha is a sister group to all other Hemiptera (i.e. Euhemiptera sensu Zrzavy), rendering Homoptera paraphyletic. Within Euhemiptera, clades Clypeorrhyncha, Archaeorrhyncha, Prosorrhyncha and Heteroptera are supported by one, three, two and three synapomorphic sites, respectively. There is equitable parsimonious inference for Archaeorrhyncha as the sister group to Prosorrhyncha (Neoherriiptera sensu Sorensen et al.) or Clypeorrhyncha, in either case rendering Auchenorrhyncha paraphyletic. Neohemiptera is supported by one synapomorphy. Within Clypeorrhyncha, clade cicada + cercopoids is the sister group of the clade cicadellids + membracid (Membracoidea sensu Dietrich & Deitz). Among archaeorrhynchans, clade delphacid + cixiid is the sister group of the clade dictyopharid + flatid + issid. Within Prosorrhyncha, the peloridiid is sister to the Heteroptera. Within Heteroptera, gerrid is the sister group of the clade mirid + lygaeid (Panheteroptera sensu Schuh). Based on secondary structure of synonymous 18S rRNA, two synapomorphies each of Sternorrhyncha, Prosorrhyncha and Heteroptera are compensatory substitutions on stem substructures. All other synapomorphies identifying major lineages of Hemiptera are noncompensatory substitutions on either bulges or stems. Short basal internodal distances suggest radiation of hemipteran lineages at the suborder level occurred rapidly. Morphological, palaeoentomological and eco-evolutionary factors supporting the 18S rDNA-based phylogenetic tree are discussed.     

A preliminary phylogeny of the Pentatomomorpha (Hemiptera: Heteroptera) based on nuclear 18S rDNA and mitochondrial DNA sequences

Pentatomomorpha is the second suborder in size only to Cimicomorpha in Heteroptera. However, the phylogenetic relationships among members of the suborder are not well established. Sequences from partial nuclear ribosomal 18S gene and mitochondrial COX1 gene were analyzed separately and in combination to generate a preliminary molecular phylogeny of Pentatomomorpha based on 40 species representing 17 putative families. Analyses of the combined sequence data provided a better-resolved and more robust hypothesis of Pentatomomorpha phylogeny than did separate analyses of the individual genes. The phylogenies were mostly congruent with morphological studies. Results strongly supported the monophyly of the infraorder Pentatomomorpha, and the placement of Aradoidea as sister to Trichophora. The monophyletic Trichophora was grouped into two major lineages, one being the superfamily Pentatomoidea, and the other comprising Lygaeoidea, Coreoidea, and Pyrrhocoroidea. The analysis of the ML and ME trees of combined dataset supported the monophyletic Pentatomoidea. In all analysis the Pyrrhocoroidea was polyphyletic; the monophyletic Lygaeoidea was supported only in the analysis of ME tree, and Coreoidea was polyphyletic except in the MP tree of combined dataset. The molecular and morphylogical data both indicated that the family Coreoidae should be revised subsequently. Our phylogenetic results suggested that the COX1 segment alone might not be an optimal molecular marker for the phylogeny of Pentatomomorpha.