The morphological evolution of the Adephaga (Coleoptera)

The evolution of the coleopteran suborder Adephaga is discussed based on a robust phylogenetic background. Analyses of morphological characters yield results nearly identical to recent molecular phylogenies, with the highly specialized Gyrinidae placed as sister to the remaining families, which form two large, reciprocally monophyletic subunits, the aquatic Haliplidae + Dytiscoidea (Meruidae, Noteridae, Aspidytidae, Amphizoidae, Hygrobiidae, Dytiscidae) on one hand, and the terrestrial Geadephaga (Trachypachidae + Carabidae) on the other. The ancestral habitat of Adephaga, either terrestrial or aquatic, remains ambiguous. The former option would imply two or three independent invasions of aquatic habitats, with very different structural adaptations in larvae of Gyrinidae, Haliplidae and Dytiscoidea.     

基于线粒体基因组序列的鞘翅目肉食亚目水生类群系统发育分析

【目的】明确肉食亚目(Adephaga)水生类群线粒体基因组的基本特征,并基于线粒体基因组序列分析肉食亚目水生类群的系统发育关系。【方法】基于Illumina HiSeq X Ten测序技术测定了圆鞘隐盾豉甲Dineutus mellyi和齿缘龙虱Eretes sticticus的线粒体全基因组序列,对其进行了基因注释,并对其tRNA基因二级结构进行了预测分析。加上已公布的鞘翅目(Coleoptera)肉食亚目水生类群17个种的线粒体基因组序列,对该类群共19个种线粒体的蛋白质编码基因(protein-coding genes, PCGs)开展了比较基因组学分析,包括AT含量、密码子偏好性、选择压力等。基于13个PCGs的氨基酸序列和核苷酸序列,利用最大似然法(ML)和贝叶斯法(BI)分别构建鞘翅目肉食亚目水生类群的系统发育关系,并通过FcLM分析进一步评估伪龙虱科(Noteridae)和瀑甲科(Meruidae)的系统发育位置。【结果】圆鞘隐盾豉甲和齿缘龙虱的线粒体基因组全长分别为16 123 bp(GenBank登录号: MN781126)和16 196 bp(GenBank登录号: MN781132),都包含13个PCGs、22个tRNA基因、2个rRNA基因和1个D-loop区(控制区)。19个肉食亚目水生类群线粒体基因组PCGs的碱基组成都呈现A+T偏好性,在密码子使用上也都偏向于使用富含A+T的密码子;在进化过程中13个PCGs的进化模式相同,都受到纯化选择。基于线粒体基因组13个PCGs的氨基酸序列的肉食亚目水生类群的系统发育关系为(豉甲科Gyrinidae+(沼梭甲科Haliplidae+((壁甲科Aspidytidae+(两栖甲科Amphizoidae+龙虱科Dytiscidae))+(水甲科Hygrobiidae+(瀑甲科Meruidae+伪龙虱科Noteridae)))))。【结论】研究结果表明,豉甲科是肉食亚目水生类群的基部类群,接下来是沼梭甲科和龙虱总科;伪龙虱科和瀑甲科互为姐妹群,并一起作为龙虱总科内部的一个分支;两栖甲科与龙虱科具有更近的亲缘关系。     

A genus-level supertree of Adephaga (Coleoptera)

A supertree for Adephaga was reconstructed based on 43 independent source trees – including cladograms based on Hennigian and numerical cladistic analyses of morphological and molecular data – and on a backbone taxonomy. To overcome problems associated with both the size of the group and the comparative paucity of available information, our analysis was made at the genus level (requiring synonymizing taxa at different levels across the trees) and used Safe Taxonomic Reduction to remove especially poorly known species. The final supertree contained 401 genera, making it the most comprehensive phylogenetic estimate yet published for the group. Interrelationships among the families are well resolved. Gyrinidae constitute the basal sister group, Haliplidae appear as the sister taxon of Geadephaga+Dytiscoidea, Noteridae are the sister group of the remaining Dytiscoidea, Amphizoidae and Aspidytidae are sister groups, and Hygrobiidae forms a clade with Dytiscidae. Resolution within the species-rich Dytiscidae is generally high, but some relations remain unclear. Trachypachidae are the sister group of Carabidae (including Rhysodidae), in contrast to a proposed sister-group relationship between Trachypachidae and Dytiscoidea. Carabidae are only monophyletic with the inclusion of a non-monophyletic Rhysodidae, but resolution within this megadiverse group is generally low. Non-monophyly of Rhysodidae is extremely unlikely from a morphological point of view, and this group remains the greatest enigma in adephagan systematics. Despite the insights gained, our findings highlight that a combined and coordinated effort of morphologists and molecular systematists is still required to expand the phylogenetic database to enable a solid and comprehensive reconstruction of adephagan phylogeny. See also Supplementary material in the online edition at doi:10.1016/j.ode.2006.05.003     

Ultraconserved elements show utility in phylogenetic inference of Adephaga (Coleoptera) and suggest paraphyly of ‘Hydradephaga’

The beetle suborder Adephaga has been the subject of many phylogenetic reconstructions utilizing a variety of data sources and inference methods. However, no strong consensus has yet emerged on the relationships among major adephagan lineages. Ultraconserved elements (UCEs) have proved useful for inferring difficult or unresolved phylogenies at varying timescales in vertebrates, arachnids and Hymenoptera. Recently, a UCE bait set was developed for Coleoptera using polyphagan genomes and a member of the order Strepsiptera as an outgroup. Here, we examine the utility of UCEs for reconstructing the phylogeny of adephagan families, in the first in vitro application a UCE bait set in Coleoptera. Our final dataset included 305 UCE loci for 18 representatives of all adephagan families except Aspidytidae, and two polyphagan outgroups, with a total concatenated length of 83 547 bp. We inferred trees using maximum likelihood analyses of the concatenated UCE alignment and coalescent species tree methods (astral ii , ASTRID, svdquartets ). Although the coalescent species tree methods had poor resolution and weak support, concatenated analyses produced well‐resolved, highly supported trees. Hydradephaga was recovered as paraphyletic, with Gyrinidae sister to Geadephaga and all other adephagans. Haliplidae was recovered as sister to Dytiscoidea, with Hygrobiidae and Amphizoidae successive sisters to Dytiscidae. Finally, Noteridae was recovered as monophyletic and sister to Meruidae. Given the success of UCE data for resolving phylogenetic relationships within Adephaga, we suggest the potential for further resolution of relationships within Adephaga using UCEs with improved taxon sampling, and by developing Adephaga‐specific probes.     

On the phylogeny and evolution of Mesozoic and extant lineages of Adephaga (Coleoptera,Insecta)

The relationships of extant and extinct lineages of Adephaga were analysed formally for the first time. Emphasis is placed on the aquatic and semiaquatic groups and their evolution in the Mesozoic. ?Triadogyrus and ?Mesodineutus belong to Gyrinidae, the sister group of the remaining families. ?Triaplidae are the sister group of the following groups (Haliplidae, Geadephaga, Dytiscoidea incl. ?Liadytidae, ?Parahygrobiidae and ?Coptoclavidae [major part]). The lack of a ventral procoxal joint and a very short prosternal process are plesiomorphies of ?Triaplidae. ?Coptoclavidae and ?Timarchopsinae are paraphyletic. ?Timarchopsis is placed in a geadephagan clade. In contrast to other coptoclavids, its metathorax is close to the condition found in Haliplidae, with a complete transverse ridge and coxae with large plates and free mesal walls. ?Coptoclavidae s.str., i.e. excl. ?Timarchopsis, is a dytiscoid subgroup. The mesal metacoxal walls are fused, the coxal plates are reduced, and the transverse ridge is absent. ?Stygeonectes belongs to this dytiscoid coptoclavid unit and is therefore misplaced in ?Timarchopsinae. ?Liadytidae belongs to a dytiscoid subgroup, which also comprises the extant families Aspidytidae, Amphizoidae, Hygrobiidae and Dytiscidae. ?Parahygrobia is the sister group of Hygrobiidae. The larvae are characterized by a broad gula, the absence of the lacinia, retractile maxillary bases and very long urogomphi set with long setae. ?Liadytiscinae is the sister group of extant Dytiscidae. There is no support for a clade ?Eodromeinae and for Trachypachidae incl. ?Eodromeinae. ?Fortiseode is nested within Carabidae. The exclusion of fossil taxa has no effect on the branching pattern. The evolution of Adephaga in the Mesozoic is discussed. Possible reasons for the extinction of ?Coptoclavidae are the rise of teleost fish and the competition of Gyrinidae and Dytiscidae, which possess efficient defensive glands and larval mandibular sucking channels.     

On the thoracic anatomy of the Madagascan Heterogyrus milloti and the phylogeny of Gyrinidae (Coleoptera)

Gyrinidae is a group of beetles with a unique specialization of swimming on the water surface. Heterogyrus milloti Legros (Heterogyrinae) from Madagascar is a species with various preserved plesiomorphic features. The information on the morphology and biology was very limited until recently, and the thoracic anatomy remained largely unknown. Consequently, the aim of the present study is to describe external and internal thoracic features of Heterogyrus Legros in detail and to interprete them with respect to their phylogenetic and functional significance, with a special focus on the unusual flight apparatus of Gyrinidae. Characters documented with innovative techniques are compared to conditions found in other gyrinid genera and other groups of Adephaga, including characters of other body parts and larvae. A data matrix with 144 characters of adults, larvae and eggs was compiled and analysed cladistically. Gyrinidae excluding Spanglerogyrus Folkers (Heterogyrinae + Gyrininae) is supported by many apomorphies, mainly by a unique locomotor apparatus with paddle‐like middle and hind legs. The results confirm Heterogyrus as the earliest diverging branch in Gyrinidae except Spanglerogyrus, implying a sister‐group relationship between this genus and Gyrininae, a clade comprising Gyrinini, Dineutini and Orectochilini. The presence of an opening between the mesanepisternum and elytra, reduction of the lateral metafurcal arms, loss of the metathoracic M. furcacoxalis lateralis, and modifications of the head, including the dorsal shift of the upper subcomponent of the compound eyes, are synapomorphies of the three tribes. The monophyly of Gyrinini is moderately well‐supported, whereas Orectochilini is strongly supported by different characters including a highly simplified but functioning flight apparatus. A clade comprising Orectochilini and the dineutine genera is suggested by synapomorphies of adults and larvae. The monophyly of Dineutini was supported in a recent study, but not by the characters analysed here. Features of adults, larvae and eggs indicate that Gyrinidae are the sister group to the remaining adephagan families, as suggested in some earlier morphology‐based studies and recent analyses of large molecular datasets.     

Systematic placement of the recently discovered beetle family Meruidae (Coleoptera: Dytiscoidea) based on molecular data

The family Meruidae has been established recently for the newly discovered species Meru phyllisae Spangler & Steiner, 2005 from Southern Venezuela. These beetles are morphologically highly distinct and at a body length of 0.8 mm represent the perhaps smallest individuals of Adephaga. Here, we use DNA sequence data to place this enigmatic taxon relative to other aquatic groups in this suborder. Meruidae was most closely associated with Noteridae, supporting a previous analysis of morphological structures which had suggested this sister relationship, albeit with weak support. While different alignment strategies did not affect the topology, the precise placement of Meruidae was affected by the choice of tree reconstruction method. Bayesian inference suggests a sister relationship of Meruidae + Noteridae, while parsimony analyses retrieve Meruidae + Notomicrus (a basal noterid genus), which combined are the sister group of all remaining Noteridae. Considering morphological evidence, the former placement appears more plausible.     

Phylogenomic analysis of the beetle suborder Adephaga with comparison of tailored and generalized ultraconserved element probe performance

Adephaga is the second largest suborder of beetles (Coleoptera) and they serve as important arthropod predators in both aquatic and terrestrial ecosystems. The suborder is divided into Geadephaga comprising terrestrial families and Hydradephaga for aquatic lineages. Despite numerous studies, phylogenetic relationships among the adephagan families and monophyly of the Hydradephaga itself remain in question. Here we conduct a comprehensive phylogenomic analysis of the suborder using ultraconserved elements (UCEs). This study presents the first in vitro test of a newly developed UCE probe set customized for use within Adephaga that includes both probes tailored specifically for the suborder, alongside generalized Coleoptera probes previously found to work in adephagan taxa. We assess the utility of the entire probe set, as well as comparing the tailored and generalized probes alone for reconstructing evolutionary relationships. Our analyses recovered strong support for the paraphyly of Hydradephaga with whirligig beetles (Gyrinidae) placed as sister to all other adephagan families. Geadephaga was strongly supported as monophyletic and placed sister to a clade composed of Haliplidae + Dytiscoidea. Monophyly of Dytiscoidea was strongly supported with relationships among the dytiscoid families resolved and strongly supported. Relationships among the subfamilies of Dytiscidae were strongly supported but largely incongruent with prior phylogenetic estimates for the family. The results of our UCE probe comparison showed that tailored probes alone outperformed generalized probes alone, as well as the full combined probe set (containing both types of probes), under decreased taxon sampling. When taxon sampling was increased, the full combined probe set outperformed both tailored probes and generalized probes alone. This study provides further evidence that UCE probe sets customized for a focal group result in a greater number of recovered loci and substantially improve phylogenomic analysis.     

The systematic position of Aspidytidae, the diversification of Dytiscoidea (Coleoptera, Adephaga) and the phylogenetic signal of third codon positions

Characters of the newly discovered larvae of the South African Cliff Water Beetle Aspidytes niobe were examined and integrated into a data matrix including all families of Dytiscoidea as well as Haliplidae. Fifty-three morphological characters of adults and larvae were analysed separately and combined with molecular data from six nuclear and mitochondrial genes. The phylogeny of the group is reconstructed for the study of the evolution of swimming behaviour and larval feeding habits, as well as the shift in diversification rates leading to the two most speciose lineages. The parsimony analysis of all equally weighted morphological and molecular characters combined resulted in a single well supported tree with the topology (Noteridae (Hygrobiidae ((Aspidytidae, Amphizoidae) Dytiscidae))), in agreement with the molecular data alone, but in contradiction to the morphological data, which favoured a topology in which Hygrobiidae is sister to Dytiscidae. The exclusion of third codon positions of the three protein coding genes resulted in a topology identical to that obtained with the morphological data alone, but the use of Bayesian probabilities or the amino acid sequence resulted in the same topology as that of the tree obtained with parsimony using all equally weighted characters. We concluded that interactions of third codon positions with the other data are complex, and their removal is not justified. There was a significant increase in the diversification rate at the base of the richest families (Noteridae and Dytiscidae), which could be associated with the development of simultaneous stroke and higher swimming performance, although data on the swimming behaviour of some basal groups of Noteridae are incomplete. The presence of larval mandibular sucking channels may have contributed to the diversification of Dytiscidae and the species-rich noterid genera Hydrocanthus and Canthydrus .     

Phylogeny and classification of whirligig beetles (Coleoptera: Gyrinidae): relaxed‐clock model outperforms parsimony and time‐free Bayesian analyses

Phylogenetic relationships among members of the family Gyrinidae (Coleoptera: Adephaga) were inferred from analysis of 42 morphological characters and DNA sequence data from the genes 12S rRNA, cytochrome c oxidase I and II, elongation factor 1 alpha (2 different copies) and histone III. Eighty‐nine species of Gyrinidae were included representing all known subfamilies, tribes and genera. Outgroups include species from Noteridae, Paelobiidae and Dytiscidae. Analyses include parsimony analysis, and partitioned time‐free and relaxed‐clock Bayesian analyses of the combined data using reversible‐jump MCMC to simultaneously integrate over all possible 4 × 4 nucleotide substitution models. Analyses resulted in conflicting topologies between the combined parsimony and Bayesian analyses on the one hand, and the relaxed‐clock analysis on the other. The marginal likelihoods of competing models were calculated with stepping‐stone sampling and used in a Bayes factor test, which, along with arguments from morphology, supported the topology generated by the relaxed‐clock analysis. This phylogenetic hypothesis is adopted to revise the higher classification of Gyrinidae. Major taxonomic conclusions include: (i) monophyletic Gyrinidae, (ii) the Nearctic Spanglerogyrinae Folkerts (with one species, Spanglerogyrus albiventris Folkerts) sister to all other Gyrinidae, (iii) the Madagascar endemic Heterogyrinae Brinck stat. n. (with one species, Heterogyrus milloti Legros) sister to all Gyrinidae except Spanglerogyrinae, (iv) monophyletic Gyrininae Latreille including three monophyletic tribes with the following relationship: Orectochilini Régimbart + (Gyrinini Latreille + Enhydrini Régimbart), (v) monophyletic Orectochilini comprising four monophyletic genera with the following relationships: (Gyretes Brullé + Patrus Aubé stat. n. ) + (Orectogyrus Régimbart + Orectochilus Dejean), (vi) monophyletic Gyrinini comprising three genera with the following relationships: Gyrinus Geoffroy + (Metagyrinus Brinck + Aulonogyrus Motschulsky), each monophyletic except Metagyrinus with only one included species and not tested for monophyly, and (vii) monophyletic Enhydrini comprising five genera with the following relationships: (Porrorhynchus Laporte + Dineutus MacLeay) + (Enhydrus Laporte + (Andogyrus Ochs + Macrogyrus Régimbart)), each monophyletic except Porrorhynchus, Enhydrus and Andogyrus each with one included species and untested for monophyly. Each subfamily, tribe and genus is diagnosed and discussed. The female reproductive tract of each group is presented, illustrated and discussed with respect to the phylogenetic conclusions.     

水生肉食亚目(Hydradephaga)系统发育学研究简论

水生肉食亚目(Hydradephaga)属于鞘翅目Coleoptera,是一类具有水生习性的食肉性真正水生甲虫(True water beetles)。在真正水生甲虫的系统分类中存在三种假说,一种是肉食亚目(Adephaga)位于该系统的基部,一种是多食亚目(Polyphaga)位于该系统基部,第三种是藻食亚目(Myxophaga)位于该系统基部。最近研究结果更多倾向第一种假说。目前水生肉食亚目大约有5 500个种,200多个属,含8个科。水生肉食亚目的科间水平系统发育关系虽被广泛研究,但观点仍不统一。有代表意义的有三个假说,一是豉甲科(Gyrinidae)位于系统基部,接下来是龙虱科(Dytiscidae)、两栖甲科(Amphizoidae)、水甲科(Hygrobiidae)、小粒龙虱科(Noteridae)与沼梭科(Haliplidae);二是沼梭科位于系统的基部;三是豉甲科位于系统的基部,接下来是沼梭科和龙虱总科(Dytiscoidea),其中龙虱总科由两栖甲科、水甲科、龙虱科、小粒龙虱科组成。目前根据形态学的分类,并结合分子系统学研究方法,第三种假说更符合水生肉食亚目的系统分类,也支持了水生肉食亚目作为一个单系,其祖先来自陆生的假说。     

On the systematic position of the family Gyrinidae (Coleoptera: Adephaga)

Various characters of adult and larval members of Adephaga and Cupedidae were analyzed, and suggest that Gyrinidae are the sister-group of the remaining Adephaga, and are not closely related to the remaining aquatic Adephaga. The aquatic families Noteridae, Amphizoidae, Hygrobiidae and Dytiscidae seem to form a well founded monophyletic unit. The following characters are considered as synapomorphies of Adephaga excluding Gyrinidae: bifurcate condition of the muscle (= M.) tentoriopraementalis inferior, reduction of hypopharynx, strongly developed prosternal process, reduction in size and specialized modification of the ventral sclerite of the mesothorax, strongly developed mesofurcal arms, a high mesopleural ridge, globular mesocoxae restricted to rotatory movements, invaginated sternum VIII (coxostemum), the strongly curved base of the median lobe of the aedeagus, which articulates with the parameres, the rotated position of the aedeagus in repose, fusion of the larval clypeolabrum with the frons and reduction of the larval lacinia. Mesal shifting of M. episterno-coxalis prothoracis, and the fusion of the apical portions of the malpighian tubules of either side are considered as synapomorphies of Adephaga excluding Rhysodidae and Gyrinidae. Lateral reduction of the meta “sternal” transverse ridge and the presence of the subcubital setal binding patch of the hind wing are considered as synapomorphic characters of Trachypachidae, Noteridae, Amphizoidae, Hygrobiidae and Dytiscidae. We postulate that the metacoxal fusion occurred independently in gyrmids and the common ancestor of Trachypachidae, Noteridae, Amphizoidae, Hygrobiidae and Dytiscidae. Consequently we consider this character state as another synapomorphy of Trachypachidae and Hydradephaga excluding Haliplidae and Gyrinidae. The following characters are considered as synapomorphies of Noteridae, Amphizoidae, Hygrobiidae and Dytiscidae: Loss of tactile setae on the head capsule, metafurcal origin on the intercoxal wall, expansion of the intercoxal wall, elongation of the subcubital setal binding patch, loss of Mm. furca-coxale anterior and posterior, reduction of the larval abdominal segments IX and X, and the shifting of the uropmphi onto the ventral side of segment VIII. Presence of M. tentorio-mandibularis and M. stipitopalpalis intemus are certainly primitive features of adult gyrinids but the distribution of these character states among most members of Adephaga is yet unclear. Chemical defence gland constituents point towards a very isolated position of Gyrinidae. The old age of the group, documented by a larva found in upper Permian deposits, may support the hypothesis of a sister-group relation-ship between Gyrinidae and the remainder of Adephaga.     

Phylogenetic analysis of Adephaga (Coleoptera) based on characters of the larval head

Abstract. Characters of the head of adephagan larvae were examined and analysed phylogenetically. A labrum which is completely fused to the clypeofrons and the presence of a closed prepharyngeal tube are autapomorphies of Adephaga. Partial reduction of the fossa maxillaris, cardo and stipes forming a functional unit, the immobilization of the lacinia, attachment of M. craniolacinialis to the lateral stipital wall, and loss of one stipitopalpal muscle, are considered autapomorphies of Adephaga excluding Gyrinidae. Complete reduction of the fossa maxillaris and the presence of M. craniostipitalis medialis are possible autapomorphies of Adephaga excluding Gyrinidae and Haliplidae. The presence of caudal tentorial arms, insertion of the galea on the mesal side of palpomere I, and absence of the lacinia are considered synapomorphies of Trachypachidae and Dytiscoidea (Noteridae, Amphizoidae, Hygrobiidae, Dytiscidae). The presence of a slender, elongated process of the head capsule, which articulates with a corresponding socket of the cardo, is a possible autapomorphy of Dytiscoidea. The sinuate frontal sutures, distinctly protruding prementum, shortened M. craniostipitalis medialis, and absence of M. submentopraementalis are considered autapomorphies of Geadephaga excluding Trachypachidae. The presence of a regular row of hairs along the anterior hypopharyngeal margin is a possible autapomorphy of Geadephaga excluding Trachypachidae and Rhysodidae. Improvement of the hypopharyngeal filter apparatus suggests the monophyly of Anisochaeta. Presence of a penicillum and partial reduction of the lacinia are possible autapomorphies of Anisochaeta excluding Omophronini. Larvae of Cychrini, Carabini, Nebriini and Notiophilini are characterized by a strongly developed, cone-shaped hypodon. Postocular and cervical ridges, crosswise arrangement of antennal muscles, and a completely flattened hypopharynx are considered autapomorphies of Caraboidea Limbata.     

Molecular phylogeny of the highly disjunct cliff water beetles from South Africa and China (Coleoptera: Aspidytidae)

The superfamily Dytiscoidea contains six families with an aquatic lifestyle, with most of its extant diversity in two families: the burrowing water beetles (Noteridae) and the diving beetles (Dytiscidae). The other families have few species (up to six) and generally highly disjunct extant distributions. Aspidytidae currently contains one genus with two species, one in China and one in South Africa. Here we provide the first molecular data for the Chinese species, allowing us to explore the phylogenetic relationships and position of both species of this small family for the first time. Based on a matrix of 11 genes we inferred a phylogenetic hypothesis for Dytiscoidea including all extant families. Unexpectedly, Aspidytidae were consistently recovered as paraphyletic relative to Amphizoidae, despite being well characterized by apparently synapomorphic adult features. A re‐examination of larval characters in the two aspidytid species revealed that the larva of the Chinese species is strikingly similar to that of Amphizoidae. Both share a series of plesiomorphic features but also some potential synapomorphies, including a dense vestiture of short setae on the head capsule, anteriorly shifted posterior tentorial grooves and widely separated labial palps. Arguably these features may belong to the groundplan of the clade Aspidytidae + Amphizoidae, with far‐reaching secondary modifications (including reversals) in the South African Aspidytes niobe. At present we retain the family Aspidytidae, however, due to the strong adult morphological synapomorphies of the two extant species, and the fact that the molecular paraphyly of the family may result from the highly divergent nature of the two extant species. This long evolutionary separation and strong divergence, in terms of gene sequences and larval features, is undeniable, substantial levels of saturation in third codon positions of protein‐coding genes being present between the two taxa. We address this issue taxonomically by introducing the new genus S inaspidytes gen. nov. for the Chinese Aspidytes wrasei. The continued contentious relationships amongst Dytiscidae, Hygrobiidae, Aspidytidae and Amphizoidae highlight the need for more data to address dytiscoid phylogenetics, possibly involving a genomic approach. © 2016 The Linnean Society of London     

Molecular phylogeny of cockroaches (Blattaria) based on mitochondrial COII gene sequences

Phylogenetic relationships among five cockroach families (Cryptocercidae, Polyphagidae, Blattidae, Blattellidae and Blaberidae) using seventeen species, were estimated based on the DNA sequences of the mitochondrial cytochrome oxidase subunit II (COII) gene. A cladogram inferred using the neighbour‐joining method indicated that Polyphagidae and Cryptocercidae are closely related to each other, and that these two groups are a sister group to the remaining cockroach families. The monophyly of this clade, however, was not strongly supported in terms of bootstrap percentages. Blaberidae and Blattellidae were shown to be sister groups as previously proposed, with Blattidae as a sister group to that clade. Non‐weighted and weighted parsimony analyses were also performed following analyses of nucleotide substitution patterns that indicated saturation of the COII gene among these taxa had occurred. These parsimonious cladograms suggested that Polyphagidae was the basal family, and Polyphaginae, including Cryptocercus as proposed by Grandcolas 1994a ), was not monophyletic. The inferred relationships among cockroach families (Polyphagidae, Cryptocercidae + (Blattidae + (Blattellidae + Blaberidae))) is partly in agreement with some previously published analyses. Additionally, based on molecular data, Asian and American Cryptocercus are suggested to have diverged from one another before the Oligocene (～20 mya).     

Wolbachia distribution in selected beetle taxa characterized by PCR screens and MLST data

Wolbachia (Alphaproteobacteria) is an inherited endosymbiont of arthropods and filarial nematodes and was reported to be widespread across insect taxa. While Wolbachia's effects on host biology are not understood from most of these hosts, known Wolbachia‐induced phenotypes cover a spectrum from obligate beneficial mutualism to reproductive manipulations and pathogenicity. Interestingly, data on Wolbachia within the most species‐rich order of arthropods, the Coleoptera (beetles), are scarce. Therefore, we screened 128 species from seven beetle families (Buprestidae, Hydraenidae, Dytiscidae, Hydrophilidae, Gyrinidae, Haliplidae, and Noteridae) for the presence of Wolbachia. Our data show that, contrary to previous estimations, Wolbachia frequencies in beetles (31% overall) are comparable to the ones in other insects. In addition, we used Wolbachia MLST data and host phylogeny to explore the evolutionary history of Wolbachia strains from Hydraenidae, an aquatic lineage of beetles. Our data suggest that Wolbachia from Hydraenidae might be largely host genus specific and that Wolbachia strain phylogeny is not independent to that of its hosts. As this contrasts with most terrestrial Wolbachia–arthropod systems, one potential conclusion is that aquatic lifestyle of hosts may result in Wolbachia distribution patterns distinct from those of terrestrial hosts. Our data thus provide both insights into Wolbachia distribution among beetles in general and a first glimpse of Wolbachia distribution patterns among aquatic host lineages.     

On the evolution of adult head structures and the phylogeny of Hydraenidae (Coleoptera, Staphyliniformia)

External and internal head structures of adults of Orchymontiinae, Prosthetopinae, Hydraeninae and Ochthebiinae were studied and those of Ochthebius semisericeus and Limnebius truncatellus are described in detail. The results are evaluated with respect to their relevance for a reconstruction of hydraenid phylogeny and also compared with structural features found in adults of other staphyliniform families. The monophyly of Hydraenidae is supported by the presence of a plate‐like, trilobed premento‐hypopharyngeal extension, an unusual origin of m. tentoriohypopharyngalis, dorsal tentorial arms firmly fused with the head capsule, modified basal antennomeres, and palpigers connected by a transverse sclerotized bar. Orchymontiinae are monophyletic and the basal sister group of the remaining Hydraenidae. The presence of a ventral transverse genal bulge and of a pubescent antennal club with more than two antennomeres (reversal in some prosthetopines: e.g. Mesoceration abstrictum) are possible apomorphies of Hydraenidae excluding Orchymontiinae. Prosthetopinae are probably monophyletic and the sister group of Ochthebiinae + Hydraeninae. The latter clade is characterized by a distinct cupula formed by antennomere VI, a loose five‐segmented pubescent antennal club, and a modified antennal musculature. The presence of an unusual tentorio‐pharyngeal dilator is a shared derived feature of Ochthebiinae and the genus Davidraena. The monophyly of Ochthebiinae was confirmed and Ochtheosus is the sister group of the remaining ochthebiine genera, which are characterized by a perforated wall‐like structure formed by the posterior tentorial arms. The absence of this tentorial modification and the fimbriate galea are plesiomorphies retained in Ochtheosus. Calobius differs strongly from other subgenera of Ochthebius and a generic status may be appropriate. The monophyly of Hydraeninae is not supported. Hydraena was confirmed as a clade and Laeliaena and Limnebius are sister groups. The latter genus is characterized by several autapomorphies. The basal position of Orchymontiinae and Prosthetopinae suggests a Gondwanan origin of Hydraenidae and a primary preference for life in running water. Important evolutionary changes of head structures are complex transformations of the antennae and related structures. Yet, the use of the antennae as accessory breathing organs is not a groundplan feature of the family. The results of this study strengthen the case of staphylinoid affinities of Hydraenidae.