Towards the phylogeny of the Curculionoidea (Coleoptera): Reconstructions from mitochondrial and nuclear ribosomal DNA sequences

Phylogenomic Data Yield New and Robust Insights into the Phylogeny and Evolution of Weevils

The phylogeny and evolution of weevils (the beetle superfamily Curculionoidea) has been extensively studied, but many relationships, especially in the large family Curculionidae (true weevils; > 50,000 species), remain uncertain. We used phylogenomic methods to obtain DNA sequences from 522 protein-coding genes for representatives of all families of weevils and all subfamilies of Curculionidae. Most of our phylogenomic results had strong statistical support, and the inferred relationships were generally congruent with those reported in previous studies, but with some interesting exceptions. Notably, the backbone relationships of the weevil phylogeny were consistently strongly supported, and the former Nemonychidae (pine flower snout beetles) were polyphyletic, with the subfamily Cimberidinae (here elevated to Cimberididae) placed as sister group of all other weevils. The clade comprising the sister families Brentidae (straight-snouted weevils) and Curculionidae was maximally supported and the composition of both families was firmly established. The contributions of substitution modeling, codon usage and/or mutational bias to differences between trees reconstructed from amino acid and nucleotide sequences were explored. A reconstructed timetree for weevils is consistent with a Mesozoic radiation of gymnosperm-associated taxa to form most extant families and diversification of Curculionidae alongside flowering plants-first monocots, then other groups-beginning in the Cretaceous.

A Combined Molecular and Morphological Approach to Explore the Higher Phylogeny of Entimine Weevils (Coleoptera: Curculionidae), with Special Reference to South American Taxa

The Entiminae are broad-nosed weevils constituting the most diverse subfamily of Curculionidae, with over 50 tribes. We performed Bayesian and Maximum Parsimony combined phylogenetic analyses with the main objective of testing higher-level relationships and the naturalness of the major Neotropical and Southern South American (Patagonia and Andes) tribes, including some members from other regions. We compiled a data matrix of 67 terminal units with 63 Entiminae species, as well as four outgroup taxa from Cyclominae, by 3522 molecular (from nuclear 18S rDNA and 28S rDNA, and mitochondrial 16S rDNA and COI gene sequences) and 70 morphological characters. The resulting trees recover a clade Entiminae with a monophyletic Cylydrorhinini and Premnotrypes branching off early. The tree resulting from parsimony analysis shows a clade of Leptopiini from the Australian region and another clade including taxa mainly distributed in the Palaearctic and Neotropical regions, but in the Bayesian tree the South American and Australian Leptopiini are grouped together. The mainly Palaearctic Entiminae (e.g., Brachyderini, Laparocerini, Otiorhynchini, Peritelini, Polydrusini, Phyllobiini and Sciaphylini) form a subclade separated from Southern Hemisphere taxa. Among the latter, the well-supported Naupactini are the sister group of the South American Tanymecini, excluding Platyaspistes, herein transferred to Leptopiini (new placement). Another well-justified clade is Eustylini–Geonemini, which also includes the enigmatic Galapagonotus, and the genus Artipus, thus corroborating its recent exclusion from Naupactini.

Weevils as Targets for Biological Control, and the Importance of Taxonomy and Phylogeny for Efficacy and Biosafety

Curculionidae are a large mainly herbivorous family of beetles, some of which have become crop pests. Classical biological control has been attempted for about 38 species in 19 genera, and at least moderate success has been achieved in 31 % of cases. Only two weevil species have been considered to be completely controlled by a biological control agent. Success depends upon accurately matching natural enemies with their hosts, and hence taxonomy and phylogeny play a critical role. These factors are discussed and illustrated with two case studies: the introduction of the braconid parasitoid Mictroctonus aethiopoides into New Zealand for biological control of the lucerne pest Sitona discoideus, a case of complex phylogenetic relationships that challenged the prediction of potential non-target hosts, and the use of a mymarid egg parasitoid, Anaphes nitens, to control species of the eucalypt weevil genus Gonipterus, which involves failure to match up parasitoids with the right target amongst a complex of very closely related species. We discuss the increasing importance of molecular methods to support biological control programmes and the essential role of these emerging technologies for improving our understanding of this very large and complex family.

Morphological and Molecular Perspectives on the Phylogeny, Evolution, and Classification of Weevils (Coleoptera: Curculionoidea): Proceedings from the 2016 International Weevil Meeting

The 2016 International Weevil Meeting was held immediately after the International Congress of Entomology (ICE). It built on the topics and content of the 2016 ICE weevil symposium Phylogeny and Evolution of Weevils (Coleoptera: Curculionoidea): A Symposium in Honor of Dr. Guillermo "Willy” Kuschel. Beyond catalyzing research and collaboration, the meeting was intended to serve as a forum for identifying priorities and goals for those who study weevils. The meeting consisted of 46 invited and contributed lectures, discussion sessions and introductory remarks presented by 23 speakers along with eight contributed research posters. These were organized into three convened sessions, each lasting one day: (1) weevil morphology; (2) weevil fossils, biogeography and host/habitat associations; and (3) molecular phylogenetics and classification of weevils. Some of the topics covered included the 1K Weevils Project, major morphological character systems of adult and larval weevils, weevil morphological terminology, prospects for future morphological character discovery, phylogenetic analysis of morphological character data, the current status of weevil molecular phylogenetics and evolution, resources available for phylogenetic and comparative genomic studies of weevils, the weevil fossil record, weevil biogeography and evolution, weevil host plants, evolutionary development of the weevil rostrum, resources available for weevil identification and the current status of and challenges in weevil classification.

Revision of the genus Limobius, with the description of a new species (Coleoptera, Curculionidae, Hyperini)

The new species, Limobius winkelmannisp. n. is described, keyed, and illustrated. This enigmatic new species has seven desmomeres as other Hyperini-species, but according to shape of elytra and aedeagus, which are typical for representatives of Limobius, it is treated in this genus. The actualised key and check-list of Limobius is presented. The taxonomical position and status of the genus Limobius within the tribe Hyperini is also discussed here.

Phylogenetic analysis of the genus Laparocerus, with comments on colonisation and diversification in Macaronesia (Coleoptera, Curculionidae, Entiminae)

The flightless Entiminae weevil genus Laparocerus is the species-richest genus, with 237 species and subspecies, inhabiting Macaronesia (Madeira archipelago, Selvagens, Canary Islands) and the continental 'Macaronesian enclave' in Morocco (one single polytypic species). This is the second contribution to gain insight of the genus and assist in its systematic revision with a mitochondrial phylogenetic analysis. It centres on the Canarian clade, adding the 12S rRNA gene to the combined set of COII and 16S rRNA used in our first contribution on the Madeiran clade (here re-analysed). The nuclear 28S rRNA was also used to produce an additional 4-gene tree to check coherency with the 3-gene tree. A total of 225 taxa (95%) has been sequenced, mostly one individual per taxa. Plausible explanations for incoherent data (mitochondrial introgressions, admixture, incomplete lineage sorting, etc.) are discussed for each of the monophyletic subclades that are coincident with established subgenera, or are restructured or newly described. The overall mean genetic divergence (p-distance) among species is 8.2%; the mean divergence within groups (subgenera) ranks from 2.9 to 7.0% (average 4.6%), and between groups, from 5.4% to 12.0% (average 9.2%). A trustful radiation event within a young island (1.72 Ma) was used to calibrate and produce a chronogram using the software RelTime. These results confirm the monophyly of both the Madeiran (36 species and subspecies) and the Canarian (196 species and subspecies) clades, which originated ca. 11.2 Ma ago, and started to radiate in their respective archipelagos ca. 8.5 and 7.7 Ma ago. The Madeiran clade seems to have begun in Porto Santo, and from there it jumped to the Desertas and to Madeira, with additional radiations. The Canarian clade shows a sequential star-shape radiation process generating subclades with a clear shift from East to West in coherence with the decreasing age of the islands. Laparocerus garretai from the Selvagens belongs to a Canarian subclade, and Laparocerus susicus from Morocco does not represent the ancestral continental lineage, but a back-colonisation from the Canaries to Africa. Dispersal processes, colonisation patterns, and ecological remarks are amply discussed. Diversification has been adaptive as well as non-adaptive, and the role of 'geological turbulence' is highlighted as one of the principal drivers of intra-island allopatric speciation. Based on the phylogenetic results, morphological features and distribution, five new monophyletic subgenera are described: Aridotroxsubg. n., Belicariussubg. n., Bencomiussubg. n., Canariotroxsubg. n., and Purpuraniussubg. n., totalling twenty subgenera in Laparocerus.

Sclerotised spines in the female bursa associated with male's spermatophore production in cantharidin-producing false blister beetles

Cantharidin is a defence chemical synthesised in only two beetle families Meloidae and Oedemeridae. In Meloidae, cantharidin is used as a defence chemical in eggs. However, in Oedemeridae the function of cantharidin remains unclear. Based on morphological comparison of female internal reproductive organs in 39 species of Oedemeridae, we found that some species have sclerotised spines in the bursa copulatrix (bursal spines), while others have no such spines. Molecular phylogenetic trees inferred from mitochondrial 16S and nuclear 28S rRNA gene sequences suggested multiple evolutionary origins of bursal spines from an ancestor without spines. In the species which lacked spines, males transferred small amounts of ejaculates to females; however, in species with spines, males transferred large spermatophores. Deposited spermatophores gradually disappeared in the bursa, probably owing to absorption. To compare the amounts of cantharidin in eggs laid by species with and without bursal spines, we constructed a new bioassay system using the small beetle Mecynotarsus tenuipes from the family Anthicidae. M. tenuipes individuals were attracted to droplets of cantharidin/acetone solution, and the level of attraction increased with cantharidin concentration. This bioassay demonstrated that the eggs of Nacerdes caudata and N. katoi, both of which species have conspicuous bursal spines, contain more cantharidin than the eggs of N. waterhousei, which lacks spines. In the former species, males transfer large spermatophores to the female, and spermatophores are eventually broken down and digested within the female's spiny bursa. Thus, females with bursal spines may be able to provide more cantharidin to their eggs.

The morphology of the immature stages of Metadonus vuillefroyanus (Capiomont, 1868) (Coleoptera, Curculionidae, Hyperini) and notes on its biology

Last instar larva and pupa of Metadonusvuillefroyanus (Capiomont, 1868) (Curculionidae: Hyperini) are described and compared with known larvae of the other 43 hyperine taxa. The thorn-like setae located on distinct black protuberances on the larval body are characteristic features of the genus Metadonus and the subgenus Eririnomorphus of the genus Hypera. The biological singularity of this species was studied and described. The variable colouration of larvae has been confirmed in association with the variability of the host plant’s colouration at the studied localities. This species’ reported inability to spin cocoons has been disproven. A different type of cocoon with two layers, where the inner layer consists of proteins from Malpighian tubules while the outer layer contains soil particles, is described. This type of cocoon is unique compared with those known from other hyperines, which usually pupate on or above the ground and do not use substrate particles in building their cocoons.

Phylogenetic analysis of the complete mitogenome sequence of the raspberry weevil, Aegorhinus superciliosus (Coleoptera: Curculionidae), supports monophyly of the tribe Aterpini

The superfamily Curculionoidea is one of the most diverse groups of insects in the world, including many species which are crop pests. Within this group, the native raspberry weevil, Aegorhinus superciliosus (Guérin, 1830), is an important pest in blueberry and raspberry fields in southern South America. Using a 454 sequencing approach, we sequenced and annotated the mitogenome of A. superciliosus, it, providing the first such information for any species in the tribe Aterpini, subfamily Cyclominae. The assembled mitogenome is a circular DNA molecule 15,121bp in length containing all 37 genes normally found in metazoans. Mitogenome organization and transcriptional orientation in A. superciliosus showed the same pattern that characterizes the suborder Polyphaga. Bayesian and Maximum Likelihood phylogenetic analyses supported the monophyly of the tribe Aterpini and the subfamily Cyclominae, recovering this clade in a sister group relationship with Entiminae and Hyperinae. The monophyly of these three subfamilies defines a critical transition to an ectophagous lifestyle in the larvae, from an ancestrally endophagous larval lifestyle in all other lineages. The sequenced mitogenome of A. superciliosus can provide basic data for future studies investigating population history, molecular systematics, stress ecophysiology and phylogeography.

Classification of weevils as a data-driven science: leaving opinion behind

Data and explicit taxonomic ranking criteria, which minimize taxonomic change, provide a scientific approach to modern taxonomy and classification. However, traditional practices of opinion-based taxonomy (i.e., mid-20(th) century evolutionary systematics), which lack explicit ranking and naming criteria, are still in practice despite phylogenetic evidence. This paper discusses a recent proposed reclassification of weevils that elevates bark and ambrosia beetles (Scolytinae and Platypodinae) to the ranks of Family. We demonstrate that the proposed reclassification 1) is not supported by an evolutionary systematic justification because the apparently unique morphology of bark and ambrosia beetles is shared with other unrelated wood-boring weevil taxa; 2) introduces obvious paraphyly in weevil classification and hence violates good practices on maintaining an economy of taxonomic change; 3) is not supported by other taxonomic naming criteria, such as time banding. We recommend the abandonment of traditional practices of an opinion-based taxonomy, especially in light of available data and resulting phylogenies.

Bulk de novo mitogenome assembly from pooled total DNA elucidates the phylogeny of weevils (Coleoptera: Curculionoidea)

Complete mitochondrial genomes have been shown to be reliable markers for phylogeny reconstruction among diverse animal groups. However, the relative difficulty and high cost associated with obtaining de novo full mitogenomes have frequently led to conspicuously low taxon sampling in ensuing studies. Here, we report the successful use of an economical and accessible method for assembling complete or near-complete mitogenomes through shot-gun next-generation sequencing of a single library made from pooled total DNA extracts of numerous target species. To avoid the use of separate indexed libraries for each specimen, and an associated increase in cost, we incorporate standard polymerase chain reaction-based "bait" sequences to identify the assembled mitogenomes. The method was applied to study the higher level phylogenetic relationships in the weevils (Coleoptera: Curculionoidea), producing 92 newly assembled mitogenomes obtained in a single Illumina MiSeq run. The analysis supported a separate origin of wood-boring behavior by the subfamilies Scolytinae, Platypodinae, and Cossoninae. This finding contradicts morphological hypotheses proposing a close relationship between the first two of these but is congruent with previous molecular studies, reinforcing the utility of mitogenomes in phylogeny reconstruction. Our methodology provides a technically simple procedure for generating densely sampled trees from whole mitogenomes and is widely applicable to groups of animals for which bait sequences are the only required prior genome knowledge.

Mitogenome sequences stabilize the phylogenetics of weevils (Curculionoidea) and establish the monophyly of larval ectophagy

The weevils and their relatives (superfamily Curculionoidea) constitute a huge radiation of beetles, but basal relationships in this group remain controversial, in particular within the largest family, Curculionidae. We used next-generation sequencing to generate mitochondrial genome data comprising 12 protein coding genes for 27 taxa. Together with two published ingroup sequences, (sub)family relationships were assessed with Bayesian and ML searches under various models and partitioning schemes. Forward and reverse strands of the mitochondrial genome differed in nucleotide skew. Consequently synonymous codon usage differed substantially on either strand for each amino acid, whereby codons ending in AT and GC were favored on the forward and reverse strands, respectively. Data partitioning by forward/reverse strand and codon position greatly improved likelihood scores and nodal support, whereas the tree topology was largely stable. The analysis generally supports the basal position of several 'orthocerus' lineages with straight antennae and male genitalia of an ancestral type; a paraphyletic mixed group of Heteromorphi exhibiting mixed ancestral and derived antennal and genitalic characters; and the derived 'gonathocerous' lineages with kinked antennae corresponding to the strongly supported Curculionidae. The latter did not include the wood boring Platypodinae that was recovered as sister to Dryophthoridae, while the Scolytinae and Cossoninae formed two independent lineages of wood borers within Curculionidae. A basal split in Curculionidae placed the Entiminae and Hyperinae as sister to all other subfamilies with high support, which provides a new ecological concept for structuring the Curculionidae according to the ectophagous larval life style in the former versus endophagous larvae in all others. This basal split is also supported by gene order rearrangements in a tRNA cluster. Recent studies supporting the monophyly of wood boring weevils may be attributable to long-branch attraction, as molecular rates in their mitochondrial genomes were found to be higher than in other lineages, but this did not confound tree searches under combined analysis of mitochondrial protein coding genes.

Application of COI sequences in studies of phylogenetic relationships among 40 Apionidae species

The systematics of the family Apionidae, as well as the superfamily Curculionoidea, is currently in a state of flux. The comparative analyses of COI sequences from our studies shed some light on the systematics of these weevils. To study the relationship among the organisms of the family Apionidae, we determined the COI sequences of representatives of 23 species and 15 genera, i.e., Apion, Betulapion, Catapion, Ceratapion, Cyanapion, Eutrichapion, Exapion, Hemitrichapion, Holotrichapion, Ischnopterapion, Protapion, Pseudoperapion, Psudoprotapion, Pseudostenapion, and Stenopterapion. Then, they were compared with the COI sequences of 19 species and eight genera from GenBank (Aspidapion, Ceratapion, Exapion, Ischnopterapion, Lepidapion, Omphalapion, Oxystoma, and Protapion). The phylogenetic relationships inferred from molecular data are similar to the classification system developed by Alonso-Zarazaga and Lyal ( 1999 ), with some exceptions within the tribe Oxystomatini, and genera Ceratapion and Exapion.

New genus and species of broad-nosed weevils from Baltic amber and notes on fossils of the subfamily Entiminae (Coleoptera, Curculionidae)

Arostropsis groehnigen. et sp. n. is described from Baltic amber and temporarily placed in the tribe Naupactini. It differs from all recent Naupactini genera with open corbels by very short and flattened scape, distinct lateral carina of the pronotum and elytra, and the rostrum distinctly narrower than the head capsule. The shape of head in the extinct genus is somewhat similar to that of the extant Naupactini genera with enclosed corbels (Platyomus Sahlberg, 1823 and Aptolemus Schoenherr, 1842), but differs in the slender body, open corbels, very short antennal scape and epifrons without a median sulcus (only a longitudinal depression is slightly visible). It is also similar to the Tanymecine genus Pandeleteius Schoenherr, 1834 in general appearance, but distinct by the straight anterior edge of the pronotum, lack of postocular spurs, lobes, and vibrissae, a slightly sloping elytral declivity, lateral ridges on the pronotum, subflattened antennal scape, elongate rostrum, and sparsely setose epistome. A new synonymy of the generic names Protonaupactus Zherikhin, 1971 and Sucinophyllobius Wanat & Borowiec, 1986, syn. n., is established. The Madagascan genus Corecaulus Fairmaire, 1903 is transferred from the tribe Naupactini to the Brachyderini because of its connate claws and the similarity in chaetotaxy of the epistomal area with African and Madagascar Brachyderini genera. A key to the identification of known Baltic amber genera of Entiminae is proposed. A checklist of the prepleistocene fossil Entiminae, based on V.V. Zherikhin’s data, with remarks and corrections, is presented.

The age and phylogeny of wood boring weevils and the origin of subsociality

A large proportion of the hyperdiverse weevils are wood boring and many of these taxa have subsocial family structures. The origin and relationship between certain wood boring weevil taxa has been problematic to solve and hypotheses on their phylogenies change substantially between different studies. We aimed at testing the phylogenetic position and monophyly of the most prominent wood boring taxa Scolytinae, Platypodinae and Cossoninae, including a range of weevil outgroups with either the herbivorous or wood boring habit. Many putatively intergrading taxa were included in a broad phylogenetic analysis for the first time in this study, such as Schedlarius, Mecopelmus, Coptonotus, Dactylipalpus, Coptocorynus and allied Araucariini taxa, Dobionus, Psepholax, Amorphocerus-Porthetes, and some peculiar wood boring Conoderini with bark beetle behaviour. Data analyses were based on 128 morphological characters, rDNA nucleotides from the D2-D3 segment of 28S, and nucleotides and amino acids from the protein encoding gene fragments of CAD, ArgK, EF-1α and COI. Although the results varied for some of the groups between various data sets and analyses, one may conclude the following from this study: Scolytinae and Platypodinae are likely sister lineages most closely related to Coptonotus; Cossoninae is monophyletic (including Araucariini) and more distantly related to Scolytinae; Amorphocerini is not part of Cossoninae and Psepholax may belong to Cryptorhynchini. Likelihood estimation of ancestral state reconstruction of subsociality indicated five or six origins as a conservative estimate. Overall the phylogenetic results were quite dependent on morphological data and we conclude that more genetic loci must be sampled to improve phylogenetic resolution. However, some results such as the derived position of Scolytinae were consistent between morphological and molecular data. A revised time estimation of the origin of Curculionidae and various subfamily groups were made using the recently updated fossil age of Scolytinae (100 Ma), which had a significant influence on node age estimates.

La morfología de Laparocerus undatus Wollaston, 1864 y consideraciones sobre la tribu Laparocerini Lacordaire, 1863 (Coleoptera, Curculionidae, Entiminae)

Se presenta un estudio morfológico de Laparocerus undatus Wollaston, 1864 que comprende la anatomía externa e interna del adulto, incluido el canal alimentario, sistema nervioso central y sistema reproductor. También se describen las anatomías de la larva y de la pupa, hasta ahora desconocidas en el género. Los Laparocerus son curculiónidos entiminos que muestran algunos caracteres primitivos infrecuentes en el grupo. Se plantea si se justifica o no mantener la tribu Laparocerini, pendiente de revisión desde que fuera establecida por Lacordaire en 1863. Se discuten las semejanzas halladas en los caracteres imaginales y preimaginales con otros géneros y tribus, y se buscan las relaciones genéticas más cercanas empleando secuencias parciales del gen 16SrRNA de una veintena de especies, obtenidas de GenBank. Laparocerus presenta importantes caracteres singulares o combinación de ellos, y se separa claramente de los demás Entiminae estudiados, ocupando una posición posiblemente basal dentro del grupo. Se proponen algunos caracteres diagnósticos para Laparocerini: presencia de mandíbulas con prolongación dehiscente (o su cicatriz), piezas bucales fanerognatas, escapo antenal largo, ojos y escrobas no dorsales, sutura entre el primer y segundo ventrito sinuosa al medio, éste tan largo como el tercero y cuarto reunidos; fémures sin dientes, tibias mucronadas con cestilla abierta, uñas soldadas y esternito VIII masculino completamente membranoso y provisto de un pequeño espículo relicto; en la larva coinciden las antenas de base oval con sensilo en forma de almohadilla y una mala con cinco setas en su cara ventral; la pupa carece de setas mandibulares. En función de estos y otros caracteres, se discuten los demás géneros atribuidos a Laparocerini, corroborando las exclusiones hechas por otros autores recientemente, y proponiendo la exclusión de Merimnetes, Neomerimnetes y Cyrtozemia. Quedan pendientes de confirmar si son Laparocerini dos géneros africanos: Asmaratrox y Straticus. Finalmente se discute en contexto biogeográfico la conveniencia de desglosar Laparocerus en una quincena de géneros independientes, o de mantenerlo unificado como un único género con varios subgéneros.