Publications

2015
Evans AM, McKenna DD, Bellamy CL, Farrell BD. Large-scale molecular phylogeny of metallic wood-boring beetles (Coleoptera: Buprestoidea) provides new insights into relationships and reveals multiple evolutionary origins of the larval leaf-mining habit. Systematic Entomology. 2015;40 (2) :385-400. DOI (full text)Abstract

The family Buprestidae (jewel beetles or metallic wood-boring beetles), contains nearly 15000 species in 522 genera. Together with the small family Schizopodidae (seven species, three genera), they form the superfamily Buprestoidea. Adult Buprestoidea feed on flowers or foliage, whereas larvae are mostly internal feeders, boring in roots or stems, or mining the leaves of woody or herbaceous plants. The subfamilial and tribal classification of Buprestoidea remains unsettled, with substantially different schemes proposed by different workers based on morphology. Here we report the first large-scale molecular phylogenetic study of the superfamily Buprestoidea based on data from four genes for 141 ingroup species. We used these data to reconstruct higher-level relationships and to assess the current classification and the origins of the larval leaf-mining habit within Buprestoidea. In our analyses, the monophyly of Buprestoidea was strongly supported, as was the monophyly of Schizopodidae and its placement sister to Buprestidae. Our results are largely consistent with the generally accepted major lineages of buprestoids, including clearly-defined agrilines, buprestines-chrysochroines and early-branching julodines-polycestines. In addition to Schizopodidae, three of the six subfamilies were monophyletic in our study: Agrilinae, Julodinae and the monogeneric Galbellinae (Galbella). Polycestinae was monophyletic with the exception of the enigmatic Haplostethini. Chrysochroinae and Buprestinae were not monophyletic, but were recovered together in a large mixed clade along with Galbella. The interrelationships of Chrysochroinae and Buprestinae were not well resolved; however they were clearly polyphyletic, with chrysochroine genera falling into several different well-supported clades otherwise comprising buprestine genera. All Agrilinae were contained in a single strongly supported clade. Coraebini were dispersed throughout Agrilinae, with strong nodal support for several clades representing subtribes. Neither Agrilini nor Tracheini were monophyletic. The leaf-mining genus Paratrachys (Paratracheini) was recovered within the Acmaeoderioid clade, consistent with the current classification, and confirming the independent origins of leaf-mining within Polycestinae and Agrilinae. Additionally, our results strongly suggest that the leaf-mining agriline tribe Tracheini is polyphyletic, as are several of its constituent subtribes. External root feeding was likely the ancestral larval feeding habit in Buprestoidea. The apparent evolutionary transitions to internal feeding allowed access to a variety of additional plant tissues, including leaves. Interestingly, the several genera of leaf-mining agrilines do not form a monophyletic group. Many of these genera are diverse and highly specialized, possibly indicating adaptive radiations.

McKenna DD, Farrell BD, Caterino MS, Farnum CW, Hawks DC, Maddison DR, Seago AE, Short AEZ, Newton AF, Thayer MK. Phylogeny and evolution of Staphyliniformia and Scarabaeiformia: forest litter as a stepping stone for diversification of nonphytophagous beetles. Systematic Entomology. 2015;40 (1) :35-60. DOI (full text)Abstract

The beetle series Staphyliniformia exhibits extraordinary taxonomic, ecological and morphological diversity. To gain further insight into staphyliniform relationships and evolution, we reconstructed the phylogeny of Staphyliniformia using DNA sequences from nuclear 28S rDNA and the nuclear protein-coding gene CAD for 282 species representing all living families and most subfamilies, a representative sample of Scarabaeiformia serving as a near outgroup, and three additional beetles as more distant outgroups. Under both Bayesian inference (BI) and maximum likelihood inference (MLI), the major taxa within Staphyliniformia are each monophyletic: (i) Staphylinoidea, (ii) Hydrophiloidea s.l., and the contained superfamilies (iii) Hydrophiloidea s.s. and (iv) Histeroidea, although Staphylinoidea and Hydrophiloidea s.l. are not strongly supported by MLI bootstrap. Scarabaeiformia is monophyletic under both methods of phylogenetic inference. However, the relative relationships of Staphylinoidea, Hydrophiloidea s.l. and Scarabaeiformia differ between BI and MLI: under BI, Staphyliniformia and Scarabaeiformia were sister groups; under MLI, Hydrophiloidea s.l. and Scarabaeiformia were sister groups and these together were sister to Staphylinoidea. The internal relationships in Scarabaeiformia were similar under both methods of phylogenetic inference, with Cetoniinae, Dynastinae+Rutelinae, Hybosoridae, Passalidae, Scarabaeidae and Scarabaeinae recovered as monophyla. Histeridae comprised two major clades: (1) Abraeinae, Trypanaeine and Trypeticinae; and (2) Chlamydopsinae, Dendrophilinae, Haeteriinae, Histerinae, Onthophilinae, Saprininae and Tribalinae. The relationships among early-divergent Hydrophiloidea differed between BI and MLI, and overall were unresolved or received only moderate to low nodal support. The staphylinoid families Agyrtidae, Hydraenidae and Ptiliidae were recovered as monophyletic; the latter two were sister taxa, and Staphylinidae+Silphidae was also monophyletic. Silphidae was placed within Staphylinidae in close relation to a subset of Tachyporinae. Pselaphinae and Scydmaeninae were both recovered within Staphylinidae, in accordance with recent analyses of morphological characters, although not always with recently proposed sister taxa. None of the four major groups of Staphylinidae proposed by Lawrence and Newton (1982) was recovered as monophyletic. Certain highly specialized staphyliniform habits and morphologies, such as abdominal defensive glands and reduced elytra, have arisen in parallel in separate lineages. Further, our analyses support two major transitions to an aquatic lifestyle within Staphyliniformia: once within Staphylinoidea (Hydraenidae), and once within Hydrophiloidea s.l. (Hydrophiloidea s.s.). On a smaller scale, the most common transition is from litter to subcortical or to periaquatic microhabitats and the next most common is from litter to carrion and to fungi. Overall, transitions to periaquatic microhabitats were the most numerous. The broad picture in Staphyliniformia seems to be a high level of evolutionary plasticity, with multiple possible pathways to and from many microhabitat associations, and litter as a major source microhabitat for diversification. In Scarabaeiformia, the most common transitions were from litter to foliage, with flowers to litter, litter to flowers, and litter to dung being next, and then litter to roots, logs or carrion. Litter is again the largest overall source microhabitat. The most common transitions were to foliage and flowers.It thus seems that the litter environment presents ecological and evolutionary opportunities/challenges that facilitate entry of Staphyliniformia and Scarabaeiformia into new' and different ecological adaptive zones.

2014
de Medeiros BAS, Bena DD, Vanin SA. Curculio Curculis lupus: biology, behavior and morphology of immatures of the cannibal weevil Anchylorhynchus eriospathae G. G. Bondar, 1943. Peerj. 2014;2. DOI (full text)Abstract

Weevils are one of the largest groups of living organisms, with more than 60,000 species feeding mostly on plants. With only one exception, their described larvae are typical plant-feeders, with mouthparts adapted to chewing plant material. Here we describe the second case of a weevil with early-instar larvae adapted to killing conspecifics. We have studied the life history of Anchylorhynchus eriospathae G. G. Bondar, 1943 (Curculioninae: Derelomini sensu Caldara, Franz & Oberprieler (2014)), a species whose immatures feed internally on palm flowers and fruits. We provide detailed descriptions of all immature stages, including the extremely modified first-instar larva. Unlike other weevils and later instars, this stage exhibits a flat body with very long ventropedal lobe setae, a large and prognathous head with a gula, and falciform mandibles, each with a serrate retinaculum, that are used to fight with and eventually kill other first-instar larvae. We also provide biological notes on all stages and the results of behavioral tests that showed that larval aggression occurs only among early life stages. Finally we show that adult size is highly dependent on timing of oviposition. This specialized killer first instar probably evolved independently from the one other case known in weevils, in Revena rubiginosa (Conoderinae: Bariditae sensu Prena, Colonnelli & Hespenheide (2014)). Interestingly, both lineages inhabit the same hosts, raising the possibility that both intra-and inter-specific competition shaped those phenotypes. Given the scarcity of knowledge on early larval stages of concealed insect herbivores, it is possible that our findings represent an instance of a much broader phenomenon. Our observations also allowed us to conclude that Anchylorhynchus eriospathae and A. hatschbachi G. G. Bondar, 1943 are actually the same species, which we synonymize here by considering the latter as a junior synonym(new synonymy).

2013
Rykken JJ, Farrell BD. Boston Harbor Islands all taxa biodiversity inventory: Discovering the “microwilderness” of an urban island park. Natural Resources Technical Report NPS/BOHA/NRTR—2013/746. 2013;(Published Report-2195282). Full text from NPSAbstract

The Boston Harbor Islands Partnership (BHIP) and the Museum of Comparative Zoology (MCZ) at Harvard University collaborated to conduct the first phase of an All Taxa Biodiversity Inventory (ATBI) in Boston Harbor Islands national park area, Boston, Massachusetts.  This six-year phase of the ATBI focused on the “microwilderness” of the park, a vast realm of invertebrate animals. The main objectives of this phase of the ATBI were threefold:  (1) to document the diversity and distribution of arthropod and mollusk taxa in the park; (2) to engage and educate students and the public about local invertebrate biodiversity; (3) to use biodiversity data to inform park management. The project relied on the participation of more than fifty students, interns, citizen scientists, and volunteers to collect invertebrates on nineteen islands, and to sort, prepare, image, and database more than 75,000 specimens in the lab.  Additionally, more than forty taxonomists from North America and Europe donated their time and expertise to identify 1,732 species and morphospecies.  All specimens are permanently housed in the collections at the MCZ. Exploratory analyses of selected taxa suggested that, as predicted by the theory of island biogeography (MacArthur and Wilson 1967), island size was a reasonable predictor of species richness.  However, an island’s distance from the mainland was correlated with species richness for only two of six taxa.  Additional factors such as habitat diversity and habitat type (i.e., presence of freshwater or mature forests), as well as human-aided transport of species, appeared to be significant drivers of invertebrate distribution patterns across the islands.  Numbers of introduced species were proportionally higher on the islands than on the coastal mainland for several beetle families, but comparable data for the mainland were lacking for most taxa, pointing to the lack of basic species distribution data that exist for invertebrates even in temperate, accessible locales. A large proportion of introduced species also had extremely high population counts and widespread distributions across islands, relative to native species.

Rykken JJ, Farrell BD. Discovering the microwilderness in parks and protected areas. In: Management of Insects in Recreation and Tourism. Cambridge, UK: Cambridge U. Press ; 2013. pp. 306-322.
Valente RD, de Medeiros BAS. A new species of Anchylorhynchus Schoenherr (Coleoptera: Curculionidae) from the Amazon, with a record of a new host palm for the genus. Zootaxa. 2013;3709 (4) :394-400. DOI (full text)Abstract

Anchylorhynchus vanini sp. nov. from the Amazon is described, including the mouthparts and male genitalia. The new species is compared with similar species within the genus and the key to the species of Anchylorhynchus provided by Vaurie (1954) is modified to include the new species. Adult specimens were collected in flowers of the palm Syagrus vermicularis Noblick and additional collections in other palms species suggest that this association is specific. This is the first record of the palm Syagrus vermicularis as host for a species of Anchylorhynchus.

Vanin SA, de Medeiros BAS. A new species of Sicoderus Vanin from Bolivia (Coleoptera: Curculionidae: Curculioninae: Otidocephalini). Zootaxa. 2013;3734 (1) :81-85. DOI (full text)Abstract

Sicoderus robini sp. nov. (type locality: Bolivia, Santa Cruz de la Sierra, Buena Vista, El Cairo) is described and illustrated. The new species is assigned to the Sicoderus appendiculatus species group, compared with similar species of the group and with the two other species of Sicoderus that occur in Bolivia. The previously published key for species identification of the S. appendiculatus group is updated to include the new species.

de Medeiros BAS, Núñez-Avellaneda LA. Three new species of Anchylorhynchus Schoenherr, 1836 from Colombia (Coleoptera: Curculionidae; Curculioninae; Acalyptini). Zootaxa. 2013;3636 (2) :394-400. DOI (full text)Abstract

Three new species of the genus Anchylorhynchus from Colombia, are described: Anchylorhynchus pinocchio sp. nov., A. centrosquamatus sp. nov. and A. luteobrunneus sp. nov.. A morphological description, including the male genitalia, is provided for each species as well as a comparison with similar species within the genus. All three species are found in inflorescences of species of Syagrus Mart. (Arecaceae). The adults are pollinators and the larvae develop inside fruits and feed on the endosperm, interrupting seed formation and causing fruit abortion.

2012
Barghini A, de Medeiros BAS. UV Radiation as an Attractor for Insects. Leukos. 2012;9 (1) :47-56. Publisher's VersionAbstract

Light pollution due to exterior lighting is a rising concern. While glare, light trespass and general light pollution have been well described, there are few reported studies on the impact of light pollution on insects. By studying insect behavior in relation to artificial lighting, we suggest that control of the UV component of artificial lighting can significantly reduce its attractiveness, offering a strong ability to control the impact on insects. Traditionally, the attractiveness of a lamp to insects is calculated using the luminous efficiency spectrum of insect rhodopsin. This has enabled the development of lamps that emit radiation with wavelengths that are less visible to insects (that is, yellow lamps). We tested the assumption that the degree of visibility of a lamp to insects can predict its attractiveness by means of experimental collections. We found that the expected lamp's visibility is indeed related to the extent to which it attracts insects. However, the number of insects attracted to a lamp is disproportionally affected by the emission of ultraviolet radiation. UV triggers the behavior of approaching lights more or less independently of the amount of UV radiation emitted. Thus, even small amounts of UV should be controlled in order to develop bug-free lamps.

2011
Davidson RL, Rykken JJ, Farrell BD. Carabid beetle diversity and distribution in Boston Harbor Islands national park area (Coleoptera, Carabidae). Zookeys. 2011;(147) :497-526. DOI (full text)Abstract

As part of an All Taxa Biodiversity Inventory in Boston Harbor Islands national park area, an inventory of carabid beetles on 13 islands was conducted. Intensive sampling on ten of the islands, using an assortment of passive traps and limited hand collecting, resulted in the capture of 6,194 specimens, comprising 128 species. Among these species were seven new state records for Massachusetts (Acupalpus nanellus, Amara aulica, Amara bifrons, Apenes lucidulus, Bradycellus tantillus, Harpalus rubripes and Laemostenus tern cola terricola-the last also a new country record; in passing we report also new state records for Happalus rubripes from New York and Pennsylvania, Amara ovata from Pennsylvania, and the first mainland New York records for Asaphidion curtum). For most islands, there was a clear relationship between species richness and island area. Two islands, however, Calf and Grape, had far more species than their relatively small size would predict. Freshwater marshes on these islands, along with a suite of hygrophilous species, suggested that habitat diversity plays an important role in island species richness. Introduced species (18) comprised 14.0% of the total observed species richness, compared to 5.5% (17 out of 306 species) documented for Rhode Island. We surmise that the higher proportion of introduced species on the islands is, in part, due to a higher proportion of disturbed and open habitats as well as high rates of human traffic. We predict that more active sampling in specialized habitats would bring the total carabid fauna of the Boston Harbor Islands closer to that of Rhode Island or eastern Massachusetts in richness and composition; however, isolation, human disturbance and traffic, and limited habitat diversity all contribute to reducing the species pool on the islands relative to that on the mainland.

Clark A, Rykken JJ, Farrell BD. The Effects of Biogeography on Ant Diversity and Activity on the Boston Harbor Islands, Massachusetts, USA. Plos One. 2011;6 (11). DOI (full text)Abstract

Many studies have examined how island biogeography affects diversity on the scale of island systems. In this study, we address how diversity varies over very short periods of time on individual islands. To do this, we compile an inventory of the ants living in the Boston Harbor Islands National Recreation Area, Boston, Massachusetts, USA using data from a five-year All Taxa Biodiversity Inventory of the region's arthropods. Consistent with the classical theory of island biogeography, species richness increased with island size, decreased with island isolation, and remained relatively constant over time. Additionally, our inventory finds that almost half of the known Massachusetts ant fauna can be collected in the BHI, and identifies four new species records for Massachusetts, including one new to the United States, Myrmica scabrinodis. We find that the number of species actually active on islands depended greatly on the timescale under consideration. The species that could be detected during any given week of sampling could by no means account for total island species richness, even when correcting for sampling effort. Though we consistently collected the same number of species over any given week of sampling, the identities of those species varied greatly between weeks. This variation does not result from local immigration and extinction of species, nor from seasonally-driven changes in the abundance of individual species, but rather from weekly changes in the distribution and activity of foraging ants. This variation can be upwards of 50% of ant species per week. This suggests that numerous ant species on the BHI share the same physical space at different times. This temporal partitioning could well explain such unexpectedly high ant diversity in an isolated, urban site.

Rykken JJ, Jepson PC, Moldenke AR. Ground-dwelling Arthropod Distribution and Movement Across a Fragmented Riparian Forest. Northwest Science. 2011;85 (4) :527-541. DOI (full text)Abstract

The ability to predict patterns of species dispersal across habitat edges takes on increasing conservation relevance as landscapes become more fragmented. We assessed edge responses for four ground-dwelling arthropod taxa by measuring their distribution and movement patterns across a forest edge associated with a forested riparian buffer and an adjacent upslope clearcut at a single site. We used Spatial Analysis by Distance Indices to describe the spatial distribution of arthropods, habitat variables, and the associations between them across a 49 x 63 m pitfall trapping grid with 80 trapping stations. We used mark-release-recapture techniques to measure the distance, rate, and direction of arthropod movement within and between habitat types. Scaphinotus angusticollis (Coleoptera; Carabidae) was restricted to the cool, moist portion of the riparian buffer and was not observed to cross the forest edge. The carabids Pterostichus lattini and Scaphinotus marginatus had more eurytopic distributions across all habitats. Higher overall mobility for S. marginauts may explain, in part, the greater frequency of movement for this species across the forest/clearcut edge. Lycosid spiders, strongly associated with the clearcut, also moved into one portion of the riparian buffer that was warmer and drier. They had a relatively high frequency of movement across the clearcut/forest boundary. These results suggest that ground-dwelling arthropod taxa are likely to respond differently to habitat edges, and that their habitat affinities and mobility strongly influence movement patterns across the landscape. Understanding these patterns of distribution and movement will aid the sustainable management of forest and riparian arthropod taxa in fragmented landscapes.

Davidson RL, Rykken JJ. Rediscovery of Bembidion (Lymnaeum) nigropiceum (Marsham) (= puritanum Hayward) in Massachusetts, with remarks on biology and habitat (Coleoptera, Carabidae, Bembidiini). Zookeys. 2011;(147) :487-496. DOI (full text)Abstract

Bembidion (Lymnaeum) nigropiceum (Marsham) (=puritanum Hayward), a European species introduced into Massachusetts but presumed not to have become established, has been rediscovered during the Boston Harbor Islands All Taxa Biodiversity Inventory undertaken by the Museum of Comparative Zoology and the National Park Service. A summary is presented of treatment of this species in North America. Data on specimens collected are presented, along with observations on habitat and biology. Some speculations are presented about its highly specialized habitat in the gravel pushed up by high tide, which may act as a food-trapping sieve. A few words are included about future actions needed to resolve questions of distribution and behavior.

2010
McKenna DD, Farrell BD. 9-Genes Reinforce the Phylogeny of Holometabola and Yield Alternate Views on the Phylogenetic Placement of Strepsiptera. Plos One. 2010;5 (7). DOI (full text)Abstract

Background: The extraordinary morphology, reproductive and developmental biology, and behavioral ecology of twisted wing parasites (order Strepsiptera) have puzzled biologists for centuries. Even today, the phylogenetic position of these enigmatic "insects from outer space'' [1] remains uncertain and contentious. Recent authors have argued for the placement of Strepsiptera within or as a close relative of beetles (order Coleoptera), as sister group of flies (order Diptera), or even outside of Holometabola.Methodology/Principal Findings: Here, we combine data from several recent studies with new data (for a total of 9 nuclear genes and similar to 13 kb of aligned data for 34 taxa), to help clarify the phylogenetic placement of Strepsiptera. Our results unequivocally support the monophyly of Neuropteroidea (= Neuropterida + Coleoptera) + Strepsiptera, but recover Strepsiptera either derived from within polyphagan beetles (order Coleoptera), or in a position sister to Neuropterida. All other supra-ordinal- and ordinal-level relationships recovered with strong nodal support were consistent with most other recent studies.Conclusions/Significance: These results, coupled with the recent proposed placement of Strepsiptera sister to Coleoptera, suggest that while the phylogenetic neighborhood of Strepsiptera has been identified, unequivocal placement to a specific branch within Neuropteroidea will require additional study.

Archibald SB, Bossert WH, Greenwood DR, Farrell BD. Seasonality, the latitudinal gradient of diversity, and Eocene insects. Paleobiology. 2010;36 (3) :374-398. DOI (full text)Abstract

In the modern world, biotic diversity is typically higher in low-latitude tropical regions where there is abundant insolation (light and heat) and low thermal seasonality. Because these factors broadly covary with latitude, separating their possible effects on species diversity is difficult. The Eocene was a much more equable world, however, with low temperature seasonality extending into lower-insolation higher, cooler latitudes, allowing us to test these factors by comparing insect species diversity in (1) modern, temperate, low-insolation, highly seasonal Harvard Forest, Massachusetts, U.S.A., 42 degrees 29'N; (2) modern, tropical, high-insolation, low-seasonality La Selva, Costa Rica, 10 degrees 26'N, and; (3) Eocene, temperate, low-insolation, yet low-seasonality McAbee, British Columbia, Canada, above 50 degrees N paleolatitude. We found insect diversity at McAbee to be more similar to La Selva than to Harvard Forest, with high species richness of most groups and decreased diversity of ichneumon wasps, indicating that seasonality is key to the latitudinal diversity gradient. Further, midlatitude Eocene woody dicot diversities at McAbee, Republic (Washington, U.S.A.), and Laguna del Hunco (Argentina) are also high, similar to modern tropical samples, higher than at the modern midlatitude Harvard Forest. Modern correlations between latitude, species diversity, and seasonal climates were established some time after the Eocene.

Linnen CR, Farrell BD. A test of the sympatric host race formation hypothesis in Neodiprion (Hymenoptera: Diprionidae). Proceedings of the Royal Society B-Biological Sciences. 2010;277 (1697) :3131-3138. DOI (full text)Abstract

Theory suggests that sympatric speciation is possible; however, its prevalence in nature remains unknown. Because Neodiprion sawflies are host specialists and mate on their hosts, sympatric speciation via host shifts may be common in this genus. Here, we test this hypothesis using near-complete taxonomic sampling of a species group, comprehensive geographical and ecological data, and multiple comparative methods. Host-use data suggest that host shifts contributed to the evolution of reproductive isolation in Neodiprion and previous work has shown that gene flow accompanied divergence. However, geographical data provide surprisingly little support for the hypothesis that host shifts occurred in sympatry. While these data do not rule out sympatric host race formation in Neodiprion, they suggest that this speciation mode is uncommon in the genus and possibly in nature.

Marvaldi AE, McKenna DD, Farrell BD. Weevils in the Beetle Tree of Life: Exploring the phylogeny of Curculionoidea using morphology and molecules. Cladistics. 2010;26 (2) :216-216. DOI (full text)
2009
McKenna DD, Farrell BD. Beetles (Coleoptera). In: Hedges SB, Kumar S The timetree of life. Oxford: Oxford University Press ; 2009. pp. 278–289.
McKenna DD, Sequeira AS, Marvaldi AE, Farrell BD. Temporal lags and overlap in the diversification of weevils and flowering plants. Proceedings of the National Academy of Sciences of the United States of America. 2009;106 (17) :7083-7088. DOI (full text)Abstract

The extraordinary diversity of herbivorous beetles is usually attributed to coevolution with angiosperms. However, the degree and nature of contemporaneity in beetle and angiosperm diversification remain unclear. Here we present a large-scale molecular phylogeny for weevils (herbivorous beetles in the superfamily Curculionoidea), one of the most diverse lineages of insects, based on approximate to 8 kilobases of DNA sequence data from a worldwide sample including all families and subfamilies. Estimated divergence times derived from the combined molecular and fossil data indicate diversification into most families occurred on gymnosperms in the Jurassic, beginning approximate to 166 Ma. Subsequent colonization of early crown-group angiosperms occurred during the Early Cretaceous, but this alone evidently did not lead to an immediate and major diversification event in weevils. Comparative trends in weevil diversification and angiosperm dominance reveal that massive diversification began in the mid-Cretaceous (ca. 112.0 to 93.5 Ma), when angiosperms first rose to widespread floristic dominance. These and other evidence suggest a deep and complex history of coevolution between weevils and angiosperms, including codiversification, resource tracking, and sequential evolution.

Friedrich F, Farrell BD, Beutel RG. The thoracic morphology of Archostemata and the relationships of the extant suborders of Coleoptera (Hexapoda). Cladistics. 2009;25 (1) :1-37. DOI (full text)Abstract

Thoracic structures of Tetraphalerus bruchi are described in detail. The results were compared with features found in other representatives of Archostemata and other coleopteran suborders. Differences between thoracic structures of Tetraphalerus and members of other archostematan subgroups are discussed. External and internal characters of larval and adult representatives of 37 genera of the coleopteran suborders are outlined, coded and analysed cladistically, with four groups of Neuropterida as outgroup taxa. The results strongly suggest the branching pattern Archostemata + [Adephaga + (Myxophaga + Polyphaga)]. Coleoptera excluding Archostemata are supported with a high Bremer support. Important evolutionary changes linked with this branching event are simplifications of the thoracic skeleton resulting in reduced degrees of freedom (i.e. a restricted movability, especially at the leg bases), and a distinct simplification of the muscle system. This development culminates in Polyphaga, which are also strongly supported as a clade. Internalization of the partly reduced propleura, further muscle losses, and the fusion of the mesoventrites and metaventrites-with reversal in Scirtoidea and Derodontidae-are autapomorphies of Polyphaga. Archostemata is a small relict group in contrast to highly successful xylobiontic groups of Polyphaga. The less efficient thoracic locomotor apparatus, the lack of cryptonephric Malpighian tubules, and the rise of angiosperms with beetle groups primarily adjusted to them may have contributed to the decline of Archostemata.(C) The Willi Hennig Society 2008.

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