Browsing by Author "Barden, Phillip."
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ItemAnts (Hymenoptera, Formicidae) through space, time, and sociality : a history from amber.(2015-06) Barden, Phillip.With over 13,000 ecologically diverse species exhibiting worldwide ubiquity in vegetated terrestrial ecosystems, ants are one of nature's greatest success stories. Colonies range from a few dozen tiny workers housed inside of an acorn to millions of nomadic army ants known to consume even vertebrates. The ant fossil record is very rich, comprising thousands of amber and impression specimens spanning a hundred million years, the vast majority of which is Cenozoic. Until very recently, early ant history has been obfuscated by a lack of well-preserved fossils from the Cretaceous. Here, utilizing CT-scanning methodology and traditional methods, diverse species of ~99 million-year-old Cretaceous ants are described from Burmese amber, which together comprise over one-third of all known Cretaceous ants. Among them are trap-jaw predators with scythelike mandibles not known in any living or extinct ants, as well as enigmatic feeders with hair-coated mouthparts, and several species with morphology analogous to that found in modern ants while retaining plesiomorphic features. These and other unusual Cretaceous taxa are contextualized for the first time, with results that challenge traditional viewpoints regarding the diversity, phylogenetic placement, and sociality of the earliest ants known. In the age of molecular phylogenetics the role of fossils can be unclear. Most frequently, fossils are included in analyses solely as calibration points for divergence date estimates, a practice that relies on assumed taxonomy and excludes biogeographic information. To explore alternative roles for fossils in molecular-based biogeographic, phylogenetic, and temporal reconstruction, combined analysis methodology is explored -- first, with respect to a small genus, and then finally applied to a large sampling of all ant subfamilies. The genus Leptomyrmex is endemic to eastern Australia, New Caledonia and New Guinea. Over 25 years ago, a putative fossil Leptomyrmex was described from Dominican amber dated to the Miocene. In the absence of compelling evidence other than taxonomic discussions in literature, researchers have typically excluded the Dominican fossil from phylogenetic and biogeographic reconstruction. To test the placement of the fossil, published molecular sequences for modern Leptomyrmex and related groups were merged with a novel morphological matrix. Through combined analysis the fossil was recovered among modern Australasian Leptomyrmex, indicating that the current distribution is a reflection of a great contraction and more complex biogeographic history. This same methodology is applied to a much larger dataset including members of all modern ant subfamilies in a preliminary total-evidence analysis of ants. ItemBiological inclusions in amber from the Paleogene Chickaloon Formation of Alaska. (American Museum novitates, no. 3908)(American Museum of Natural History., 2018-09-28) Grimaldi, David A.; Sunderlin, David.; Aaroe, Georgene A.; Dempsky, Michelle R.; Parker, Nancy E.; Tillery, George Q.; White, Jaclyn G.; Barden, Phillip.; Nascimbene, Paul C.; Williams, Christopher J. (Christopher James), 1970-The Chickaloon Formation in south-central Alaska contains rich coal deposits dated very close to the Paleocene-Eocene boundary, immediately beneath which occur dispersed nodules of amber along with abundant remains of Metasequoia, dicots, and monocots. The nodules are small (less than 10 mm in length), nearly 10,000 of which were screened, yielding several inclusions of fungi and plant fragments, but mostly terrestrial arthropods: 29 specimens in 10 orders and 13 families. The fungi include resinicolous hyphae and a dark, multiseptate hyphomycete. Plants include wood/bark fragments and fibers, and the microphylls of a bryophyte (probably a moss, Musci). Among the arthropods are arachnids: mites (Acari: Oribatida), Pseudoscorpionida, and the bodies and a silken cocoon of spiders (Araneae). Insecta include Blattodea, Thysanoptera, Hemiptera (Heteroptera and Aphidoidea), Coleoptera (Dermestidae: Megatominae), Trichoptera, Diptera (Chironomidae: Tanypodinae), and Hymenoptera (Formicidae: Formicinae). Nymphal aphids predominate (65% of the arthropod individuals), which were probably feeding on the source tree, likely Metasequoia. There is a bias in preservation toward small arthropods (mean body length 0.75 mm) that are surface-dwelling (nonwinged) stages and taxa. Chickaloon amber contains the most northerly fossil records of pseudoscorpions, thrips, Dermestidae, and Cenozoic ants and mites, so the deposit is contributing unique data on high-latitude paleodiversity of the Paleogene hothouse earth. ItemDirect optimization, sensitivity analysis, and the evolution of the hymenopteran superfamilies. (American Museum novitates, no. 3789)(American Museum of Natural History., 2013-12-05) Payne, Ansel.; Barden, Phillip.; Wheeler, Ward.; Carpenter, James M. (James Michael), 1956-Even as recent studies have focused on the construction of larger and more diverse datasets, the proper placement of the hymenopteran superfamilies remains controversial. In order to explore the implications of these new data, we here present the first direct optimization-sensitivity analysis of hymenopteran superfamilial relationships, based on a recently published total evidence dataset. Our maximum parsimony analyses of 111 terminal taxa, four genetic markers (18S, 28S, COI, EF-1[alpha]), and 392 morphological/behavioral characters reveal areas of clade stability and volatility with respect to variation in four transformation cost parameters. While most parasitican superfamilies remain robust to parameter change, the monophyly of Proctotrupoidea sensu stricto is less stable; no set of cost parameters yields a monophyletic Diaprioidea. While Apoidea is monophyletic under eight of the nine parameter regimes, no set of cost parameters returns a monophyletic Vespoidea or a monophyletic Chrysidoidea. The relationships of the hymenopteran superfamilies to one another demonstrate marked instability across parameter regimes. The preferred tree (i.e., the one that minimizes character incongruence among data partitions) includes a paraphyletic Apocrita, with (Orussoidea + Stephanoidea) sister to all other apocritans, and a monophyletic Aculeata. "Parasitica" is rendered paraphyletic by the aculeate clade, with Aculeata sister to (Trigonaloidea + Megalyroidea). ItemThe Mesozoic family Eremochaetidae (Diptera, Brachycera) in Burmese amber and relationships of Archisargoidea. (American Museum novitates, no. 3865)(American Museum of Natural History., 2016-09-29) Grimaldi, David A.; Barden, Phillip.All 16 species of the family Eremochaetidae occur from the late Jurassic to the mid-Cretaceous of eastern and Central Asia. The first species in amber, and the latest occurrence of the family, was recently described as Zhenia xiai, from the mid-Cretaceous of Myanmar, ca. 100 Ma. New observations of a finely preserved specimen allow refinement of the morphological interpretations in the original description. The female of Zhenia, for example, has the distinctive piercing oviscapt of the superfamily Archisargoidea, formed from modified cerci (not tergites 8 and 9 as originally reported). The pretarsus of Zhenia bears an enormous empodial pad and pair of pulvillae, but the claws are highly vestigial (contra Zhang et al., 2016). The fly was almost certainly a parasitoid. A cladistic analysis of 26 binary-state characters and six continuously variable characters, using 47 exemplar Archisargoidea species from most genera and all four families, and five outgroup Brachycera, has very poor support for most clades but confirms the position of Zhenia in Eremochaetidae. Evidence on the relationships of Archisargoidea to other Brachycera is reviewed, and a close relationship to the Nemestrinoidea or Muscomorpha is best supported. A catalog of the species and some higher taxa of Archisargoidea is provided. ItemRediscovery of the bizarre Cretaceous ant Haidomyrmex Dlussky (Hymenoptera, Formicidae), with two new species. (American Museum novitates, no. 3755)(American Museum of Natural History., 2012-09-14) Barden, Phillip.; Grimaldi, David A.;The discovery of two distinct, near-complete specimens belonging to the Cretaceous ant genus Haidomyrmex Dlussky prompts a detailed description and discussion of a remarkable mandibular morphology. The specimens, preserved in 98 million-year-old amber from northern Myanmar, are described here as Haidomyrmex scimitarus, n. sp., and Haidomyrmex zigrasi, n. sp., with diagnostic differences provided between them as well as with H. cerberus Dlussky (also in Burmese amber). Relationships and comparisons of H. scimitarus, H. zigrasi, H. cerberus, and the recently described Haidomyrmodes mammuthus Perrichot from Cretaceous French amber are also discussed. Haidomyrmex was probably arboreal, cursorial, and a specialized trap-jaw predator, utilizing its enormous mandibles and cranial morphology in concert to capture prey. Mandibles appear to have moved in a plane oblique to the dorsoventral and horizontal axes of the body, unlike the lateral-plane movement of modern ants. The additions of these new fossils provide insight into some of the earliest yet surprisingly specialized ants that roamed the earth.