Fossil versus molecular datings of major ant subfamilies

International audienceDespite the interest the ants (Formicidae) have long generated, the group's evolutionary history has become more clearly established only recently, and yet our understanding of the diversity and phylogeny of these organisms is far from complete. Substantial advances have been made in the last decade by the discoveries of primitive fossil and extant lineages, and by molecular phylogenetic analyses. Recent molecular divergence dating estimates suggest that crown group ants arose some time between 115 and 168 million years ago, depending on the methodology applied (BEAST, penalized likelihood, etc.) and the assignment of fossils as stem group or crown group calibration points. This time interval is devoid of fossil ants, however, and the earliest known fossils are currently reported from mid-Cretaceous (ca. 100 Mya) ambers from France and Myanmar. These included only members of extinct or uncertain subfamilies thus far, but new discoveries presented here have revealed the presence of three of the 'big four' modern subfamilies in this time frame, i.e. Dolichoderinae, Formicinae, and Ponerinae. These findings and an overview of other known Cretaceous ants show that molecular divergence datings proposed respectively for each three subfamilies, which did not exceed 90 Mya in previous studies, were all underestimated. Meanwhile, this argues for an age of crown group ants within the 139-158 Mya as proposed by the most recent study, thus closer to the Jurassic/Cretaceous boundary than previously thought

A new species of Baikuris (Hymenoptera: Formicidae: Sphecomyrminae) in mid-Cretaceous amber from France

International audienceA new species of the extinct ant genus Baikuris Dlussky, 1987 (Formicidae: Sphecomyrminae) is describedand figured from a male preserved in a piece of w100 Myr amber from Charentes, in southwesternFrance. Baikuris maximus sp. nov., is distinguished from other species notably by its larger size, itsforewing with vein 2MþCu absent and vein 3Cu tubular, and the presence of a subpetiolar process. Thediagnosis of the genus is emended, and its distribution during the Cretaceous is briefly discussed

Introduction to thematic volume “Fossil arthropods in Late Cretaceous Vendean amber (northwestern France)”

There is growing knowledge of the insect and arachnid Cretaceous diversity worldwide, most notably as a result of the discovery, in the past twenty years, of numerous Konservat-Lagerstätten (highly fossiliferous deposits) that provide a plethora of fossil arthropods (Wang & Szwedo, 2014). Early Cretaceous (Berriasian–Aptian) insects are known primarily from imprints in rocks, while fossiliferous amber yielding arthropod inclusions range mostly from the Albian to the Campanian – the sole exception being Hauterivian-Barremian amber of Lebanon and Jordan

Diverse barklice (Psocodea) from Late Cretaceous Vendean amber

International audienceThe fossil psocodeans from Late Cretaceous (Cenomanian to Santonian) amber of Vendée, in northwestern France, are studied. Two new genera and three new species are described and illustrated, as Proprionoglaris axioperierga n. sp. (Archaeatropidae), Scocompus atelisus n. gen. and sp. (uncertain family within the Amphientometae), and Mesopsocoides dupei n. gen. and sp. (earliest fossil record of the Mesopsocidae). The new fossils are distinguished from their congeners, and their respective systematic placement is discussed. Other fragmentary fossil psocodeans from the same outcrop are illustrated and discussed.Les psoques fossilisés dans l’ambre crétacé supérieur (Cénomanien à Santonien) de Vendée, dans le nord-ouest de la France, sont étudiés. Deux nouveaux genres et trois nouvelles espèces sont décrits et illustrés: Proprionoglaris axioperierga n. sp. (Archaeatropidae), Scocompus atelisus n. gen. et sp. (famille incertaine au sein des Amphioentometae), et Mesopsocoides dupei n. gen. et sp. (plus ancien Mesopscocidae fossile). Ces nouveaux taxons sont comparés à leurs congénères, et leur position systématique respective est discutée. D’autres psoques fossiles fragmentaires issus du même gisement sont discutés

A new genus and species of pemphredonine wasp in Late Cretaceous Vendean amber (Hymenoptera: Crabronidae)

International audienceA new genus and species of pemphredonine wasp is described and figured in Late Cretaceous (Cenomanian to Santonian) amber from Vendée, in northwestern France. Menopsila dupeae n. gen. and sp., is based on a partial male preserved in a small sliver of translucent amber. The genus is placed incertae sedis within the Pemphredonini, as it intermingles features, likely plesiomorphies, of various lineages within the tribe. It likely represents a stem group to one or more of the constituent subtribes, yet it is arguably most similar to the Spilomenina.Un nouveau genre et une nouvelle espèce de guêpe pemphredonine sont décrits de l’ambre crétacé supérieur (Cénomanien à Santonien) de Vendée, nord-ouest de la France. Menopsila dupeae n. gen. et sp., est basé sur un mâle fragmentaire préservé dans un minuscule morceau d’ambre translucide. Le genre est placé incertae sedis au sein des Pemphredonini, car mêlant des caractères probablement plésiomorphes de plusieurs lignées de cette tribu. Il représente vraisemblablement un groupe souche de l’une ou plus des sous-tribus constitutives des Pemphredonini, mais il est sans doute plus proche des Spilomenina

The earliest occurrence and remarkable stasis of the family Bostrichidae (Coleoptera: Polyphaga)in Cretaceous Charentes amber.

A new fossil species of auger beetle (Coleoptera: Bostrichidae), preserved in mid-Cretaceous (Albian-Cenomanian) amber from south-western France, is described as Stephanopachys vetus Peris, Delclòs et Perrichot sp. n. The species is the earliest fossil bostrichid discovered to date, but is remarkably similar to Recent species of the genus Stephanopachys, supporting long morphological conservation in wood boring beetles. The specimen is fossilized in fully opaque amber and was imaged in 3D using propagation phase-contrast X-ray synchrotron microtomography. Based on the ecology of extant related species habits, it is suggested that S. vetus sp. n. was a primary succession pioneer following wildfires in mid-Cretaceous forests. The fossil record of the family is reviewed

Evolutionary and paleobiological implications of Coleoptera (Insecta) from Tethyan-influenced Cretaceous ambers

The intense study of coleopteran inclusions from Spanish (Albian in age) and French (AlbianeSantonian in age) Cretaceous ambers, both of Laurasian origin, has revealed that the majority of samples belong to the Polyphaga suborder and, in contrast to the case of the compression fossils, only one family of Archostemata, one of Adephaga, and no Myxophaga suborders are represented. A total of 30 families from Spain and 16 families from France have been identified (with almost twice bioinclusions identified in Spain than in France); 13 of these families have their most ancient representatives within these ambers. A similar study had previously only been performed on Lebanese ambers (Barremian in age and Gondwanan in origin), recording 36 coleopteran families. Few lists of taxa were available for Myanmar (Burmese) amber (early Cenomanian in age and Laurasian in origin). Coleopteran families found in Cretaceous ambers share with their modern relatives mainly saproxylic and detritivorous habits in the larval or adult stages, rather than wood-boring behavior. Fifteen of the coleopteran families occur in both the Lebanese and Spanish ambers; while only five are present in both Spanish and French. Considering the paleogeographic proximity and similarity of age of the Spanish and French ambers, the small number of taxa found in common at both areas is surprising. The ancient origin for the Lebanese and Spanish ambers, the paleogeography (including some barriers for terrestrial biota) and the local paleohabitats are factors that may explain the dissimilarity with the French specimens. Wildfires are believed to be a more likely cause of resin production during the Cretaceous than infestation by beetles. Current knowledge of the beetle species found in the Cretaceous ambers is introduced

Cretaceous snakefly larvae

11 p. : ill. ; 26 cm.Includes bibliographical references (p. 10-11).Snakefly (Raphidioptera) larvae are newly documented from the early Cretaceous ambers of Lebanon, Myanmar (Burma), and France. Previously only two Cretaceous larvae had been documented, one in late Cretaceous (Turonian) amber from New Jersey and another in early Cretaceous (Albian) amber from Myanmar. The specimens discussed herein are likely representative of the extinct family Mesoraphidiidae, but definitive familial assignment is currently not possible. The new fossil material is described and placed into context with the known larval morphology of modern and fossil species, as well as with the geological history of the order as documented by the remains of adults

Parasitaxus parasitized: Novel infestation of Parasitaxus usta (Podocarpaceae).

The world’s sole ‘parasitic’ gymnosperm Parasitaxus usta (Podocarpaceae) is endemic to the island of Grande Terre, New Caledonia. It is a threatened species because of its limited geographic range and progressing habitat fragmentation. Here, we report a novel scale insect outbreak on a Parasitaxus sub-population from Monts Dzumac in the southern part of Grande Terre. The identity of the scale insect was determined through combining morphological and molecular methods. The field collection of scale insects and their secretions from infested Parasitaxus specimens allowed morphological identification of the superfamily Coccoidea. Subsequent genetic sequencing using CO1 markers allowed phylogenetic placement of the wax scale insects to the genus Ceroplastes (Coccoidea, Coccidae), a widespread pest genus. The identified species, C. pseudoceriferus, has not been previously recorded from New Caledonia. As Parasitaxus is already vulnerable to extinction, this new threat to its long-term survival needs to be monitored. Other New Caledonian endemic plant species are potentially at risk of this new species, although it was not observed on Falcatifolium taxoides, the host of Parasitaxus.Peer reviewe

Phase Contrast X-Ray Synchrotron Imaging

A significant portion of Mesozoic amber is fully opaque. Biological inclusions in such amber are invisible even after polishing, leading to potential bias in paleoecological and phylogenetic studies. Until now, studies using conventional X-ray microtomography focused on translucent or semi-opaque amber. In these cases, organisms of interest were visualized prior to X-ray analyses. It was recently demonstrated that propagation phase contrast X-ray synchrotron imaging techniques are powerful tools to access invisible inclusions in fully opaque amber. Here we describe an optimized synchrotron microradiographic protocol that allowed us to investigate efficiently and rapidly large amounts of opaque amber pieces from Charentes (southwestern France). Amber pieces were imaged with microradiography after immersion in water, which optimizes the visibility of inclusions. Determination is not accurate enough to allow precise phylogenetic studies, but provides preliminary data on biodiversity and ecotypes distribution; phase contrast microtomography remains necessary for precise determination. Because the organisms are generally much smaller than the amber pieces, we optimized local microtomography by using a continuous acquisition mode (sample moving during projection integration). As tomographic investigation of all inclusions is not practical, we suggest the use of a synchrotron for a microradiographic survey of opaque amber, coupled with microtomographic investigations of the most valuable organisms.Peer Reviewe