Alexandr P. Rasnitsyn

A Probable Pollination Mode Before Angiosperms: Eurasian, Long-Proboscid Scorpionflies

Long-Lost Pollinators The rise of angiosperms in the Early Cretaceous (∼140 million years ago) was accompanied by coevolution of a variety of insects, including flies, bees, and wasps required for pollination. Ren et al. (p. 840; see the Perspective by Ollerton and Coulthard) show that three families of scorpionflies had already evolved specialized mouth parts for feeding on the nectar of gymnosperms, as early as the Middle Jurassic (∼170 million years ago). The diversity and specialization of these insects and related plant structures suggests that they were also involved in pollination. These families died out later in the Cretaceous as angiosperms began to dominate. Prior to the coevolution of angiosperms and pollinating insects, scorpionflies may have been pollinating gymnosperms. The head and mouthpart structures of 11 species of Eurasian scorpionflies represent three extinct and closely related families during a 62-million-year interval from the late Middle Jurassic to the late Early Cretaceous. These taxa had elongate, siphonate (tubular) proboscides and fed on ovular secretions of extinct gymnosperms. Five potential ovulate host-plant taxa co-occur with these insects: a seed fern, conifer, ginkgoopsid, pentoxylalean, and gnetalean. The presence of scorpionfly taxa suggests that siphonate proboscides fed on gymnosperm pollination drops and likely engaged in pollination mutualisms with gymnosperms during the mid-Mesozoic, long before the similar and independent coevolution of nectar-feeding flies, moths, and beetles on angiosperms. All three scorpionfly families became extinct during the later Early Cretaceous, coincident with global gymnosperm-to-angiosperm turnover.

New Transitional Fleas from China Highlighting Diversity of Early Cretaceous Ectoparasitic Insects

Fleas are a group of highly specialized blood-feeding ectoparasites whose early evolutionary history is poorly known. Although several recent discoveries have shed new light on the origin of the group, a considerable gap exists between stem fleas and crown fleas. Here we report a new transitional flea, Saurophthirus exquisitus sp. nov., assigned to a new family Saurophthiridae fam. nov., from the Lower Cretaceous Yixian Formation of northeastern China. Saurophthirids are more similar to crown fleas than other stem fleas in having a relatively small body size, relatively short and slender piercing-sucking stylet mouthparts, comparably short and compact antennae, rows of short and stiff bristles on the thorax, and highly elongated legs. The new finding greatly improves our understanding of the morphological transition to the highly specialized body plan of extant fleas. However, saurophthirids also display several features unknown in other fleas, and some of these features are suggestive of a possible ectoparasitic relationship to contemporaneous pterosaurs, though other possibilities exist. The new fossils, in conjunction with previous discoveries, highlight a broad diversity of ectoparasitic insects in the mid-Mesozoic.

Fossil Insects of the Middle and Upper Permian of European Russia

Fossil insects of European Russia from the Urzhumian to Vyatkian stages are reviewed, new taxa are described, and dynamics of insect taxonomic diversity around the Permian-Triassic boundary in light of the Paleozoic-Mesozoic boundary global extinction problem is analyzed. Traces of interactions between arthropods and plants are analyzed. Insect-bearing deposits of the Late Paleozoic found in the northern and eastern areas of the East European Platform are unique on the global scale in their completeness and continuity, allowing us to trace especially comprehensively the biotic processes that occurred around the boundary described as the time of the greatest biotic catastrophe of the Phanerozoic. A total of 28 genera and 111 species are newly described. Within the range from the Urzhumian to the Permo-Triassic boundary, 15 representative successive assemblages, including 112 families, are recognized (seven in the area in question and eight in other regions of Asia, Australia, and Africa). New tools are developed for the analysis of the dynamics of diversity. These tools show an approximately equilibrium (slightly positive) dynamics in the Urzhumian and Severodvinian and a drop in diversity during the Vyatkian Age. It is shown that Permian insect assemblages acquired a substantially post-Paleozoic pattern much earlier than the end of the Paleozoic. The character of changes that took place in the Induan and Olenekian remains uncertain, but a large-scale extinction event did not occur here: most families that have not been recorded at the beginning of the Triassic are recorded again in the Middle and Upper Triassic. Nevertheless, a biotic crisis probably actually took place, but was reduced to reorganization of the biota’s structure, which provided enormous growth of biodiversity over subsequent hundreds of millions of years, rather than resulted in catastrophic extinction. This study is intended for entomologists, stratigraphers, and all readers interested in the biotic events that took place around the Permian-Triassic boundary.

Potrerilloxyela menendezi gen. et sp. nov. from the Late Triassic of Argentina: The oldest representative of Xyelidae (Hymenoptera: Symphyta) for Americas

Potrerilloxyela menendezi gen. et sp. nov. from the Potrerillos Formation, Cuyo Basin, early Upper Triassic, Mendoza Province, Argentina is described. It is included in the living family Xyelidae and tentatively placed in Liadoxyelini of Xyelinae, which is otherwise known only from the Jurassic of Asia. This record is the first for Hymenoptera in the Triassic of the New World and provides new evidence about the close faunal connections between Laurasia and Gondwana during Mesozoic times. The phylogenetic position of the new genus is discussed.

Some ichneumonids (Insecta, Hymenoptera, Ichneumonoidea) from the Upper Mesozoic of China and Mongolia

Five new species and one new genus of ichneumonids (wasps) are established herein, namely Tanychora exquisita sp. nov., Tanychora beipiaoensis sp. nov., Tanychora spinata sp. nov. and Tanychorella dubia sp. nov. from the uppermost Jurassic or Lower Cretaceous Yixian Formation of Beipiao, China, and Paratanychora mongoliensis gen. et sp. nov. from the Lower Cretaceous Anda-Khuduk Formation of Anda-Khuduk, Mongolia. They are all assigned to the family Ichneumonidae (Insecta: Hymenoptera: Ichneumonoidea). Paratanychora can be considered to be an intermediate between Tanychora Townes and Tanychorella Rasnitsyn. The Mesozoic Ichneumonidae that have been found in China are reviewed. 2003 Published by Elsevier Ltd.

Two New Fossil Sawflies (Hymenoptera, Xyelidae, Xyelinae) from the Middle Jurassic of China

Two new genera with two new species of sawflies, Cathayxyela extensa gen. et sp. nov. and Aequixyela immensa gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation of southeastern Inner Mongolia, China, are assigned to the subfamily Xyelinae (Hymenoptera, Xyelidae). Cathayxyela gen. nov. can be distinguished by the third antennal article longer than the head; mesoprescutum and mesoscutellum nearly equal in length; the forewing with Sc meeting C before the junction of 1-M and 1-Rs; a weak and narrow pterostigma; and 3-Cu at least 1.5 times longer than the 1m-cu. Aequixyela gen. nov. is characterized by the third antennal article nearly as long as the head; the forewing with Rs+M approximately equal to 2-Rs in length; 2m-cu inclined toward the wing base and nearly reaching the middle of cell 3rm; 1m-cu as long as the 2-Cu and 3-Cu; and the cell 2cua of regular hexagonal shape.

Phylogenetic analyses elucidate the inter‐relationships of Pamphilioidea (Hymenoptera, Symphyta)

The phylogeny of the superfamily Pamphilioidea is reconstructed using morphology and DNA sequence data of living and fossil taxa by employing two phylogenetic methods (maximum parsimony and Bayesian inference). Based on our results, the monophyly of Pamphilioidea and Pamphiliidae are corroborated, whereas two extinct families, Xyelydidae and Praesiricidae, are not monophyletic. Because members of Praesiricidae together with Megalodontes form a monophyletic group, we propose that the paraphyletic Praesiricidae is synonymized under Megalodontesidae (syn. nov.). The origin of Pamphilioidea is hypothesized to be as early as the Early Jurassic. To better understand morphological evolution in the early lineages of Pamphilioidea, ancestral states of the first flagellomere and the first and second abdominal terga are reconstructed on the morphology‐based tree. In addition, three new genera (Medilyda, Brevilyda, Strenolyda) with five new species (Medilyda procera, M. distorta, Brevilyda provecta, Strenolyda marginalis and S. retrorsa) are described based on well‐preserved xyelydid fossils from the Middle Jurassic Jiulongshan Formation of north‐eastern China.

A new sawfly fossil from the lower Cretaceous of China elucidates antennal evolution in the lower Hymenoptera (Pamphilioidea: Praesiricidae: Archoxyelydinae subfam.n.)

Archoxyelyda mirabilis gen.n. and sp.n., is described from the Yixian Formation of Liaoning Province, China. It is placed in the family Praesiricidae based on the loss of forewing Sc. The fossil is placed in Archoxyelydinae subfam.n. based on a modified antennal flagellum (consisting of two distinct multisegmented parts: a thick and tightly connected basal part, and a thin and more loosely articulated distal one). The incompletely preserved genus Xyelydontes Rasnitsyn, 1983 is tentatively transferred to Archoxyelydinae. The new material demonstrates a unique feature in the antennal anatomy: the composite third antennomere can be seen to consist of tightly connected primary antennomeres. Antennal evolution in the lower Hymenoptera is reviewed and three hypothetical pathways in their transformation are discussed.

Hoplitolyda duolunica gen. et sp. nov. (Insecta, Hymenoptera, Praesiricidae), the Hitherto largest sawfly from the Mesozoic of China.

Background Large body size of an insect, in general, enhances its capability of predation, competition, and defense, resulting in better survivability and reproduction. Hymenopterans, most being phytophagous or parasitic, have a relatively small to medium body size, typically under 50.0 mm in body length. Principal Findings Herein, we describe Hoplitolyda duolunica gen. et sp. nov., assigned to Praesiricidae, from the Early Cretaceous Yixian Formation of China. This new species is the largest fossil hymenopteran hitherto with body estimated >55.0 mm long and wing span >92.0 mm. H. duolunica is, to our knowledge, the only sawfly with Sc present in the hind wing but not in the forewing. Its Rs1 and M1 meeting each other at 145° angle represents an intermediate in the transition from “Y” to “T” shapes. Even though Hoplitolyda differs significantly from all previously described genera in two subfamilies of Praesricidae, we leave the new genus unplaced in existing subfamilies, pending discovery of material with more taxonomic structure. Conclusions/Significance Hoplitolyda has many unique and interesting characters which might have benefitted its competition, survival, and reproduction: large body size and head with robust and strong mandibles for defense and/or sexual selection, unique wing venation and setal arrangements for flight capability and mobility, dense hairs on body and legs for sensing and protection, etc. Considering the reported ferocious predators of feathered dinosaurs, pterosaurs, birds, and mammals coexisting in the same eco-system, Hoplitolyda is an interesting case of “survival of the fittest” in facing its evolutionary challenges.

A new Cretaceous genus of xyelydid sawfly illuminating nygmata evolution in Hymenoptera

BackgroundNygmata are prominent glandular structures on the wings of insects. They have been documented in some extant insects, including several families of Neuroptera and Mecoptera, the majority of Trichoptera, and a few of the hymenopteran Symphyta. However, because nygmata are rarely preserved in compression fossils, their early development and evolution are still enigmatic. For example, the only documented nygmata in the Hymenoptera are on the forewings of the Triassic xyelids Asioxyela paurura and Madygenius primitives.ResultsThis study describes and illustrates a new genus and species from the family Xyelydidae, Rectilyda sticta gen. et sp. nov., from the Early Cretaceous Yixian Formation of Duolun County, Inner Mongolia, China. This genus has 1-RS reclival and linearly aligned with 1-M, which is different from all other genera in the Xyelydidae. In addition, R. sticta gen. et sp. nov. has clearly preserved nygmata: four symmetrical nygmata on each forewing and two on each hind wing.ConclusionPrevious reports of nygmata on the forewings of Triassic xyelids and extant sawflies, together with this new fossil record of nygmata, provide rare insights into their developmental trends, as well as into the evolution of hymenopterans and insects in general.