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

New Pamphiliids with Varying Venations from Lower Cretaceous Yixian Formation of Northeast China (Hymenoptera, Pamphiliidae)

One new genus and three new species of Pamphiliidae, Dolicholyda obtusata gen. et sp. nov., Dolicholyda confluens sp. nov., and Dolicholyda angusta sp. nov. are described and illustrated. All of them were collected from the Lower Cretaceous Yixian Formation in Duolun County, Inner Mongolia, China. The new genus is established based on the following characters: body surface without punctations; forewing with pterostigma lanceolate and sclerotized around the margins; angle between 1-M and 1-Cu nearly 90°; cell 1mcu long and obviously longer than length of pterostigma. In most cases, the ap-Cu is present, and its length varied. Additionally, we revise the diagnostic characteristics of Juralydinae based on the new specimens. New findings enhance our understanding of the wing venation characteristics of fossil pamphiliids and expand the diversity of Pamphiliidae in the Mesozoic.

Two New Fossil Sawflies of Pamphiliidae (Hymenoptera: Symphyta) from the Mesozoic of Northeastern China

Simple Summary

Two new species and one new specimen of Scabolyda (Pamphiliidae) are described from the Mesozoic of northeastern China. Structures of antennae, genitalia, and legs, especially the hind tarsal claw, are preserved. The documentation of these new structures helps to link extant and fossil taxa of Pamphiliidae.

Abstract

Two new species of Pamphiliidae, Scabolyda latusa sp. nov. and Scabolyda tenuis sp. nov. are described and illustrated from the late Middle Jurassic Jiulongshan Formation and the Lower Cretaceous Yixian Formation of northeastern China, respectively. A new specimen of Scabolyda orientalis Wang, Rasnitsyn, Shih and Ren, 2014 with distinct male genitalia is documented for the first time. Based on the specimens with new and distinct structures of legs, antennae, and genitalia, the morphological characters of Scabolyda are supplemented: antenna with ca. 13–14 flagellomeres; fore leg with tibia without pre-apical spur; hind leg nearly 0.6 times as long as the body, hind tarsal claw without setae and its inner tooth not developed. In addition, the tarsal claw characteristics found in the new species may suggest Scabolyda has a closer relationship with Cephalciinae, rather than with Pamphiliinae.

The early wasp plucks the flower: disparate extant diversity of sawfly superfamilies (Hymenoptera: ‘Symphyta’) may reflect asynchronous switching to angiosperm hosts

The insect order Hymenoptera originated during the Permian nearly 300 Mya. Ancestrally herbivorous hymenopteran lineages today make up the paraphyletic suborder ‘Symphyta’, which encompasses c. 8200 species with very diverse host-plant associations. We use phylogeny-based statistical analyses to explore the drivers of diversity dynamics within the ‘Symphyta’, with a particular focus on the hypothesis that diversification of herbivorous insects has been driven by the explosive radiation of angiosperms during and after the Cretaceous. Our ancestral-state estimates reveal that the first symphytans fed on gymnosperms, and that shifts onto angiosperms and pteridophytes – and back – have occurred at different time intervals in different groups. Trait-dependent analyses indicate that average net diversification rates do not differ between symphytan lineages feeding on angiosperms, gymnosperms or pteridophytes, but trait-independent models show that the highest diversification rates are found in a few angiosperm-feeding lineages that may have been favoured by the radiations of their host taxa during the Cenozoic. Intriguingly, lineages-through-time plots show signs of an early Cretaceous mass extinction, with a recovery starting first in angiosperm-associated clades. Hence, the oft-invoked assumption of herbivore diversification driven by the rise of flowering plants may overlook a Cretaceous global turnover in insect herbivore communities during the rapid displacement of gymnosperm- and pteridophyte-dominated floras by angiosperms.

The first mitogenomes of the superfamily Pamphilioidea (Hymenoptera: Symphyta): Mitogenome architecture and phylogenetic inference

The Pamphilioidea represents a small superfamily of the phytophagous suborder Symphyta (Hymenoptera). Here, nearly complete mitochondrial genomes (mitogenomes) of three pamphilioid species: Chinolyda flagellicornis (Pamphiliidae), Megalodontes spiraeae and M. cephalotes (Megalodontesidae) were newly sequenced using next generation sequencing and comparatively analysed with the previously reported symphytan mitogenomes. A positive AT skew (0.013) and a negative GC skew (-0.194) were found in pamphilioid mitogenome, and a deviation from strand asymmetry was also observed in the PCGs encoded on both strands. Several gene rearrangement events were observed in four tRNA gene clusters (WCY, IQM, ARNS1EF and TP clusters), which have not been reported from symphytan mitogenomes to date. As the most parsimonious explanation, compared with the inferred insect ancestral mitogenome architecture, the occurrence of gene rearrangements in pamphilioid mitogenomes requires totally five evolutionary steps, including four transpositions and one inversion. The predicted secondary structures of tRNAs, rrnS and rrnL genes are mostly consistent with reported hymenopteran species. Phylogenetic analyses recovered the monophyly of superfamily Pamphilioidea and indicated the relationship Tenthredinoidea + (Pamphilioidea + (Cephoidea + (Orussoidea + Apocrita))) with strong nodal supports.

Mirolydidae, a new family of Jurassic pamphilioid sawfly (Hymenoptera) highlighting mosaic evolution of lower Hymenoptera

We describe Pamphilioidea: Mirolydidae Wang, Rasnitsyn et Ren, fam. n., containing Mirolyda hirta Wang, Rasnitsyn et Ren, gen. et sp. n., from the late Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. The new taxon is characterized by unique forewing venation with the presence of forewing SC, 1-RS almost as long as 1-M, M + Cu straight, 2r-rs strongly reclival, and antenna with homonomous flagellum, revealing new and important details in antennal evolutionary transformations. Thus, M. hirta with a combination of primitive and more derived characters highlights its transitional state in the Pamphilioidea and complex mosaic evolution within Pamphilioidea in the late Middle Jurassic. The body of this species is densely covered with thin and long setae, suggesting its possible habit of visiting gymnosperm reproductive organs for pollen feeding and/or pollination during the late Middle Jurassic, much earlier than the appearance of angiosperm flowers.

Two new species of Prolyda from the Middle Jurassic of China (Hymenoptera, Pamphilioidea)

Two new species of the genus Prolyda Rasnitsyn, 1968, Prolyda dimidia sp. n. and Prolyda elegantula sp. n., are described and illustrated. Both specimens were well-preserved and collected from the latest Middle Jurassic Jiulongshan Formation of Daohugou Village in Inner Mongolia, China. Based on the new morphological data, a key to the five known species of Prolyda is provided. In addition, Prolyda has an enlarged first antennal flagellomere, which means it might have revert to the elongate plesiomorphic state for the antennal configuration as previously documented.