Palaeodictyopteroida: new finds, morphology and development of wings

Publication Type:Conference Paper
Year of Publication:2016
Authors:J. Prokop, Nel, A., Engel, M. S., Pecharová, M., Ren, D., Hörnschemeyer, T.
Conference Name:The 7th International Conference on Fossil Insects, Arthropods and Amber
Date Published:26/04/2016
Publisher:Siri Scientific Press
Conference Location:National Museum of Scotland, Edinburgh

Palaeodictyopteroida are a specialised group of Paleozoic insects well known for the possession of unique rostrum-like piercing-sucking mouthparts and remarkable diversity in Carboniferous and Permian palaeoecosystems. However, the excessive adaptations of this group were probably the main reason why its members did not survive the Permian–Triassic mass extinction. Recently discovered new material of Brodioptera sinensis from Early Pennsylvanian deposits in Xiaheyan (Ningxia Autonomous region, China) documented by a large series of specimens, enhanced our knowledge on the intraspecific variability of megasecopteran wing venation. B. sinensis uncovers the detailed morphology of the haustellate mouthparts with conspicuous elongated stylets and male and female external copulatory organs that were previously unknown in Brodiopteridae or were poorly preserved. The female genitalia comprise an endophytic ovipositor with apical parts of the first and second valvulae bearing oblique ridges, and the male styliger plate has long two-segmented forceps.Discovery of a palaeodictyopteran nymph Bizarrea obscura and a new adult specimen of Homaloneura cf. dabasinskasi in the Pennsylvanian ironstone nodules of Mazon Creek enlighten the morphology of immatures in Spilapteridae. Both taxa share a particularly unique division of the abdominal segments by two transverse sulci and apically pointed laterotergites. Nevertheless, an alternative hypothesis for the placement within Homoiopteridae based on the size of the wing pads is also considered. Our comparative study of the morphology of abdominal segments revealed the presence of subcircular sclerotised structures beneath the nymphal laterotergites I–VII, ?VIII. These structures are well delimited and lack any emerging filaments. Instead the morphology is that of abdominal spiracles, indicative of a terrestrial or semiaquatic habitat for these immatures. Furthermore, our re-examination of the enigmatic Vogesonymphidae (Protereismatina), known from the Middle Triassic of Grès à Voltzia in France, confirms the presence of homologous structures, also interpreted as spiracles. Thus, our discovery supports the parallel coexistence of ancestrally terrestrial or semi-terrestrial lineages of Ephemerida in early Mesozoic ecosystems.

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