Ecomorphological diversification of the Late Palaeozoic Palaeodictyopterida reveals different larval strategies and amphibious lifestyle in adults

This work is licensed under a Creative Commons Attribution 4.0 International License.The Late Palaeozoic insect superorder Palaeodictyopterida exhibits a remarkable disparity of larval ecomorphotypes, enabling these animals to occupy diverse ecological niches. The widely accepted hypothesis presumed that their immature stages only occupied terrestrial habitats, although authors more than a century ago hypothesized they had specializations for amphibious or even aquatic life histories. Here, we show that different species had a disparity of semiaquatic or aquatic specializations in larvae and even the supposed retention of abdominal tracheal gills by some adults. While a majority of mature larvae in Palaeodictyoptera lack unambiguous lateral tracheal gills, some recently discovered early instars had terminal appendages with prominent lateral lamellae like in living damselflies, allowing support in locomotion along with respiratory function. These results demonstrate that some species of Palaeodictyopterida had aquatic or semiaquatic larvae during at least a brief period of their post-embryonic development. The retention of functional gills or gill sockets by adults indicates their amphibious lifestyle and habitats tightly connected with a water environment as is analogously known for some modern Ephemeroptera or Plecoptera. Our study refutes an entirely terrestrial lifestyle for all representatives of the early diverging pterygote group of Palaeodictyopterida, a greatly varied and diverse lineage which probably encompassed many different biologies and life histories

Megasecoptera: morphology and taxonomy of newly discovered specimens from Upper Carboniferous of northern China (Insecta: Palaeodictyopteroida)

The extinct insect group of Palaeodictyopteroida (Insecta: Palaeoptera) comprised mainly phytophagous species and occurred from Upper Carboniferous to Upper Permian. Megasecoptera is one of several orders of belonging to this group. Although, the order Megasecoptera comprised over 20 described families, morphology of some body structures are insufficiently studied. The present thesis deals with evaluation of new material comprising the extensive set of 76 fossil insect specimens from the Upper Carboniferous (Bashkirian) of northern China. The fossils having excellent state of preservation of the wings and other body structures provide new insights concerning the external morphology of Megasecoptera. All studied specimens were attributed based on wing venation pattern into two known megasecopteran genera within families Brodiopteridae and Sphecopteridae. The aim of the present thesis is examine the morphology and variability of wing venation of two newly proposed species Brodioptera sp. n. and Cyclocelis sp. n. from site in northern China. In addition the following methods of geometric morphometrics based on landmarks were used for comparison of venational characters: a comparison of centroid size, procrustes analysis, principal component analysis and thin plate spline. Variability of wing venation..

Morphology and evolution of selected groups of Palaeodictyopterida (Insecta: Palaeoptera)

Palaeodictyopterida is remarkable insect superorder, which formed a significant part of the diversity of upper Palaeozoic insects, but disappeared by the end of the Permian. The main synapomorphy of the superorder is the piercing-sucking mouthparts in the form of a rostrum consisting of five styles. This rostrum was probably used to pierce on plant tissue and for the juice sucking. The same type of mouthparts shared by adults was present also in larvae of Palaeodictyopterida. The external copulatory organs of the superorder members was also showed some morphological interests. The male genitalia consist of a pair of gonostyli and two penial lobes, similarly to the genitalia of recent Ephemeroptera. The female genitalia of Palaeodictyopterida are developed in a form of the ovipositor that can be compared with the endophytic ovipositor of some recent Odonata. This morphological features support placement of Palaeodictyopterida as sister group of Odonatoptera + Panephemeroptera. The main aim of the work was to describe new representatives of the order Megasecoptera, the second largest group of Palaeodictyopterida. Wing venation of Megasecoptera exhibits a reduction of the longitudinal and transverse veins in comparison with the order Palaeodictyoptera. Other body structures were examined mainly in the..

Gigantism of Paleozoic insects and other arthropods

Gigantism of insects and other arthropods was rather common in Late Paleozoic. Hypothesis of the oxygen limitation is one the probable explanations caused the phenomenon. Carboniferous insect gigantism was probably directly caused by the higher level of atmospheric oxygen due to direct effectiveness on the tracheal system. Therefore the possibility to grow to large sizes is clearly dependent on the amount of available oxygen. Another fact supporting the hypothesis is the extinction or the change of the giant insect forms at the end of the Permian, when the level of atmospheric oxygen suddenly decreased. This thesis also describes the ecological relationships of the Late Paleozoic arthropods, which is clearly connected to the evolution of giant forms. Gigantism during this period was thus developed by the interplay of several factors related to the global elements cycles. Another part covers major groups and representatives of Palaeozoic gigantic insects and other arthropods. The final part is devoted to describing the physiological experiments related to this topic

New palaeodictyopterans from the Late Carboniferous of the UK (Insecta: Palaeodictyopteroida)

New palaeodictyopterans, Vernooijia sassoonae gen. et sp. nov. (Breyeriidae) and Mazonopterum cooperi sp. nov. (Homoiopteridae) are described from the Middle Pennsylvanian (Westphalian D/Late Asturian) of Writhlington, near Radstock (UK). Based on the re-examination of venation in Breyeria harlemensis, we propose the transfer of this species to the genus Vernooijia as V. harlemensis (Brauckmann & Gröning, 1996) comb. nov. We report the first record of Homaloneura sp. (Spilapteridae) from the Langsettian to Duckmantian of Coseley, Staffordshire. Additionally, we report a fragmentary wing from the Middle Pennsylvanian (late Westphalian D/early Cantabrian) of the Forest of Dean, Gloucestershire, tentatively belonging to the Lycocercidae. Our re-examination of a putative blattodean nymph described by Rolfe (1967) allows re-assignment to Palaeodictyoptera, as it has well-developed wing pads with a corrugated pattern of probably original tracheation and lacunal channels, identified as presumably nymphal exuvia of Idoptilus sp. Surprisingly, our study reveals the presence of three triangular caudal appendages bearing prominent lateral lamellae emerging from the terminal abdominal segment, previously unknown in other nymphs of Palaeodictyoptera. We assume that these lamellae were originally covered with dense setae and possibly represent modified caudal appendages in the form of tracheal gills, as known in the nymphs of damselflies (Odonata: Zygoptera). Thus, the scenario of a possible aquatic lifestyle for nymphs of at least some members of Palaeodictyoptera, as considered by Brongniart (1885, 1893) and Handlirsch (1906), cannot be definitely excluded

Additional file 3: of Redefining the extinct orders Miomoptera and Hypoperlida as stem acercarian insects

Nexus file used for the phylogenetic analysis. (NEX 9 kb

Additional file 1: of Redefining the extinct orders Miomoptera and Hypoperlida as stem acercarian insects

Phylogenetic analysis and list of characters. (DOC 81 kb