@article {447, title = {The tracheal system of scutigeromorph centipedes and the evolution of respiratory systems of myriapods}, journal = {Arthropod Structure \& Development}, volume = {60}, year = {2020}, month = {26/11/2020}, pages = {1-14}, abstract = {

The tracheal system of scutigeromorph centipedes (Chilopoda) is special, as it consists of dorsally arranged unpaired spiracles. In this study, we investigate the tracheal systems of five different scutigeromorph species. They are strikingly similar to each other but depict unique characters compared to the tracheal systems of pleurostigmophoran centipedes, which has engendered an ongoing debate over a single versus independent origin of tracheal systems in Chilopoda. Up to now, only the respiratory system of Scutigera coleoptrata was investigated intensively using LM-, TEM-, and SEM-techniques. We supplement this with data for species from all three families of Scutigeromorpha. These reveal interspecific differences in atrial width and the shape and branching pattern of the tracheal tubules. Further, we investigated the tracheal system of Scutigera coleoptrata with three additional techniques: light sheet microscopy, microCT and synchrotron radiation based microCT analysis. This set of techniques allows a comparison between fresh versus fixed and dried material. The question of a unique vs. multiple origin of tracheal systems in centipedes and in Myriapoda as a whole is discussed with regard to their structural similarities and differences and the presence of hemocyanin as an oxygen carrier. We used morphological and molecular data and the fossil record to evaluate the alternative hypotheses.

}, keywords = {Chilopoda, Evolution, Notostigmophora, Terrestrialization, tracheal system}, issn = {1467-8039}, doi = {10.1016/j.asd.2020.101006}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1467803920301298}, author = {Hilken, Gero and Rosenberg, J{\"o}rg and Edgecombe, Gregory D. and Bl{\"u}ml, Valentin and Hammel, J{\"o}rg U. and Hasenberg, Anja and Sombke, Andy} } @article {420, title = {A new Devonian euthycarcinoid reveals the use of different respiratory strategies during the marine-to-terrestrial transition in the myriapod lineage}, journal = {Royal Society Open Science}, volume = {7}, year = {2020}, month = {21/10/2020}, pages = {1-9}, abstract = {

Myriapods were, together with arachnids, the earliest animals to occupy terrestrial ecosystems, by at least the Silurian. The origin of myriapods and their land colonization have long remained puzzling until euthycarcinoids, an extinct group of aquatic arthropods considered amphibious, were shown to be stem-group myriapods, extending the lineage to the Cambrian and evidencing a marine-to-terrestrial transition. Although possible respiratory structures comparable to the air-breathing tracheal system of myriapods are visible in several euthycarcinoids, little is known about the mechanism by which they respired. Here, we describe a new euthycarcinoid from Upper Devonian alluvio-lagoonal deposits of Belgium. Synchrotron-based elemental X-ray analyses were used to extract all available information from the only known specimen. Sulfur X-ray fluorescence (XRF) mapping and spectroscopy unveil sulfate evaporation stains, spread over the entire slab, suggestive of a very shallow-water to the terrestrial environment prior to burial consistent with an amphibious lifestyle. Trace metal XRF mapping reveals a pair of ventral spherical cavities or chambers on the second post-abdominal segment that do not compare to any known feature in aquatic arthropods, but might well play a part in air-breathing. Our data provide additional support for amphibious lifestyle in euthycarcinoids and show that different respiratory strategies were used during the marine-to-terrestrial transition in the myriapod lineage.

}, keywords = {air-breathing, fossil arthropods, synchrotron radiation, Terrestrialization, X-ray fluorescence imaging, X-ray spectroscopy}, issn = {2054-5703}, doi = {10.1098/rsos.201037}, url = {https://royalsocietypublishing.org/doi/10.1098/rsos.201037}, author = {Gueriau, Pierre and Lamsdell, James C. and Wogelius, Roy A. and Manning, Phillip L. and Egerton, Victoria M. and Bergmann, Uwe and Bertrand, Lo{\"\i}c and Denayer, Julien} } @article {300, title = {Aquatic stem group myriapods close a gap between molecular divergence dates and the terrestrial fossil record}, journal = {Proceedings of the National Academy of Sciences}, volume = {117}, year = {2020}, month = {06/04/2020}, pages = {8966 - 8972}, abstract = {

Identifying marine or freshwater fossils that belong to the stem groups of the major terrestrial arthropod radiations is a longstanding challenge. Molecular dating and fossils of their pancrustacean sister group predict that myriapods originated in the Cambrian, much earlier than their oldest known fossils, but uncertainty about stem group Myriapoda confounds efforts to resolve the timing of the group\’s terrestrialization. Among a small set of candidates for membership in the stem group of Myriapoda, the Cambrian to Triassic euthycarcinoids have repeatedly been singled out. The only known Devonian euthycarcinoid, Heterocrania rhyniensis from the Rhynie and Windyfield cherts hot spring complex in Scotland, reveals details of head structures that constrain the evolutionary position of euthycarcinoids. The head capsule houses an anterior cuticular tentorium, a feature uniquely shared by myriapods and hexapods. Confocal microscopy recovers myriapod-like characters of the preoral chamber, such as a prominent hypopharynx supported by tentorial bars and superlinguae between the mandibles and hypopharynx, reinforcing an alliance between euthycarcinoids and myriapods recovered in recent phylogenetic analysis. The Cambrian occurrence of the earliest euthycarcinoids supplies the oldest compelling evidence for an aquatic stem group for either Myriapoda or Hexapoda, previously a lacuna in the body fossil record of these otherwise terrestrial lineages until the Silurian and Devonian, respectively. The trace fossil record of euthycarcinoids in the Cambrian and Ordovician reveals amphibious locomotion in tidal environments and fills a gap between molecular estimates for myriapod origins in the Cambrian and a post-Ordovician crown group fossil record.

}, keywords = {Arthropoda, euthycarcinoid, molecular dating, Myriapoda, Terrestrialization}, issn = {0027-8424}, doi = {10.1073/pnas.1920733117}, url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1920733117}, author = {Edgecombe, Gregory D. and Strullu-Derrien, Christine and G{\'o}ral, Tomasz and Hetherington, Alexander J. and Thompson, Christine and Koch, Markus} } @article {65, title = {Carboniferous Onychophora from Montceau-les-Mines, France, and onychophoran terrestrialization}, journal = {Invertebrate Biology}, volume = {135}, year = {2016}, month = {Jan-09-2016}, pages = {179 - 190}, abstract = {

The geological age of the onychophoran crown-group, and when the group came onto land, have been sources of debate. Although stem-group Onychophora have been identified from as early as the Cambrian, the sparse record of terrestrial taxa from before the Cretaceous is subject to contradictory interpretations. A Late Carboniferous species from the Mazon Creek biota of the USA, Helenodora inopinata, originally interpreted as a crown-group onychophoran, has recently been allied to early Cambrian stem-group taxa. Here we describe a fossil species from the Late Carboniferous Montceau-les-Mines Lagerst\ätte, France, informally referred to as an onychophoran for more than 30 years. The onychophoran affinities of Antennipatus montceauensis gen. nov., sp. nov. are indicated by the form of the trunk plicae and the shape and spacing of their papillae, details of antennal annuli, and the presence of putative slime papillae. The poor preservation of several key systematic characters for extant Onychophora, however, prohibits the precise placement of the Carboniferous fossil in the stem or crown of the two extant families, or the onychophoran stem-group as a whole. Nevertheless, A. montceauensis is the most compelling candidate to date for a terrestrial Paleozoic onychophoran.

}, keywords = {Antennipatus montceauensis gen. nov. sp. nov., Carboniferous, Ecdysozoa, fossils, Onychophora, Terrestrialization, velvet worms}, issn = {1744-7410}, doi = {10.1111/ivb.12130}, url = {http://doi.wiley.com/10.1111/ivb.12130}, author = {Garwood, Russell J. and Edgecombe, Gregory D. and Charbonnier, Sylvain and Chabard, Dominique and Sotty, Daniel and Giribet, Gonzalo} }