The Lower Devonian scorpionWaeringoscorpio and the respiratory nature of its filamentous structures, with the description of a new species from the Westerwald area, Germany

Abstract

wl-N 8 fiGUFES AND 1 "IABIE POSCHMANN, M.; DUNLOP, J.A.; KAMENZ, C. & SCHOLTZ, G. 2008. The Lower Devonian scorpion Waeringoscorpio and the respiratory nature of its filamentous structures, with the description of a new species from the Westerwald area, Germany. -Pal~iontologische Zeitschrift 82 (4): 418-436, 8 figs., 1 tab., Stuttgart, 31.12. 2008. Abstract:The fossil scorpion Waeringoscorpio hefteri STORMER, 1970 (Arachnida: Scorpiones) from the Lower Devonian of the Rhenish Massif of Germany is redescribed based on both the original type and newly collected material. A second, more tuberculate species from Siegenian strata near BiJrdenbach in the Westerwald (also part of the Rhenish Massif) is described as W. westerwaldensis n. sp. Details of the coxo-stemal region -including the lack of an oral tube -and the number of ventral mesosomal plates are discussed. Waeringoscorpio STORMER, 1970 is I~est known for its possession of extemally-projecting 'gills'. Our new material reveals that these are indeed pair-wise bundles of rigid, branching filaments which originate laterally, quite possibly from those segments of the mesosoma associated with the book lungs in extant scorpions. Their gross morphology is most consistent with a respiratory organ adapted for use in water. Indeed their closest modem analogues are the tracheal gills of secondarily aquatic insects. We suggest that the morphology and likely palaeoenvironment of Waeringoscorpio could indicate an aquatic animal, but we draw attention to the uniqueness of its gill-structures, which may not be part of the scorpion groundpattern. Thus, Waeringoscorpio was perhaps a secondarily aquatic scorpion adapted for benthic life in oxygenstressed, freshwater-brackish environments.Kurzfassung: Der fossile Skorpion Waeringoscorpio hefieri STORMER, 1970 (Arachnida: Scorpiones) aus dem Unterdevon (Emsium) des Rheinischen Schiefergebirges wird anhand des Typusmaterials und weiterer Funde neu beschrieben. Eine zweite, st~irker tuberkulierte Art aus dem Siegenium von Btirdenbach im Westerwald wird als W. westerwaldensis n. sp. beschrieben. Details der Coxo-Stemal-Region -ein Mundvorraum ist nicht ausgebildet -und die Anzahl der ventralen, mesosomalen Platten werden diskutiert. Waeringoscorpio STORMER, 1970 ist aufgrund der Ausbildung seitlich abstehender, mrglicherweise schlauchartiger Filamente am Mesosoma und ihrer mrglichen Funktion als ,,Kiemen" yon besonderem Interesse. Unser neues Material zeigt, dass es sich bei diesen Strukturen um paarige Btindel steifer, sich distad verzweigender Rrhren handelt, die seitlich der mesosomalen Segmente entspringen, welche bei rezenten Skorpionen die Buchhmgen tragen. Ihre ~iuBere Anatomie l~isst sich am ehesten mit einer Funktion als Atmungsorgan, angepasst an ein aquatisches Milieu, in Einklang bringen. Eine bemerkenswert grol3e morphologische Ubereinstimmung zeigen die Tracheenkiemen einiger Larven heutiger, sekund/~r aquatischer Insekten. Morphologie und der wahrscheinliche Lebensraum von Waeringoscorpio weisen auf ein wasserlebende...

Redescription and palaeobiology ofPalaeoscorpius devonicusLehmann, 1944 from the Lower Devonian Hunsrück Slate of Germany

“…External gills were described in Waeringoscorpio hefteri Størmer, 1970, a Lower Devonian scorpion from Alken an der Mosel, Germany. These structures appear to be genuine having been recorded in further specimens (Brauckmann 1987) and in a second species of the genus (Poschmann et al . 2008).…”

“…2008). As noted above, Poschmann et al . (2008) reported filamentous external breathing organs in Waeringoscorpio , but speculated that these scorpions may have been secondarily aquatic, implying that scorpion terrestrialization must have pre‐dated the Lower Devonian.…”

Trigonotarbid arachnids from the Lower Devonian (Siegenian) of Bürdenbach (Lahrbach Valley, Westerwald area, Rhenish Slate Mountains, Germany)

“…The trace fossil ''Spirophyton'' isp., linguloid brachiopods, and the articulate brachiopod Crassirensselaeria crassicosta occur within the sequence, but were not recorded in intimate association with chelicerate arthropods (Poschmann et al 2008).…”

“…In the past decade a number of new promising Fossil Lagerstätten of Siegenian age were detected in the Westerwald area. Among chelicerate arthropods, trigonotarbids and other arachnids were encountered, such as the extinct phalangiotarbids (Poschmann and Jansen 2003;Poschmann et al 2005) and scorpions (Poschmann et al 2008).…”

Scorpion Fragments from the Silurian of Powys, Wales

“…They also note that this provides strong evidence for arach nid monophyly and a single shared terrestrial arachnid ancestor. Highly unusual Lower Devonian Waeringoscorpio may have been secondarily aqua tic as its unique filamentous external organs strongly resemble the tracheal gills of (se condarily) aquatic insects (Poschmann et al 2008;Kühl et al 2012).…”