Internal gonopod reconstruction in an amber-preserved millipede from the Cretaceous: Laeviglyphiulus patrickmuelleri n. gen., n. sp. (Diplopoda, Spirostreptida, Cambalopsidae)

Abstract Micro computed tomography (µCT) scans allow a 3D reconstruction of characters otherwise hidden in fossil amber specimens. In this study we reveal the male copulatory legs (gonopods) retracted into the body, and other important morphological characters, for a fossil Juliformia millipede. Characters of the male gonopods are essential for the classification of numerous recent millipede groups. This made it previously almost impossible to correctly assign fossil millipedes to a recent taxon, especially in the Juliformia, where the gonopods are often retracted into the body. The millipede specimen analyzed here is preserved in Myanmar amber dating back to the Cretaceous, 98 MYA (± 0.63 MY). Gonopod and mouthpart characters identify the millipede as a member of the order Spirostreptida, family Cambalopsidae, the first known fossil of one of the most diverse extant SE Asians millipede groups. While the gonopods show similarities to the extant genera Hypocambala Silvestri, 1897, Plusioglyphiulus Silvestri, 1923 and Glyphiulus Gervais, 1847, the presence of neither carinate body rings, nor longitudinally striate metazona, nor a flattened leg pair 2, absence of both an enlarged collum and an enlarged leg pair 2 allows us to describe it as a new genus and species, Laeviglyphiulus patrickmuelleri n. gen., n. sp.