New Carboniferous fossils of Spilapteridae enlighten postembryonic wing development in Palaeodictyoptera

Abstract

Abstract A new palaeodictyopterid nymph Bizarrea obscura gen.n. et sp.n. ( S pilapteridae) and a new adult specimen of Homaloneura cf. dabasinskasi C arpenter are described from the P ennsylvanian ( M oscovian) ironstone nodules of M azon C reek (IL, U.S.A. ). Both taxa share enlarged prothoracic lobes (interpreted by some as winglets), heteronomous meso‐ and metathoracic wing pads or wings, a slender abdomen with pointed laterotergites, and a unique division of the abdominal segments by two transverse sulci. An alternative hypothesis for the placement of Bizarrea within H omoiopteridae is considered on the basis of its large body size and relatively short wing pads. Based on the morphology of the new material, postembryonic development of wing pads in P alaeodictyoptera ( P alaeodictyopterida) is reconsidered. Detailed investigation of the abdominal segments, including examination by scanning electron microscopy, reveals the presence of subcircular, sclerotized structures partially covered at the bases of the nymphal laterotergites I–VII, ? VIII . Based on their position and shape, these structures are interpreted as abdominal spiracles, and thus a terrestrial or semiaquatic habitat for these immatures is hypothesized. Moreover, our discovery of the same, supposedly homologous structures in the enigmatic V ogesonymphidae ( P ermoplectoptera), from the M iddle T riassic of G rès à V oltzia in F rance, is evidence for the parallel coexistence of ancestrally terrestrial and derived aquatic lineages of E phemerida ( E phemeropterida) in early M esozoic ecosystems. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:A7270D99‐5B48‐4EAC‐AEB8‐EFB8A9F55FBD .