Shcherbakov D.E. 2015. Permian and Triassic ancestors of webspinners (Embiodea) // Russian Entomol. J. Vol.24. No.3: 187–200 [in English].
Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow, Russia; email@example.com
KEY WORDS: Embiodea, Alexarasniidae, Protorthoptera, Atactophlebiidae, Sheimiidae, Miomoptera, wings, fossil, phylogeny.
ABSTRACT. The extinct family Alexarasniidae known from isolated wings shows several characters considered unique of webspinners, including the radial blood sinus and hyaline intervenal lines, and therefore is assigned to Embiodea as Palembiodea subordo n. In this family, Nikolembia kusnezovi gen. et sp.n. from the terminal Permian (or basal Triassic) of Babiy Kamen’, Kuznetsk Basin and Nestorembia novojilovi gen. et sp.n. from Middle or Late Triassic of Madygen, Kyrgyzstan are described. The latter genus is assigned to Nestorembiinae subfam.n. along with the monobasic Middle Triassic genus Palaeomesorthopteron Aristov, Grauvogel-Stamm et Marchal-Papier, 2011 originally described in the family Mesorthopteridae, order Grylloblattodea. Other pre-Cretaceous fossils related to webspinners are discussed. The webspinner lineage is traceable back via Jurassic Sinembiidae and Late Permian–Triassic Alexarasniidae to the Early–Middle Permian Atactophlebiidae (Protorthoptera s.l.). Some embiid characters are found isolated in several protorthopteran families, including flexible wings with a radial blood sinus in Soyanopteridae and several blood sinuses in Soyaniidae fam.n. (created for Soyania Aristov et Rasnitsyn, 2009 described in Permembiidae Sheimiinae). Pseudosheimia alligans Aristov et Rasnitsyn, 2009 is singled out into Magniscapa gen.n. and its caudal appendages are reinterpreted as two-segmented cerci instead of male gonopods, discarding the argument in favor of assigning Sheimiidae, Letopalopteridae and Permembiidae to Oligoneoptera. The fossil evidence suggests that, contrary to common opinion, the slender body, short legs, enlarged hind femora, oligosegmented cerci, and flexible wings with sinus veins apparently evolved in webspinner ancestors living in confined spaces, long before the gallery-making habit.