New cockroach assemblage from the Lower Cretaceous Kitadani Formation, Fukui, Japan

Abstract

Despite nearly global occurrence of cockroaches in the Cretaceous, such fossil record had been absent in Japan. Here, we describe the first Cretaceous cockroach assemblage of Japan from the Lower Cretaceous of Fukui, central Japan. The assemblage includes Praeblattella inexpecta sp. n., Praeblattella arcuata sp. n., Petropterix fukuiensis sp. n., ?Vitisma sp., and ?Morphna sp. from the AptianAlbian Kitadani Formation, Tetori Group. The Cretaceous Praeblattella-Petropterix-Vitisma assemblage in the Kitadani Formation is comparable to those in the Dzun-Bain Formation of Bon Tsagaan Nuur, Mongolia, and the Zaza Formation of Baissa, Russia, while being in contrast to the one in the Yixian Formation of Liaoning, northeastern China. It may indicate that such assemblages typify the cockroach fauna adapted to shifting humidity conditions. Additionally, ?Morphna sp. from the Kitadani Formation represents the earliest record of the family Blaberidae. The present study facilitates our understanding about the global distributions of the diverse Cretaceous cockroaches in Laurasia and adjacent areas.