Morphology of the ovarioles and the mode of oogenesis of Arixenia esau support the inclusion of Arixeniina to the Eudermaptera

Abstract

The Dermaptera is a small insect order, traditionally divided into three separate taxa: the Hemimerina, Arixeniina and Forficulina. The first two suborders are highly modified and adapted for epizoic (ectoparasitic) life conditions. Recent morphological and molecular analyses have suggested that the Hemimerina and Arixeniina should be placed among the most derived subgroup of the Forficulina, the Eudermaptera.Here we present the results of the histological and EM analyses of oogenesis and ovariole structure/ultrastructure in a representative of Arixeniina, Arixenia esau. We show that the studied species shares several important “ovariolar” characters with derived earwigs (Forficulidae). We believe that this finding reinforces the inclusion of the Arixeniina to the Eudermaptera. Our studies indicate additionally that the vitellogenic and postvitellogenic oocytes of A. esau show interesting features that can be interpreted as the adaptations to viviparity, and consequently epizoic life conditions. Thus, the oogenesis of A. esau exemplifies unique mixture of the characters shared with derived earwigs (Forficulidae) and adaptations to the viviparity.