The Genus Planoendothyra Reitlinger, 1959 from the Visean–Serpukhovian (Lower Carboniferous) of Eurasia

The morphology of the type genus Planoendothyra Reitlinger, in: Rauser-Chernousova et Fursenko, 1959, family Endothyridae, Brady, 1854, and of some species previously described among the five groups of species of the genus Endothyra identified by Reitlinger (1950, p. 30), based on the shell morphology, from the Middle Carboniferous deposits in the central part of the Russian Platform. The validity of the originally morphological genus Planoendothyra and its first appearance in the Upper Visean–Serpukhovian interval of the Lower Carboniferous are confirmed. The species Planoendothyra aljutovica (Reitlinger), P. minuta (Reitlinger), P. mosquensis (Reitlinger), P. rzhevica (Reitlinger), P. siviniensis (Reitlinger), P. irinae (Reitlinger), P. spirilliniformis (Brazhnikova, Potievskaya) described again and translated (hic) into the composition of the genus Planoendothyra . The species composition of the genus for the Upper Visean–Serpukhov interval of the Lower Carboniferous has been emended. Three groups of species are recognized based on the type of supplementary deposits in the shell. The phylogeny of the genus Planoendothyra Reitlinger, 1959 is discussed.