A new Early Devonian palaeozygopleurid gastropod from the Prague Basin (Bohemia) with notes on the phylogeny of the Loxonematoidea

A new palaeozygopleurid gastropod, Palaeozygopleura vaneki sp. nov., is described from the Emsian Chynice Limestone (Novakia elegans Zone, upper part of the Zlichov Formation; late Early Devonian) of the Prague Basin (Bohemia). The phylogeny of the superfamily Loxonematoidea and the origin of planktotrophy are briefly discussed. It is suggested that the large protoconchs of the Palaeozy gopleuridae and Loxonematidae might represent a grade before the inception of planktotrophy.