The Cyclopteris of Laveineopteris (Late Carboniferous pteridosperm). Fancies and facts: methodological and taxonomical implications

Abstract

Cyclopterid folioles commonly borne on the fronds of Late Carboniferous neuropterid plants were recently interpreted as entire shade leaves that were, among the taxa exhibiting a neuropteroid pinnate foliage, only present in the medullosalean genus Laveineopteris. Numerous speculations concerning the physiology, growth habit, ecology and the reconstruction of the Laveineopteris plant were derived from this assertion. It is shown in this paper that this assertion is inaccurate. Cyclopterids are not entire leaves. They are heteromorphic folioles confined to the fronds, and mainly located in the proximal parts of them. They are homologous to ultimate pinnae sometines being slightly bipinnatifid at the base. In addition to a photosynthetic role, cyclopterids were also playing a protective role for the circinately coiled pinnate foliage segments during the early differentiation of the fronds. It is also shown that cyclopterids are not restricted to the sole genus Laveineopteris among the neuropterids. The cuticular information on which several recent taxonomic treatments of the neuropterids were based is critically analyzed and found inadequate. The diagnoses of several neuropterid taxa are emended