First data on the leaf cuticle ultrastructure of the Mesozoic genus Pseudotorellia Florin

Abstract

In this paper we present the first data on the cuticle ultrastructure of leaves of Pseudotorellia – a genus of Mesozoic gymnosperms, attributed by various authors to either ginkgoaleans or conifers, or related to either corystosperms or peltasperms. An ultrastructural transmission electron microscope (TEM) study of Pseudotorellia asiatica Nosova et Kiritchkova and P. samylinae Nosova et Kiritchkova from the Toarcian (Lower Jurassic) of the Mangyshlak Mountains (Kazakhstan) was conducted. The cuticular membrane of Pseudotorellia leaves belongs to the type 1 of the cuticle classification: it is made up of the cuticle proper (composed of an outer polylamellate layer and an inner granular and homogeneous layer) and a cuticular fibrillate layer. The polylamellate layer has parallel, sometimes wavy translucent lamellae alternating with opaque lamellae in the upper part, and 1–3 rows of dispersed translucent lamellae in some fragments of the lower part. The studied Pseudotorellia species differ from each other in the thickness of the leaf cuticular membrane, the ratio of the thickness of the cuticle proper and of the cuticular layer, the thickness and features of the polylamellate layer. The fine details of the Pseudotorellia cuticle are compared to those in ginkgoaleans, leptostrobaleans and conifers.