ON THE TAXONOMY OF THE GENUS TRITAENIA MäGDEFRAU ET RUDOLF (CONIFERALES), WITH DESCRIPTIONS OF NEW SPECIES

Abstract

Conifers of the genus Tritaenia Mägdefrau et Rudolf are reported for the first time from European Russia. The locality of Peski (Middle Jurassic, Moscow Region) contains two newly described species, T. striata sp. nov. and T. glabra sp. nov. A comparison with the members of this genus from the type localities in western Europe (T. linkii Mägdefrau et Rudolf from the Lower Cretaceous of Osterwald in Germany and T. scotica (Van der Burg et Van Konijnenburg-Van Cittert) Wilde from the Upper Jurassic of Scotland) has shown that the leaf outline, number of stomatal bands, orientation of stomata, and development of encircling cells vary within species, and their ranges of variation overlap in close species. The relief of the outer surface of the lower epidermis is crucial for specific differentiation. The presence of resin ducts can be considered as a constant character in Tritaenia. On the basis of epidermal characters, Tritaenia is compared with the Podocarpaceae.