Palaeogene leaf compressions of myrtaceous affinity from Pasekovo, Middle Russian Upland, southern European Russia

Abstract

Leaf compressions from Pasckovo, Voronezh oblast, a Late Eocene site, constitute the first record of mummified ‘paper coal’ leaves of myrtaceous affinity in Russia. The fossil leaves are assigned to the organ-genus Rhodomyrtophyllum Rüffle & Jähnichen (Myrtaceac) on the basis of epidermal and venation features. The exceptionally high level of preservation is illustratcd by LM and SEM reproductions of anomo-, anomostauro- and laterocytic stomatal sets including giant stomata, double cuticular rims, trichome bases (scars) and a buttressed structure of the epidermal cell wall. Leaf structure is mesoxeromorphic. In both western and eastern Europe, species of the genus do not post-date the terminal Eocene and are the index taxa for the middle to late Eocene interval. The newly described Russian species R.pasekovicum Vikulin, sp.nov. is considered against the background of British, German and Czech extinct species along with comparisons with possible ‘nearest living relatives’ which include mesoxeromorphic Eugenia L., Syzygium Gartn.and Rhodomyrtus DC, from South-East Asia, Australia and South America. Ancient Tethys-ocean migrational channels may explain European palacofloristic relations with the Australo-Malesian area during Eocene time S. A later Eocene age is postulated of the Pasekovo palaeoflora in contrast to the early Oligocene age suggested by other authors.