Mummified Leaves of Two New Species of Myrtaceae From the Eocene of Victoria, Australia

Abstract

Leaf collections made from Lenses A and B of Pit II at the Eocene Alcoa Anglesea locality produced the first Eocene record of mummified leaves of the Myrtaceae. In order to determine their diversity and affinities a set of 19 architectural and cuticular characters was selected with which to analyse the leaves. This character set was tested with 65 extant leaves from 11 species of six genera within the Myrtaceae. Operational taxonomic units were analysed using a semi-Euclidian distance metric and the UPGMA clustering algorithm. Results indicated that the character set and analyses successfully clustered all members of each species used, and in the case of Syzygium loosely clustered most species of the genus that were tested. When applied to 34 fossil Myrtaceae leaves, the character sets and analyses revealed that two distinct fossil leaf taxa were present. The organ genus Myrtaciphyllum Christophel & Lys is proposed for mummified leaves with affinities to the Myrtaceae. Two species are erected: the type species M. undulatum, and M. douglasii. The two species are primarily differentiated on cuticular features. The analyses further showed that, in addition to the two fossil groups being distinct from each other, neither demonstrated close affinities with any of the 11 species of extant Myrtaceae used in the analysis. Two fossil Myrtaceae leaves included from the Miocene Bacchus Marsh locality showed moderate affinity to Myrtaciphyllum undulatum.