Phytolith analysis in leaves of extant and fossil populations of Nothofagus subgenus Lophozonia

Abstract

The phytolith morphology of leaves of all six extant species, one fossil species and a fossil population of an extant species of Nothofagus subgenus Lophozonia was examined to determine the utility of phytolith morphology for phylogenetic studies. One extant species of subgenus Fuscospora (N. gunnii (Hook.f.) Oerst.) was included to allow a comparison between subgenera. Phytolith morphology and frequency in subgenus Lophozonia is quite similar among the extant evergreen species, and clearly distinguishes the evergreen from the deciduous species rather than reflecting subgeneric differences. However, the deciduous species are not particularly similar to one another, which may be due to their phylogenetic distance by comparison to the closely related evergreen species. The Early-Middle Pleistocene population of Nothofagus cunninghamii (Hook.f.) Oerst. had well preserved phytoliths, which in morphology and relative abundance were consistent with the extant species. However, the leaves of the Oligocene population of N. tasmanica R.S. Hill had poorly preserved phytoliths, which were relatively sparse and lacking in diversity. This is probably at least partly a result of taphonomic processes, but may also reflect phylogenetic differences.