Identifying fossil Myrtaceae leaves: the first described fossils of Syzygium from Australia.

PREMISE OF THE STUDY: Although leaves of Myrtaceae are easily identified to family level, very few studies have convincingly identified fossil Myrtaceae leaves to living genera. We used a broadly comparative approach with a large data set of extant taxa to confidently assign the mummified remains of myrtaceous leaves from early Miocene sediments at Kiandra (New South Wales, Australia) to a living genus. METHODS: Fossils were identified using a nearest living relative approach, against a database of 232 extant broadleaf rainforest species of Myrtaceae. Leaf cuticles were prepared from 106 species, sourced from herbarium specimens as well as some living individuals, and a further 127 records were assembled from the literature. A set of simple but phylogenetically informative cuticular characters were observed, described, and recorded under both scanning electron microscopy and standard light microscopy. KEY RESULTS: A new fossil species of Syzygium Gaertn. is described from mummified remains found in early Miocene (21.5-21.7 Ma) sediments. The fossil taxon is here named Syzygium christophelii sp. nov., in honor of the late Australian paleobotanist David Christophel. CONCLUSIONS: These fossils represent some of the most confidently described Myrtaceae leaf fossils published to date and are the first and oldest described fossil record of Syzygium from Australia. While several fossil parataxa have been illustrated from New Zealand, and several fossil species of Syzygium have previously been proposed in the literature, many of these fossils lack characters for a confident diagnosis.

Early Oligocene Callitris and Fitzroya (Cupressaceae) from Tasmania.

This paper documents Early Oligocene fossilized foliage and ovulate cones from Lea River, Tasmania and identifies them as belonging to two extant southern hemisphere Cupressaceae genera, Callitris and Fitzroya. Most importantly, it sheds some light on evolutionary trends within Callitris, a genus with numerous extant Australian species and two extant New Caledonian species. Callitris has a very poor fossil record and, because of the present absence of a molecular data set that includes all species, its phylogeny remains somewhat ambiguous. Although Fitzroya foliage has previously been described from a number of Tasmanian sites, this is the first recording of fertile material. The ovulate cones of the Callitris and Fitzroya macrofossils are characterized by bract-scale complexes in two whorls of three and are subtended by scale-like leaves in whorls of three. The fossilized foliage specimens consist of scale-like leaves in whorls of three. These morphological characteristics are only exhibited by three extant southern hemisphere cupressaceous genera, Callitris, Actinostrobus, and Fitzroya. The assignment of the fossils to extinct Callitris and Fitzroya species is made by comparisons with species from these three extant genera. Although much of the Lea River flora are wet rainforest taxa, the Callitris fossils have characteristics of both wet- and dry-adapted extant species.