Elaborating the fossil history of Banksiinae: A new species of Banksieaephyllum (Proteaceae) from the late paleocene of New South Wales

Leaf fragments from Late Paleocene sediments at Cambalong Creek in the Sout hern Highlands of New South Wales are assigned to a new species of Banksiea ephyllum Cookson & Duigan, B. praefastigatum. A study of leaf form and micr omorphological characters of extant Banksieae was carried out to identify p ossible affinities for the new taxon, and a compendium of the architectural and micromorphological characters of leaves of all described species of Ba nksieaephyllum and Banksieaeformis Hill & Christophel is presented. Banksie aephyllum praefastigatum has characteristic stomatal and trichome features of both extinct and extant species of Banksiinae, bur is dissimilar in leaf morphology to any extant species of Banksia L.f., Dryandra R.Br., or the o ldest previously described species of Banksieaephyllum, B. taylorii Carpent er, Hill & Jordan, with which it was contemporaneous. Banksieaephyllum prae fastigatum, with its strongly developed areolation and superficial stomates , is different from extant species of Banksiinae and Musgraveinae, and may represent a now-extinct sister taxon to these subtribes in Banksieae, one w hich had not changed substantially from hypothesised mesophytic ancestral P roteaceae. Leaf morphology of B. praefastigatum indicates that serrate-, lo bed- and entire-margined forms of Banksieaephyllum were coeval in many loca lities throughout southern Australia during the Tertiary, and that Banksiin ae had diversified significantly by the Early Tertiary, reflecting diversif ication of at least several other subtribes of subfamily Grevilleoideae by that time.