Banksia strahanensis

taxobox
name = "Banksia strahanensis"
fossil_range = Early - Middle Pleistocene
regnum = Plantae
unranked_divisio = Angiosperms
unranked_classis = Eudicots
ordo = Proteales
familia = Proteaceae
genus = "Banksia"
subgenus = "Banksia" subg. "Banksia"
sectio = "Banksia" sect. "Oncostylis"
series = "Banksia" ser. "Spicigerae"
species = "B. strahanensis"
binomial = "Banksia strahanensis"
binomial_authority = Jordan & Hill|

"Banksia strahanensis" is an extinct species of tree or shrub in the plant genus "Banksia". It is known only from a fossil leaf and several fossil leaf fragments found in Early to Middle Pleistocene sediment at Regatta Point in western Tasmania. These are long and very narrow, with entire margins, superficially resembling leaves of the extant "B. spinulosa" (Hairpin Banksia).

The fossils clearly belong to genus "Banksia", section "Oncostylis", series "Spicigerae", the only difficulty being that all "Oncostylis" taxa have a visible network of veins on the upper leaf surface, whereas the fossil leaves appear not to. They are most similar to the leaves of "B. spinulosa", differing only in the absence of surface venation; a longer petiole; and the combination of narrow leaves with hairless undersides (all forms of "B. spinulosa" with leaves as narrow as those of "B. strahanensis" have hairy undersides). Because of these differences, the fossils are considered a separate species. The species is believed to represent an extinct lineage; it is unlikely to be an ancestor of any extant "Banksia" species, as the absence of leaf surface venation is thought to be an adaptation rather than a primitive state. Extinction was probably caused by the climatic and physical disruption of the Early Pleistocene Glaciations.

The fossils of "B. strahanensis" were discovered in sediment at Regatta Point during the early 1980s. A formal description was published in 1991 by Gregory J. Jordan and Robert S. Hill, who named the species after the nearby town of Strahan. Hence the species' full name is "Banksia strahanensis" Jordan & Hill". The holotype and a number of other specimens are stored in the Department of Plant Science at the University of Tasmania.

References

*cite journal | author = Jordan, Gregory J. and Robert S. Hill | year = 1991 | title = Two New "Banksia" Species from Pleistocene Sediments in Western Tasmania | journal = Australian Systematic Botany | volume = 4 | issue = 3 | pages = 499–511 | url = http://www.publish.csiro.au/?act=view_file&file_id=SB9910499.pdf | accessdate = 2006-08-28 | doi = 10.1071/SB9910499