MCKOWN, ATHENA D.1*, RUTH A. STOCKEY2, and CHARLES E. SCHWEGER3. 1Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada; 2Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada; 3Department of Anthropology, University of Alberta, Edmonton, AB, T6G 2E9, Canada. - A new species of Pinus, Subgenus Pinus, Subsection Contortae based on fossil cones from Ch'ijee's Bluff, Yukon Territory, Canada.
Three structurally preserved conifer ovulate cones are described from
the Pliocene sediments of Ch'ijee's Bluff on the Porcupine River, near
Old Crow, Yukon Territory. Cones are ovoid to conical, symmetrical,
3.4-4.4 cm and 2.8-3.4 cm wide. Ovuliferous scales are woody, 2 cm
long and 1 cm wide, with a minute dorsal umbo. Bracts are 6 mm long,
lack an abaxial lobe and contain a single terete trace accompanied by
two resin canals. The pith is parenchymatous with few scattered
sclerenchyma cells near its outer margin. Vascular tissue consists of
a continuous cylinder of secondary xylem with few resin canals. The
inner cortex is parenchymatous and contains between 12 – 15 resin
canals of uniform diameter. The outer cortex is also parenchymatous
with a thin layer of sclerenchyma at its outer edge. Vascular tissues
in the ovuliferous scale and bract originate as single, continuous
cylindrical strands from the axis stele and diverge in the outer
cortex. The abaxially concave ovuliferous scale trace splits into
separate vascular bundles that alternate with resin canals in the most
distal sections. Paired ovules on the ovuliferous scales are smooth,
elliptical in shape, 2.7-3.9 mm long and 2.1-2.5 mm wide. Seed wings
are detachable, 16 mm long and have a basal parenchymatous pad. Some
megagametophyte tissue is preserved however, no embryos were found.
Fossils were compared to extant species of Pinus Section
Pinus and most closely resemble those of Pinus contorta
Dougl. ex Loud. Symmetrical cone shape, non-reflexed cone base,
flattened apophyses, cone serotiny and seed wing length distinguish
the fossil cones from the extant subspecies and fossils of P.
contorta. The fossil cones will be described in a new species
of Pinus, Subgenus Pinus, Subsection Contortae.
Key words: fossil conifers, Pinaceae, Pinus contorta, Pliocene, Yukon Territory