Buarcospermum tetragonium E.M.Friis, K.R.Pedersen et P.R.Crane

Plant Fossil Names Registry Number: PFN002849

Act LSID: urn:lsid:plantfossilnames.org:act:2849

Authors: E. M. Friis, K. R. Pedersen & P. R. Crane

Rank: species

Genus: Buarcospermum E.M.Friis, K.R.Pedersen et P.R.Crane

Reference: Friis, E. M., Pedersen, K. R. & Crane, P. R. (2009): Early Cretaceous mesofossils from Portugal and eastern North America related to the Bennettitales-Erdtmanithecales-Gnetales group. – American Journal of Botany 96(1): 252–283.

Page of description: 254

Illustrations or figures: figs 1–28

Name is type for

Types

Original diagnosis/description

Seeds small, radially symmetrical, broadly ovoid, micropylar region pointed; four-angled in cross section. Integument thin, micropylar tube long, narrow. Integument enclosed by a seed envelope, except for the micropylar opening, and attached to the envelope only at the base. Nucellus thin, enclosed by the integument; nucellus free distally, otherwise fused to the integument. Micropyle open at the apex. Below, micropylar closure distinct, multicellular, formed mainly from a layer of larger cells that are expanded radially toward the center of the micropylar tube. Inner surface of seed envelope smooth, nonpapillate; outer surface smooth. Seed envelope with an inner and outer sclerenchyma layer. Inner sclerenchyma layer continuous around the integument and surrounding the micropylar tube; circular in transverse section around micropylar tube, but four-angled below with four narrow wing-like crests radiating through the outer sclerenchyma layer to the surface and dividing it into four valves. Inner sclerenchyma layer almost circular in transverse section in the middle of the seed. Cells long, fi brous arching upwards in a chevron pattern and forming longitudinal ridges toward the outside. Arches short, formed by the fi bers. Cells of outer sclerenchyma layer short, irregularly arranged. Demarcation between inner and outer sclerenchyma layers irregular, with a transitional zone of open spaces.

Etymology

Referring to the four-angled shaped of the seeds.

Stratigraphy

Cretaceous, Lower Cretaceous
Calvaria Member, Figueira da Foz Formation; late Aptian or early Albian

Locality

Portugal
Buarcos, Northwest of Figueira da Foz (40°09′54˝N, 8°52′11˝W)