Austrohamia asfaltensis D.Contr., Escapa, Irib. et Cúneo

Plant Fossil Names Registry Number: PFN003160

Act LSID: urn:lsid:plantfossilnames.org:act:3160

Authors: D. Contreras, I. H. Escapa, R. Iribarren & N. R. Cúneo

Rank: species

Genus:

Reference: Contreras, D., Escapa, I. H., Iribarren, R. & Cúneo, N. R. (2019): Reconstructing the Early Evolution of the Cupressaceae: A Whole-Plant Description of a New Austrohamia Species from the Cañadón Asfalto Formation (Early Jurassic), Argentina. – International Journal of Plant Sciences 180(8): 834–868., link

Page of description: 837

Illustrations or figures: figs 3-8

Types

Original diagnosis/description

Branching alternate to subopposite. Leaves helically arranged, decurrent, with single midvein, entire margins, apexes mostly rounded. Free portion of blade lanceolate to oblong or slightly tapering, departing from shoot at angles up to 907, curving or twisting at base to orient blades in roughly one plane. Epidermal cells rectangular, elongate, in longitudinal files, with straight walls. Stomata in two bands on either side of the midvein. Pollen cones arranged in clusters, with up to five cones. Each pollen cone borne in axil of broadly ovate bract with acute apex. Pollen cones ovate to elliptic in shape, consisting of a central axis surrounded by helically arranged, imbricate microsporophylls. Microsporophylls consist of a narrow stalk broadening to an upturned, ovate distal lamina. Pollen sacs elongate-elliptic, attached at the base of the distal lamina, and oriented parallel to the microsporophyll stalk. Seed cones terminal on penultimate or ultimate shoots, greater than 1.5 cm long at maturity, with helically arranged, imbricate ovuliferous complexes. Ovuliferous complexes do not show a morphological distinction between bract and ovuliferous scale. Each ovuliferous complex coriaceous and bifacially flattened, with a narrow stalk and a broadly ovate distal face, an acuminate apex, and a prominent abaxial keel extending from the base to the tip of each bract. Each ovuliferous complex bears two inverted ovules/seeds on the adaxial surface, positioned medially to slightly distally on the complex. Ovules/seeds elliptic, narrowed slightly toward the micropylar end.

Etymology

The specific epithet refers to the Cañadón Asfalto Formation, which yields the plant fossils.

Stratigraphy

Jurassic, Lower Jurassic, Toarcian
Cañadón Asfalto Formation in the Cañadón Asfalto Basin; Early Jurassic, ~179 Ma.

Locality

Argentina
Sitio Frenguelli.