Classostrobus arkansensis Axsmith, M.Krings et Waselkov

Plant Fossil Names Registry Number: PFN003130

Act LSID: urn:lsid:plantfossilnames.org:act:3130

Authors: B. J. Axsmith, M. Krings & K. Waselkov

Rank: species

Genus:

Reference for this name: Axsmith, B. J., Krings, M. & Waselkov, K. (2004): Conifer pollen cones from the Cretaceous of Arkansas: implications for diversity and reproduction in the Cheirolepidiaceae. – Journal of Paleontology 78(2): 402–409.

Page of description: 405

Illustrations or figures: 2.3–2.9

Original diagnosis/description

Cones born terminally on Pseudofrenelopsis parceramosa (Fontaine) Watson, 1977 shoots; microsporophylls helically arranged, semipeltate to dorsiventral, expanded distal head rhomboidal with acute to slightly rounded apex, lateral margins entire to scarious, often with patches of prominent unicellular trichomes at widest point; pollen sac(s) large, probably two(?), attached along abaxial surface of sporophyll stalk and proximal region of head inner surface. Abaxial cuticle of microsporophyll head thin, cutinized hypodermis absent, epidermal cells of central area in head generally isodiametric, each bearing one hollow, thick-walled papilla with rounded apex; abaxial cuticle of microsporophyll head marginal region with rows of elongate cells radiating to all margins; stomata mostly confined to papillate region, in regular to somewhat irregular rows, guard cells slightly sunken, surrounded by five to seven papillate subsidiary cells, papillae typically overarching stomatal opening. In situ Classopollis-type pollen with thickened equatorial belt bearing seven to 12 internal striations, external sculpture of pollen and orbicules consisting of short spinules, often with recurved tips.

Etymology

The specific epithet "arkansensis" honors the state of Arkansas, source of the described specimens.

Stratigraphy

Cretaceous, Lower Cretaceous
the Holly Creek Formation, Trinity Group (Lower Cretaceous - Aptian/Albian boundary)

Locality

United States
the James Hardie Gypsum Quarry, 25 km north of the town of Nashville, Howard County, south- western Arkansas. GPS coordinates: N 34°04.934' W
93°50.847'