Alkastrobus Fueyo et S.Archang.

Plant Fossil Names Registry Number: PFN001166

Act LSID: urn:lsid:plantfossilnames.org:act:1166

Authors: G. M. del Fueyo & S. Archangelsky

Rank: genus

Reference: del Fueyo, G. M. & Archangelsky, S. (2005): A new araucarian pollen cone with in situ Cyclusphaera Elsik from the Aptian of Patagonia, Argentina. – Cretaceous Research 26(5): 757–768.

Page of description: 758

Type

Original diagnosis/description

Pollen cones cylindrical, elliptical, sessile, up to 10 mm long and 5 mm wide. Microsporophylls spirally arranged on a central axis 0.5 mm wide; peltate with a pedicel 0.9 mm long and a distal rhomboidal head of 1 × 1.2 mm. Abaxial to the head and parallel to the pedicel, more than six elongate pollen sacs are attached. Microsporophyll tissues consist of: epidermis of the sporophyll head; exothecium, one parietal layer and the peritapetal membrane of the microsporangium. Ubisch bodies present. Cyclusphaera Elsik pollen embedded in the peritapetal membrane, shape discoid, 50–58 μm in diameter, two polar apertures and equatorial thickening present. Exine apparently laevigate under LM but showing granules and spines under SEM. Pollen wall with a sculptured sexine and a lamellate nexine; fully developed in the equatorial areas, thinning towards the apertures. Outer part of the sexine with loosely disposed granules that gradually fuse towards the nexine as irregularly aligned vermiform elements. Nexine composed of at least eight parallel, wavy lamellae.

Etymology

The generic name is a combination of Alka, male (indigenous ‘‘mapuche’’ word from southern South America), and strobus, cone-like.