Classostrobus doylei, a new cheirolepidiaceous cone with in situ pollen from the Figueira da Foz Formation (lower Aptian – upper Albian), western Portugal

Abstract

The genus Classostrobus was established to accommodate unattached Classopollis-containing cones. It is noteworthy that Classopollis as a whole shows significant variation in morphological structure, and male cones bearing Classopollis pollen grains are rarer than vegetative organs of cheirolepidiaceous conifers. A new cheirolepidiaceous microsporangiate cone, Classostrobus doylei, containing Classopollis triangulus pollen grains is described for the first time based on a single specimen from sedimentary rocks exposed in the Carregueira open-cast clay pit complex close to the small village of Juncal, in the Estremadura region, (Lusitanian Basin, western Portugal). The plant-bearing horizon from Carregueira is included in the basal part of the Famalicão Member of the Figueira da Foz Formation, considered to be of late Aptian – early Albian age. The new microsporangiate cone is small, about 2.0 mm long and 1.5 mm wide, ovoid in shape and of typically coniferous structure, probably belonging to Pseudofrenelopsis zlatkoi. The male cone consists of about 16 peltate, imbricated microsporophylls of deltoid shape. Each sporophyll is composed of a stalk and deltoid head showing abaxially 4-5 ovoid pollen sacs. The marginal parts of the sporophylls display long and unicellular trichomes. The observed in situ pollen grains are triangular to subcircular in outline, 16-28 μm in diameter, with an equatorial girdle, subequatorial rimula, proximal trilete scar and a distal cryptopore. The pollen ultrastructure is typical for Classopollis, except for the destroyed condition of the exine. The in situ pollen grains under study are consistent with the data on known dispersed Classopollis triangulus.