Mayoa portugallica E.M.FRIIS, K.R.PEDERSEN et P.R.CRANE, 2004

Friis, Else Marie, Crane, Peter R. & Pedersen, Kaj Raunsgaard, 2019, The Early Cretaceous Mesofossil Flora Of Torres Vedras (Ne Of Forte Da Forca), Portugal: A Palaeofloristic Analysis Of An Early Angiosperm Community, Fossil Imprint 75 (2), pp. 153-257 : 205

Mayoa portugallica E.M.FRIIS, K.R.PEDERSEN et P.R.CRANE, 2004

Text-fig. 34

D e s c r i p t i o n a n d r e m a r k s. Mayoa portugallica was established based on a large group of pollen found in a poorly preserved floral fragment ( Text-fig. 34a ) that was studied using SEM and TEM ( Friis et al. 2004). The pollen grains are inaperturate and distinctly striate (polyplicate) with two sets of ribs and grooves that are almost perpendicular to each other ( Text-fig. 34b–d ).

A f f i n i t y a n d o t h e r o c c u r r e n c e s. Based on the unusual crossed arrangement of the ribs and grooves, and the structure of the pollen wall, the relationships of Mayoa were interpreted to be with extant Araceae ( Friis et al. 2004) , potentially within the family and close to Spathiphyllum SCOTT and Holochlamys ENGL. of the Spathiphylleae . To our knowledge this assignment has not been challenged and the presence of fossil aroids in the Early Cretaceous is now well established ( Friis et al. 2004, Sender et al. 2018). The pollen wall of Mayoa is unlike that of superficially similar ephedroid grains.

A single grain of Mayoa portugallica was reported from the Casal do Borracho palynoflora collected close the Torres Vedras mesofossil site, apparently in the same part of the Almargem Formation (Mendes et al. 2018), but otherwise Mayoa has not been reported from other mesofossil floras in Portugal or elsewhere.

Figures

Text-fig. 34. Scanning electron microscope (SEM) images of monocolpate pollen of Mayoa portugallica from a fragmentary stamen; Torres Vedras locality, Portugal. a) Stamen fragment that yielded the pollen in this Text-figure; b–d) Pollen grains showing the distinctive perpendicular orientation of two broad bands of striae that converge at the ends of the grains. Specimen, TV44-S136663. Scale bars 150 Μm (a), 6 Μm (b, c), 3 Μm (d).