Mcdougallia irregularis E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN, 2019

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 : 233

Mcdougallia irregularis E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN sp. nov.

Text-fig. 51a–f

H o l o t y p e. Designated here. S148215 (Torres Vedras sample 43; figured Text-fig. 51a–f ).

P l a n t F o s s i l N a m e s R e g i s t r y N u m b e r.

PFN000494 (for new species).

R e p o s i t o r y. Palaeobotanical Collections , Department of Palaeobiology, the Swedish Museum of Natural History, Stockholm, Sweden .

E t y m o l o g y. From Latin: irregularis referring to the irregular folds and colpi.

T y p e l o c a l i t y. Torres Vedras (NE of Forte de

Forca; 39°06′13″ N, 9°14′47″ W).

T y p e s t r a t u m a n d a g e. Lower member of the Almargem Formation; Early Cretaceous (late Barremianearly Aptian).

D i a g n o s i s. As for the genus.

D i m e n s i o n s. Equatorial diameter of pollen grains: about 19–20 µm.

D e s c r i p t i o n a n d r e m a r k s. Mcdougallia irregularis is based on a fragment of a stamen, about 0.48 mm long and 0.135 mm wide ( Text-fig. 51a ). Pollen grains in situ are small, almost spherical, about 19–20 µm in diameter and tricolpate ( Text-fig. 51b–d ). The colpi are long, reaching almost to the poles and have a distinct margin ( Text-fig. 51b–d ). Shorter folds that appear as openings in the tectum are irregularly spaced between the regular colpi on all grains. The tectum is punctate in the polar regions and along the colpi. In the mesocolpial regions the tectum is foveolate to irregularly reticulate, and sometimes discontinuous ( Text-fig. 51c ). Columellae are very short ( Text-fig. 51f ). The colpus membrane is finely verrucate ( Text-fig. 51c, d ). Orbicules are densely spaced on the inner surface of the anther wall and scattered on the surface of the pollen. They are small and spherical with a faintly striate surface ( Text-fig. 51e ).

Affinity and other occurrences. Mcdougallia irregularis is known only from the Torres Vedras locality. The triaperturate pollen grains clearly indicate a relationship to eudicots, but specific relationships to extant taxa within the group are uncertain.

Figures

Text-fig. 51. Scanning electron microscope (SEM) images of tricolpate pollen of Mcdougallia irregularis gen. et sp. nov. from a stamen fragment; Torres Vedras locality, Portugal. a) Holotype; stamen fragment that yielded the pollen in this Text-figure; b) Polar view of tricolpate pollen grain showing the continuous psilate tectum in the apocolpium and the poorly developed discontinuous foveolate-reticulate tectum in the mesocolpial areas, note irregular fold in tectum wall (arrowhead); c) Equatorial view of pollen grain showing the discontinuous tectum in the mesocolpial areas; d) Pollen grains showing variably developed tectum, colpi with a finely granular aperture membrane and the folds (arrowheads) associated with the irregular development of the colpi; e) Orbicule showing faintly striate surface; f) Pollen wall showing very short columellae, thin tectum and thin foot layer. Specimen, TV44-S148215 (holotype). Scale bars 300 Μm (a), 6 Μm (b–d), 3 Μm (e, f).