Vedresia elliptica 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 : 227-228

Vedresia elliptica E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN sp. nov.

Text-fig. 49a–c

H o l o t y p e. Designated here. S136735 (Torres Vedras sample 43; figured Text-fig. 49a–c ).

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.

PFN000488 (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: ellipticus referring to the elliptical shape of the fruit.

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. Length of fruit: 0.8 mm; width of fruit: 0.6 mm. Long axis of pollen grains parallel with the colpus: about 18 µm.

D e s c r i p t i o n a n d r e m a r k s. Vedresia elliptica is based on a single fruit that has been studied only by SEM and details of its internal structure are unknown. The fruit is small, elliptical in lateral view, and there is no attachment scar or scars from detached floral organs ( Text-fig. 49a ). The outline of the fossil strongly suggests that the fruit is unilocular and contains a single seed. Slight irregularities in the fruit surface also suggest that the enclosed seed had an irregular, reticulate surface. There are no clear indications of oil cells in the fruit wall. The stigmatic area is sessile, indistinct and has numerous pollen grains, all of the same kind, adhering to the stigma ( Text-fig. 49b ). Pollen is broadly elliptical to circular in equatorial outline, and monocolpate with a long colpus that extends for the full length of the grains. Grains are semitectate-reticulate and heterobrochate. Lumina over most of the pollen surface are of various sizes, up to about 1.5 µm in diameter. Bordering the colpus margin lumina are smaller and grade into foveae ( Text-fig. 49c ). Muri are smooth, lack supratectal ornamentation and are supported by long, scattered columellae. The reticulum is only loosely attached to the foot layer and has been lost in several of the grains.

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. The similarities of the Vedresia elliptica fruit and its associated pollen grains to fruits of Canrightiopsis and Canrightia and their associated pollen grains strongly suggest a relationship to the clade comprising extant Ascarina , Chloranthus and Sarcandra , among extant Chloranthaceae . However, information on internal structures including seed coat anatomy is lacking and assignment of Vedresia to the Chloranthales is currently not secure.

Pollen grains associated with Vedresia elliptica are very similar to those of Eckhartia brevicolumella (see p. 210 and Text-fig. 37 ) and it is possible that they were produced by the same species, or a very similar kind of plant.

Figures

Text-fig. 49. Scanning electron microscope (SEM) and synchrotron radiation X-ray tomographic microscopy (SRXTM) images of Vedresia elliptica gen. et sp. nov. (a–c) and a multicarpellate fruit of Choffaticarpus compactus gen. et sp. nov. and associated pollen (d–j); Torres Vedras locality, Portugal. a) Holotype; small fruit showing apical stigmatic region with attached pollen; b) Group of pollen grains from the stigmatic surface of the fruit in (a) showing the long colpus and reticulate tectum; c) Pollen grains from the stigmatic surface showing the long colpus and well developed reticulum, with smooth muri and short columellae

Text-fig. 37. Scanning electron microscope (SEM) images of anthers and monocolpate pollen of Eckhartia brevicolumella gen. et sp. nov. from stamen fragment; Torres Vedras locality, Portugal. a) Dithecate, tetrasporangiate anther partially split along the elongated sporangia; b) Dithecate, tetrasporangiate anther; c) Holotype; distal view of pollen grain from holotype showing the long colpus with a distinct margin and a heterobrochate reticulum; d) Distal view of pollen grain from a stamen fragment showing long colpus, colpus margin and heterobrochate reticulum; e) Inner surface of anther wall from stamen fragmentshowing densely spaced dentate orbicules; f) Lateral view of pollen grains from stamen showing the psilate to foveolate-microreticulate colpus margin; g) Detail of pollen grain from holotype showing the slightly rounded profile of the muri, the short, densely spaced columellae and the dentate orbicules. Specimens, TV44-S136662 (a), TV44-S149204 (b), TV44-S136760 (holotype; c, g), TV44-S148021 (d, e), TV44-S136752 (f). Scale bars 300 Μm (a, b), 6 Μm (c, d, f), 3 Μm (e, g).