Eckhartia brevicolumella 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 : 210

Eckhartia brevicolumella E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN sp. nov.

Text-fig. 37a–g

H o l o t y p e. Designated here. S136760 (Torres Vedras sample 44; figured Text-fig. 37c, g ).

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.

PFN000472 (for new species).

P a r a t y p e s. Designated here. S136661, S136662, S136751, S136752, S136673, S136765, S137920, S137921, S148021, S149204 (Torres Vedras sample 44).

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: brevis for short and columella referring to short columellae supporting the muri.

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 with the following additions: Anthers elongate. Reticulum coarse. Columellae short, densely spaced or sometimes laterally merged.

D i s t i n g u i s h i n g f e a t u r e s. Eckhartia brevicolumella is distinct from E. longicolumella (below) mainly in having much longer stamens, pollen grains with larger and fewer lumina and shorter, more densely spaced columellae. The coarse reticulum of the pollen grains also distinguishes Eckhartia brevicolumella from E. intermedia (below) although these two taxa both have similar short and densely spaced columellae.

D i m e n s i o n s. Length of anthers: about 1.2 mm; width of anthers: 0.12–0.16 mm. Length of pollen grains: 16–17 µm.

D e s c r i p t i o n a n d r e m a r k s. Eckhartia brevicolumella is based on many isolated stamens with pollen grains in situ. It was first illustrated by Friis et al. (2010a), but not formally described and named. The anthers are very long and narrow, about 1.2 mm long and 0.12–0.16 mm wide, dithecate and tetrasporangiate ( Text-fig. 37a, b ). The anther wall is usually well preserved and pollen grains are only visible in cracks or fragmented specimens. Pollen grains are about 16–17 µm in equatorial diameter and monocolpate. The exine is semitectate-reticulate, heterobrochate and columellate ( Text-fig. 37c, d, f, g ). The reticulum over most of the pollen grain is coarse with lumina of two sizes, with the larger lumina up to about 1.8 µm in diameter (Textfig. 37g). Towards the colpus margin, and especially around the end of the colpus, the lumina become very small and the colpus margin is psilate ( Text-fig. 37f, g ). Muri are about 0.2 µm wide with rounded or flattened profiles. Columellae are short, about 0.2 µm long, usually densely spaced, and sometimes fused into a short plates ( Text-fig. 37g ). Orbicules are densely spaced on the inner surface of the anther wall ( Text-fig. 37e ) and scattered over the surface of the pollen grains ( Text-fig. 37g ). They are about 1.8 µm long, irregular in shape with a solid rounded base bearing densely spaced rod-like protrusions that give the individual orbicules the appearance of a tooth with crown and roots (Textfig. 37e, g).

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.Thepollen grains show similarities to grains adhering to the stigmatic surface of Vedresia elliptica ( Text-fig. 49c ) and they may have been produced by the same kind of plant. Eckhartia brevicolumella has so far not been observed in any other mesofossil flora from Portugal.

Figures

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).

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