Burgeria striata 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 : 201

Burgeria striata E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN sp. nov.

Text-figs 31a–h , 32a–e

H o l o t y p e. Designated here. S149216 (Torres Vedras sample 44; figured Text-fig. 31a–h ).

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.

PFN000468 (for new species).

P a r a t y p e s. Designated here. S174620 (Torres Vedras sample 39), S136676 (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: striatus to emphasize the finely striate pollen wall.

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. Pollen grains: 28–29 µm long (smaller, abnormal? grains about 18 µm long); 22–25 µm wide (smaller, abnormal? grains about 15 µm wide).

D e s c r i p t i o n a n d r e m a r k s. Burgeria striata is based on three pollen clumps, probably fragments of stamens, with numerous pollen grains in situ ( Text-figs 31a , 32a ). The holotype (S149216) was first thought to be a coprolite ( Friis et al. 2010a), but the pollen grains are all of the same kind and the fragment includes remains of the pollen wall with the characteristic striate orbicules. In this fragment, the pollen grains are all of the same size and all are apparently fully developed ( Text-fig. 31b–e ). In one of the paratypes (S174620), larger, apparently fully developed grains co-occur with smaller, perhaps aborted grains (Textfig. 32c–e). The larger pollen grains are of medium size, broadly ellipsoidal in equatorial outline and monocolpate ( Text-figs 31b–e , 32c, d ). Smaller grains are subcircular in equatorial outline. The exine is about 0.8 µm thick, tectatepunctate and columellate with short columellae and a thin foot layer ( Text-fig. 31f ). The exine surface is finely striate ( Text-figs 31f–g , 32b ). In the specimen that has pollen of two sizes the surface of the smaller grains is sometimes rugulate, perhaps indicating that the wall is not fully expanded (Textfig. 32c–e). In the larger (fully developed) grains the colpus is broad and almost as long as the longest axis of the grains ( Text-figs 31b, d, e , 32c, d ). In smaller (aborted?) grains the colpus is short, and extends for about half the length of the longest axis ( Text-fig. 32c, e ). Orbicules occur scattered on the surface and between the grains ( Text-figs 31b–e, h , 32c–e ). Orbicules are spherical, and range in size from about 1–3 µm. They are similar to the pollen grains in their perforated wall and finely striate surface ( Text-fig. 31h ).

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. Burgeria striata has so far only been recorded from the Torres Vedras locality. The affinities of B. striata are uncertain, but among extant plants are most likely with Saururaceae among Piperales (see comments on the genus).

Figures

Text-fig. 31. Scanning electron microscope (SEM) images of monocolpate pollen of Burgeria striata gen. et sp. nov. from a pollen clump; Torres Vedras locality, Portugal. a) Holotype; pollen clump that yielded the pollen in this Text-figure; b) Pollen grains showing the distal colpus and the undulating tectum perforated by scattered punctae; c–e) Equatorial (c) and distal views (d, e) of pollen grains showing the long distal colpus with granular ornamentation and the undulating tectum perforated by scattered punctae; f) Detail of section through pollen wall showing thick tectum with fine striate ornamentation, perforated by punctae and supported by short stout columellae attached to the thin foot layer; g–h) Surface of tectum (g) and orbicule (h) showing fine striate ornamentation. Specimen, TV44-S149216 (holotype). Scale bars 300 Μm (a), 30 Μm (b), 6 Μm (c–e), 1.5 Μm (f–h).

Text-fig. 32. Scanning electron microscope (SEM) images of monocolpate pollen of Burgeria striata gen. et sp. nov. from a pollen clump; Torres Vedras locality, Portugal. a) Pollen clump that yielded the pollen in this Text-figure; b) Pollen surface showing fine striate ornamentation; c–e) Pollen grains showing broad distal colpus with distinct granular ornamentation and the undulating tectum perforated by scattered punctae; note the very different sizes of pollen grains in the same pollen clump. Specimen, TV44-S174620. Scale bars 300 Μm (a), 6 Μm (c–e), 1.5 Μm (b).