The Early Cretaceous Mesofossil Flora Of Torres Vedras (Ne Of Forte Da Forca), Portugal: A Palaeofloristic Analysis Of An Early Angiosperm Community
Author
Friis, Else Marie
Author
Crane, Peter R.
Author
Pedersen, Kaj Raunsgaard
text
Fossil Imprint
2019
2019-11-25
75
2
153
257
http://dx.doi.org/10.2478/if-2019-0013
journal article
10.2478/if-2019-0013
2533-4069
5386203
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).