Reyanthus lusitanicus 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 : 231

Reyanthus lusitanicus E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN sp. nov.

Text-fig. 50a–j

H o l o t y p e. Designated here. S136716 (Torres Vedras sample 299; figured Text-fig. 50a–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.

PFN000492 (for new species).

P a r a t y p e. Designated here. S136717 (Torres Vedras sample 299).

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: Lusitania for Portugal where the fossil was discovered.

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 flower without stalk: ca.

0.48 mm; width of flower: ca. 0.58 mm.

D e s c r i p t i o n a n d r e m a r k s. Reyanthus lusitanicus is based on a single multiparted flower and a group of detached carpels, all of which have been studied with SEM and SRXTM. The flower is borne on a stout stalk that has an associated bract ( Text-fig. 50a, b ). Below the flower is another bract with a small bud in its axil, which is probably an undeveloped flower ( Text-fig. 50b ). The outer parts the flower are abraded and tepals and stamens are poorly preserved. The number and arrangement of tepals and stamens is uncertain. Small dorsiventrally flattened structures immediately outside the carpels are the probable remains of stamens, or perhaps staminodes ( Text-fig. 50e ). The tepals and stamens are each apparently arranged in a single series. The gynoecium is multicarpellate and apocarpous. It consists of about 20 carpels borne helically on a short conical receptacle ( Text-fig. 50a–f ). The carpels are crescent-shaped, slightly flattened laterally and have a straight ventral margin. The stigma is sessile, indistinct. The flower appears to be preserved at anthesis and the number of ovules is not clear. However, the detached carpels are larger and probably more mature ( Text-fig. 50g –j ). These detached carpels are assigned to Reyanthus lusitanicus based on their shape, and also the anatomy of the carpel wall. They contain several ovules borne along either side of the ventral suture. None of the fossil material is sufficiently well preserved to provide information on the organization of the ovules. All floral parts contain large, spherical cells that are densely spaced throughout the tissues, which we interpret as oil cells. In the larger, isolated carpels the oil cells are embedded in the outer tissue of the carpel wall ( Text-fig. 50i, j ) and are often visible on the carpel surface or sometimes as holes in the fruit wall ( Text-fig. 50g, h ).

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. Reyanthus lusitanicus is known only from the Torres Vedras locality. Taken together, the multiparted organization, the presence of oil cells and the several ovules per carpel indicate affinity with Magnoliales , but there is no clear relationship to a specific extant taxon.

Figures

Text-fig. 50. Scanning electron microscope (SEM) and synchrotron radiation X-ray tomographic microscopy (SRXTM) images of a flower and mature carpels of Reyanthus lusitanicus gen. et sp. nov.; Torres Vedras locality, Portugal. a) Holotype; multicarpellate flower showing numerous carpels surrounded by remains of the androecium and perianth; note the bract subtending the flower (arrowhead); b, c) Longitudinal sections perpendicular to section in (f) (b, SRXTM orthoslice xz0461) and (c, SRXTM cut voltex xz0540-0580) showing receptacle, carpels and remains of the androecium and perianth; note prominent cavities formed by the oil cells, subtending bract (arrow) and bract subtending fragmentary bud (arrowhead); d, e) Apical (d) and lateral (e) views of gynoecium showing laterally flattened carpels and dorsi-ventrally flattened stamen or staminode (* in e); f) Longitudinal section (SRXTM orthoslice yz0405) of gynoecium showing conical receptacle and carpels with densely spaced oil cells; g, h) Mature carpel of Reyanthus lusitanicus gen. et sp. nov. showing slightly curved form, rounded apex and base that tapers toward the attachment to the receptacle; i) Surface of carpel showing embedded oil cells; j) Transverse section through three carpels showing attachment of developing ovules near the ventral sutures and oil cells in the wall just below the surface (SRXTM cut voltex xy0770-0845). Specimens TV299-S136716 (holotype; a–f), TV299-S136717 (g–j). Scale bars 300 Μm (a–d, f–h), 150 Μm (e, j), 30 Μm (i).