Mugideiriflora portugallica E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN, 2020

Friis, Else Marie, Crane, Peter R. & Pedersen, Kaj Raunsgaard, 2020, Multiparted, Apocarpous Flowers From The Early Cretaceous Of Eastern North America And Portugal, Fossil Imprint 76 (2), pp. 279-296 : 281-283

Mugideiriflora portugallica E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN sp. nov.

Text-figs 1a–f , 2a–g

H o l o t y p e. Designated here. S174254 (Catefica sample 150; figured Text-figs 1a–f , 2a–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.

PFN000907 (for new species).

R e p o s i t o r y. Palaeobotanical Collections, Swedish

Museum of Natural History , Stockholm, Sweden ( S) .

E t y m o l o g y. From Portugal where the fossil was collected.

T y p e l o c a l i t y. Catefica (39° 03′ 16″ N, 09° 14′ 24″ W), between the villages of Catefica and Mugideira, about 4 km south of Torres Vedras, Portugal .

T y p e s t r a t u m a n d a g e. Almargem Formation,

Early Cretaceous (Aptian-early Albian).

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: 1.1 mm (full length not preserved; estimated full length about 2 mm); diameter: 1.75 mm.

D e s c r i p t i o n a n d r e m a r k s. The species is based on a single, slightly abraded flower (S174254) and two small flower fragments from the same locality (S174770, S174771, Catefica sample 50). The flower is small, about 1.75 mm in diameter, open and apparently preserved in a young anthetic stage with stamens and carpels not fully mature ( Text-figs 1a–f , 2a–g ). The flower is structurally bisexual, with multiparted perianth, androecium and gynoecium ( Text-figs 1a–f , 2a–g ). The floral receptacle is flat to slightly concave but is extended into a short conical gynoecial zone in the pistillate region ( Text-fig. 2b, e, f ). The phyllotaxis of all floral organs is apparently spiral ( Text-figs 1a–c , 2c–e ). Because the flower is abraded, the total number of floral parts is unknown, but is estimated based on the well-preserved parts of the flower.

The perianth has about 50 tepals in several series. The tepals are broad with correspondingly broad, transversely elongate and narrowly rhomboidal bases. The tepals are composed of thin-walled, equiaxial cells. The tepals of the outer one or two series are covered by a thin cuticle (Textfig. 2c, d) while those of the inner three or four series have a thick cuticle on their outer surface over a layer of epidermal cells that also appear to be thick-walled ( Text-fig. 2c, d ).

The androecium consists of more than 50 stamens in about four series ( Text-fig. 2b–e ). Each stamen has a short, broad base that is poorly differentiated from the anther and that is rhomboidal in transverse section ( Text-fig. 2d, e ). The anthers are apparently dithecate and tetrasporangiate with an expanded and slightly pointed connective apex. The pollen sacs appear to be embedded in a lateral to slightly dorsal position. The mode of dehiscence is not clear. No pollen has been observed.

The gynoecium is superior, apocarpous and consists of more than 50 free carpels borne on the conical gynoecial portion of the receptacle in several series ( Text-fig. 2b, e–g ). The carpels appear ascidiate, but because the flower is preserved at a very young stage, the nature of the carpels is not completely certain.

Figures

Text-fig. 1. Scanning electron micrographs of Mugideiriflora portugallica gen. et sp. nov. from the Early Cretaceous Catefica locality, Portugal (holotype, S174254, Catefica sample 150). a) Flower in oblique lateral view showing numerous broad tepals, numerous inwardly curved stamens and the flat floral receptacle with a conical gynoecial region; b–c) Flower in two different oblique apical views showing numerous broad laminar tepals and inwardly curved stamens surrounding the carpels; note cellular differences between outer (op) and inner (in) perianth parts, as well as bases of anthers, apparently with laterally to slightly dorsally placed pollen sacs (arrow heads); d) Detail of flower showing a cluster of poorly differentiated carpels in the center surrounded by elongated stamens; note grooves in the dorsal surface of the stamens indicating the position of the pollen sacs; e) Detail of flower showing the broad bases of the laminar tepals, rhomboidal stamen bases and poorly differentiated carpels; f) Detail of flower showing inwardly arched stamens and poorly differentiated carpels. Scale bars = 1 mm (a–c), 200 µm (d–f).

Text-fig. 2. Synchrotron radiation X-ray tomographic microscopy volume renderings (a, b) and orthoslices (c–e) of Mugideiriflora portugallica gen. et sp. nov. from the Early Cretaceous Catefica locality, Portugal (holotype, S174254, Catefica sample 150). Yellow dots – stamens, red dots – carpels. a) Flower in lateral view showing the broad bases of the laminar tepals; b) Flower in longitudinal section showing the flat to slightly concave floral receptacle with a central conical gynoecial region (cut between orthoslices yz0800 and 1220); c) Flower in transverse section showing the numerous laminar tepals in several series and the stamens cut in the region of the poorly differentiated anthers; note cellular differences between outer (op) and inner (in) perianth parts, as well as and transverse sections of anthers, apparently with laterally to slightly dorsally placed pollen sacs (arrow heads) (cut at orthoslice xy0770); d) Flower in transverse section showing the numerous laminar tepals in several series, flattened rhomboidal stamen bases in several series, and poorly differentiated carpels (cut at orthoslice xy0820); e) Flower in transverse section showing the numerous laminar tepals in several series, flattened rhomboidal stamen bases in several series, and poorly differentiated carpels (cut at orthoslice xy0920); f) Flower in longitudinal section showing the shallowly concave floral receptacle with laminar tepals, stamens, and a central conical gynoecial region bearing poorly differentiated carpels (cut at orthoslice yz0900); g) Flower in longitudinal section perpendicular to that in (f) showing stamens and poorly differentiated carpels (cut at orthoslice xz1630). Scale bars = 1 mm (a, b), 500 µm (c–g).