Kvacekispermum rugosum E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN, 2018

Friis, Else Marie, Crane, Peter R. & Pedersen, Kaj Raunsgaard, 2018, Rightcania And Kvacekispermum: Early Cretaceous Seeds From Eastern North America And Portugal Provide Further Evidence Of The Early Chloranthoid Diversification, Fossil Imprint 74 (1 - 2), pp. 65-76 : 72-73

Kvacekispermum rugosum E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN sp. nov.

Text-figs 3 , 4

H o l o t y p e. Designated here, S174951 (Vale de Água

141; illustrated here on Text-figs 3a–f , 4a–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.

PFN000107 (for new species).

R e p o s i t o r y. Palaeobotanical Collections, Department of Palaeobiology, Swedish Museum of Natural History (S).

E t y m o l o g y. The specific epithet is from Latin rugosus: wrinkled.

T y p e l o c a l i t y. Vale de Água locality, Portugal

(39° 37′ 15″ N, 08° 51′ 30″ W).

T y p e h o r i z o n a n d a g e. Early Cretaceous (late Aptian – early Albian; basal part of the Figueira da Foz Formation).

D i a g n o s i s. As for the genus.

D i s t i n g u i s h i n g f e a t u r e s f o r K v a c e k i s p e r m u m

r u g o s u m. As for the genus.

D i m e n s i o n s. Length of seed: 1.14 mm; width of seed: 1.04 mm.

D e s c r i p t i o n a n d r e m a r k s. Kvacekispermum rugosum is known from a single well-preserved seed. The seed is abraded, and the fruit wall is missing except near the apex where stigma is preserved. There is no information on organization of the flower, but synchrotron radiation X-ray microtomographic microscopy ( SRXMT) of the seed (Holotype, S174951 ) has revealed fine details of the endotesta and nutritive tissue .

The seed is broadly obovate in lateral view, almost circular in transverse section, about 1.14 mm long and 1.04 mm in diameter, with rounded (apical) chalazal region and slightly pointed (basal) micropylar region ( Text-figs 3a–f , 4a–e ). The stigma, at the seed apex is sessile, slightly raised and hemispherical ( Text-fig. 3a–d ). The position of the stigma and the shape of the seed, as well as comparison to fruits and seeds of Canrightiopsis , suggest that the fruits of Kvacekispermum were one-seeded.

The seed is orthotropous and pendent, bitegmic and endotestal. The seed surface is coarsely rugulate to reticulate due to differences in the size of the cells comprising the endotesta with the resulting depressions arranged in poorly defined grooves. The endotesta is 60–125 µm thick consisting of a single layer of palisade-shaped crystal cells with endoreticulate infillings of fibres and imprints of small cubic crystals ( Text-figs 3c–e , 4a, c ). The crystals appear to be more densely packed close to the outer surface of the irregular grooves in the coarsely rugulate to reticulate surface ( Text-fig. 4c, d ). The exotesta consists of small, thinwalled cells that are preserved only in small patches in the grooves of the endotesta. The tegmen is collapsed in the mature seed, but the narrow, longitudinally arranged cells of the exotegmen are well preserved ( Text-fig. 4 a–d, f ).

The embryo is not preserved, but there is a very small well-defined embryo cavity ( Text-figs 3c, f , 4a, e ) indicating that the embryo was tiny. The surrounding nutritive tissue consists of thin-walled cells that do not show signs of shrinkage ( Text-fig. 4a, b, d, e ). Based on comparison with extant angiosperms the nutritive tissue is interpreted as endosperm.

Figures

Text-fig. 3. Synchrotron radiation X-ray tomographic microscopy (SRXTM) images of Kvacekispermum rugosum gen. et sp. nov. from the Early Cretaceous Vale de Água locality, Portugal (Holotype, S174951, Vale de Água sample 141). a, b, d) Volume renderings of seed in lateral (a, b) and apical (d) views showing the coarsely rugulate to reticulate surface of the endotesta with the depressions arranged in poorly defined grooves and remains of the sessile, slightly raised stigma (arrow head). c) Volume rendering of specimen cut longitudinally through the median plane (cut at orthoslice yz0805) showing apical stigmatic area (arrow head), chalaza (asterisk) and endotesta (oi-en) surrounding the endosperm (endo) and embryo cavity (arrow). e, f) Volume renderings of specimen cut transversely close to the middle of the seed (e, cut at orthoslice xy0922) and near the base (f, cut at orthoslice xy1466) showing endostesta (oi-en) surrounding endosperm (endo) and embryo cavity (arrow). Scale bars = 500 µm (a–f).

Text-fig. 4. Synchrotron radiation X-ray tomographic microscopy (SRXTM) images of Kvacekispermum rugusum gen. et sp. nov. from the Early Cretaceous Vale de Água locality, Portugal (Holotype, S174951, Vale de Água sample 141). a–f) Longitudinal (a, b, c, e, f) and transverse (d) orthoslices through seed showing slightly raised stigma (arrow head) chalaza (asterisk) and endotesta (oi-en) surrounding endosperm with embryo cavity (arrow); details of endotesta (c, f) show clusters of crystals in grooves of the endotesta (oi-en) and cells of exotegmen (ii-ex). Scale bars = 500 µm (a, d); 200 µm (b, e); 250 µm (f); 100 µm (c).