Pazlia hilaris, Friis & Crane & Pedersen, 2018

Friis, Else Marie, Crane, Peter R. & Pedersen, Kaj Raunsgaard, 2018, Extinct Taxa Of Exotestal Seeds Close To Austrobaileyales And Nymphaeales From The Early Cretaceous Of Portugal, Fossil Imprint 74 (1 - 2), pp. 135-158 : 140-143

Pazlia hilaris gen. et sp. nov.

Text-figs 3a–e , 4a, b

H o l o t y p e. Designated here, S175096 (Famalicão sample 025; illustrated here on Text-figs 3a–d , 4a, b ).

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.

PFN000091 (for new species).

P a r a t y p e s. Designated here, S174336, S174342, S175083, S175098, S175105, S175106 (Famalicão sample 025).

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: hilaris, relating to the hilum to emphasis the large hilar scar and strongly developed sclerenchyma tissue under hilum.

T y p e l o c a l i t y. Famalicão , Portugal (39°42′16″N;

8°46′12″W).

T y p e s t r a t u m a n d a g e. Below the Figueira da Foz Formation; Early Cretaceous (late Aptian – early Albian or older).

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 seeds: 1.1–1.4 mm; width of seeds: 0.9–1.2 mm.

O t h e r m a t e r i a l. S175109 (Vale de Água 330).

D e s c r i p t i o n a n d r e m a r k s.Thespeciesisbased on about 20 seeds of which five were studied using SRXTM (S174336, S174342, S175083, S175096, S175098). All seeds are isolated and there is no information on the fruit in which they were borne. The seeds are small, anatropous, bitegmic and exotestal with bilateral symmetry. The seed surface is almost smooth with a jigsaw puzzle-like pattern formed from the raised undulate anticlinal walls of the exotesta cells. The seeds are almost circular in lateral view with a truncate hilar-micropylar region ( Text-figs 3a–c , 4a ), and they are broadly elliptical in transverse section (Textfigs 3b, 4b).

The micropyle and hilum are separated by a broad zone of sclerenchyma tissue beneath the very large and distinct hilar scar ( Text-figs 3a–c , 4a ). This hilar sclerenchyma is strongly expanded toward the inside of the seed by cells that are thin-walled, elongate and radiate perpendicular to the hilar scar ( Text-figs 3c , 4a ). The hilum lacks a rim. The course of the raphe is distinct on the seed surface and seen as a slightly raised, rounded ridge extending from hilum to the chalazal end of the seed ( Text-fig. 3b, c ). The micropyle is formed from the inner integument, and seen on the seed surface as a narrow slit. There is a strongly thickened zone of sclerenchyma cells between micropyle and raphe ( Text-figs 3b , 4a ).

Most of the seed coat is composed of exotesta, which is one cell layer deep. The mesotesta/endotesta and tegmen are typically collapsed. The exotesta is one cell layer deep and consists of columnar sclerenchyma cells that are about 105 µm tall over most of the seed, but that gradually become shorter towards the hilar-micropylar region ( Text-fig. 4a, b ). The exotestal cells are arranged in longitudinal rows over the raphe and on the anti-raphal side, but otherwise their arrangement appears irregular. The anticlinal walls of the exotestal cells are thickened and of almost even thickness from the outside to the inside resulting in an almost straight lumen ( Text-fig. 4a, b ). They are strongly undulate towards the outside and inside forming a jigsaw puzzle-like pattern on the surface with rounded, deep, sometimes bifurcate, lobes in the stellate-undulate facets ( Text-fig. 3d ). The cell walls are also undulate over the raphe and in the micropylar region.

Patchy remains of cellular nutritive tissue were observed in one of the specimens studied using SRXTM, but none of the specimens show sufficient internal details to reveal the size or nature of the embryo.

Figures

Text-fig. 3. Pazlia hilaris gen. et sp. nov. (a–e) from the Early Cretaceous Famalicão locality (sample 025), Portugal (holotype, S175096) and Pazliopsis reyi gen. et sp. nov. (f–i) from the Early Cretaceous Torres Vedras locality, Portugal; Synchrotron radiation X-ray tomographic microscopy (SRXTM, volume renderings a–f, i) and scanning electron microscopy (SEM, g, h). a, b) Seed in lateral (a) and oblique apical (b) views showing the truncate hilar-micropylar region; note prominent hilar scar (hi) and micropyle (mi) at the seed apex and the raphe (ra) seen as slightly raised ridge; remains of mounting media (¤). c) Cut volume rendering (cut at yz0647) showing course of raphe (ra), hilar scar (hi) and micropyle (mi); note the strongly radially elongated cells below the hilar scar. d) Seed in antiraphal view. e) Seed surface showing the raised undulate anticlinal walls of the exotestal cells. f) Seed enclosed in remains of thin-walled fruit (fr) (S174632, Torres Vedras sample 298). g) Holotype, seed enclosed in remains of fruit (fr); raphal view showing the faintly ribbed surface of the seed (S171534, Torres Vedras sample 043). h) Apical view of seed fragment showing hilar scar (hi), position of raphe (ra) and the ribbed seed surface (S136683, Torres Vedras sample 044). i) Seed surface showing the raised undulate anticlinal walls of the exotestal cells (S171534; Torres Vedras sample 043). Scale bars = 250 µm (a–d, f–h); 125 µm (e, i).

Text-fig. 4. Pazlia hilaris gen. et sp. nov. (a, b) from the Early Cretaceous Famalicão locality (sample 025), Portugal (holotype, S175096) andPazliopsis reyi gen. etsp.nov. (c, d) from the Early Cretaceous TorresVedras locality(sample 038), Portugal (S174614); Synchrotron radiation X-ray tomographic microscopy (SRXTM, orthoslices). a) Longitudinal orthoslice (xy0984) through the median plane of the seed showing the strongly thickened sclerenchyma under the hilar scar (hi), micropylar slit (mi) and the raphe (ra); note cells of exotesta are almost equally tall on both raphal and anti-raphal sides of the seed and gradually become shorter towards the micropyle. b) Transverse orthoslice (xy0984) through middle of seed showing the thickened cells of the exotesta; note that cells of the exotesta are almost equally tall on both raphal and anti-raphal sides. c) Longitudinal orthoslice (yz0812) through apical part of seed in the median plane showing embryo with two rudimentary cotyledons (asterisks) and surrounding nutritive tissue; note the tiny cells of embryo with central structures we interpret as the fossilized remains of nuclei. d) Detail of (4c) showing tiny embryo with two rudimentary cotyledons (asterisks); nutritive tissue immediately surrounding the embryo is interpreted as endosperm (endo); whether there is any delimitation between this inner endosperm and the outer part of the nutritive tissues is not clear. Scale bars = 250 µm (a–c); 125 µm (d).