Pazliopsis reyi, 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 : 143-144

Pazliopsis reyi gen. et sp. nov.

Text-figs 3f–i , 4c, d

H o l o t y p e. Designated here, S171534 (Torres Vedras sample 043; illustrated here on Text-fig. 3g ).

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.

PFN000093 (for new species).

P a r a t y p e s. Designated here, S174735 (Torres Vedras sample 043), S174636, S174637, S175024 (Torres Vedras sample 044), S175120 (Torres Vedras sample 144), S174632 (Torres Vedras sample 298).

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. In recognition of Jacques Rey (*1940, †2018) for his important contributions to understanding the Cretaceous geology of Portugal.

T y p e l o c a l i t y. Torres Vedras, Portugal (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 part of the Almargem Formation; Early Cretaceous (late Barremian – early 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 fruit: 1.1 mm; length of seeds: 0.7–0.9 mm; width of seeds: 0.66–0.84 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 two fruits and 30 isolated seeds. Four specimens (S171534, S174614, S174632, S174633) were studied using SRXTM. The fruits or fruitlets are small and each contains a single seed ( Text-figs 3f, g , 4c, d ). They are isolated from the floral receptacle and it is unknown whether they were from monocarpellate gynoecia or multicarpellate gynoecia that were apocarpous. The fruit wall is thin, collapsed and partly abraded exposing the seed. It consists of an outer zone of small thin-walled cells and an inner zone of obliquely arranged, longitudinally elongate, fibers ( Text-fig. 3f ). The fibrous inner zone suggests that the fruit was dry.

The seeds are small, anatropous, bitegmic and exotestal with bilateral symmetry, ovate to almost circular in lateral view with a truncate profile at the hilar-micropylar end of the seed ( Text-fig. 3f, g ). The hilar scar is large and ovate in outline and lacks a hilar rim ( Text-fig. 3h ). Where the raphal bundle enters the seed the micropyle and hilum are separated by expanded sclerenchyma tissue beneath the hilar scar ( Text-fig. 4c ), and marked on the seed surface by a transverse slit through the outer integument (testa) adjacent to the hilar scar.

The seed coat is mainly comprised of the exotesta, which consists of a single layer of tall, columnar sclerenchyma cells. These cells are about 100 µm tall over most of the seed but gradually become shorter towards the hilarmicropylar region ( Text-fig. 4c ). The anticlinal walls of the exotestal cells are thickened, and of almost even thickness from the outside to the inside resulting an almost straight lumen ( Text-fig. 4c ). The anticlinal walls of the exotestal cells are strongly undulate towards the outside and inside forming a jigsaw puzzle-like pattern on the seed surface with rounded, deep, undivided lobes ( Text-fig. 3i ). The cell walls are also undulate over the raphe and in the micropylar region. The inner layers of the testa (mesotesta/endotesta) and the tegmen, which is poorly preserved in the micropylar region, are composed of thin walled cells that are typically collapsed.

One specimen has well-preserved nutritive tissue and an embryo ( Text-fig. 4c, d ), and another specimen has a remains of the embryo preserved. In both cases the embryo is tiny, with two rudimentary cotyledons ( Text-fig. 4c, d ). The embryo to seed (E:S) ratio is about 0.02. As in Gastonispermum portugallicum , the cells of the embryo are much smaller than those of surrounding nutritive tissue ( Text-fig. 4c, d ), and each contains a central structure that we interpret as the probable remains of a nucleus ( Text-fig. 4d ). The nutritive tissue immediately surrounding the embryo consists of equiaxial cells with thin-walled, straight to slightly wavy cells walls ( Text-fig. 4d ). This tissue is clearly endosperm. However, the transition between these inner thin-walled endosperm cells and the bulk of the surrounding nutritive tissue is not well preserved so it is uncertain whether all the nutritive tissue is endosperm or whether the outer part of the nutritive tissue could be perisperm.

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).