Gastonispermum antiquum 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 : 175-176

publication ID	https://doi.org/ 10.2478/if-2019-0013
persistent identifier	https://treatment.plazi.org/id/0396DC10-BF19-C214-CE2F-B46CE5EA1A5F
treatment provided by	Diego
scientific name	Gastonispermum antiquum E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN
status	sp. nov.

Treatment

Gastonispermum antiquum E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN sp. nov.

Text-fig. 14a–e View Text-fig

H o l o t y p e. Designated here. S136736 (Torres Vedras sample 43; figured Text-fig. 14b View Text-fig ).

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.

PFN000453 (for new species).

P a r a t y p e s. Designated here. S136737, S136738, S170085 (Torres Vedras sample 43); S136680, S136681, S174629 (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. From Latin: antiquus referring to the great age of these seeds.

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).

S p e c i f i c d i a g n o s i s. Isolated seeds occurring singly. Seeds small, anatropous, bitegmic and exotestal. Seed surface smooth without longitudinal ridges. Course of raphe seen as a slightly raised rounded ridge. Hilum and micropyle separated by a narrow zone of sclerenchyma. Hilar scar small, slightly raised without a hilar rim. Micropyle formed by the inner integument (tegmen) and marked on the seed surface by a Y-shaped slit through the outer integument (testa) adjacent to the hilar scar. Exotesta of palisade-shaped sclerenchyma cells; mesotesta/endotesta of thin-walled parenchyma cells. Palisade-shaped cells of exotesta with evenly thickened anticlinal walls and a straight lumen. Anticlinal walls of palisade-shaped sclerenchyma strongly undulate toward the inside and toward the outside, resulting in stellate-undulate facets and a jigsaw puzzle-like pattern on the seed surface. Tegmen thin.

D i s t i n g u i s h i n g f e a t u r e s. Gastonispermum antiquum is distinguished from Gastonispermum portugallicum E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN described from the Famalicão locality ( Friis et al. 2018b) by its smaller size, the circular rather than elliptical shape and the thinner seed coat.

D i m e n s i o n s. Length of seed: 0.9–1 mm; width of seeds: 0.85–1 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 five isolated seeds, one of which (S174629) was studied using SRXTM. The seeds are small, anatropous, bitegmic and exotestal ( Text-fig. 14a–e View Text-fig ). They are almost spherical with a smooth, dull surface. On the surface the slightly raised anticlinal walls of the exotestal cells form a faint jigsaw-puzzle-shaped pattern ( Text-fig. 14d View Text-fig ).

As in Gastonispermum portugallicum the micropyle and hilum are positioned close together and slightly displaced towards the raphal side ( Text-fig. 14b, c, e View Text-fig ). The hilum is small and circular, and the micropylar opening is seen externally as a small Y-shaped slit in the exotesta ( Text-fig. 14c View Text-fig ). The course of the raphe is not distinct on the outside of the seeds. The seed coat consists of a thick exotesta of tall palisade-shaped cells with undulate anticlinal walls, a thin mesotesta/endotesta and a crushed tegmen ( Text-fig. 14e View Text-fig ). Exotestal cells are about 60 µm tall over most of the seed, but this exotestal layer is thicker over the raphe (about 80 µm) and thinner towards the hilum and micropyle (Textfig. 14e). Nutritive tissue is not preserved in the specimen studied using SRXTM.

Two specimens (S136748, S136749) in which the fruit wall is partly preserved ( Text-fig. 14f, g View Text-fig ) provide information on the probable fruits of Gastonispermum antiquum . The fruits are thin-walled and each contains a single exotestal seed. In both cases, the seeds are comparable in size, shape and the jigsaw-puzzle-shaped pattern on the seed surface to the isolated seeds of Gastonispermum antiquum (Textfig. 14h). However, the seed cuticle appears thinner than in the isolated seeds and critical comparison is not possible because features of the micropylar-hilar region are covered by the fruit wall.

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. Seed characters of Gastonispermum strongly suggest a relationship to extant Nymphaeales and Austrobaileyales , but the fossils cannot be placed in any of the extant taxa ( Friis et al. 2018b). Gastonispermum antiquum is recorded only from the Torres Vedras locality. The type species of the genus, Gastonispermum portugallicum E.M.FRIIS, P.R.CRANE et K.R.PEDERSEN , is from the Famalicão locality and is also recorded from the Vale de Água locality.