Kvacekispermum 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 : 71-72

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

T y p e. Designated here, Kvacekispermum rugosum

E.M.FRiiS, P.R.CRANE et K.R. PEDERSEN gen. et sp. nov.

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.

PFN000106 (for new genus).

E t y m o l o g y. The name Kvacekispermum is in honor of Zlatko Kvaček for his numerous contributions to palaeobotany.

D i a g n o s i s. Seeds broadly obovate in lateral view and almost circular in transverse section with coarsely rugulate to reticulate surface formed from the uneven outer surface of endotesta in which the depressions are arranged in poorly defined grooves. Stigmatic area sessile on the fruit apex, slightly raised, hemispherical. Ovule pendent, orthotropous, bitegmic, endotestal. Endotesta comprised of a single layer of palisade-shaped cells with densely spaced crystals and fibrous infillings. Tegmen crushed in mature seeds. Embryo tiny; nutritive tissue of isodiametric thin-walled cells.

C o m m e n t s o n t h e g e n u s. The fruit wall of Kvacekispermum is abraded except in the region of the stigma. There is no indication of floral organization or pollen, and detailed comparison with the floral organization in Canrightia and Canrightiopsis is not possible. However, Kvacekispermum is similar to Canrightiopsis in having a pendent, orthotropous and bitegmic ovule/seed with a thick endotestal seed coat. The shape of the seed, together with the central position of the stigma, also indicate

that Kvacekispermum had single-seeded fruits similar to Canrightiopsis . Both also have a tiny embryo surrounded by a nutritive tissue of small, equiaxial cells with thin cell walls. Kvacekispermum is distinguished from seeds

of Canrightiopsis by the coarsely rugulate surface of the endotesta, which contrasts with the foveolate endotesta surface characteristic of all species of Canrightiopsis .

The fossil fruits and seeds of Kvacekispermum and Canrightiopsis share many features with fruits and seeds of extant Ascarina , Sarcandra and Chloranthus , but Canrightiopsis is distinguished from the extant taxa by features of its androecium. Floral organisation is not known for Kvacekispermum , but the seed is distinguished from seeds of extant taxa by its thicker seed coat and the coarsely rugulate surface of the endotesta.