Rightcania E.M.FRIIS, P.R.CRANE et

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: 68-69

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http://doi.org/ 10.2478/if-2018-0006

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Rightcania E.M.FRIIS, P.R.CRANE et


Genus Rightcania E.M.FRIIS, P.R.CRANE et  

K.R. PEDERSEN   gen. nov.

T y p e. Designated here, Rightcania kvacekii   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.

PFN000104 (for new genus).

E t y m o l o g y. Rightcania   is an anagram of Canrightia  

to indicate similarity to this fossil genus.

D i a g n o s i s. Fruit a berry with three to five ovules/

seeds and a fruit wall of thin-walled parenchyma cells.

Stigmatic area sessile, indistinct. Hypanthium fused to

lower part of ovary wall. Ovules pendent, orthotropous to semi-orthotropous, bitegmic, endotestal with a testa of multiple cell layers. Exotesta of several layers of slightly elongate, irregular wavy cells; endotesta a single layer of cubic to palisade-shaped cells containing densely spaced crystals and fibrous infillings. Outer surface of endotesta smooth. Tegmen several cell layers thick; exotegmen of elongated fibrous cells, mesotegmen and endotegmen with large, slightly elongate and thin-walled cells; inner layers of 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 Rightcania   is abraded, but remains of the hypanthium are preserved in one specimen indicating that the floral organization was semi-inferior as in the extinct chloranthoid genus Canrightia ( Friis and Pedersen 2011)   . Other floral features are unknown, but Rightcania   is also similar to Canrightia   in having several orthotropous ovules/seeds enclosed in a thin-walled, probably fleshy fruit, and in having seeds with a seed coat structure closely similar to that of extant and fossil Chloranthaceae   . Rightcania   is very rare in the Puddledock mesofossil assemblages and include three-, four- and five-seeded fruits, whereas in the more abundant Canrightia   material from Portugal the number of seeds varies between two and five ( Friis and Pedersen 2011).

Prominent resin bodies in the fruit wall are characteristic for Canrightia   , but have not been observed in Rightcania   . Whether this reflects poor preservation of the fruit wall or original absence is unknown. Rightcania   also differs from Canrightia   in its thicker outer testa composed of several layers of irregular sclerenchyma cells, as well as its thicker endotesta. In both genera the inner integument (tegmen) is several cells thick with the exotegmen consisting of thickwalled cells, and the meso- and endotegmen composed of larger and thin-walled cells. The cells of the tegmen are well preserved in ovules that are not mature, but they are collapsed or consumed in mature seeds. In Canrightia   the endotegmen is developed as a distinctive endothelium of radially elongated cells, while in Rightcania   the endotegmen is less distinct and less clearly differentiated from mesotegmen, as is also the case in Canrightiopsis   . Canrightiopsis   is distinguished from Rightcania   by its one-seeded fruits and thicker cell walls of the meso- and endotegmen ( Friis et al. 2015).