Nilssonia weii Zheng Y.Cao

Plant Fossil Names Registry Number: PFN002725

Act LSID: urn:lsid:plantfossilnames.org:act:2725

Author: Z. Cao

Rank: species

Genus:

Reference: Cao, Z. (1989): Some Lower Cretaceous gymnospermae from Zhejiang with study of their cuticules. – Acta Palaeontologica Sinica 28(4): 435–446., link

Page of description: 436, 441

Illustrations or figures: pl. 1, figs 1–6, pl. 3, figs 5–8

Types

Original diagnosis/description

Leaf very large, probably linear or lanceolate; preserved length 20.5 cm; width in middle region about 5.8 cm; apex and base unknown, Rachis rather slender, 6–7 mm broad. Lamina attached to upper edge of rachis, entirely concealing it from above and cutting it transversely into equal segments. Lamina segments nearly elongate-rectangular, with their lateral margins straight, parallel to the uppermost portion of segment and then slightly curved towards the obliquely round apex, 3 cm long and about 6 cm wide basically in the middle of leaf, very closely set, in contact with adjacent segments and forming an angle of about 70° with the rachis. Distal margins of segments slightly thickened. Venation unsatisfactorily shown; only those near the rachis clearly observable Parallel veins about 12 in each segment, arising from the rachis at an angle of about 70°.
Cuticle of lamina thick, but very fragile in preparation. Epidermal cells composed of more elongated cells mixed with the group of shorter cells; veins unmarked. More elongated cell nearly rectangular or long-polygonal, 30–70 μm long and 15–20 μm wide, irregular in arrangement but all in one direction; shorter cell isodiametric, 15–25 μm in diameter. Surface of cell irregularly thickened, without papillae; anticlinal cell walls straight and broad. Stomata present in lower cuticle, scattered, round or elliptical, about 30–50 μm in diameter, deeply sunken. Subsidiary cell unspecialized, with 6–8 in number, placed around the stomatal pit and forming a more regular ring. Guard cell unpreserved.
The present specimen is simillar to Ptilophyllum in its external appearance, but in the latter, the interior base is somewhat contact and the posterior base is more or less decurrent, instead of being straight as in the present specimen. Moreover, most important is that in the cuticular structure of the former, the stoma belongs to the haplocheilic type and the anticlinal cell wall is straight, whereas in the latter, the stoma belongs to the syndetocheilic type and the anticlinal cell wall is curved.
This specimen is distinguished from all previously described species of Nilssonia by its characteristic form and cuticular structure and therefore it has been determined as a new species by the present writer.

Etymology

This species is named from Mr. Wei Feng of Zhejiang Natural Museum, the collector of the valuable specimen.

Stratigraphy

Cretaceous, Lower Cretaceous
Shouchang Formation

Locality

China
Shenjia, Zhuji County, Zhejiang Province