Almargemia incrassata S.Archang.
Plant Fossil Names Registry Number: PFN000771
Act LSID: urn:lsid:plantfossilnames.org:act:771
Author: S. Archangelsky
Rank: species
Reference: Archangelsky, S. (1966): New gymnosperms from the Ticó flora, Santa Cruz province, Argentina. – Bulletin of the British Museum (Natural History). Geology. 13(5): 261–295, 8 pls., link
Page of description: 267
Illustrations or figures: figs 6–10, 13, 1, figs 3, 4, pl. 3, figs 13, 14
Name is type for
Other combinations
Eobowenia incrassata (S.Archang.) Coiro et C.Pott 2017
Types
Holotype LP 6255, Palaeobotanical Collection, Museo de La Plata, La Plata, Argentina
Figures: figs 6–10, 13, pl. 1, fig. 4, pl. 3, figs 13, 14
Note: Coiro and Pott stated (2017: BioMed Centr. Evol. Biol., 17: 97, p. 4):
"Remark on types: Specimen LP6255, published by Archangelsky [43], automatically becomes the holotype of the new combination and the new genus. However, we chose specimen v52265 (a cuticle slide obtained from LP6255) as epitype; it serves as interpretative type because it perfectly presents the combination of characters necessitating the erection of the new genus."
Specimen v52265 (a cuticle slide) is housed Natural History Museum (NHM), London and figured by Coiro and Pott stated (2017: BioMed Centr. Evol. Biol., 17: 97, figs 2c, d, 3a, c, e, 4a).
Original diagnosis/description
Leaf (fragmentary) simply pinnate. Rachis delicate 1.5 mm. wide. Pinnae subopposite, inserted at angle of about 45° (more acute towards apex), with decurrent catadromic side and constricted anadromic side, oblong, with broadly dentate apex, up to 1 cm. long × 0.4 cm. wide at the middle; lateral margins dentate towards apical sector. Uniform veins, 3–4 per pinna, parallel to margins, converging at base. Fine lines between veins clearly differentiated.
Both cuticles 2 μ thick, with markedly elongated and similar epidermal cells, about 20 μ wide. They are of two kinds: (1) numerous, with thin anticlinal walls (1 μ), and (2) less numerous, with thick anticlinal walls (7 μ), and less elongated. The thick-walled cells from longitudinal rows one, or occasionally more than one, cell broad. Cells on rachises markedly elongated with the same two types of thin and thick-walled cells and occasional papillae on the thick-walled cells.
Stomata present on lower cuticle only, longitudinally orientated, sometimes obliquely, placed in rows of thick-walled cells, typically monocyclic to imperfectly dicyclic. Subsidiary cells typically 4–6 in number. Polar subsidiary cells occasionally differentiated; longer than lateral subsidiary cells wich sometimes slightly overhang guard cells. All subsidiary cells usually thick-walled (there are a few exceptions). Stomata sometimes with subsidiary cells in contact. Guard cells with poles on epidermal surface and aperture slightly sunken, 50–55 μ long. Poles, ventral and dorsal walls strongly cutinized. Longitudinal ridge of cutin occasionally present near dorsal wall of guard cells.
Emended diagnosis
Coiro and Pott (2017: BioMed Centr. Evol. Biol., 17: 97, p. 4):
As for the genus [Eobowenia], with the following additions: Leaflet base with constricted acroscopic margin and decurrent basiscopic margin. Striations are visible in between the veins.
Stratigraphy
Cretaceous, Lower Cretaceous, Aptian
Baquero Group, Anfiteatro de Ticó Formation, Auracarites Bed (according to Coiro and Pott 2017: BioMed Centr. Evol. Biol., 17: 97, p. 4)
Locality
Argentina
Estancia Bajo Grande, Santa Cruz Province Coiro and Pott (2017: BioMed Centr. Evol. Biol., 17: 97)
Coiro and Pott stated (2017: BioMed Centr. Evol. Biol., 17: 97, p. 4): "not Bajo Tigre as erroneously reported by Archangeslky".
Plant fossil remain
macro- and meso-fossils-embryophytes except wood
Comments
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