Sphenopteris elegans (BRONGN.) STERNB., 1825

Cleal, Christopher J., Strullu-Derrien, Christine & Spencer, Alan R. T., 2024, Early Coal Swamp Vegetation From The Serpukhovian Lower Clackmannan Group Of Scotland, Fossil Imprint 80 (1), pp. 35-67 : 47-49

Sphenopteris elegans (BRONGN.) STERNB., 1825

Text-fig. 7a

1820 Filicites adiantoides SCHLOTH. , nom. inval., p. 408, pl. 21, fig. 2.

1822 Filicites (Sphenopteris) elegans BRONGN. , p. 233, p. 2, fig. 2.

1825 Sphenopteris elegans (BRONGN.) STERNB. , p. xv.

1834 Sphenopteris adiantoides SCHLOTH. ex LINDL. et HUTTON , p. 91, fig. 115.

1877 Diplothmema adiantoides (SCHLOTH. ex LINDL. et HUTTON) STUR , p. 230.

1903 Diplotheca stellata KIDST. in Peach, p. 131.

1923 Diplothmema adiantoides (SCHLOTH. ex LINDL. et HUTTON) STUR ; Kidston, p. 242, pl. 64, figs 1–4, pl. 65, pl. 66, figs 1–3, pl. 67, figs 4, 5.

1924 Diplotheca stellata KIDST. ; Kidston, p. 462, pl. 104, figs 1, 2.

2023 Sphenopteris elegans (BRONGN.) STERNB. ; Cleal and Thomas, fig. 2.

D e s c r i p t i o n. Fronds bone spirally on stem up to 40 mm wide. Petiole of frond bifurcates at wide angle to produce two asymmetrically-deltoid, primary pinna branches up to 0.2 m long; no pinnae attached below main frond bifurcation. Primary rachis branches bear once or twice pinnate secondary pinnae. All rachises have central longitudinal zone with transverse ridges. Pinnules alternate, cuneate to deltoid in shape, digitate with linear to cuneate lobes.

R e m a r k s. This is the most abundant and distinctive pteridosperm species in the Serpukhovian floras of Scotland. It is the type species of the fossil-genus Sphenopteris . Sporangial clusters that may have been borne on S. elegans fronds were described by Kidston (in Peach 1903) as Diplotheca stellata KIDST. , although that genus name is illegitimate ( Diplotheca KIDST. was a later homonym of a name used for extant angiosperms). A large specimen of this species showing the frond architecture from the Upper Limestone Formation was figured by Cleal and Thomas (2023).

O c c u r r e n c e s. Abundant in between the Johnstone Shell Bed (lower Limestone Coal Formation) and the Lyoncross Cement Limestone (upper Upper Limestone Formation).

Figures

Text-fig. 7. a: Sphenopteris elegans (BRONGN.) STERNB.; Cuthill Shore (near highwater mark) between Musselburgh and Prestonpans, Haddingtonshire; between Nos 4 and 5 Limestones, Upper Limestone Formation; BGS Kidst.3816. b: Sphenopteris dicksonioides (GÖPP.) C.E.WEISS; No. 6 Pit, Grange, Bo’ness, Linlithgowshire; above Red Coal, Limestone Coal Formation; BGS Kidst.781. c: Sphenopteris taitiana KIDST.; Cuthill Shore between Musselburgh and Prestonpans, Haddingtonshire; between Nos 4 and 5 Limestones, Upper Limestone Formation; BGS Kidst.341. d: Sphenopteris mira KIDST.; New Braidbar Quarry, Giffnock, East Renfrewshire; below Orchard Limestone, Upper Limestone Formation; BGS Kidst.2416. e: Sphenopteridium dissectum (GÖPP.) SCHIMP.; Swinless Glen, Dalry, Ayrshire; above Garibaldi Ironstone, Limestone Coal Formation; BGS Kidst.5320. All scale bars = 10 mm.