Calymmotheca divaricata (GÖPP.) STUR , 1877

Calymmotheca divaricata (GÖPP.) STUR, 1877

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1836 Cheilanthites divaricatus GÖPP. , p. 238, pl. 12, figs 1, 2.

1836 Gleichenites linkii GÖPP. , p. 182, pl. 2, fig. 1.

1875 Sphenopteris falkenhainii STUR , p. 26, pl. 6, fig. 1.

1877 Calymmotheca divaricata (GÖPP.) STUR , p. 165, pl. 13, figs 1–3.

1923 Sphenopteris falkenhainii STUR ; Kidston, p. 79, pl. 19, fig. 1.

1923 Sphenopteris fragilis KIDST. (non Schlotheim), p. 86, pl. 17, figs 1–5.

1923 Schuetzia bennieana KIDST. ; Kidston, pl. 107, fig. 8.

1924 Schuetzia cf. bennieana KIDST. ; Kidston, pl. 107, figs 9–13.

D e s c r i p t i o n. Bifurcate fronds attached to stems up to 15 mm wide with elongate-anastomosed surface markings. Primary rachis ca. 3 mm wide, bifurcating at 35° about 40 mm away from the attachment to the stem to form bipinnate to tripinnate primary rachis branches. Gentlytapered ultimate pinnae attached at 70‒90°, oppositely or suboppositely arranged, spaced up to 15 mm apart. Pinnules up to 5 mm long and 3 mm wide, alternately to suboppositely arranged, and somewhat obliquely (70‒80°) attached to rachis by a broad but short petiole; pinnule shape deltoid to subrhomboidal. The most proximal pinnules are deeply incised with five to seven cuneate lobes, with each lobe sometimes being further shallowly divided; more distal pinnules are less divided and at the ends of the ultimate pinnae they become simple or bifid.

R e m a r k s. This fossil-species is widespread in the upper Visean and Serpukhovian of Europe ( Mosseichik 2010). Historically it has often been referred to as “ Sphenopteris fragilis SCHLOTH. ”. That name was not validly published as Schlotheim’s (1820) work pre-dated the starting point for palaeobotanical nomenclature but was subsequently validated by Brongniart (1828). As pointed out by Strullu-Derrien et al. (2021), however, the type of that name ( Schlotheim 1804: pl. 10, fig. 17) is difficult to interpret and the earliest legitimate name with a type that can definitely be assigned to this species is Cheilanthites divaricatus the basionym of Calymmotheca divaricata .

Kidston (1923: pl. 17, figs 1–5) figured specimens of this species from the Upper Limestone Formation as S. fragilis BRONGN. He also ( Kidston 1923: pl. 19, fig. 1) figured a specimen with somewhat less divided pinnules as Sphenopteris falkenhainii STUR ( Stur 1875) but Patteisky (1957) regarded this species as being merely a variety of C. divaricata and the distinction is not recognised here.

Clusters of sporangia associated with C. divaricata fronds were described by Kidston (1924) as Schuetzia cf. bennieana but Walton (1931) showed this generic attribution to be incorrect; they are almost certainly the pollen organs of C. divaricata .

O c c u r r e n c e s. Widespread through the Limestone Coal Formation from the coal-bearing interval above the Black Metals Band, and through the Upper Limestone Formation to just below the Castlecary Limestone.