Cordaites karvinensis

Šimůnek, Zbyněk, 2019, Revision Of The Late Bashkirian Cordaitalean Cordaites Karvinensis And Allied Dispersed Cuticles From Upper Silesia, The Czech Republic, Fossil Imprint 75 (2), pp. 258-267 : 260

Cordaites karvinensis ŠIMŮNEK, 2007

Pl. 1, Figs 1–7, Pl. 2, Figs 1–7, Pl. 3, Fig. 1

2000 “ Cordaites principalis ”; Šimůnek, p. 27, fig. 2:1, 2.

2001 Cordaites “ principalis ” (GEMAR) GEINITZ (morfotyp 1 sensu Šimůnek 2000); Šimůnek, pp. 32–34, fig. 15a–e, pl. 2, fig. 1, pl. 4, figs 1–4.

2001 Cordaites “ principalis ” (GEMAR) GEINITZ (morfotyp 2 sensu Šimůnek 2000); Šimůnek, pp. 34–36, fig. 16a–g, pl. 2, fig. 2, pl. 4, figs 5–9, pl. 5, figs 1–3.

2007 Cordaites karvinensis ŠIMŮNEK, p. 108, text-fig. 10a–e, pl. 2, fig. 1, pl. 4, figs 1–4.

2007 Cordaites sustae ŠIMŮNEK, p. 109, text-fig. 11a–g, pl. 2, fig. 2, pl. 4, figs 5–9, pl. 5, figs 1–3.

H o l o t y p e. Inv. no. A 5999, coll. Ostrava Museum

( Šimůnek 2007: text-fig. 10a–e, pl. 2, fig. 1, pl. 4, figs 1–4).

Ty p e l o c a l i t y. Karviná, Hlubina Mine, Upper

Silesian Basin, the Czech Republic.

Ty p e h o r i z o n. Karviná Formation, Upper Suchá

Member, Coal seam No. 19, Langsettian (Westphalian A).

A d d i t i o n a l m a t e r i a l. Inv. no. A 6581 , coll . V. Šusta, Ostrava Museum (holotype of Cordaites sustae; Šimůnek 2007: text-fig. 11a–g, pl. 2, fig. 2, pl. 4, figs 5–9, pl. 5, figs 1–3) .

E m e n d e d d i a g n o s i s. Haplocheilic, relatively narrow, lanceolate hypostomatic leaves with medium-dense parallel venation and bluntly pointed apex. 1 or 2 thin veins (sclerotic bundles) alternate with each thick (true) vein. Adaxial cuticle with oblong to trapezoidal cells. Cells of the abaxial cuticle are papillary, tetragonal, stomata dispersed in more or less poorly defined, rare stomatal rows. Guard cells surrounded by proximal papillae more or less joined at the base. Polar ends of the guard cells form a swallow-tail extension.

D e s c r i p t i o n. The holotype is a fragment of a leaf ( A 5999 ) 205 mm long and 20 mm wide. The specimen A 6581 is 180 mm long and 28 mm wide. The venation is parallel. There are 34 veins per cm at the leaf margin, and 38 veins per cm in the middle of the leaf (Pl. 1, Fig. 3). One to two thin veins (sclerotic bundles) alternate with each thick (true) vein. The leaves are hypostomatic. (Only one putative stoma was observed on the adaxial cuticle; see Pl. 3, Fig. 1) .

Adaxial cuticle (Pl. 1, Fig. 4, Pl. 2, Fig. 7, Pl. 3, Fig. 1): The ordinary cells are differentiated into costal and intercostal areas. Bands formed by relatively narrow cells (15–20 μm) alternate with bands consisting of cells 20–30 μm wide (Pl. 3, Fig. 1). The cells are markedly elongate, 40– 100 μm long, usually of oblong or trapezoidal shape. The anticlinal walls are straight. The cells are oriented parallel to the veins.

Abaxial cuticle (Pl. 2, Figs 3–6): The ordinary cells are not differentiated into costal and intercostal fields. Stomata are arranged in poorly defined stomatal rows. The cells are papillate, elongated, of tetragonal (oblong) shape. The ordinary cells among the stomata are 35–60 μm long and 15–20 μm wide. At certain intervals, unicellular rows of elongated cells occur. These cells are 100–200 μm long and about 15 μm wide. The anticlinal walls are ± straight. The cells and stomatal complexes are oriented parallel to the veins. The guard cells are of crescent shape, 40–55 μm long (including their swallow-tail elongation) and 5–8 μm wide (Pl. 2, Fig. 6). They are usually surrounded by 2 polar and 2 lateral subsidiary cells of the same shape as the ordinary epidermal cells, i.e. oblong. The stomatal pore is surrounded by proximal papillae growing from the subsidiary cells. The stomatal density is 170–190 stomata per mm 2 (sample A 5999) and only 89–143 stomata per mm 2 in the case of sample A 6581. The stomatal index could be calculated only for this sample: SI = 13.3–17.

D i s c u s s i o n. The leaves and venation of the species Cordaites karvinensis belong to narrow-leaved forms. Cordaites karvinensis and C. sustae were distinguished by slightly different venation pattern. However, it can be caused by taphonomical processes. The adaxial cuticle in both specimens representing holotypes of C. karvinensis and C. sustae is practically identical. The reason why the two species were separated was due to differences in their abaxial cuticles. However, it seems that these are caused by differences in preservation. Cuticles of Cordaites karvinensis were poorly preserved with dirt on the abaxial surface, poorly visible anticlinal walls which were dashed in Šimůnek’s (2007) drawing. During the new observation, it was recognized that the small piece of dirt is a papilla in reality and in some guard cells the same swallow-tail polar endings were distinguished as in the holotype of C. sustae. In addition, because both taxa come from the same locality and the same stratigraphy – roof of the coal seam 19, it is very probable that the two earlier recognized species belong to one species. Now, the correct name should be Cordaites karvinensis .