Dichophyllum cuneatum Boyarina, 1994

Boyarina, Natalya, 2010, Late Gzhelian pteridosperms with callipterid foliage of the Donets Basin, Ukraine, Acta Palaeontologica Polonica 55 (2), pp. 343-359 : 348

Dichophyllum cuneatum Boyarina, 1994

Fig. 5A, D–J.

1960 Callipteris aff. zbyšoviensis Augusta var. microphylla ; Stschegolev 1960: 51–52, pl. 2.

1994 Dichophyllum “ cuneata ” sp. nov.; Boyarina 1994: 127–130, text−fig. 8, 9.

Material.—Single fragment of the middle frond part— SNM PMC 2216/60; four fragments of penultimate order pinnae— SNM PMC 2216/11, SNM PMC 2216/15, SNM PMC 2216/37, SNM PMC 2216/51; three fragments of ultimate order pinnae— SNM PMC 2216/14, SNM PMC 2216/65, SNM PMC 2216/38.

Brief characterisation.—Frond bipartite in the upper part, and bipinnate. Primary rachis bifurcating and bearing pinnate pinnae below the bifurcation. Primary rachis weakly ribbed, longitudinally striated. Pinnules wedge−shaped to broadly flabelliform with three−five wedge−shaped segments. Midvein bifurcating near the pinnule base. Each segment with a single lateral vein bifurcating 1–2 times. Intercalary pinnules resembling the other pinnules; attached to the rachis between the pinnae.

Description.—The angle of bifurcation is 35 ° ( Fig. 5F). The penultimate order pinnae above the bifurcation have larger and stronger developed ultimate order pinnae on the external than on internal side ( Fig. 5A, F). The pinnules show a wide variation in size—being 2–22 mm long and 0.7–20 mm wide and vary from entire−margined ( Fig. 5F) to dissected into three−five segments ( Fig. 5A, F–J, Table 1). The pinnules have a pronounced midvein bifurcating near the pinnule base and a pronounced lateral vein in each segment.

Stratigraphic and geographic range.—Upper Gzhelian (Upper Carboniferous) of Ukraine.