Raminervia mariopteroides Boyarina, 1994

Boyarina, Natalya, 2010, Late Gzhelian pteridosperms with callipterid foliage of the Donets Basin, Ukraine, Acta Palaeontologica Polonica 55 (2), pp. 343-359 : 352

Raminervia mariopteroides Boyarina, 1994

Figs. 7C, D, F–H, 8.

1994 Raminervia mariopteroides sp. nov.; Boyarina, 1994: 120–127, text−figs. 2–5.

Material.—Five fragments of fronds with a bifurcation of the primary rachis, figured are SNM PMC 2216/6, SNM PMC 2216/118 and SNM PMC 2216/27; 24 fragments of penultimate order pinnae, the most informative are SNM PMC 2216/4, SNM PMC 2216/32, SNM PMC 2216/35, SNM PMC 2216/36, SNM PMC 2216/39, SNM PMC 2216/47, SNM PMC 2216/49, SNM PMC 2216/74, SNM PMC 2216/76; 27 fragments of ultimate order pinnae, figured are SNM PMC 2216/5, SNM PMC 2216/10 and SNM PMC 2216/119.

Emended diagnosis.—Frond bipartite in the upper part, and bipinnate. Primary rachis bifurcating. Axes of penultimate or− der pinnae longitudinally striated, terminating in a pseudodichotomy. Pinnules obovate or wedge−shaped to prolonged, decurrent. Lateral pinnule margins vary from entire−margined and lobed to dissected into five to seven segments. Segments obovate to wedge−shaped, relatively broad, with obtuse or rounded apex and convex lateral margins. Midvein thin, bifurcating in the basal or middle part of the pinnule. Lateral veins thin, bifurcating 1–2 times near the midvein. Intercalary pinnules resembling the other pinnules.

Description.—The primary rachis bifurcates with an angle of 35 ° ( Fig. 8A). The pinnae of penultimate order bear larger and stronger developed ultimate order pinnae on the external than on the internal side ( Figs. 7C, G, H; 8A, D, F). The apical part of the axis of penultimate order shows the pseudodichotomy ( Fig. 7F). Pinnules vary in the size, being 8–30 mm long and 5–12 mm wide. The pinnules, up to 8–12 mm long and 5 mm wide, are obovate or wedge−shaped, with crenulate lateral margins to slightly lobed ( Figs. 7C, D, G, H; 8B, F). The pinnules with a length of 13–30 mm and a width of 6–15 mm are lobed to dissected into five to seven segments ( Fig. 8G 1 ). One of the fragments of the penultimate or− der pinnae shows the basal basiscopic pinnule on the ultimate order pinna being stronger developed than other pinnules as in mariopterids ( Fig. 8C).

Remarks.—The foliage of Raminervia mariopteroides is different from other callipterids. Nevertheless, some morphological similarity is observed between the small pinnules of the Raminervia mariopteroides fronds and the small pinnules of Rhachiphyllum schenkii (Heyer, 1884) Kerp, 1988 . However, because the genus Rhachiphyllum Kerp, 1988 has been established for forms with a monopodial frond ( Kerp and Haubold 1988), the asymmetrically developed pinnae of the penultimate order of R. mariopteroides are easily distinguished from the symmetrical frond of R. schenkii . However, isolated pinnae or small fragments of the fronds with small pinnules are difficult to identify. After the revision, some specimens originally attributed to R. schenkii deserved re−interpretation. One specimen ( Fig. 3J) has been identified as Autunia naumannii , the rest has been attributed to R. mariopteroides . Two specimens are figured in the present paper ( Figs. 7G, 8D).

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

Figures

Fig. 1. Location of the outcrop at Luganskoye (starlet) in the Donets Basin.