Mihai's Paleobotany Chronicles

Pachypteris rhomboidalis (ETTINGSHAUSEN) DOLUDENKO 1974

1852 Thinnfeldia rhomboidalis ETTINGSHAUSEN, p. 2-4, Pl. 1, Figs. 4-7.
1855 Pachypteris thinnfeldi ANDRAE, p. 43-44, Pl. 11, Fig. 6, Pl. 12, Figs. 7-9.
1969 Thinnfeldia rhomboidalis HUMML, p. 396.
1994 Pachypteris rhomboidalis BARBACKA, p. 7, Pl. 1, Fig. 3, Pl. 5, Figs. 3, 5.
1997 Pachypteris rhomboidalis DRAGASTAN and POPA, p. 55, Pl.
1997 Pachypteris rhomboidalis POPA, p. 81-87, Pl. 1, Figs. 3-4, Pl. 2, Fig. 6, Text-fig. 4.

Pteridospermopsida/Corystospermales/Incertae sedis

The leaf is pinnate, with a stout rachis, 0.7-1 mm wide. The rachis is not ornamented, having the same position as the pinnules level. Pinnules are attached in opposed or slightly sub-opposed position. Their shape is typically rhomboidal, with a narrow base (1.5-2 mm width), with the acroscopic margin almost parallel to the rachis, entire margins and rounded apex, having a constant shape. The midrib is slightly defined, with secondary veins undivided. The substance of lamina is thick. The leaf is hypostomatic, with the upper cuticle thicker than the lower one. On the upper cuticle, the parenchimatous cells are usually square, triangular or irregular in shape, frequently with irregular anticlinal walls. The midrib is slightly expressed epidermally on the upper cuticle, but no secondary veins. The midrib is expressed by rows of parallel, slightly elongated cells. The stomata are very rare on the upper epidermis, their occurrence remaining atypical. The lower cuticle has also parenchimatous cells irregular in shape, with the midrib expressed in the same way, very pale. The stomata have an elongated ostiole, with guard cells rarely preserved during maceration. The subsidiary cells form a wide ring of 3-5 cells irregular in shape, not distributed in a lower plane with regard to the ostiole. The stomata are randomly distributed in the whole surface of the pinnule, excepting the midrib and a narrow zone close to the pinnule’s margin. The margin has 7-12 rows of elongated cells.

The species has been defined by Ettingshausen (1852) as Thinnfeldia rhomboidalis, on material collected from the Thinnfeld Pit, in Steierdorf, Anina. Andrae (1855) and Doludenko (1974) emended the diagnosis of the species on material collected also from Anina, given by A. Badaluta to V. Vachrameev, attributing the species to the Pachypteris genus. Humml (1969), Barbacka (1994) described Romanian material too. Popa (1997, 2000) redescribed material collected from Anina and Cristian.

The species was collected from Anina, Holbav and Cristian, all these localities belonging to the Getic Nappe, South Carpathians.

Hettangian-Sinemurian in age.

Marsh, humid areas. P. rhomboidalis is a possible coal generator in Anina and Holbav.

In Anina, P. rhomboidalis is frequent, well preserved, with large fragments. The material collected from Holbav and Cristian is also very well preserved.

Andrae, C., 1855. Beitrage zur kenntniss der fossilen Flora Siebenburgens und des Banates. Abhandlungen der K. K. geologischen Reichsanstalt, III(4): 1-48.

Ettingshausen, C., 1852. Begrundung einiger neuen oder nicht genau bekannten Arten der Lias- und Oolithflora. Abhandlungen der K. K. geologischen Reichsanstalt, 1(3 (3)): 1-10.

Humml, H., 1969. Contributii la flora fosila a Liasicului inferior de la Steierdorf-Anina. Studii si cercetari de geologie, geofizica, geografie, Sectia geologie, 14(2): 385-404.

Popa, M.E., 1997. Corystospermal pteridosperms in the Liassic continental deposits of Romania. Acta Palaeontologica Romaniae(1): 81-87.

Popa, M.E., 2000. Early Jurassic land flora of the Getic Nappe, University of Bucharest, Bucharest, 258 pp.

Pachypteris rhomboidalis, Dragoie collection, University of Bucharest, Holbav.

Lower cuticle of Pachyperis rhomboidalis, Holbav.