Polypora darashamensis Nikiforova, 1933

Ernst, Andrej, Senowbari-Daryan, Baba & Hamedani, Ali, 2006, Middle Permian Bryozoa from the Lakaftari area, northeast of Esfahan (central Iran), Geodiversitas 28 (4), pp. 543-590 : 569

Polypora darashamensis Nikiforova, 1933 ( Fig. 10 A-F; Table 24)

Polypora timorensis var. darashamensis Nikiforova, 1933: 22 , pl. 4, figs 4-9.

Polypora darashamensis – Morozova 1970a: 219, 220, pl. 51, fig. 1.

Polypora aff. darashamensis – Sakagami 1980: 282, 283, pl. 32, fig. 9.

LECTOTYPE. — Central Museum of Geological Prospecting, Saint Petersburg, Russia. Pictured in Nikiforova 1933: pl. 4, fig. 8 (designated by Morozova 1970a: 219).

MATERIAL EXAMINED. — Single colony 21-2 (two thin sections).

OCCURRENCE. — Transcaucasia, Upper Permian, Dzhulfian ( Morozova 1970a). Abadeh region: central Iran, Middle Permian ( Sakagami 1980). Lakaftari: central Iran, Jamal Formation, Middle Permian.

DESCRIPTION

Micrometric formula: 7-8.5/6//16-17. Reticulated colonies with straight branches, joined by dissepiments. Bifurcation common.Autozooecia arranged in 3-4 alternating rows on branches, becoming 5 at the site of bifurcation. Apertures circular, spaced 2-3 per length of a fenestrule; 1-4 small nodes developed in peristome. Shape of fenestrules varying from oval to rectangular. Keels absent. Nodes small to moderately large, irregularly spaced on the obverse colony surface between apertures, displaying radial arrangement of rods. Internal granular skeleton thick, well developed, continuous with nodes, rods, peristome and across dissepiments.Outer lamellar skeleton moderately thick, containing abundant rods 5-6 µm in diameter.

INTERIOR DESCRIPTION

Autozooecia rhombic to hexagonal in the middle tangential section, irregularly shaped in the place of

bifurcation; high and short in longitudinal section, with well developed vestibule protruding highly above the colony surface; elongate to branch length; aperture positioned at distal to distal-abaxial end of chamber. Hemisepta absent.

COMPARISON

Polypora darashamensis differs from P. soyanensis in having thicker branches and larger fenestrules.

REMARK

Morozova (1970a: 220) mentioned the finding of three colonies of Polypora darashamensis in the Lower Triassic (Indian) of Transcaucasia. However, it seems very likely that this material was re-deposited from the Upper Permian rocks, and is not autochthonous to the Triassic rocks.

Figures

FIG. 10. — A-F, Polypora darashamensis Nikiforova,1933; A, 21-2, tangential section showing aperture with apertural nodes; B, 21-2, tangential section showing aperture with apertural nodes and high peristome;C, 21-2,tangential section showing aperture with apertural nodes and nodes on the colony surface; D, 21-2, deep tangential section; E, 21-2, tangential section showing apertures and nodes on the colony surface; F, 21-2, deep tangential section showing autozooecial chambers;G-J, Polypora magnicava Morozova, 1970; G, I, 19-1, tangential section; H, 19-1, tangential section showing aperture with apertural nodes and nodes on the colony surface; J, 19-1, cross section of the branch; K-O, Polypora aff.anshunensis Yang & Lu, 1980;K, 25-3-1,tangential section;L, M, 25-3-1, cross section; N, 25-3-1, tangential section showing apertures with apertural nodes; O, 25-3-1, deep tangential section;P, Polypora sinokoninckiana Yang & Lu, 1962, 1-3-4, tangential section. Scale bars: A-C, H, N, 0.1 mm; D, G, K, M, P, 1 mm; E, F, I, J, L, O, 0.5 mm.