Mackinneyella praepluriformis ( Morozova, 1965 )

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 : 564-566

Mackinneyella praepluriformis ( Morozova, 1965) ( Fig. 8 G-K; Table 20)

Polypora consanguinea Bassler, 1929: 79 , 80, pl. 19, figs 5-10.

Polypora sp. ex. gr. consanguinea – Nikiforova 1933: 25, pl. 6, fig. 5.

Polypora praepluriformis Morozova, 1965: 194 , pl. 28, fig. 2; 1970a: 218, pl. 50, figs 2, 3.

Mackinneyella praepluriformis – Morozova & Lisitsyn 1996: 45.

HOLOTYPE. — No. 1613/106, PIN; Transcaucasia; Gnishik Horizon, Middle Permian (Murgabian).

MATERIAL EXAMINED. — 4-5-3, 5-7, 7-2-1, 7-5, 23-2-2, 23-8, 24-5, 25-4-1, 25-10, 25-12-1.

OCCURRENCE. — Xainza, Northern Xizang, Southern China; Upper Xarla Formation, Lower Permian. Transcaucasia (Nakhichevan), Gnishik Horizon, Middle Permian, Murgabian (= Wordian). Lakaftari: central Iran, Jamal Formation, Middle Permian.

DESCRIPTION

Micrometric formula: 4.5-6.5/3-4//12-15. Reticulated colonies with straight branches, joined by dissepiments. Bifurcation common. Autozooecia arranged in 4-6 alternating rows on branches, becoming 7-9 in the place of bifurcation. Apertures circular, spaced 5-8 per length of a fenestrule, surrounded by thin peristomes; usually 1-2 small nodes near the aperture. Shape of fenestrules varying from oval to slightly rectangular. Keels absent. Nodes small, regularly spaced on the obverse colony surface. Internal granular skeleton thick, well developed, continuous with nodes, rods, peristome and across dissepiments. Outer lamellar skeleton moderately thick, containing abundant rods 5- 10 µm in diameter.

INTERIOR DESCRIPTION

Autozooecia rhombic in the middle tangential section, high and short in longitudinal section, with well developed vestibule; elongate to branch length; aperture positioned at distal to distal-abaxial end of chamber. Hemisepta absent.

COMPARISON

Mackinneyella praepluriformis is similar to M. robustiformis from the Middle Permian (Gnishik Horizon, Guadalupian) of Transcaucasia. The two species differ in branch thickness (1.04 mm in M. praepluriformis vs. 0.75 mm in M. robustiformis ), as well as in fenestrule dimensions which are larger in M. praepluriformis . Furthermore, M. robustiformis has abundant microacanthostyles on the reverse side and abundant nodes on the obverse side.

Figures

FIG. 8. — A-C, Septopora flabellata Nikiforova,1933;A, 1-7-4, longitudinal section showing autozooecial chambers and cyclozooecia; B, 20-5-4,longitudinal section showing autozooecial chambers,cyclozooecia and the outer laminated skeleton with microacanthostyles; C, 1-3-1, cross section showing autozooecial chambers and cyclozooecia; D-F, Penniretepora afghanica n. sp.; D, paratype 14, free colony;E, 10-2-11, tangential section;F, holotype SMF 2114,tangential section; G-K, Mackinneyella praepluriformis (Morozova,1965); G, 24-5-2, deep tangential section showing autozooecial chambers; H, 24-5-2, tangential section showing autozooecial apertures, nodes and hyaline rods; I, 25-12-1, tangential section; J, 16-1, fragment of the colony; K, 16-1-4, cross section of the branch; L, M, Mackinneyella dzhulfensis (Morozova, 1965); L, 13b, cross section of the branch; M, 13, fragment of the colony. Scale bas: A-C, G, K, L, 0.5 mm; D, 2 mm; E, 1 mm; F, 0.25 mm; H, 0.1 mm; I, J, M, 10 mm.