Mackinneyella robustiformis ( 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 : 566-568

Mackinneyella robustiformis ( Morozova, 1965) ( Fig. 9D , F-K; Table 22)

Polypora robustiformis Morozova, 1965: 195 , pl. 28, fig. 4; 1970a: 220, 221, pl. 5, fig. 2, text-fig. 40. — Xia 1986: 228, pl. 10, fig. 1.

Mackinneyella robustiformis – Morozova & Lisitsyn 1996: 45.

HOLOTYPE. — No. 1613/199, PIN; Transcaucasia (Nakhichevan); Gnishik Horizon, Middle Permian, Murgabian (= Wordian).

MATERIAL EXAMINED. — 4-18-2, 20-1, 24-5.

OCCURRENCE. — Transcaucasia (Nakhichevan); Gnishik Horizon, Middle Permian, Murgabian (= Wordian). Lakaftari: central Iran, Jamal Formation, Middle Permian.

DESCRIPTION

Micrometric formula: 6-10/4-6.5//16-18.5. Reticulated colonies with straight branches, joined by dissepiments. Bifurcation common. Autozooecia arranged in 4-5 alternating rows on branches, becoming 7-8 in the place of bifurcation. Apertures circular, arranged in regular alternating rows, spaced 4-5 per length of a fenestrule. Shape of fenestrules varying from oval to rectangular. Keels absent. Nodes small, regularly spaced on the obverse colony surface.Internal granular skeleton thick, well developed, continuous with nodes, peristome and across dissepiments. Outer lamellar skeleton moderately thick, containing abundant hyaline rods 5-10 µm in diameter. Microacanthostyles moderately abundant, having distinct hyaline cores and dark laminated sheaths, 10-15 µm in diameter.

INTERIOR DESCRIPTION

Autozooecia rhombic 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

Mackinneyella robustiformis differs from M. praepluriformis in having smaller fenestrules and thinner branches, as well as in arrangement of microacanthostyles on the reverse surface.

Figures

FIG. 9. — A-C, E, Mackinneyella dzhulfensis (Morozova,1965);A, 13a, deep tangential section;B, 12-2-3,tangential section; C, 12-2-3, deep tangential section; E, 12-2-3, tangential section showing apertures and nodes; D, F-K, Mackinneyella robustiformis (Morozova, 1965); D, 4-18-2, deep tangential section; F, 4-18-2, tangential section showing apertures with apertural nodes; G, 4-18-2, tangential section of the branch; H, 4-18-2, deep tangential section showing autozooecial chambers; I, 19-4-10, cross section of the branch; J, 4-18-2, thin section showing reverse surface with microacanthostyles and hyaline rods; K, 19-4-10, cross section of the branch showing outer laminated skeleton with microacanthostyles; L-R, Polypora soyanensis Morozova, 1970; L, 23-6-3, tangential section; M, 18-1-6, tangential section; N, 1-8-2, tangential section; O, 18-1-6, cross section; P, 18-1-6, tangential section showing ovicell; Q, 23-6-3, tangential section showing radial structure of a node; R, 23-6-3, tangential section showing apertures and nodes. Scale bars: A, L, M, 1 mm; B, D, 2 mm; C, E, G-I, O, 0.25 mm; F, 0.2 mm; J, K, P-R, 0.1 mm; N, 0.5 mm.