Rectifenestella microretiformis (Morozova, 1970) Ernst & Senowbari-Daryan & Hamedani, 2006

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 : 556-558

Rectifenestella microretiformis (Morozova, 1970) n. comb. ( Fig. 5 F-I; Table 11)

Fenestella microretiformis Morozova, 1970a: 166-168 , pl. 32, fig. 5a, b, text-figs 35, 36. — Xia 1986: 220, 221, pl. 7, fig. 6; 1991: 175, pl. 1, fig. 7.

HOLOTYPE. — No. 1692/182, PIN; Arkhangelsk region ( Russia); Middle Permian (lower Kazanian).

MATERIAL EXAMINED. — 1-6-1, 4-5-5, 5-9, 7-2, 10-1, 10-2, 22-1-3, 23-1-2, 25-5-1, 25-8.

OCCURRENCE. — Xizang, Southern China; Upper Xarla Formation, Lower Permian and Chanaha Formation (Chihsan-Maokauan Stages), Middle Permian ( Xia 1986, 1991). Russian Platform; lower Kazanian, Middle Permian. Khabarovsk region; Chandalazki Horizon (= Metadoliolina zone),?Murgabian-Midian, Middle Permian. Lakaftari: central Iran, Jamal Formation, Middle Permian.

DESCRIPTION

Micrometric formula: 22.5-31.5/18-25//22-26.5. Reticulated colonies with straight branches, joined by dissepiments.Bifurcation common. Autozooecia arranged in 2 alternating rows on branches, becoming 3 in the place of bifurcation. Apertures circular, spaced 2-2.5 per length of a fenestrule, containing 8 small nodes in the peristome shaping it as regular octagons. Shape of fenestrules varying from oval to slightly rectangular. Keel low, carrying single row of moderately large and closely spaced nodes. Internal granular skeleton thick, well developed, continuous with obverse keel, nodes, microacanthostyles, peristome and across dissepiments.Outer lamellar skeleton moderately thick. Abundant microacanthostyles on the reverse surface, having distinct cores and wide laminated sheaths, 15-25 µm in diameter.

INTERIOR DESCRIPTION

Autozooecia pentagonal in the middle tangential section; low and elongated, with well developed vestibule in longitudinal section; aperture positioned at distal to distal-abaxial end of chamber. Superior hemisepta short; inferior hemisepta absent.

COMPARISON

Rectifenestella microretiformis n. comb. differs from R. permulta (Morozova, 1970) ( Morozova 1970a) in having thinner branches and smaller fenestrules. This species differs also from R. araxensis n. comb. in having thinner branches (0.25 vs. 0.30 mm averagely in R. araxensis n. comb.) and smaller fenestrules (fenestrule length 0.36 vs. 0.45 mm; fenestrule width 0.18 vs. 0.21 mm in R. araxensis n. comb.).

REMARK

Fenestella microretiformis is placed in the genus Rectifenestella because of its pentagonally shaped autozooecial chambers in the middle tangential section and presence of singular row of nodes on the keel ( Morozova 1974: 61).

Figures

FIG. 5. — A-E, Rectifenestella araxensis (Nikiforova,1933) n.comb.;A, 7-1-1, thin section of reverse surface showing abundant microacanthostyles; B, 17-1-6, tangential section showing apertures with apertural nodes and carinal nodes; C, 9-5-7, cross section of the branch showing autozooecial chambers; D, 1-4-3, tangential section of the branch with three rows of autozooecia; E, 1-4-1, deep tangential section of the branch with three rows of autozooecia and dichotoming branch;F-I, Rectifenestella microretiformis (Morozova, 1970) n. comb.; F, 23-1-2, deep tangential section; G, 7-2, thin section of the reverse surface showing abundant microacanthostyles; H, 10-1-6, tangential section; I, 7-2-3, tangential section. Scale bars: A-C, F, 0.1 mm; D, E, 0.5 mm; G, 0.2 mm; H, I, 0.25 mm.