Spinofenestella, Termier & Termier, 1971

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 : 558

Spinofenestella sp. 1 ( Fig. 6 A-E; Table 12)

MATERIAL EXAMINED. — 4-15, 5-12-1, 7-4, 9-1-2, 9-4, 9-5-8, 9-5-10, 17-1, 23-3-1.

OCCURRENCE. — Lakaftari: central Iran, Jamal Formation, Middle Permian.

DESCRIPTION

Micrometric formula: 15-20/13-16//19-26. Reticulated colonies with straight or slightly undulating branches, joined by dissepiments. Bifurcation common. Autozooecia arranged in 2 alternating rows on branches.Apertures circular, containing 12-13 small nodes and 8 septa in the peristome, spaced 2 per length of a fenestrule. Shape of fenestrules varying from oval to slightly rectangular. Keel low, carrying single row of large and widely spaced nodes. Internal granular skeleton thick, well developed, continuous with obverse keel, nodes, peristome and across dissepiments. Outer lamellar skeleton sometimes extremely thick. Microacanthostyles abundant on the obverse surface; usually absent on reverse side, having distinct narrow hyaline cores and wide laminated sheaths, 10-30 µm in diameter.

INTERIOR DESCRIPTION

Autozooecia triangular in a middle tangential section, low and elongated, with well developed vestibule; aperture positioned at distal to distal-abaxial end of chamber. Superior hemisepta short; inferior hemisepta absent. Apertures often closed by terminal diaphragms.

COMPARISON

The present material is similar to Fenestella otae Sakagami, 1964 from the Lower Permian of Japan ( Parafusulina kaerimizensis -zone). Spinofenestella sp. 1 differs in having thicker branches (0.31-0.47 vs. 0.23-0.32 mm in F. otae ), and thinner dissepiments (0.20-0.30 vs. 0.228 -0.368 mm in F.otae ). It is also similar to Spinofenestella popovi (Nekhoroshev, 1959) from the Upper Permian of the Northern Urals ( Morozova 1981). The two species differ in fenestrule length (0.80-0.90 mm in S. popovi vs. 0.42-0.58 mm in Spinofenestella sp. 1).

REMARK

Both species of Spinofenestella described here contain eight regular septa in their apertures. These septa are similar to those described by Engel (1975) for his new family Septatoporidae including the single genus Septatopora . However, similar structures occur in many fenestrate bryozoans, but are often destroyed by weathering. Furthermore, species placed by Engel (1975) in his family reveal different internal morphologies.

Figures

FIG. 6. — A-E, Spinofenestella sp. 1; A, B, 17-1-1, tangential section; C, 23-3-1, tangential section showing apertures with apertural nodes; D, 9-5-7, cross section showing the autozooecial chamber with terminal diaphragm (arrow: terminal diaphragm); E, 9-5-10, cross section showing the autozooecial chamber and extensive depositions of outer laminated skeleton; F-I, Spinofenestella sp. 2; F, 9-7, tangential section showing the autozooecial apertures with septa and nodes; G, 9-5-8, tangential section showing the autozooecial apertures and carinal nodes; H, 9-7, tangential section showing the autozooecial apertures with septa and nodes; I, 7-3-5, tangential section; J-L, Alternifenestella sayensis Termier & Termier, 1971; J, 13-4-1, tangential section showing the autozooecial apertures and carinal nodes; K, 5-8-1, tangential section showing the autozooecial apertures and autozooecial chambers; L, 13-4-1, tangential section; M, N, Minilya perelegans (Waagen & Pichl, 1885); M, 25-3-5, tangential section; N, 4-7-3, tangential section; O, P, Fabifenestella jabiensis (Waagen & Pichl, 1885), 25-10-5, tangential section. Scale bars: A, 1 mm; B, I-N, P, 0.5 mm; C, 0.2 mm; D, F, H, 0.1 mm; E, G, O, 0.25 mm.