Anastomopora cf. quebecensis FRITZ , 1938

Ernst, Andrej, Tolokonnikova, Zoya & Yarahmadzahi, Hamed, 2012, Upper Devonian (Frasnian) Bryozoa from the Shishtu 1 Formation of Niaz area (eastern Tabas, central Iran), Revue de Paléobiologie 31 (1), pp. 1-14 : 6-10

Anastomopora cf. quebecensis FRITZ, 1938

Pl. III, figs 6-8, Pl. IV, figs 1-8; Table 5

1938. Anastomopora quebecensis FRITZ, 1938, p. 91 -92, pl. 1, fig. 5.

Plate I All specimens come from the Shishtu 1 Formation, Upper Devonian, Frasnian. Niaz section, eastern Tabas, central Iran.

1: Lateral view of the colony (SMF 21.098). 2: Transverse section of the colony, polished slab (SMF 21.098). 3: Transverse thin section of the colony (SMF 21.097). 4: Longitudinal thin section of multilayered colony (SMF 21.088). 5-6: Longitudinal thin section of multilayered colony showing autozooecial chambers, hemicylindrical cystlike structures and vesicular skeleton (SMF 21.084). 7: Tangential thin section showing macula consisting of vesicle skeleton (SMF 21.087). 8: Longitudinal thin section of multilayered colony showing autozooecial chambers, hemicylindrical cystlike structures and vesicular skeleton between autozooecia and in macula (SMF 21.097). 9: Longitudinal thin section showing hemicylindrical cystlike structure in autozooecial chamber (SMF 21.088). 10: Tangential thin section showing autozooecial apertures and vesicles (SMF 21.086). 11-12: Shallow tangential thin section showing autozooecial apertures, lunaria and extensively developed granular skeleton (SMF 21.093).

Material: Four thin sections of two colonies SMF 21.100- SMF 21.103.

Exterior description: Reticulate colonies, composed of undulating branches and joined by dissepiments. Branches oval in transversal section. Fenestrules circular to oval. Autozooecia arranged in 3 to 4 rows on the branches. Dissepiments short. Autozooecial apertures circular, 4-7 spaced per length of a fenestrule, containing 10-12 long styles. Microstyles on the reverse surface common, irregularly and densely spaced, originating from interior granular skeleton, 0.005 -0.015 mm in diameter. Interior granular skeleton variable in thickness, usually well-developed, continuous in microstyles. Extrazooidal skeleton finely laminated, well-developed on reverse side. Branch reverse side carrying distinct striation.

Interior description: Autozooecial chambers relatively short, deep, displaying rhombic shape in mid tangential section; elongate parallel to branch length; aperture positioned at distal to distoabaxial end of chamber; with moderately long vestibule. Hemisepta absent. Tubes connecting endozonal zooecial chambers with the obverse surface present, 3-7 spaced between adjacent apertures, 0.010 -0.035 mm in diameter. Heterozooecia are brood chambers represented by enlarged zooecia, rounded to oval in mid tangential section, situated on branches near dissepiments, 0.2-0.3 mm wide.

Remarks: Anastomopora quebecensis FRITZ, 1938 is similar to A. petoskeyensis MCNAIR, 1937 from the Traverse Group(Middle Devonian, Givetian)of Michigan, but differs from it in having narrower branches (0.58- 0.75 mm vs. 0.4-1.0 mm in A. petoskeyensis MCNAIR, 1937 ), and in shorter and wider fenestrules (average fenestrule length 0.8 mm vs. 0.9 mm in A. petoskeyensis , and average fenestrule width 0.52 vs. 0.45 mm in A. petoskeyensis ). Unfortunately, both species were described externally. Anastomopora quebecensis FRITZ, 1938 is similar to A. stellata ( KRASNOPEEVA, 1935) from the Upper Devonian (Frasnian) of Altai in its internal morphology (zooecial shape, apertural styles), but differs in wider branches and larger fenestrules (branch width 0.58-0.75 mm vs. 0.32-0.45 mm, fenestrule length 0.60- 1.05 mm vs. 0.61-0.72 mm, and fenestrule width 0.32- 0.70 vs. 0.23-0.29 mm A. stellata).

Occurrence: Upper Devonian (Frasnian); Quebec,

Plate II All specimens come from the Shishtu 1 Formation, Upper Devonian, Frasnian. Niaz section, eastern Tabas, central Iran.

Figs 10-12: Trepostomata sp. indet., SMF 21.107. Tangential thin section showing autozooecial apertures and aktinotostyles.

Canada. Shishtu 1 Formation, Upper Devonian (Frasnian); Niaz section, eastern Tabas, central Iran.