Fistuliphragma modica, Ernst & Tolokonnikova & Yarahmadzahi, 2012

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 : 4

Fistuliphragma modica n. sp.

Pl. II, figs 1-9; Table 2

2000. Fistulipora sp. 1 , BIGEY, p. 98, pl. 8, figs 8-10.

Etymology: The species name refers to the moderate size of autozooecial apertures (from Latin “ modica ” = moderate).

Holotype: Single specimen with two thin sections SMF 21.104 - SMF 21.105 .

Type locality: Niaz section, eastern Tabas, central Iran.

Type horizon: Shishtu 1 Formation, Upper Devonian (Frasnian).

Diagnosis: Solid subramose colony with multilayered secondary overgrowths and endozone consisting of large irregular thinwalled vesicles. Autozooecia arising in endozone or growing from thin epitheca, bending sharply in exozone, with circular apertures and distinct lunaria. Hemiphragms present, positioned in alternating pattern in autozooecia, originating in laminated skeleton of autozooecia. Basal diaphragms common. Vesicular skeleton well-developed. In the centre of each vesicle roof a single acanthostyle present. Maculae present, consisting of vesicular skeleton.

Description: Solid subramose colony with multilayered secondary overgrowths, 14 mm in diameter. Secondary overgrowths 0.42-0.66 mm in thickness. Endozone consisting of large irregular thinwalled vesicles. Autozooecia arising in endozone or growing from thin epitheca, bending sharply in exozone. Autozooecial apertures circular to oval, having laminated, thickwalled peristomes. Lunaria distinct, horse-shoe shaped to triangular, directed towards monticules. Thick and short hemiphragms positioned in alternating pattern in autozooecia, often overlapping each other, curved proximally to distally, originating in laminated skeleton of autozooecial walls. Basal diaphragms common, thin, horizontal or inclined, often positioned on edges of neighbouring hemiphragms. Vesicles in endozone large, irregular in shape. In exozones, vesicles medium in size, separating autozooecia in 1-2 rows, polygonal in tangential section, box-like to hemispheric, with plane or concave roofs, consisting of granular skeleton. Inner parts of vesicular roofs containing single style, positioned in the centre of vesicle, 0.015 -0.030 mm in diameter. Acanthostyles rare common, positioned in walls between vesicles, having laminated sheaths and distinct hyaline cores, 0.03-0.04 mm in diameter. Autozooecial walls granular, 0.003 -0.005 mm thick in endozones; laminated, 0.01-0.04 mm thick in exozones. Maculae with central cluster of vesicles, 1.4-2.2 mm in diameter, spaced 3.6- 5.4 mm from centre to centre.

Remarks: Fistuliphragma modica n. sp. is similar to F. parva ERNST & KÖNIGSHOF, 2010 from the uppermost Givetian of Morocco but differs from it in larger autozooecial apertures (average aperture width 0.22 mm vs. 0.20 mm in F. parva ) and larger distance between aperture centres (average distance between aperture centres 0.38 mm vs. 0.34 mm in F. parva ). Fistuliphragma modica n. sp. differs from F. eifelensis ERNST, 2008 from the Eifelian of the Rhenish Massif in having smaller apertures (average aperture width 0.22 mm vs. 0.28 mm in F. eifelensis ).

Other occurrence: Upper Devonian (Frasnian); Kuh-e Kaftar, central Iran.