Orbignyella multitabulata Coryell 1921

Orbignyella multitabulata Coryell, 1921 (Fig. 6 E-G; Appendix 1) Orbignyella multitabulata Coryell, 1921: 284, pl. 5, figs 3-4. MATERIAL EXAMINED. — CEGH-UNC 27505 a-c, CEGH-UNC 27518 a-c. OCCURRENCE. — La Pola Formation, Upper Ordovician, Sandbian; La Pola creek section near Albardon village, San Juan Province, Argentine Precordillera, western Argentina. Pierce Limestone, Upper Ordovician (Sandbian); Tennessee, United States. DESCRIPTION Massive, subramose multilayered colonies. Secondary overgrowths common, 1-2 mm thick. Autozooecia bending gently from endozone, intersecting colony surface at right angles. Autozooecial apertures rounded to polygonal. Diaphragms in autozooecia common to abundant, straight to curved. Exilazooecia rare, polygonal in cross section, restricted to exozone. Acanthostyles common, moderately large, situated at junctions of autozooecial apertures. Autozooecial walls granular-prismatic, 0.005 -0.010 mm thick in endozone; irregularly thickened, finely laminated, displaying reverse V-structure in longitudinal section, 0.020 -0.033 mm thick in exozone. Maculae of macrozooecia 0.70-1.25 mm in diameter, spaced 1.9-2.0 mm from centre to centre. COMPARISON The present material is morphologically similar to Orbignyella multitabulata Coryell, 1921 from the Sandbian of United States. The only metric characteristic for O. multitabulata is the number of apertures per 2 mm given as 8-8.5 (Coryell 1921: 284). Interpolated, it gives apertural spacing of c. 0.23-0.25 mm what overlaps the range in the present species (0.13-0.22 mm). The present material differs from Orbignyella wetherbyi (Ulrich, 1890) from the Upper Ordovician of United States in smaller autozooecia (aperture width 0.11-0.19 mm vs 0.25-0.28 mm in O. wetherbyi).
Published as part of Ernst, Andrej & Carrera, Marcelo G., 2022, A cool-water bryozoan association from the La Pola Formation (Sandbian, Ordovician) of Argentine Precordillera, pp. 563-601 in Geodiversitas 44 (20) on page 572, DOI: 10.5252/geodiversitas2022v44a20, http://zenodo.org/record/6725916
{"references":["CORYELL H. N. 1921. - Bryozoan faunas of the Stone River Group of Central Tennessee. Proceedings of Indiana Academy of Sciences 1921: 261 - 340.","ULRICH E. O. 1890. - Palaeozoic Bryozoa: III. Report of the Geological Survey of Illinois 8: 283 - 688."]}