Monticulipora aff. mammulata d’Orbigny, 1850

Ernst, Andrej & Carrera, Marcelo G., 2022, A cool-water bryozoan association from the La Pola Formation (Sandbian, Ordovician) of Argentine Precordillera, Geodiversitas 44 (20), pp. 563-601 : 570-572

Monticulipora aff. mammulata d’Orbigny, 1850

( Fig. 6 B-D; Appendix 1)

For full synonymy of the species Monticulipora mammulata d’Orbigny, 1850 , see in Brown & Daly (1985: 68).

MATERIAL EXAMINED. — Single colony (three thin sections) CEGH-UNC 27516 a, b, d.

OCCURRENCE. — La Pola Formation, Upper Ordovician, Sandbian; La Pola creek section near Albardon village, San Juan Province, Argentine Precordillera, western Argentina.

DESCRIPTION

Submassive colony, multilayered, weakly differentiated into exo- and endozone. Autozooecia prismatic, bearing abundant cystiphragms.Autozooecial diaphragms common to abundant, mainly inclined or cystoid. Autozooecial apertures polygonal. Mesozooecia common, polygonal in tangential section, bearing closely spaced diaphragms, locally beaded. Zooecial walls laminated, serrated, 0.01-0.02 mm thick. Acanthostyles rare, 0.030 -0.035 mm in diameter. Maculae not observed.

COMPARISON

The present material is similar to Monticulipora mammulata d’Orbigny, 1850 from the Upper Ordovician of North America. However, the typical monticules consisting of abundant mesozooecia, were not found in the present material. Monticulipora parallela McKinney, 1971 from the Middle Ordovician of United States (Alabama) differs from the present material in encrusting colony and larger autozooecial apertures (average aperture width 0.20 mm vs 0.18 mm in the present material).

Figures

FIG. 6. — A, Dianulites rocklandensis Wilson,1921, tangential section showing autozooecial apertures, CEGH-UNC 27503 a; B-D, Monticulipora aff. mammulata d’Orbigny,1850,CEGH-UNC 27516 d; B, C, tangential thin section showing autozooecial apertures;D, longitudinal thin section showing autozooecial chambers with cystiphragms; E-G. Orbignyella multitabulata Coryell, 1921; E, F, longitudinal thin section showing autozooecia with diaphragms, CEGH-UNC 27505 a; G, tangential thin section showing autozooecial apertures, CEGH-UNC 27505 b. Scale bars: A, C, 0.2 mm; B, G, 0.5 mm; D, F, 1 mm; E, 2 mm.