Chazydictya ornata, Ernst & Carrera, 2022

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 : 590

Chazydictya ornata n. sp.

( Fig. 16 A-F; Appendix 1)

urn:lsid:zoobank.org:act:7D79E434-3513-4C96-8424-3A17DF9BB46A

HOLOTYPE. — CEGH-UNC 27535 a.

PARATYPES. — CEGH-UNC 27538 a, CEGH-UNC 27539 h.

TYPE LOCALITY. — La Pola creek section near Albardon village, San Juan Province, Argentine Precordillera, western Argentina.

TYPE HORIZON. — La Pola Formation, Upper Ordovician, Sandbian.

DIAGNOSIS. — Bifoliate lenticular, branched colony; autozooecia short, arranged in 12-15 rows on branches; few basal diaphragms occurring; paurostyles abundant, large.

ETYMOLOGY. — The species is named because of the ornamentation by abundant paurostyles (from Latin “ ornatus ” – adorned, decorated)

DESCRIPTION

Bifoliate lenticular, branched colony. Branches 1.4-2.0 mm wide and 0.6-1.0 mm thick. Mesotheca straight, 0.015 to 0.020 mm thick, without median rods. Autozooecia short, tubular, bending sharply to branch surface, rectangular to subrhomboidal at their bases, becoming oval at branch surface, arranged in 12 to 15 regular alternating rows on branches. Rare diaphragms occurring. Autozooecial walls granular, 0.01 to 0.02 mm thick in endozone; thick, finely laminated in exozone. Laminated skeleton well developed. Paurostyles abundant, 0.015 -0.035 mm in diameter.

COMPARISON

Chazydictya ornata n. sp. differs from C. chazyensis Ross, 1963 in presence of 12-15 rows of autozooecia on branches vs 8-12 in C.chazyensis ,and in smaller autozooecial apertures(aperture width 0.06-0.08 mm vs 0.09-0.10 mm in C. chazyensis ). Furthermore, Chazydictya ornata n. sp. has fewer diaphragms in autozooecia (none to one vs two-three in C. chazyensis ) as well as larger paurostyles (0.015 -0.035 mm vs 0.010 mm in C. chazyensis ).

Figures

FIG. 16. — A-F, Chazydictya ornata n. sp., holotype CEGH-UNC 27535 a: A, B, branch transverse thin section showing autozooecial chambers and mesotheca without rods; C, branch transverse thin section showing autozooecial walls with paurostyles; D, E, tangential thin section showing autozooecial apertures and paurostyles; branch transverse thin section showing autozooecial mesotheca without rods; G, Parachasmatopora sp. A, tangential section showing reticulate colony, CEGH-UNC 27526 a. Scale bars: A, G, 0.5 mm; B, D, 0.2 mm; C, E, F, 0.1 mm.