Albardonia bifoliata, 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 : 576-578

Albardonia bifoliata n. gen., n. sp.

( Figs 8G, H ; 9 A-F; Appendix 1)

urn:lsid:zoobank.org:act:8C45367C-9280-4982-A6C2-9E757EFFD061

HOLOTYPE. — CEGH-UNC 27538 c.

PARATYPES. — CEGH-UNC 27507 a, b, CEGH-UNC 27520 a, b, d, CEGH-UNC 27528 a, CEGH-UNC 27529 a, CEGH-UNC 27530 a, b, e, f, g, CEGH-UNC 27532 a, CEGH-UNC 27533 a, b, CEGH-UNC 27537 b, CEGH-UNC 27538 a, b, CEGH-UNC 27539 b, CEGH-UNC 27541 a (in total, 19 thin sections of 10 colonies).

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. — As for genus.

ETYMOLOGY. — The species name refers to the bifoliate colony shape of the new species.

DESCRIPTION

Bifoliate (frondose) colony starting from encrusting sheets. Fronds 0.70-1.30 mm in thickness. Encrusting sheets 0.66- 1.31 mm thick. Secondary overgrowths occurring. Autozooecia budding from mesotheca, having angular shape of transverse section in endozone. Autozooecial apertures angular with rounded corners. Mesotheca 0.01-0.02 mm in thickness. Basal diaphragms common both in endozone and exozone, straight, or inclined. Mesozooecia abundant, 3-8 surrounding each autozooecial aperture, containing densely spaced diaphragms. Aktinotostyles moderately large, abundant, 5-7 surrounding each autozooecial aperture, originating in the outer exozone. Autozooecial walls granular, 0.010 -0.015 mm thick, irregularly undulating in endozones; laminated, integrated with dark median lining, showing reversal V-shaped lamination, without cingulum, 0.02-0.05 mm thick in exozones. Maculae not observed.

COMPARISON

As for genus.

Figures

FIG. 8. — A-F, Heterotrypa enodis n. sp.: A-C, branch transverse section showing autozooecial chambers and mesozooecia, holotype CEGH-UNC 27504 b; D, branch longitudinal section showing autozooecial chambers with diaphragms and mesozooecia, CEGH-UNC 27504 a; E, F, tangential thin section showing autozooecial apertures,mesozooecia,and acanthostyles,CEGH-UNC 27504 c; G, H, Albardonia bifoliata n. gen., n. sp., oblique thin section through the bifoliate colony, holotype CEGH-UNC 27538 c. Scale bars: A, B, D, E, G, H, 1 mm; C, F, 0.2 mm.

FIG. 9. — A-F, Albardonia bifoliata n. gen., n. sp.: A, B, tangential thin section showing autozooecial apertures, mesozooecia, and aktinotostyles, holotype CEGH-UNC 27538 c; C, D, longitudinal section showing autozooecial chambers with diaphragms and mesozooecia, paratype CEGH-UNC 27530 a; E, F, branch transverse thin section showing autozooecial chambers with diaphragms, mesozooecia, and mesotheca, paratype CEGH-UNC 27541 a; G, Diplotrypa sp. A, CEGH-UNC 27543 a, oblique thin section through the colony. Scale bars: A, C, E, 0.5 mm; B, D, 0.2 mm; F, 0.1 mm; G, 2 mm.