Altshedata gracilis, Ernst & Fernández & Fernández-Martínez & Vera, 2012

Ernst, Andrej, Fernández, Luis Pedro, Fernández-Martínez, Esperanza & Vera, Carmen, 2012, Description of a bryozoan fauna from mud mounds of the Lebanza Formation (Lower Devonian) in the Arauz area (Pisuerga-Carrión Province, Cantabrian Zone, NW Spain), Geodiversitas 34 (4), pp. 693-738 : 700-704

Altshedata gracilis n. sp. ( Figs 6 D-G, 7A-D; Appendix)

HOLOTYPE. — SMF 21.150 . PARATYPES. — SMF 21.151- SMF 21.164.

ETYMOLOGY. — The species name refers to the small sizes of colonies and autozooecia of the new species (derived from Latin “ gracilis ” = slender).

TYPE LOCALITY. — Arauz Sur (Arroyo section), Province of Palencia, NW-Spain (Cantabrian Mountains).

TYPE HORIZON. — Lebanza Formation, Lower Devonian (Pragian).

DIAGNOSIS. — Encrusting colonies; autozooecia prismatic; autozooecial diaphragms common, straight, thin; lunaria well-developed, prominent; megazooecia or other heterozooecia not observed; vesicles occasionally present, never isolating autozooecia; communication pores absent; maculae not observed.

DESCRIPTION

Encrusting colonies, 0.9-1.2 mm thick. Autozooecia prismatic, budding from the basal epitheca, hemispherical to trapezoidal at their bases, becoming rhombic to hexagonal, recumbent in proximal parts, then bending sharply and intersecting colony surface at right angles. Autozooecial diaphragms common, straight, thin, locally absent. Autozooecial apertures rounded-polygonal. Lunaria well-developed, prominent, rounded, deeply indenting autozooecial cavity, originating from bases of autozooecia, consisting of hyaline material. Heterozooecia not observed. Vesicles rarely present, irregular in shape and size, occurring at the base of exozone. Autozooecial walls in the endozone granular, straight, 0.005 -0.010 mm thick; in exozone irregularly thickened, showing indistinct granular microstructure with deep annulations, 0.03-0.05 mm thick. Short style-like projections present in autozooecial walls and in the granular skeleton on the colony surface. Communication pores not observed. Maculae not observed.

COMPARISON

Altshedata gracilis n. sp. differs from Altshedata hispanica n. sp. in having smaller autozooecia (average autozooecial width 0.27 vs 0.3 mm in A. hispanica ), presence of megazooecia and the absence of style-like projections in autozooecial walls.

Figures

FIG. 6. — A-C, Altshedata hispanica n. sp.; A, B, longitudinal section showing vesicles, paratype SMF 21.144; C, longitudinal section showing lunarial deposits in exozone, paratype SMF 21.142; D-G, Altshedata gracilis n. sp.; D, tangential section showing autozooecial apertures, holotype SMF 21.150; E, tangential section, paratype SMF 21.155; F, G, longitudinal section, paratype SMF 21.163. Scale bars: A, F, 1 mm; B, D, E, 0.2 mm; C, G, 0.5 mm.