Cystodictya gallensis, Ernst & Wyse Jackson & Aretz, 2015

Ernst, Andrej, Wyse Jackson, Patrick N. & Aretz, Markus, 2015, Bryozoan fauna from the Mississippian (Visean) of Roque Redonde (Montagne Noire, southern France), Geodiversitas 37 (2), pp. 151-213 : 166-168

Cystodictya gallensis n. sp.

( Fig. 13 A-H; Appendix)

ETYMOLOGY. — The species name is derived from the Latin Gallia for France.

HOLOTYPE. — SMF 21.815 .

PARATYPES. — SMF 21.816- SMF 21.823, TCD.60333, 60335, 60336, 60337, 60340, 60341.

TYPE LOCALITY. — Roque Redonde (Montagne Noire, southern France).

TYPE HORIZON. — Carboniferous, Mississippian (upper Visean).

DIAGNOSIS. — Bioliate branches with mesotheca; median tubules absent; autozooecia tubular; diaphragms lacking; blunt proximolateral hemisepta at zooecial bent present; autozooecial apertures circular to oval, arranged in 7-9 alternating rows on the colony surface; lunaria distinct, horseshoe-shaped; vesicular skeleton well developed; vesicles small to moderate in size, partly separating autozooecia in at mesotheca, and completely separated them in exozone in 1-2 rows; stereom thick, containing abundant tubules.

DESCRIPTION

Bifoliate branches, 1.64-2.42 mm wide and 1.23-1.64 mm thick. Mesotheca 0.010 -0.015 mm thick; median tubules absent. Autozooecia tubular, teardrop-shaped at their bases, quadrate in cross-section, recumbent on the mesotheca for a relatively short distance, then bending upwards at low angles in exozone and intersecting the surface almost perpendicularly. Diaphragms lacking; blunt proximolateral hemisepta at zooecial bend present. Autozooecial apertures circular to oval, arranged in 7-9 alternating rows on the colony surface. Lunaria distinct, horseshoe-shaped. Vesicular skeleton well developed, covered in exozone by thick stereom. Vesicles small to moderate in size, polygonal in tangential section, with rounded roofs, partly separating autozooecia in at mesotheca, and completely separated them in exozone in 1-2 rows. Autozooecial walls laminated, with serrated boundaries, 0.005 -0.010 mm thick in endozone. Stereom thick, consisting of laminated material, completely separating autozooecia in exozone, containing abundant tubules. Tubules 0.005 -0.010 mm in diameter.

COMPARISON

Cystodictya gallensis resembles C. dichotoma Nikiforova, 1933 from the Mississippian of Turkestan with chambers separated up to two times their diameter by vesicular tissue. However hemisepta are not developed in C. dichotoma and chambers diverge at a higher angle towards the zoarial surface than observed in C. gallensis . Additionally it is similar to C. astrepta Karklins, 1986 from the Late Mississippian of Utah, USA in general form and size, but has significantly more vesicular tissue developed between autozooecial chamber. Comparison with other Cystodictya species shows that C. gallensis is distinctive.

Figures

FIG. 13. — A-H, Cystodictya gallensis n. sp.; A-B, branch oblique section, paratype SMF 21.822; C-D, tangential section, holotype SMF 21.815; E, tangential section showing autozooecial aperture, paratype SMF 21.822; F-G, branch transverse section, paratype SMF 21.819; H, branch longitudinal section, paratype SMF 21.816. Scale bars: A-C, F, H, 1mm; D, E, 0.2 mm; G, 0.5 mm.