Rectifenestella, Morozova, 1974

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 : 180-182

Rectifenestella sp.

( Figs 21 B-D; Appendix)

MATERIAL. — SMF 21.898.

OCCURRENCE. — Carboniferous, Mississippian (upper Visean); Roque Redonde (Montagne Noire, southern France).

EXTERIOR DESCRIPTION

Reticulate colony formed by straight branches joined by relatively narrow dissepiments.Fenestrules rectangular, elongated. Autozooecia arranged in two rows on branches. Autozooecial apertures circular, with low peristome with 8 apertural nodes (stellate structure); 2 to 3 apertures spaced per fenestrule length. Keel narrow, low, containing small densely spaced circular nodes.

INTERIOR DESCRIPTION

Autozooecia short, pentagonal in mid tangential section; with short to moderately long vestibule. Axial wall between autozooecial rows strongly zigzag; aperture positioned at distal end of chamber. Superior hemisepta indistinct; inferior hemisepta absent. External laminated skeleton well-developed on both obverse and reverse sides. Heterozooecia not observed.

COMPARISON

Rectifenestella sp. is similar to R. frutex ( M’Coy, 1844) from the Mississippian of Ireland, but differs from it in wider branches (0.29-0.35 mm vs 0.14-0.20 mm in R. frutex ) and longer fenestrules (0.44-0.58 mm vs 0.33-0.39 mm in R. frutex ).

Similarly Rectifenestella sp. differs from R. constans ( Foerste, 1887) described from the Mississippian of the Russian Platform by Schulga-Nesterenko (1951) in wider branches (0.29- 0.35 mm vs 0.20 mm in R. limbata ) and larger fenestrules (fenestrule length 0.44-0.58 mm vs 0.38-0.43 mm in R. limbata ; fenestrule width 0.22-0.29 mm vs 0.17-0.20 mm in R. limbata ).Tavener-Smith (1973, p. 411) considered R. frutex and R. limbata to be synonymous. It is also very close, but not identical, to R. asiatica (Nikiforova in Schulga-Nesterenko 1951). It differs mainly in the more closely spaced keel nodes (distance between node centres 0.11-0.18 vs 0.30 mm in R. asiatica ).

Figures

FIG. 21. — A, Megacanthopora enodata n. sp., longitudinal section showing autozooecial walls with aktinotostyles and mural spines, paratype SMF 21.895. B-D, Rectifenestella sp., SMF 21.898, tangential section; E-I, Spinofenestella major (Nikiforova, 1933) comb. nov., SMF 21.899; E-G, tangential section of the colony; H, mid-tangential section of the branch showing autozooecial chambers with hemisepta; I, tangential section of the branch showing autozooecial apertures. Scale bars: A, C, G, 1 mm; B, E, 2 mm, D, H, I, 0.2 mm; F, 0.5 mm.