Saffordotaxis Bassler, 1952

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 : 178

Genus Saffordotaxis Bassler, 1952

TYPE SPECIES. — Rhombopora incrassata Ulrich, 1890 by original designation. Lower Mississippian ; USA (Kentucky) .

DIAGNOSIS. — Branched colonies with distinct linear axis.Endozones and exozones distinctly separated. Autozooecia with oval apertures and regularly thickened walls in the exozone, diverging at angles of 20-30° from the axis, bending sharply in exozones and intersecting the colony surface at angles of 80-90°; polygonal in endozone becoming hexagonal and rounded at colony surface. Longitudinal arrangement of autozooecia regular.Diaphragms complete, rare.Hemisepta absent. Metazooecia and acanthostyles absent. Aktinotostyles common to abundant, arranged in single or multiple rows, arising in the exozone.

OCCURRENCE. — Middle Devonian to Lower Permian; worldwide.

COMPARISON

Saffordotaxis Bassler, 1952 differs from Primorella Romantchuk & Kiseleva, 1968 in shape of autozooecia with sharp bend in the exozone.

Saffordotaxis incrassata ( Ulrich, 1888) ( Figs 19 G-I; 20A-D; Appendix)

Rhombopora incrassata Ulrich, 1888: 89 , pl. 14, fig. 16; 1890: 652, pl. 70, fig. 12. — Nekhoroshev 1953: 148, pl. 17, fig. 5. — Trizna 1958: 199, pl. 54, figs 4-65.

Saffordotaxis incrassata – Blake 1983: 558, fig. 289, 1a-e.

Saffordotaxis incrassatus – Gorjunova 1985: 117, pl. 7, fig. 2.

MATERIAL. — SMF 21.884- SMF 21.890, TCD.60340.

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

DESCRIPTION

Branched colonies, 0.81-1.35 mm in diameter, with 0.29- 0.55 mm wide endozones and 0.26-0.40 mm wide exozones. Autozooecia tubular, growing in spiral pattern from the distinct median axis at angles of 25-29° in endozones, abruptly bending in exozones and intersecting colony surface at angles of 52–64°; having a triangular to rhombic, tear-drop shape in transverse section of endozone. Autozooecial apertures oval, arranged in regular diagonal rows on branches. Basal diaphragms rare, thin, planar. Aktinotostyles abundant, arranged in a single row between autozooecia. Autozooecial walls finely laminated, with dark dividing layer, 0.01-0.02 mm thick in endozone; laminated, without distinct boundaries in exozones. Exozonal walls containing abundant mural spines.

COMPARISON

Saffordotaxis incrassata ( Ulrich, 1888) is similar to S. retrusus Gorjunova, 1985 from the Visean of Kazakhstan, but differs in having thicker colonies (branch diameter 0.81-1.35 mm vs 0.65-0.90 mm in S. retrusus ), and smaller autozooecial apertures (aperture width 0.06-0.10 mm vs 0.15-0.19 mm in S. retrusus ).

Figures

FIG. 19. — A-F, Rhabdomeson progracile Wyse Jackson & Bancroft, 1995; A, longitudinal section showing axial cylinder, SMF 21.882; B, longitudinal section showing autozooecial chambers with hemisepta (arrow), SMF 21.882; C, tangential section showing autozooecial apertures, acanthostyles and paurostyles (arrow), SMF 21.872; D, tangential section showing acanthostyles and paurostyles (arrow), SMF 21.872; E, F, branch transverse section, SMF 21.875; G-I, Saffordotaxis incrassata (Ulrich, 1888), SMF 21.889; G, tangential section showing autozooecial apertures and aktinotostyles; H, I, branch longitudinal section. Scale bars: A, 2 mm; B, C, E, H, 1 mm; D, 0.2 mm; F, G, I, 0.5 mm.