Taxonomy Online - Carboniferous spores part I - Species details


Species name
Rotaspora fracta Schemel, 1950

Description
Radial, trilete acamerate miospores. Amb circular, subcircular or rounded triangular, spore body triangular with slightly concave sides and rounded apices. Trilete mark distinct, sutures straight, simple or accompanied by low narrow labra, extending almost to spore body margin. Width of zona more or less constant, with narrow thickening at the periphery forming equatorial rim. In compressed specimens the zona lies over the distal surface of the body in the radial positions thereby appearing narrower than in the inter-radial areas. Exine of body and zona laevigate. Folding rare.

Other descriptions
Schemel, 1950, p. 242, pl. 40, fig. 8. Smith and Butterworth, 1967, p. 227, pl. 15, figs. 8–11

Size
Overall equatorial diameter 24–40 µm. Diameter of spore body 17–24 µm

Remarks
Distinguished from Rotaspora knoxi Butterworth and Williams 1958, by its slightly smaller size, thinner exine and spore body with concave sides.

Range
Mississippian; late Visean to Serpukhovian [Pendleian]; VF to NC biozones (Clayton et al., 1977, and unpublished information)

Images

MPK 7569 MPK 7569 Figure 45a
Lower Limestone Group, Drumlemble Borehole A, 3336 feet, Machrihanish, Argyll, Scotland; Visean, NC Biozone, Sample MPA 33328, Specimen MPK 7569. Distal focus. Spore body triangular, sides straight to slightly concave, apices sharply rounded. Trilete mark distinct, sutures straight, extending to body margin, accompanied by low narrow thickened labra. Evidence of zona being reduced in width at radial margins but folded onto distal surface. Exine of body and zona laevigate. Specimen maximum dimension 40 µm.


MPK 7572 MPK 7572 Figure 45b
Lower Limestone Group, Drumlemble Borehole A, 3336 feet, Machrihanish, Argyll, Scotland; Visean, NC Biozone, Sample MPA 33328, Specimen MPK 7572. Specimen maximum dimension 33 µm.