Radial, trilete, cingulate miospores. Amb circular, subcircular to rounded triangular. Trilete mark distinct, sutures straight, extending to margin of spore body, simple or accompanied by low narrow thickened labra which typically become expanded equatorially to form triangular thickened areas that fuse to the proximal surface of the cingulum. Exine laevigate. Intexine forming spore body rarely discernible. Exoexine closely adpressed to intexine but extended in the equatorial plane to form thickened, undifferentiated cingulum, 5–15 µm wide. Exoexine developed into second ring of thickening mid way between the equator and the distal pole with irregular, radially-orientated thickened ribs in the inter-radial positions sometimes connecting it to the cingulum. A distal polar thickening 5–10 µm in diameter is also developed on the exoexine.
Love, 1960, pp. 118–119, pl. 2, figs. 1–2
Overall equatorial diameter 40–90 µm
Hoffmeister, Staplin & Malloy 1955 is distinguished by the absence of the distal polar thickening and by the presence of more prominent, radially-orientated ribs connecting the cingulum to the distal, circular ring of thickening.
Mississippian to Pennsylvanian; Visean to Moscovian [Asturian]; TS to OT biozones (Clayton, 1985, and unpublished information)
MPK 7042 Figure 25a
Shales below Swinstone House Marine Band, Mousegill Beck, Stainmore, Cumbria, England; Bashkirian [Marsdenian-Yeadonian], FR Biozone. Sample T96, Specimen MPK 7042.
Specimen maximum dimension 46 µm.
MPK 7048 Figure 25b
Halesowen Beds, Callow Brook, Staffordshire, England; Moscovian [Asturian], UP Biozone, Sample MPA 12628, Specimen MPK 7048. Proximal focus showing development of thickenings, at the end of trilete sutures, which fuse onto cingulum.
Specimen maximum dimension 45 µm.