Higgs, Clayton & Keegan, 1988
Radial, trilete, cingulate miospores. Amb subcircular to rounded triangular. Trilete mark distinct, sutures straight, sometimes open, extending to the inner margin of the cingulum, accompanied by broad prominent labra up to 20 µm in overall width. Intexine relatively thin; forms rounded triangular to subcircular inner body. Exoexine extended in equatorial plane to form undifferentiated cingulum, up to 14 µm wide. Proximal surface laevigate. Distal surface ornamented with three muri arranged in a triangular pattern with the apices of the triangle joining the cingulum in the inter-radial positions. Muri vary between 8–12 µm in width and are often slightly expanded where they fuse with the cingulum. Remainder of exine laevigate to scabrate.
Higgs, Clayton and Keegan, 1988, p. 66, pl. 8, figs. 3,6
Overall equatorial diameter 79(91)121 µm
The distinctive triangular structure created from three muri on the distal surface distinguish this species from others assigned to the genus Knoxisporites
. Higgs, Clayton and Keegan (1988) elevated this form to specific status, considering that it was sufficiently distinct from Knoxisporites literatus
(Waltz) Playford 1963 within which it had previously been allocated varietal status.
Mississippian; Tournaisian; Tn1b to Tn3c, VI to CM biozones (Higgs et al., 1988)
MPK 7031 Figure 26a
Pinskey Gill Beds, Wygarth Gill Borehole, Ravenstonedale, Cumbria, England; Tournaisian, CM Biozone, Sample MPA 292, Specimen 7031. Subcircular–pentagonal cingulate miospore. Trilete mark distinct, sutures accompanied by low, broad labra that extend almost to equatorial margin of spore body. Cingulum thick, uniform. Distal surface of spore bears three straight thickened ridges that form a distinctive triangular structure. Apices of triangle fused to distal surface of cingulum in the inter-radial positions. Exine surface laevigate or very finely roughened.
Specimen maximum dimension 105 µm.
MPK 7033 Figure 26b
Cementstone Group, Bracken Bay, Heads of Ayr, Ayrshire, Scotland; Tournaisian, CM Biozone, Sample MPA 29832, Specimen MPK 7033. Rounded triangular miospore with uniform, thick, cingulum. Trilete mark distinct, sutures apparently without thickened labra extend to equator of spore body. Characteristic triangular shaped thickening on the distal surface appears to show minor expansion at the apices where it fuses with cingulum surface.
Specimen maximum dimension 83 µm.