(Ishchenko) Playford, 1962
Radial, trilete, cingulate miospores. Amb circular to subcircular, consisting of circular to subcircular spore body surrounded by more or less conformable cingulum. Trilete mark distinct, sutures simple, or accompanied by low, thickened labra up to 8 µm wide, which extend to the margin of the spore body. Sutures straight, extending between three-quarters to almost the full radius of the spore body. Exoexine extended in the equatorial plane to form undifferentiated cingulum, 6–16 µm in width. Distal surface bears conspicuous, widely spaced, relatively low, broad, smooth, rounded muri that are connected in several places to each other and to the cingulum. Muri slightly sinuous, irregular in pattern, 8–17 µm wide and 4–7 µm high. Remainder of exine laevigate.
Ishchenko, 1956, pp. 58–59, pl. 10, fig. 121 .
Playford, 1962, pp. 634–635, pl. 90, figs. 9–12
Overall equatorial diameter 67(86)112 µm
The irregular development of low, broad muri on the distal surface distinguishes this species from other taxa assigned to Knoxisporites
. Playford (1963) made no mention of the presence of low broad labra accompanying the trilete sutures that are a common feature of the Mattson Formation specimen illustrated here.
Mississippian; Tournaisian to Visean (Playford, 1962)
MPK 7297 Figure 24a
Visean lignite, Moscow Basin, Russia; Visean, MA Biozone (Playford, 1962), Sample MOS, Specimen MPK 7297. Spore body surrounded by undifferentiated cingulum of uniform width. Trilete sutures simple, straight, extending to spore body margin. Distal surface bears irregular, low, broad, smooth muri. Exine laevigate.
Specimen maximum dimension 92 µm.
MPK 7299 Figure 24b
Mattson Formation, south face of Twisted Mountain, north-west of South Nahanni, Northwest Territories, Canada; Visean, MA Biozone (Playford, 1962), Sample MATT, Specimen MPK 7299. Trilete mark extending to spore body margin, accompanied by low, thickened, broad labra.
Specimen maximum dimension 94 µm.