(Potonié & Kremp) Bharadwaj, 1957
Radial, trilete, camerate-acamerate miospores. Amb circular to subcircular or oval. Trilete mark distinct to indistinct; rays either simple, straight, extending almost to the inner margin of the equatorial crassitude or split open to form triangular tear in the polar region. Exine characteristically thickened in the equatorial region to form crassitude; inner margin of crassitude ill-defined and commonly invaginated in radial positions. Distal surface of exine ornamented with numerous discrete coni up to 2 µm height and basal diameter. Elements project at equatorial margin but appear absent from the proximal surface. Apical papillae commonly present. Exine surface between coni, densely infrapunctate. Secondary folding common.
Potonié and Kremp, 1955, p. 71, pl. 13, figs. 208–213.
Smith and Butterworth, 1967, pp. 254–255, p1. 19, figs. 2–4
Overall equatorial diameter 40(64)105 µm
Bharadwaj 1957 originally distinguished only by size from Crassispora kosankei
, was incorporated within the circumscription of the latter species by emendation of Smith and Butterworth (1967). The size ranges recorded for different populations of the species are known to reflect different oxidation procedures.
Owens et al. (1977) and Clayton et al. (1977) considered that Crassispora kosankei
becomes abundant at the base of the KV Biozone, approximately at the Alportian–Kinderscoutian boundary, being infrequent or rare in the earliest Namurian. Later Owens in
Ramsbottom (1981) reported abundant C. kosankei
in palynomorph assemblages from the boundary stratotype section of the Chokierian.
Late Mississippian to Pennsylvanian; Serpukhovian to Kasimovian [Pendleian to Stephanian]; NC to NBM biozones (Clayton et al., 1977)
MPK 7001 Figure 12a
BGS Offshore Borehole 74/12, 18.07 m, Firth of Forth, Scotland; Bashkirian [Duckmantian], NJ Biozone, Sample CSA 1231, Specimen MPK 7001. Subcircular trilete spore with ill-defined equatorial crassitude. Trilete mark indistinct, represented by open triangular tear. Exine surface infrapunctate but also bears dense ornament of small discrete coni which project at equatorial margin. Minor exinal folding present.
Specimen maximum dimension 78 µm.
MPK 7002 Figure 12b
BGS Offshore Borehole 74/13, 18.07 m, Firth of Forth, Scotland; Bashkirian [Duckmantian], NJ Biozone, Sample CSA 1231, Specimen MPK 7002. Specimen showing trilete mark split into triangular tear in polar region but displaying rays extending almost to the equatorial margin. Ends of trilete sutures become fused with minor invagination of equatorial crassitude in equatorial region. Well-defined ornament of densely distributed small coni.
Specimen maximum dimension 72 µm.