Taxonomy Online - Carboniferous spores part I - Species details


Species name
Densosporites anulatus (Loose) Smith & Butterworth, 1967

Description
Radial, trilete, cingulate miospores. Amb rounded triangular to subcircular. Trilete mark indistinct, sutures simple, straight, extending to margin of inner body. Intexine thin, laevigate, forming rounded triangular to subcircular inner body. Exoexine thin in polar regions but extended and thickened in the equatorial plane to form undifferentiated cingulum of more or less uniform thickness. Cingulum narrow, 4(8)12 µm in width, tapering very slightly towards the equator, surface laevigate. Depending on compression, cingulum may appear to overlap equatorial portion of inner body. Two exine layers normally closely adpressed but sometimes showing weak evidence of separation in the equatorial plane. Cingulum occupies up to 40 % of total spore radius.

Other descriptions
Smith and Butterworth, 1967, p. 239, p1. 19, figs. 5–6

Size
Overall equatorial diameter 26(40)56 µm

Remarks
Densosporites anulatus is distinguished from most other species of Densosporites by its lack of ornament. D. sphaerotriangularis Kosanke 1950 appears similar but has a cingulum with a verrucose or spinose ornamentation. D. simplex Staplin 1960 and D. tripapillatus Staplin 1960 differ from D. anulatus in having broader cingula.

Range
Mississippian to Pennsylvanian; Visean to Moscovian [early Bolsovian] (from Smith and Butterworth, 1967)

Images

MPK 7655 MPK 7655 Figure 15a
Shales below Swinstone House Marine Band, Mousegill Beck, Stainmore, Cumbria, England; Bashkirian, [Marsdenian], FR Biozone, Sample T96, Specimen MPK 7655. Subcircular trilete cingulate miospore. Trilete mark distinct, suture simple, extending to inner margin of cingulum and accompanied by low narrow folds of exoexine. Evidence of minor separation in the equatorial plane between the intexine of the inner body and the exoexine of the cingulum. Cingulum occupies approximately one-third of spore radius, more or less uniform in structure and tapering slightly to the equator. Exoexine of inner body and cingulum laevigate. Specimen maximum dimension 55 µm.


MPK 7659 MPK 7659 Figure 15b
Argill Shell Bed, Argill Beck, Stainmore, Cumbria, England; Bashkirian [uppermost Langsettian], RA Biozone, Sample ASB, Specimen MPK 7659. Specimen showing indication of minor intexine–exoexine separation in the equatorial plane. Specimen maximum dimension 62 µm.