Taxonomy Online - Carboniferous spores part I - Species details


Species name
Vallatisporites drybrookensis Playford & McGregor, 1993

Description
Radial, trilete, cingulizonate miospores. Amb rounded triangular with convex sides and rounded apices, sometimes subcircular. Trilete mark distinct; sutures straight, extending to the margin of the inner body, accompanied by elevated flexuous folds of the exoexine which extend, decreasing in height, to the equatorial margin. Intexine thin, forming rounded triangular inner body, frequently folded independently and withdrawn from the exoexine at least in the equatorial plane. Exoexine thin over proximal surface but thicker over distal surface and extended in the equatorial plane to form variably thickened cingulizona consisting of two zones. Inner thinner zone contains numerous internal radially orientated vacuoles separated by thin walls. Outer zone thicker and separated from the inner thinner zone by an irregular boundary coinciding with the limits of vacuolation. Distal surface of exoexine ornamented with pointed or rounded coni up to 3 µm high and 3.5 µm in basal diameter, interspersed with galeae consisting of a bulbous base surmounted by a small sharply pointed conus. Ornamentation reduced over the outer part of the cingulum to small coni. Well-developed cuniculus developed in the equatorial plane adjacent to the margin of the intexine.

Other descriptions
Sullivan, 1964, pp. 370–371, pl. 59, figs. 14–15. Playford and McGregor, 1993, pp. 33–34, pl. 18, figs. 5, 6a,b, 7, 8a,b

Size
Overall equatorial diameter 50(62)70 µm

Remarks
Playford and McGregor (1993) considered that specimens assigned by Sullivan (1964) to his new combination Vallatisporites (Zonotriletes) ciliaris (Luber & Waltz) Sullivan 1964 were incorrectly identified. Consequently they erected Vallatisporites drybrookensis to include Sullivan’s specimens and designated a specimen of Sullivan’s as holotype.
The well-developed conate/galeate ornamentation and extensively internally vacuolate inner cingulizona distinguishes V. ciliaris from other species assigned to the genus Vallatisporites.

Range
Mississippian to Pennsylvanian: early Tournaisian to ?Kazimovian/Gzhelian [Stephanian] (Playford and McGregor, 1993)

Images

MPK 7081 MPK 7081 Figure 65a
Basement Beds, Menai Straits, North Wales; Visean, TC Biozone, Sample MPA 18030, Specimen MPK 7081. Specimen showing densely distributed, radially orientated vacuoles in the thinner inner zone of zona. Outer zone of cingulizona variably thickened. Note presence of clearly defined cuniculus at the equatorial margin of inner body. Specimen maximum dimension 63 µm.


MPK 7083 MPK 7083 Figure 65b
Basement Beds, Menai Straits, North Wales; Visean, TC Biozone, Sample MPA 18030, Specimen MPK 7083. Proximal focus. Trilete mark prominent, trilete rays obscured by low elevated exoexinal folds that extend to equatorial margin. Note significant development of internal vacuoles within the thinner inner part of the cingulizona. Outer, thicker part of cingulizona relatively narrow. Specimen maximum dimension 56 µm.