Taxonomy Online - Carboniferous spores part I - Species details


Species name
Umbonatisporites distinctus Clayton, 1971

Description
Radial, trilete, acamerate miospores. Amb circular, subcircular or oval. Trilete mark often distinct; sutures when seen, simple, straight, extending between one-third and one-half the spore radius. Exine, 1–3 µm thick, ornamented on distal surface and equatorial portion of proximal surface with cylindrical shaft-like elements which are 2–10 µm high and 1–3 µm wide, with a prominent constriction near the top and a second near the base. Terminus of each shaft-like element normally flat but commonly surmounted by a single spina or conus up to 4.5 µm high. Rare small coni and spini may be interspersed between the longer biform elements. Ornamentation elements variable in size between specimens but commonly uniform on any single specimen. Contact areas laevigate.

Other descriptions
Clayton, 1971, pp. 591–592, pl. 4, figs. 4–6

Size
Overall equatorial diameter excluding ornamentation 43(70)126 µm

Remarks
Umbonatisporites distinctus is distinguished from U. abstrusus (Playford) Clayton 1971 and U. variabilis Hibbert & Lacey 1969 by possessing cylindrical processes with flat or slightly concave tops surmounted by a single conus or spina, and by the uniformity of its ornamentation on any single specimen.

Range
Mississippian; Tournaisian; HD to CM biozones (Higgs et al., 1988)

Images

MPK 7427 MPK 7427
Cementstone Group, Bracken Bay, Heads of Ayr, Ayrshire, Scotland; Tournaisian, CM Biozone, Sample MPA 29832, Specimen MPK 7427. Subcircular miospore. ?Distal focus. Trilete mark not seen. Exine ornamented with long, narrow cylindrical processes that have at least one constriction in their width, usually near to the terminus, but sometimes also near to the base. Termination of cylindrical elements flat and surmounted by small conus or spina (detail). Specimen maximum dimension 52 µm.


MPK 7427_detail MPK 7427_detail