Upper Silurian microplankton of the Leintwardine group, Ludlow series, in the type Ludlow area and adjacent regions

Abstract

The acritarchs and prasinophyte algae from the Upper Bringewood, Lower Leintwardine, Upper Leintwardine and Lower Whitcliffe formations of the Ludlow type area and surrounding regions are described. The following new taxa are proposed: Cymatiosphaera pumila sp. nov., Melikeriopalla pustula sp. nov., Cheleutochroa beechenbankensis sp. nov., Cymbosphaeridium molyneuxii sp. nov., Flammulasphaera bella gen. et sp. nov., Percultisphaera incompta sp.nov., Salopidium aldridgei sp. nov. and Umbellasphaeridium? wicanderi sp. nov. A holotype is defined for Lophosphaeridium galeatum Hill and a further 34 new taxa are described under open nomenclature. Two biozones, identified by the first appearance of the zone taxon, are defined in the Sunnyhill section, Ludlow [Global Stratotype Section and Point (GSSP) for the base of the Ludfordian Stage, Ludlow Series]. The base of the Leoniella vilis Biozone is identified at 4.52 m below the top of the Upper Bringewood Formation at Beechenbank, Aymestrey. The base of the Triangulina sanpetrensis Biozone is identified at 15.49 m above the base of the Lower Leintwardine Formation and Ludfordian Stage at the Sunnyhill section. These biozones allow correlation with sections in north-west Spain, Podolia and Gotland. The possibility of using Visbysphaera whitcliffense and U.? wicanderi as biozonal indicators is suggested.