Revision of the Pennsylvanian fern Myriotheca anglica Kidston from the Central Pennine Basin (UK) and its transfer to the genus Pecopteris (Brongniart) Sternberg
Abstract
Two compressions of fertile Myriotheca anglica Kidston pinnae from Kidston's type collection have been studied for the first time since the publication of its protologue. The specimens came from the Lower Coal Measures Formation (middle Langsettian Substage) of the Central Pennines Basin, UK.
SEM observations have shown that this species has pinnules with 17-22 Pecopteris-type sporangia, with an apical annulus consisting of four to five rows of thick-walled cells and a stomium of five to seven rows of thick-walled cells. Based on this, a new combination, Pecopteris anglica (Kidston) comb. nov. is proposed.
Two different stages of maturity of the in situmicrospores are recognized: sculptured forms of the Convolutispora-type are interpreted as fully matured microspores; while laevigate, Punctatisporites-type spores represent relatively immature microspores.