An unusual megaspore of uncertain systematic affinity from Lower Cretaceous deposits in south-east England and its biostratigraphic and palaeoenvironmental significance

Abstract

An unusual megaspore has been recorded from beds within the Weald Clay Group of south-east England. Described as Clockhousea capelensis gen. et sp. nov., it is characterised by having a thick outer layer of exine consisting of closely packed columnar to clavate elements with constricted bases attached to a perforated inner layer and a sculpture that ranges from having the appearance of a negative reticulum through closely spaced verrucae to a mixture of verrucate and essentially baculate elements, all of which are surface manifestations and extensions of the underlying structure. These characters do not readily indicate a systematic relationship with any known heterosporous plant genus or family. The localised occurrence and relative abundance of the spores in a few beds suggest that some of the parent plants grew close to water bodies where they were deposited and preserved. Their recovery from sediments of late Hauterivian-early Barremian age indicates that the species has potential as a biostratigraphic marker in the upper Wealden succession of southern England and perhaps elsewhere.