A Late Devonian refugium for Colpodexylon (Lycopsida) at high latitude

Localities within strata of the Witpoort Formation (Witteberg Group, Cape Supergroup) of South Africa provide diverse new fossil material of Famennian plants from a high palaeolatitude marginal marine setting. Lycopsid axes with sterile leaves include material here diagnosed to two new species of Colpodexylon Banks 1944. C. pullumpedes sp. nov. from Waterloo Farm is a 'short-tipped' species, whereas C. mergae sp. nov. from Coombs Hill, is a 'long-tipped' species. The latter has leaves similar to those of the type species, C. deatsii Banks, yet differing in proportions. This provides the first definite high latitude records of the genus. Furthermore, these occurrences substantially extend the temporal range of Colpodexylon, formerly only known from lower Frasnian and older strata, indicating that the genus persisted at high-latitudes after its apparent disappearance from the palaeo-sub-tropics.