Article: Two Devonian mitrates from South Africa
The anomalocystitid mitrate Placocystella africana (Gydo and Voorstehoek shales, upper Emsian-lower Eifelian, Bokkeveld Group, Cape Province, South Africa) is redescribed. The internal anatomy of the head, the tail morphology and part of the nervous system are reconstructed for the first time. P. africana belongs to the family Allanicytidiidae, together with four other Silurian and Devonian species from Gondwana. The monophyly of the Allanicytidiidae is supported by cladistic analysis. A second mitrate from the upper Emsian of the Bokkeveld Group, Bokkeveldia oosthuizeni gen. et sp. nov. from the Gydo Shale, is described. The distinctive ventral head skeleton of this mitrate consists of 22 plates arranged in five transverse rows and is used as a reference to establish plate homologies in the anomalocystitids.