New records of the homalonotid trilobite Burmeisterella delattrei (Pillet & Waterlot, 1983) from the Lower Devonian in Belgium and Luxemburg

The homalonotid trilobite Burmeisterella delattrei is recorded from the early Emsian Ruisseau de la Forge Formation in Belgium (southern limb of the Dinant Synclinorium), somewhat lower than its previously recorded first occurrence in the overlying Vireux Formation. The species may be considered an index fossil for the German Singhofen and Vallendar groups along with the homalonotids Burmeisterella armata and Digonus ornatus ornatus. A pygidium of B. delattrei from the Clervaux Formation in Luxemburg with one of the dorsal spines in place on the first pleural rib, allows a minor modification of current reconstructions of the dorsal exoskeleton to be proposed. The holotype and two paratypes (pygidia) of B. delattrei from the Vireux Formation in northern France are refigured. In total, four species of Burmeisterella, namely B. aculeata, B. armata, B. delattrei (= B. vixarmata) and B. quadrispinosa, are now recognised in the upper Pragian to lower Emsian of Belgium.