A vicissicaudatan arthropod from the Silurian Herefordshire Lagerstätte, UK

A new arthropod, Carimersa neptuni gen. et sp. nov., is described from the Silurian (Wenlock Series) Herefordshire Konservat-Lagerstätte, UK. The head bears pedunculate eyes and five pairs of appendages. Triflagellate antennae are followed by two pairs of uniramous limbs each with an endopod bearing a pronounced gnathobasic basipod. The posterior two pairs of head limbs and all trunk limbs bear an endopod, exopod and filamentous exite. The trunk consists of ten appendage-bearing segments followed by an apodous abdomen of four segments. The arthropod resolves as sister taxon to Kodymirus and Eozetetes + Aglaspidida. It is the first representative of Vicissicaudata reported from the Herefordshire Lagerstätte and the first Silurian example with well preserved appendages. The preservation of a cluster of radiolarians apparently captured by the trunk appendages is the first direct association of predator and prey discovered in the Herefordshire fauna and suggests that Carimersa was a nektobenthic form that used its gnathobasic basipods in microdurophagy.

Methods
The concretion was serially ground at intervals of 30 μm apart from the antennae and telson which were ground at 20 μm. The surfaces were photographed under a thin layer of water with a Leica DFC420 digital camera mounted ona Leica MZ8 binocular microscope. The SPIERS software suite (www.spiers-software.org) was used to remove extraneous
material from the images and to reconstruct the VAXML 3D model.