The largest Palaeozoic whip scorpion and the smallest (Arachnida: Uropygi: Thelyphonida); a new species and a new ichnospecies from the Carboniferous of New England, USA

Abstract Palaeozoic fossils of whip scorpions (Arachnida: Uropygi: Thelyphonida) are extremely rare, with only seven species of this age previously described. A new species of fossil whip scorpion, as well as the first ichnospecies assignable to this group, are described here from the Carboniferous Narragansett Basin of Massachusetts, USA. A body fossil from the Rhode Island Formation (Moscovian) is referred to as Parilisthelyphonus bryantae gen. nov., sp. nov.. At more than 34 mm long it represents both the largest known Palaeozoic whip scorpion and the first fossil arachnid found in the Rhode Island Formation in ~130 years of scrutiny. The whip scorpion trace fossil, comprising a full-body impression and associated tracks, is described from the subjacent Wamsutta Formation (Late Bashkirian) of Massachusetts, USA as Inmontibusichnus charleshenryturneriigen. nov., isp. nov.. With an estimated body length of less than 10 mm, the producer would be the smallest known Palaeozoic thelyphonid. These discoveries within the Narragansett Basin represent only the second site in the western hemisphere, in what was western Laurasia, to yield Palaeozoic whip scorpions. The Narragansett Basin is of significant Pangaean biogeographical importance among whip scorpion sites, being located between the westernmost Mazon Creek Lagerstätte of Illinois and the eastern assemblage of localities in Europe, and serves as an important new fossil calibration point for phylogenetic studies of this arachnid group.