Two new Silurian species of Eurypterus (Chelicerata: Eurypterida) from Norway and Canada and the phylogeny of the genus

Abstract

Synopsis A new species of Eurypterus from the Wenlock of Ringerike, Norway is described as E. hankeni sp. nov., based on fine pustular ornament on the carapace and opisthosoma, an enlarged distal podomere of the swimming leg and long angular epimera on the pretelson. Eurypterus species are reviewed: the oldest species, E. minor Laurie, 1898 from the Llandovery of the Pentland Hills in Scotland is redescribed and diagnosed as having eyes with large palpebral lobes, posterior second order opisthosomal differentiation, a coarse pustular ornament on both carapace and tergites and lacking the rows of raised scales found in other representatives of the genus. Material described previously and left in open nomenclature from the Late Ludlow of Somerset Island, Canada, is here named E. leopoldi sp. nov. It is relatively similar to E. pittsfordensis, but differs in the rhombiovate outline of the metastoma. An overview of morphological features carrying phylogenetic information in Eurypterus is provided. A phylogenetic analysis indicates that the earlier‐used gen us, Baltoeurypterus Størmer, 1973, is not monophyletic and even use of the name for its type species only (and its sister taxon) will render Eurypterus paraphyletic, unless assigning most terminals to new genera. This is not considered appropriate and the genus name Eurypterus is here proposed for use for all species, including the three previously assigned to Baltoeurypterus.