Synziphosurines (Xiphosura: Chelicerata) from the Silurian of Iowa

Abstract

A new genus and species of synziphosurine (Chelicerata) is described from the Silurian (Wenlock) Scotch Grove Formation Konservat-Lagerstätte in Clinton County, Iowa.Camanchia grovensisn. gen. n. sp. is characterized by a sub-triangular carapace, ten opisthosomal segments divided into a preabdomen of seven and a postabdomen of three, and a tuberculate ornament on the carapace and pleural margins. A single new specimen from the same location is assigned toVenustulus waukeshaensis, originally described from the Late Llandovery Waukesha Konservat-Lagerstätte of Wisconsin. A comparison of the musculature ofC. grovensiswith that of livingLimulus polyphemusand the JurassicMesolimulus walchifrom Nusplingen, Germany shows that it is much simpler, consistent with the status of synziphosurines as stem xiphosurids.