Balizoma and the new genera Aegrotocatellus and Perirehaedulus: Encrinurid trilobites from the Douro Formation (Siluiran, Ludlow) of the central Canadian Arctic

Abstract

Species of two new genera of Encrinuridae occur in the Ludlow Douro Formation at Goodsir Creek, Cornwallis Island, Gamier Bay, Somerset Island, and Prince Alfred Bay, Devon Island. The encrinurine Aegrotocatellus n. gen. includes four highly autapomorphic species, and is most closely related to Balizoma Holloway, 1980. Separate taxa are recognized at low and high stratigraphic intervals at Goodsir Creek (the type species, Aegrotocatellus jaggeri n. gen. and sp., and Aegrotocatellus n. sp. A, respectively), at Gamier Bay (Aegrotocatellus n. sp. B), and at Prince Alfred Bay (Aegrotocatellus nankerphelgeorum n. gen. and sp.). Perirehaedulus n. gen. is a coronocephaline most closely related to the Chinese upper Llandovery taxon Kailia Chang, 1974. The type species, Perirehaedulus caprus (Thomas in Thomas and Narbonne, 1979) from Goodsir Creek, is distinct from P. richardsi n. gen. and sp. at Garnier Bay. The upper Wenlock–Ludlow range of Balizoma is extended into the Arctic by Balizoma aff. B. variolaris (Brongniart, 1822) from Homerian rocks of the Cape Phillips Formation near Abbott River, Cornwallis Island, and by Balizoma sp., from the late Ludlow Douro Formation at Goodsir Creek.