Ordovician Sphinctozoan Sponges from the Eastern Klamath Mountains, Northern California

Abstract

Extensive silicified faunules of Middle and Late Ordovician sphinctozoan sponges have been assembled from the northern part of the eastern Klamath Mountains in northern California. The sponges are from eugeosynclinal rocks that are the westernmost Middle Ordovician to Late Devonian rocks at that latitude in North America. Seventeen new species occur in the assemblages, including 10 porate and 7 aporate forms. New genera of porate forms areAmblysiphonelloidesandCorymbospongia, and new porate species include:Amblysiphonella grossa, Amblysiphonelloides tubula, A. reticulata, Imperatoria mega, I. media, I. minima, I. irregularis, Corymbospongia adnata, C. mica, andC.(?)perforata.These are the first reported occurrences ofAmblysiphonellaandImperatoriain the Ordovician. New aporate genera areCystothalamiellaandPorefieldia, and new aporate species include:Cystothalamiella ducta, C. craticula, C. tuboides, Porefieldia robusta, Girtyocoelia epiporata, andG. canna.This is the oldest known occurrence ofGirtyocoelia, which is generally considered a Late Paleozoic form.Cliefdenella obconican. sp. is characterized by an obconical growth form in contrast to other species of the genus that are more massive or explanate.Cliefdenellais considered here as an imperforate sphinctozoan.Minor isolated hexactines and hexactine-derived spicules of Hexactinellida were associated with the sphinctozoans. No particular taxa within the class can be distinguished from these individual elements.