Two new Devonian spine-bearing pleurotomariacean gastropod genera from Alaska

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Abstract
Two new spine-bearing gastropods, Chlupacispira spinosa n. gen. and sp. and Spinulrichospira cheeneetnukensis n. gen. and sp., are described from the late Early Devonian (Emsian) and early Middle Devonian (Eifelian), respectively, of west-central Alaska. These represent the earliest reported spiny pleurotomariacean gastropods. Otherwise, spinose pleurotomariaceans are known from strata no older than Carboniferous age. Spinulrichospira cheeneetnukensis n. gen. and sp. appears to represent a more highly ornamented derivative of Ulrichospira Donald. Both new genera are part of the more highly ornamented fauna which occurred in warm equatorial waters of the Old World Realm during the Early and Middle Devonian, in contrast to more weakly ornamented shells of the Eastern Americas Realm and even more weakly ornamented (almost totally “plain”) shells of the Malvinokaffric Realm. The latter two realms are thought to represent subtropical to warm temperate and cool temperate to cool polar conditions, respectively.