Cenozoic Muricidae of the Western Atlantic Region Part VI- Aspella and Dermomurex

Abstract

The two muricine genus-groups Aspella Morch and Dermomurex Monterosato share certain unusual shell-characters that suggest they had a common ancestor, but it has not been recognized. The two groups begin almost simultaneously in geologic time: Dermomurex is slightly older, occurring first in the early Oligocene of Mississippi then in the late Oligocene of western France, the latter together in time, although not in space, with the first Aspella in the late Oligocene of southern France. There are numerous species of both genera found in many parts of the world throughout ensuing time. In the Recent fauna Aspella occurs in both the eastern and western Pacific Ocean, in the Indian Ocean, and in the western Atlantic. There are no living eastern Atlantic or Mediterranean forms known. Dermomurex is well represented in the New World by eight species, either eastern Pacific or western Atlantic. There are but three Indo-Pacific species, plus the type of the genus found in the Mediterranean. Five of the Recent species are placed in Dermomurex s.s., two each in the subgenera Takia Kuroda, Trialatella Berry, and Gracilimurex Thiele, and one in Viator Vokes. In this paper the western Atlantic species are treated systematically, but there is only one member of Aspella as yet described, A. senex Dall, a Pliocene to Recent form often confounded with the Indo-Pacific A. anceps (Lamarck). Because of the undue amount of confusion over the Recent species of Aspella s.s., several of the Indo-Pacific species are illustrated for comparison with the western Atlantic A. senex. There are eleven western Atlantic species assigned to Dermomurex, ranging in age from early Oligocene to Recent. Of these, three each are placed in the subgenera Dermomurex s.s., Trialatella, and Viator, and one each in Gracilimurex and Takia. Of that number five are new species described herein: Dermomurex (Dermomurex) matercula, D. (Trialatella) farleyensis, and D. (? Viator) curviductus, all from the late lower Miocene Chipola Formation of northwestern Florida; D. (Takia) cookei, from the early Oligocene of Mississippi; and D. (Trialatella) antecessor, from the Pleistocene of Florida and Costa Rica