Pliocene distribution of the cirripede Verruca stroemia (O.F. Müller, 1776) and revised definitions of the verrucid genera Verruca, Metaverruca and Priscoverruca (Thoracica, Crustacea)

Abstract

The small, shallow-marine verrucid barnacle Verruca stroemia (O.F. Müller, 1776), a characteristic element of the northeast Atlantic Pliocene to present-day fauna, is recorded as occurring abundantly in the upper Pliocene (mid-Piacenzian) Rushmere Member of the Yorktown Formation in North Carolina, the first record (fossil or extant) of the species from the northwest Atlantic or its coastal plain. It is shown here that Verruca koikei Tanaka, Kawase, Narita and Karasawa in Koike et al., 2006 from the Pliocene of Japan is a synonym of V. stroemia, as is Verruca alaskana Pilsbry in MacNeil et al., 1943 from the Pliocene of Alaska, USA. Revised morphological definitions of the genera Verruca Schumacher, 1817, Metaverruca Pilsbry, 1916 and Priscoverruca Gale, 2014, are provided and the affinities of living and fossil species assigned to these genera reassessed. The presence of V. stroemia in the upper Pliocene of the north Pacific was enabled by the open Bering Strait, and the extended geographical range of the species, in both the Atlantic and Pacific, is approximately coincident with the mid-Piacenzian Warm Period (mPWP).