Verruca Schumacher, 1817

Perreault, Ray T. & Buckeridge, John S., 2019, Paleogene Verrucidae (Cirripedia: Verrucomorpha) of North America, with descriptions of three new species, Zootaxa 4712 (1), pp. 34-50 : 34-50

Genus Verruca Schumacher, 1817

Verruca Schumacher, 1817: 35 .– Darwin, 1854: 496.– Zevina, 1987b: 1812.– Newman & Hessler, 1989: 268.– Buckeridge, 1994: 90.– 1997: 128.

Verruca “Section B” Pilsbry, 1916: 23.

Verruca (Verruca) .– Newman, Zullo & Withers, 1969: R281.– Foster, 1978: 68.

Euverruca Broch, 1924: 63.

Type. Lepas stroemia Müller, 1776: 251 , OD.

Diagnosis. Verrucids with shell form depressed; apices of rostrum and carina marginal; operculum parallel to base ( Buckeridge, 1997: 128).

Discussion. Verruca , as presently defined ( Buckeridge, 1997), is a convenience group comprising those verrucids with the operculum nearly parallel to the base, and marginal apices on the rostrum and the carina. Former subgenera of Verruca sensu lato were elevated to full generic rank by Zevina (1987a, b). This classification has been accepted by later workers. Young (1998) named three more genera based on shell characters. Species of this genus, as presently restricted, fall into several lineages, which eventually may be separated into other genera ( Buckeridge, 1997). The lineage that includes depressed shells, such as Verruca stroemia (typical Verruca ), extends from the Late Cretaceous (late Maastrichtian; Gale, 2014) through the Recent, and comprises predominantly littoral species. The earliest records of this lineage occur in the Cretaceous of Western Australia with V. tasmanica tasmanica Buckeridge, 1983 and now includes the taxa described in this paper. All of the species in this lineage have a fixed scutum with a well-formed adductor plate. In some species, such as Verruca stroemia , Verruca jago Buckeridge, 1997 and Verruca reunioni Foster & Buckeridge, 1995 , this plate extends to produce a rounded myophore. However, although all of the new species described herein possess a clear adductor plate, none have a definitive myophore.

Buckeridge (1997: 130) noted that fine, regularly spaced punctae extending from the exterior through the wall plates and opercula to the interior surface also characterize some members of this lineage. In extant species, such as Verruca stroemia , Verruca laevigata G.B. Sowerby, 1827 and Verruca jago , these punctae contain chitin, and Buckeridge (1997) considered it likely that this would have mitigated shell loss. In shallow, aerated coastal waters, where localized conditions could approach a pH of less than 7, this would have been advantageous in helping to preserve shell integrity. Punctae have also been observed in some fossil verrucids, e.g. Verruca tasmanica , Verruca digitali Buckeridge in Buckeridge & Finger, 2001 (Miocene, California) and Verruca viteus Buckeridge, in Buckeridge, Lee & Robinson, 2014 (Oligocene, New Zealand). Although they have not been recorded from Verruca alabamensis sp. nov. (this paper), V. rocana Steinmann, 1921 (Palaeocene, Argentina) and Verruca sauria Buckeridge, 2011 (Late Cretaceous, New Zealand), their apparent absence may be due to diagenetic processes in some cases. They are apparently absent in V. alabamensis sp. nov., and as the specimens are well preserved, punctae probably did not develop in this taxon. Nonetheless, the presence of punctae is a useful diagnostic feature for members of this lineage.

Occurrence. Upper Cretaceous to Recent, cosmopolitan. Most known fossil species are shallow water. Living species may be found from the intertidal zone to 620 m depth.