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

Verruca sp.

Material. A movable tergum, a fixed tergum, a?carina (incomplete), fragments of other plates.

Locality and stratigraphic age. Lower Eocene, Crescent Formation, LACMIP locality 16655.

Description. All plates with and exterior ornamented by low, fine radial ridges, permeated by a single row of pores; movable tergum damaged, but quadrangular, with single and very narrow apico-basal rib and raised (incomplete) portion equating to a secondary rib close to movable scutum margin; height of fixed tergum equal to width, apex damaged, but probably close to movable tergum margin; radio-alar extensions incomplete, base of extension on carinal side suggesting a moderate size; carinal side with single, well-developed articulating rib; interior with deep apical depression occupying upper half of plate.

Measurements. Movable tergum height c.1.00mm (incomplete); fixed tergum width c. 0.5mm, height 0.45mm.

Discussion: This material is too incomplete to warrant a formal designation. The plates are very small and the fixed tergum may be from a juvenile. They also appear to have been altered diagenetically – the pores that permeate the shell are infilled with a mineral (possibly pyrite); the shell in some fragments is more iridescent than usual in a verrucid, sometimes with microcrystalline calcite attached. It differs from all other fossil Verruca by having a very narrow apico-basal rib on the movable tergum; a second rib, close to the movable scutum margin is incomplete. However, the narrow apico-basal rib may be either a deformity, or simply reflecting early ontogeny. Apart from the noted oddities of the movable tergum, these plates are unremarkable, and not unlike material from the southwest of the United States.

Nonetheless, this is an important find – it is certainly the oldest verrucid from the West Coast USA. It is hoped that further collecting will enable a full description of this taxon.

Repository: Held by the Natural History Museum of Los Angeles County, CA.