Verruca rocana Steinmann, 1921

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 rocana Steinmann, 1921

Verruca rocana Steinmann in Wilkins, 1921: 4 , pl. 2, fig. 1, pl. 3, fig. 7.– Withers, 1935: 347, pl. 45, fig. 16–17.– Zullo & Baum, 1979: 238, pl. 2, fig. 1–5.– Weisbord, 1980: 183.

Diagnosis. A Verruca with the shell depressed, closely ribbed longitudinally, the ribs standing out at the periphery, and as many as five, flat, wide, articulating ribs on rostrum. Movable scutum with lower articular rib varying in width, often very narrow, but apparently wider than the upper articular ridge. Movable tergum with apico-basal ridge narrower than the second articular ridge; first articular ridge very narrow ( Withers, 1935: 347).

Stratigraphic range. Palaeocene (Danian-Thanetian).

Distribution. Patagonia, Argentina (Danian); Beaufort Formation, (Thanetian), Mosely Creek at Lenoir County line, near Kinston, North Carolina, USA.

Holotype. A group of shells on Ostrea , in the Geological Institute of Freiburg , catalog number unavailable ( Withers, 1935). The collections are now with the University of Freiburg , Freiburg im Breisgau, Germany. However, a recent inquiry indicates that the types may be lost.

Type locality. Roca Formation, (Danian), Río Negro, Argentina. ( Weisbord, 1980).

Discussion. All presently known specimens of this species have the movable scutum and tergum cemented tightly in place. It is, therefore, impossible to examine internal details necessary for specific determination and comparison. The large temporal and geographic separation of the North Carolina specimens from the Patagonian type lot caused some concern to Zullo & Baum (1979), but morphological comparison of the two lots revealed no noticeable differences. Internal details of both lots shall be necessary to identify them precisely. This question shall be dealt with in a later paper.

More recently, Brezina et al. (2017) restudied the area stratigraphy, identified the K-T boundary and reported occurrence of acrothoracican and Verruca remains. They verified the occurrence of Verruca rocana only in Danian deposits. They also reported V. rocana as having a partial calcareous basis, which was frequently left behind as the barnacles detached.

The Late Cretaceous and Danian species Verruca prisca ( Bosquet, 1854) , from Europe, has a shell lacking longitudinal ribs. Gale (2014) reassigned this species to his new genus Priscoverruca. Verruca pusilla Bosquet, 1857 (late Maastrichtian, the Netherlands and Belgium) is similar, but has narrower, more rounded and numerous (up to 7) articular ribs between the carina and the rostrum, and by having broad, flat-topped longitudinal ribs ( Zullo & Baum, 1979). No other Cretaceous or Paleocene species are known from North America.

Type Repository. Hypotypes USNM 252260-252262.