Scalpellum, LEACH, 1817

Gale, Andrew Scott, 2016, Phylogeny of the deep-sea cirripede family Scalpellidae (Crustacea, Thoracica) based on shell capitular plate morphology, Zoological Journal of the Linnean Society 176 (2), pp. 266-304 : 297

GENUS SCALPELLUM LEACH, 1817

Type species

Lepas scalpellum Linnaeus, 1767 , by subsequent designation, Leach 1824.

Diagnosis

Derived scalpellines in which the carinal and scutal umbones are subapical, the carinolatus has a hornlike projection, often recurved, extending beyond the carinal margin, the inframedian latus is rectangular to slightly trapezoidal, with a low umbo, and the upper latus is rhomboidal with a subapical umbo; rostrum rectangular, pyramidal, with large subumbonal surface.

Included species

Lepas scalpellum Linnaeus, 1767 , Scalpellum stearnsi Pilsbry, 1890 , Scalpellum gibbum Pilsbry, 1907 , and Tarasovium orientale Ren, 1983 .

Remarks

Scalpellum evolved in the Eocene from Arcoscalpellum , and a transition series is presented here ( Figs 16 , 17; see above).

Figures

Figure 16. Eocene Scalpellinae, to illustrate the evolutionary origin of the genus Scalpellum. Scuta, terga, and carinae. A–F, Scalpellum fischeri Bertrand, 1891, Lutetian, Calcaire Grossier, Chaussy, near Mantes (Seine-et-Oise), Paris Basin, France. A, B, scutum, external and internal views (original of Withers, 1953, pl. 38, figs 3, 4), NHMUK In. 39466. C, tergum, external view (original of Withers, 1953, pl. 38, figs 5, 6), NHMUK In. 39468. D–F, carina (original of Withers, 1953, pl. 38, fig. 1), NHMUK In. 39465. L, Arcoscalpellum venablesi Withers, 1953, lower Ypresian, Division B1 of London Clay (‘Fish Tooth Bed’), Bognor Regis, Sussex, UK. G, H, scutum, in external and internal views (original of Withers, 1953, pl. 63, fig. 1), NHMUK In. 39072. I, tergum (original of Withers, 1953, pl. 63, fig. 4), NHMUK In. 39072. J–L, carina (original of Withers, 1953, pl. 63, fig. 1), NHMUK In. 39033. M–R, Arcoscalpellum quadratum (Dixon, 1850), lower Ypresian, Division A3 of London Clay (‘Bognor Rock’), Bognor Regis, Sussex, UK. M, N, scutum. O, tergum. P–R, carina. NHMUK In. 32543–32550. Note the progressive elongation of the apical part of the scutum, the change in shape of the tergum, and the subapical migration of the carinal umbo. Compare with extant Scalpellum in Figure 15. Scale bars: 5 mm.