GENUS ARCOSCALPELLUM HOEK, 1907

FIGURES 2C–H, 6F–O, 10L, M, Q, 11E–L, 13A–F, 18H–M

Type species

Scalpellum velutinum Hoek, 1883 (= Scalpellum michelottianum Seguenza, 1876).

Diagnosis

Scalpellines in which a large upper latus surface is present on the carinolatus; umbo strongly incurved, carinal margin present; lateral surface of carinolatus inturned onto interior of plate, peduncular margin concave.

Included species

Scalpellum hirsutum Hoek, 1883, Scalpellum sociabile Annandale, 1905, and Scalpellum quadratum (Dixon, 1850; Eocene).

Remarks

The name Arcoscalpellum was formerly applied to most living and many fossil scalpellids (Withers, 1935, 1953; Newman et al., 1969). After the revisions of Zevina (1978a,b, 1981), the genus was used in a restricted sense and identified by the ‘inframedian latus triangular, reaching upper latus, umbo apical’ (Shalaeva & Boxshall, 2014: 21). This condition is shown here to be plesiomorphic for scalpellids, and the genus is therefore redefined with reference to the morphology of the type species, Arcoscalpellum michelottianum . It encompasses a small group of more derived Scalpellinae (e.g. Fig. 2C, D) in which the carinolatus is in possession of a carinal margin and an upper latus surface (Fig. 10L, M). It ranges from the Eocene to the present day.

AMIGDOSCALPELLINAE SUBFAM. NOV.