Arcoscalpellum, HOEK, 1907

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 : 298-299

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.

Figures

Figure 2. A–E, H, Scalpellinae in lateral aspect: A, Diotascalpellum rubrum (Hoek, 1883); B, Regioscalpellum regium (Thomson, 1873); C, Arcoscalpellum michelottianum (Seguenza, 1876); D, Arcoscalpellum sociabile (Annandale, 1905); E, Arcoscalpellum regina (Pilsbry, 1907); F–H, Graviscalpellum pedunculatum (Hoek, 1883); F, ventral (rostral) aspect; G, dorsal (carinal) view; H, lateral view. See Table 1 for details of localities etc. Scale bars: 5 mm.

Figure 6. Evolution of lateral plate morphology, dorsal side: A–E, Amigdoscalpellum truncatum (Hoek, 1883); F–J, Arcoscalpellum sociabile (Annandale, 1905); K–O, Arcoscalpellum michelottianum (Seguenza, 1876); P–T, Regioscalpellum regium (Thomson, 1873); U–Y, Diotascalpellum rubrum (Hoek, 1883). External aspect of carinolatus (A, F, K, P, U); interior of carinolatus (B, G, L, Q, V); external view of inframedian latus (C, H, M, R, W), interior of inframedian latus (D, I, N, S, X); dorsal (carinal) view of capitulum (E, J, O, T, Y). See Table 1 for details of localities. Note the migration of the position of the carinolatus umbo from apical to nearly basal, the progressive incurvature of the umbo, and the development of an upper latus surface. The lower four species are assigned to the Scalpellinae, the uppermost one to the Amigdaloscalpellinae. Scale bars: A–E, J, K–T, Y, 1 mm; F–I, U–X, 0.5 mm.