Regioscalpellum, Gale, 2016

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

GENUS REGIOSCALPELLUM GEN. NOV.

FIGURES 2B , 6P–T , 10J, K, 11M–P, 18N–S

Diagnosis

Scalpellines in which a concave, internal upper latus surface and short carinal margin is present on the carinolatus, covered by epidermis; umbones of carinolatus incurved, lateral margin of carinolatus strongly convex.

Type species

Scalpellum regium Thomson, 1873 .

Derivation of name

In eponymous reference to the type species.

Referred species

Scalpellum darwini Hoek, 1883 , Scalpellum gigas Hoek, 1883 , Scalpellum moluccanum Hoek, 1883 , Pollicipes maximus J. de C Sowerby, 1829 , and Arcoscalpellum sanchezae Withers, 1953 .

Remarks

The distinctive R. maximum (Fig. 18N, O, P, S) is common in Cretaceous chalks and marginal marine deposits from the Coniacian to the Maastrichtian ( Withers, 1935), and Regioscalpellum gen. nov. is represented in the Eocene of Cuba by Arcoscalpellum sanchezae Withers, 1953 .

GENUS GRAVISCALPELLUM FOSTER, 1980

FIGURES 2E–H , 13A–C

Type species

Scalpellum pedunculatum Hoek, 1883 , by original designation.

Diagnosis

Scalpellinae in which the rostrolatera and inferomedian latera are very low in proportion to the height of the capitulum; carinolatera have an elongated rhomboidal outline, with a prominent ridge on the long axis; the umbonal region of the carinolatus is weakly involuted.

Included species

Scalpellum regina Pilsbry, 1907 ; Arcoscalpellum ungulatum Withers, 1953 ; Graviscalpellum grantmackiei Buckeridge, 1983 .

Remarks

Foster (1980: 526) established Graviscalpellum to include ‘Arcoscalpellids that are hermaphroditic, attain relatively large size and have lower latera about one tenth the height of the capitulum’. Subsequently, the genus was treated as a junior synonym of Anguloscalpellum Zevina, 1978b , because Zevina (1981) had included S. pedunculatum in that genus (e.g. Young, 2007); however, the type species of Anguloscalpellum , Scalpellum angulare Nilsson-Cantell, 1930 , falls within the genus Weltnerium as redefined in this paper (trapezoidal scutum; deep, transversely elongated receptacle for dwarf male; rostrum with broad triangular external surface), and is evidently not related closely to S. pedunculatum . Therefore, Graviscalpellum is resurrected from synonomy to include both the extant G. regina ( Pilsbry, 1907) and a number of fossil species from the Oligocene–Miocene of New Zealand ( Buckeridge, 1983). The molecular phylogeny of Lin et al. (2015: fig. 3) shows G. regina and G. pedunculatum as closly related taxa.

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.

Figure 13. Carinolatera: A, B, Arcoscalpellum pedunculatum (Hoek, 1883); C, Arcoscalpellum regina (Pilsbry, 1907); D, E, Arcoscalpellum michelottianum (Seguenza, 1876); F, Arcoscalpellum quadratum (Dixon, 1850), London Clay, Eocene, Minster, Sheppey, Kent, UK (original of Withers, 1953, pl. 26, fig. 13), NHMUK In. 34504; G, H, Regioscalpellum regium (Thomson, 1873); I, J, Regioscalpellum darwini (Hoek, 1883); K, L, Diotascalpellum rubrum (Hoek, 1883); M, N, Diotascalpellum gigas (Hoek, 1883); O, P, Arcuatoscalpellum arcuatum (Darwin, 1851b), Albian, Gault Clay, Paddlesworth, Kent, NHMUK In. 61368; Q, R, Cretiscalpellum striatum (Darwin, 1851b), Campanian chalk, Norwich, UK. NHMUK IC 1198. Comparative morphology of carinolatus in out-group Cretiscalpellum and Scalpellinae to illustrate morphological variation and phylogenetic trends. Note the overall progression in morphology from the out-group (Q, R), through Arcuatoscalpellum arcuatum (P, Q), to Diotascalpellum (D. rubrum, K, L), involving differentiation of the inframedian latus surface. In the more derived R. regium (G, H), R. darwini (I, J), and R. gigas (M, N) the umbo is incurved, has migrated to a more dorsal position, and a low internal shelf has developed adjacent to the upper latus. In Arcoscalpellum (Arcoscalpellum michelottianum, D, E; Arcoscalpellum quadratum, F), the umbo is more incurved, the apex subapical, and a upper latus surface has developed (see Fig. 10 for nomenclature). Scale bars: A–I, M, N, 1 mm; K, L, O–R, 0.5 mm.