Actinobalanus bisulcatus ( Darwin, 1854a )

Carriol, René-Pierre, 2008, New genus and new species of Cirripedia (Chthamalidae, Tetraclitidae, Archaeobalanidae and Balanidae) from the Middle Miocene of the faluns of Touraine (France), Zootaxa 1675, pp. 31-48 : 40-41

Actinobalanus bisulcatus ( Darwin, 1854a)

Fig. 3 (7)

Balanus bisulcatus Darwin, 1854a: 293 ; pl. 8, figs 6a–c

Synonymy: Balanus bisulcatus var. plicatus Darwin, 1854a: 293 ; 1854b: 26. Balanus (Armatobalanus) bisulcatus plicatus ( Darwin, 1854a) : Davadie, 1963: 74. Actinobalanus bisulcatus plicatus ( Darwin, 1854a) : Newman & Ross, 1976: 49. Balanus stellaris ( Brocchi, 1814) : Prieur & Philippe, 1984: 65.

Other references: Balanus bisulcatus Darwin, 1854 a: De Alessandri, 1906 (in part); 1922: 221. Balanus (Armatobalanus) bisulcatus Darwin, 1854 a: Davadie, 1963: 74. Balanus (Actinobalanus) bisulcatus Darwin, 1854 a: Moroni, 1967: 925. Actinobalanus bisulcatus ( Darwin, 1854a) : Newman & Ross, 1976: 49; Zullo & Perreault, 1989: 3; Carriol, 1992: 143.

Type locality: Corraline Crag, Ramsholt, Gedgrave, Sutton, England.

Occurrence: Ferrière-Larçon and Pauvrelay (Paulmy commune), Indre-et-Loire, France, faluns of Middle Miocene age.

Material: MNHN A24749: left scutum.

In addition to the figured scutum, two unregistered scuta, from Paulmy, have been observed.

Measurements: MNHN A24749: occludent margin 2.6 mm, tergal margin 1.5 mm. Other scutum: occludent margin 2.9 mm, tergal margin 1.5 mm.

Diagnosis (after Zullo & Perreault, 1989): Parietes smooth or markedly costate; radii narrow or broad, disparietal, scutum with two to four external longitudinal furrows; scutal adductor ridge prominent, length greater than one-half length of occludent margin; scutal articular ridge not extending beyond tergal margin; tergal spur very short, less than one-tenth length of plate, broad, occupying one-half width of basal margin, subtruncate basally, nearly confluent with basiscutal angle; juncture of spur and carinal side of basal margin arcuate.

Remarks: The capitular plates of A. bisulcatus cannot be distinguished from those of A. collinsi . However, the scuta, characteristic of the species with their external longitudinal furrows (two and three furrows for the specimens from Paulmy and three for the one from Ferrière-Larçon), conform to the diagnosis.

Stratigraphic and geographic range: Burdigalian ( France: Cestas, Aquitain basin; Faucon-Mollans- Malaucène basin), Middle Miocene ( France, faluns of Touraine), Pliocene ( England, Coralline Crag, Sutton; France, Rauville and Gourbesville, Cotentin; Belgium, Bolderberg, near Hasselt, and Karrendijke formation).

This is the first record of Balanus bisulcatus from the Middle Miocene.

Figures

FIGURE 3. 1 – 2, Actinobalanus collinsi Zullo & Perreault, 1989, external and internal side of plates: 1, scutum, MNHN A 24750; 2, tergum, MNHN A 24751. 3 – 7, Acasta vesiculosa sp. nov., external and internal side of plates: 3 a, b, carinolateral, paratype MNHN A 24753; 4, carina with broken sheath showing calcareous vesicles, holotype MNHN A 24752; 5, carino-lateral, paratype MNHN A 24755; 6, lateral, paratype MNHN A 24754. 7, Actinobalanus bisulcatus (Darwin, 1854 a), external side of a scutum, MNHN A 24749. 8, Tesseropora dumortieri (Fischer, 1866), internal side of a scutum MNHN A 24748. 9 – 10, Chthamalus grazianii sp. nov.: 9, magnified part showing protuberances on the external side of a rostro-lateral, paratype MNHN A 25741; 10, lateral showing punctuations on the internal side, paratype MNHN A 25742.