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The genus Sveltia (Gastropoda, Cancellariidae) in the Atlantic Pliocene of Iberia with a new species from the Cenozoic Mondego Basin of Portugal

Published online by Cambridge University Press:  26 August 2021

Bernard M. Landau*
Affiliation:
Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, Netherlands. International Health Centres, Av. Infante de Henrique 7, Areias São João, P-8200 Albufeira, Portugal
Carlos Marques da Silva
Affiliation:
Departamento de Geologia and Instituto Dom Luiz (IDL), Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal
*
*Corresponding author

Abstract

The cancellarid genus Sveltia Jousseaume, 1887, is widespread in western European and North African Neogene marine fossil assemblages. In Pliocene deposits it is commonly represented by Sveltia varicosa (Brocchi, 1814), which until recently was considered a widely distributed taxon in the Mediterranean Sea and adjacent Atlantic faunas. A recent review of the species from the Pliocene of Italy and Spain (Guadalquivir Basin), leading to the erection of S. confusa, prompted the reassessment of the Sveltia material from the Atlantic Pliocene of the Portuguese Mondego Basin and the subsequent description of Sveltia sofiae n. sp. Consequently, a mosaic of species has emerged from what was previously viewed as the broad Atlanto-Mediterranean range of the widespread and quite variable S. varicosa. From a biogeographic standpoint, it is now clear that S. varicosa was a Mediterranean species, occurring east of the Alboran Sea. Sveltia confusa had a mainly Atlantic distribution, from the French Pliocene Ligerian Gulf to the Gulf of Cadiz, at least, and straddling the Strait of Gibraltar into the Alboran Sea. Sveltia sofiae n. sp. was endemic to western Iberia, represented today only in the western Portuguese Mondego Basin. Sveltia is a thermophilic genus. Since early Pliocene times, because of northeastern Atlantic sea surface temperature decline, it underwent a southward range contraction, occurring today—in the eastern Atlantic—from Cape Blanc, Mauritania, south. This range reduction was coupled with the post mid-Piacenzian southward contraction of the Pliocene Mediterranean-West African tropical molluscan province and the consequent rise of the present-day Mediterranean-Moroccan subtropical province.

UUID: http://zoobank.org/0cf3c73a-8d57-472e-87e4-f1ad065e5fb6.

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Articles
Copyright
Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of The Paleontological Society
Figure 0

Figure 1.Geographical location of the study site: Vale de Freixo, Carnide, Pombal Municipality (west-central Portugal).

Figure 1

Figure 2.Gastropods of the Sveltia varicosa group from the Atlanto-Mediterranean Miocene and Pliocene. (1–10) Sveltia sofiae n. sp., Vale de Freixo, Portugal, Carnide Formation; (1, 2) (GeoFCUL VFX.03.130) paratype 3 in (1) apertural and (2) dorsal views, height 28 mm; (3, 4) (NHMW 2018/0331/0170) holotype in (3) apertural and (4) dorsal views, height 20.1 mm; (5, 6) (NHMW 2018/0331/0305) paratype 1 in (5) apertural and (6) dorsal views, height 16 mm; (7–10) (NHMW 2018/0331/0306) paratype 2 in (7) apertural and (8) dorsal views, (9) protoconch, and (10) detail of the sculpture, height 15.8 mm. (11–15) Sveltia confusa Brunetti, (11–13) (NHMW 2010/0054/0155) Lucena del Puerto, Huelva, Spain, Arenas de Huelva Formation, in (11) apertural and (12) dorsal views, and (13) detail of the sculpture, height 28 mm; (14, 15) (NHMW unnumbered) La Dixmérie, St-Julien-de-Concelles, Loire Atlantique, France, in (14) apertural and (15) dorsal views; height 20.4 mm. (16–18) (NHMW unnumbered) Sveltia varicosa (Brocchi), Poggio alla Staffa, Siena, Italy in (16) apertural and (17) dorsal views, and (18) detail of the sculpture; height 27 mm. (19–21) (NHMW1847/0058/0469) Sveltia dertovaricosa Sacco, 1894, Yaylasi, Akpinar, Turkey, Serravallian, middle Miocene in (19) apertural and (20) dorsal views, and (21) detail of the sculpture; height 32 mm.

Figure 2

Figure 3.Comparison of spiral sculpture in Pliocene species of the Sveltia varicosa group from the Atlanto-Mediterranean Pliocene discussed herein. (1) Sveltia sofiae n. sp., paratype 2, Vale de Freixo, Portugal, Carnide Formation (NHMW 2018/0331/0306, same specimen as in Fig. 2.7–2.10); scale x2.1. (2) Sveltia confusa Brunetti, Lucena del Puerto, Huelva, Spain, Arenas de Huelva Formation (NHMW 2010/0054/0155, same specimen as in Fig. 2.11–2.13); scale x2.3. (3) Sveltia varicosa (Brocchi), Poggio alla Staffa, Siena, Italy (NHMW, same specimen as in Fig. 2.16–2.18); scale x2.4. Terminology after Landau et al. (2019). P1 = primary shoulder cord, P2 = primary cord 2; P3 = primary cord 3; s2 = secondary cord between P2 and P3; t = tertiary cords.

Figure 3

Figure 4.Geographic distribution of Sveltia sofiae n. sp. (Ss), S. confusa (Sc), and S. varicosa (Sv) in the pre-3.0 Ma Atlanto-Mediterranean Pliocene. 1 = Loire Basin, Ligerian Gulf; 2 = Guadalquivir Basin; 3 = Estepona Basin; 4 = Monte Antico, Tuscany. Pliocene biogeographic provinces after Silva and Landau (2007). Paleogeography adapted from Rögl (1999), Silva (2001), and Popov et al. (2006).