Alvania Risso, 1826

Kowalke, Thorsten & Harzhauser, Mathias, 2004, Early ontogeny and palaeoecology of the Mid-Miocene rissoid gastropods of the Central Paratethys, Acta Palaeontologica Polonica 49 (1), pp. 111-134 : 118-119

Subgenus Alvania Risso, 1826

Type species: Turbo cimex Linnaeus, 1758 from the Mediterranean Sea and NE Atlantic.

Alvania (Alvania) curta ( Dujardin, 1837)

Fig. 6C .

Rissoa curta sp. nov.; Dujardin 1837: 279, pl. 19: 5.

Rissoa curta Dujardin ; Hörnes 1856: 571, pl. 48: 15 a, b.

Alvania curta Dujardin var. cristatocosta Sacco 1895: 23 .

Alvania curta Dujardin ; Meznerics 1933: 330.

Rissoa (Alvania) curta Dujardin ; Strausz 1966: 71–72, pl. 46: 8, 9. Alvania curta (Dujardin) ; Bohn−Havas 1973: 1038, pl. 2: 27.

Alvania (Alvania) curta (Dujardin) ; Bałuk 1975: 78, pl. 9: 11. Alvania (Alvania) curta (Dujardin) ; Svagrovský 1981: 117, pl. 37: 1, 2. Alvania (Alvania) curta (Dujardin) ; Atanackovic 1985: 87, pl. 20: 13, 14. Alvania (Alvania) curta (Dujardin) ; Gürs and Weinbrecht 2001: 80, fig. 2.4, pl. 1: 6.

Material.— Five specimens from the Early Badenian of Sedlec / Nový Rybník (formerly Porz) 6 km SE Mikulov, Czech Republic, NHMW 2002 z0030/0010.

Description.—The egg−shaped, thick shell comprises 5–6 slightly rounded low whorls measuring up to 2.5 mm in height. The last whorl forms about 60–70% of total shell height and is elongate, whereas the spire is conical. The teleoconch sculpture consists of 16 prominent, straight to slightly prosocline axial ribs and 10 spiral threads; these form a reticulate pattern on the early teleoconch and are subordinated on the last two whorls. The base is sculptured by 3 spiral threads. The thickened aperture has an elongate drop shape. It is characterised by a faint, broad anterior notch and by an acute parietal edge. The columellar lip is bent. The interior portion of the outer lip is characterised by 4 weak teeth.

The protoconch comprises three slightly rounded whorls measuring 0.46 mm in height and 0.44 mm in maximum diameter. The first whorl measures 0.06 mm in the width of the initial cap and 0.16–0.17 mm in maximum diameter. Embryonic ornament and the transition from the embryonic shell to the larval shell are not preserved. Remains of tuberculate spiral threads sculpture the larval shell and are apparently concentrated on the abapical half of the whorls. The protoconch is terminated by a well−developed sinusigera notch. The onset of the teleoconch is indicated by the formation of the regularly reticulate adult sculpture.

Remarks.—The protoconch indicates an indirect development including a free planktotrophic larval stage. The similar Recent Mediterranean species Alvania (Alvania) montagui ( Payraudeau, 1826) (fig. 6B) differs by its slightly larger aperture and by deeper sutures separating the whorls. The protoconch of A. (A.) montagui differs by reflecting a lecithotrophic larval development. A second Mediterranean morph assigned to A. (A.) montagui with multispiral protoconch but identical teleoconch morphology probably represents another species. Solving this problem, however, will require further anatomical studies because several species pairs of Alvania and Rissoa only differing in reproductive mode and thus in protoconch morphology exist in the Mediterranean Sea as well as in Northern Europe ( Oliverio 1994, 1996; Warén 1996).

A. (A.) curta has been described from the Badenian of Várpalota in Hungary ( Strausz 1966), Poland ( Bałuk 1975), Slovakia ( Hörnes 1856; Svagrovský 1981), Bosnia and Ukraine ( Atanackovic 1985). Gürs and Weinbrecht (2001) mentioned its occurrence in Miocene deposits of the North Sea Basin (Northern Germany). The alleged occurrences from the Middle Miocene of the Loire Basin ( Glibert 1949) and from the Burdigalian of the Aquitaine ( Cossmann and Peyrot 1919) are considered as synonyms of Alvania lachesis ( Basterot, 1825) by Lozouet et al. (2001).

Figures

Fig. 6. Four species of Alvania (Alvania) Risso, 1826. A. Alvania (Alvania) mamillata (Risso, 1826). Specimen (NHMW 2002z0030/0008), Recent, from the Adriatic Sea (A1). Apical and lateral views of the protoconch of the same specimen (A2, A3). Thickened, closely spaced growth lines are terminating the protoconch. The onset of the teleoconch is indicated by the formation of a regular reticulate sculpture. B. Alvania (Alvania) montagui (Payraudeau, 1826). Specimen (NHMW 2002z0030/0009), Recent, from the Adriatic Sea (B1). Lateral views of the protoconch of the same specimen (B2, B3). The protoconch is terminated by a slightly thickened sinuous rim and a subsequent slight incision. C. Alvania (Alvania) curta (Dujardin, 1837). Specimen (NHMW 2002z/0030/0010) from the Early Badenian of Sedlec/Nový Rybník, Czech Republic (C1). Protoconch of the same specimen in lateral view (C2). The protoconch is terminated by a well−developed sinusigera notch. D. Alvania (Alvania) ampulla (Eichwald, 1853). Specimen (NHMW 2002z0030/0011) from the Badenian of Steinebrunn, Lower Austria (D1). Lateral view of the protoconch of the same specimen as in D1 (D2). The protoconch is terminated by a sinusigera notch which is thickened in its adapical portion. Detailed apical view of the embryonic shell of the same protoconch as in D2 (D3). The embryonic shell is sculptured by fine spiral threads and it is terminated by an indistinct rim on the shell.