Alvania (Alvania) ampulla ( Eichwald, 1853 )

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 : 119-120

Alvania (Alvania) ampulla ( Eichwald, 1853)

Fig. 6D .

Rissoa ampulla Eichwald 1853: 274 , pl. 10: 16.

Rissoa Montagui Payraudeaux ; Hörnes 1856: 569, pl. 48: 13.

Alvania (Alvania) montagui var. miocaenica Sacco 1895: 23 .

Alvania miocaenica Sacco ; Meznerics 1933: 330, pl. 13: 2a, b.

Alvania (Alvania) montagui ampulla Eichwald ; Steininger 1963: 44, pl. 13: 2.

Rissoa (Alvania) montagui miocaenica Sacco ; Strausz, 1966: 74, pl. 46: 19, 20.

Alvania (Alvania) montaguiampulla Eichwald ; Bałuk 1975: 79, pl. 9: 9.

Alvania (Alvania) montagui miocaenica Sacco ; Svagrovský 1981: 114, pl. 35: 5–7.

Alvania (Alvania) montagui miocaenica Sacco ; Atanackovic 1985: 86, pl. 20: 9, 10.

Material.— Nine specimens from the Badenian of Steinebrunn , Lower Austria, NHMW 2002 z0030/0011.

Description.—The ovate shell comprises six slightly rounded whorls measuring about 3.5 mm in height. Sculpture consists of

16 prominent axial ribs crossed by 6 spiral cords, which are about as strong as the axial ribs on the early teleoconch whorls and which slightly decrease on the last two whorls. The base is sculptured by 5 strong spiral cords. The last whorl forms about 60–70% of total shell height. The slightly thickened aperture has an elongate drop shape. It is characterised by a faint anterior notch and by a pointed parietal portion. The columellar edge is bent.

The protoconch comprises two rounded whorls measuring 0.27–0.28 mm in height and 0.26–0.27 mm in maximum diameter. The embryonic shell has one whorl measuring 0.03– 0.04 mm in the width of the initial cap and 0.15–0.16 mm in maximum diameter. It is ornamented by remains of fine spiral threads. The embryonic shell is terminated by an indistinct rim on the shell. The subsequent larval shell is sculptured by remains of 6 rows of coarse granules. The protoconch is terminated by a sinusigera notch which is thickened in its adapical portion. The onset of the teleoconch is indicated by the formation of the regular adult sculptural pattern.

Remarks.—The protoconch, reflecting a planktotrophic larval development, closely resembles that of the Recent Mediterranean species Alvania (Alvania) punctura ( Montagu, 1803) , which is slightly larger, comprising half a larval whorl more ( Kowalke 1998: pl. 9: 9). The Recent Mediterranean species Alvania (A.) mamillata (Risso, 1758) (fig. 6A), with similar teleoconch morphology, differs by its thicker shell. The protoconch morphology, however, facilitated a clear separation of the taxa: A. (A.) mamillata is characterised by a lecithotrophic development, including a very short larval stage following a yolk−rich embryogenesis as indicated by a bulbous embryonic shell.

Two available names for this taxon are reported in the literature. Rissoa ampulla Eichwald was introduced for specimens from Poland, whereas Alvania montagui miocaenica Sacco referred to shells from the Vienna Basin in Austria. As already argued by Steininger (1963), both occurrences yield conspecific specimens and thus Rissoa ampulla gains priority.

Alvania (Alvania) ampulla is documented during the entire Badenian. Occurrences are known from Bosnia, Austria, Poland, Ukraine, Bulgaria, Hungary, and Slovakia. Its earliest occurrence in the Paratethys was reported by Steininger (1963) from the Eggenburgian of Lower Austria. Shells from the Tarkhanian to Konkian of the Eastern Paratethys affiliated with Alvania montagui (Payraudeau) by Iljina (1993: pl. 3: 24, 25) probably represent another species based on their regularly reticulate sculpture.

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.