Manzonia (Manzonia) crassa (Kanmacher, 1798)

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 : 122-123

Manzonia (Manzonia) crassa (Kanmacher in J. Adams, 1798)

Fig. 8C .

Manzonia costata Adams var.; Friedberg 1923: 385, pl. 23: 5. Manzonia costata (J. Adams) ; Wenz 1938–1944: 614, fig. 1707. Folinia (Manzonia) costata (Adams) ; Iljina 1966: 91, pl. 4: 2. Folinia (Manzonia) costata (Adams) ; Bałuk 1975: 74, pl. 8: 12. Manzonia (Manzonia) crassa (Kanmacher in J. Adams); Ponder 1985: fig. 99A–F.

Material.— Three specimens from the Badenian of Niederleis , Lower Austria, NHMW 2002 z0030/0018.

Description.—The small, elongated conical to spindle−shaped shell has 5 low whorls measuring up to 2.5 mm in height and up to 1.4 mm in width. Whorls are separated by deep sutures. Sculpture consists of 8–10 prominent opisthocyrt axial ribs, crossed by numerous very fine spiral threads. The base is sculptured by 2 strong spiral keels. The last whorl forms 60–70% of total shell height. The large thickened, holostomatous aperture is rounded to egg shaped.

The protoconch is heavily corroded. It comprises about two rounded whorls measuring 0.33 mm in height and in maximum diameter. The transition to the teleoconch is indicated by the formation of the regular adult sculpture.

Remarks.—Although M. (M.) crassa represents a Recent species, it is not possible to distinguish our material based on conchological features from the Mediterranean representatives. Recent M. costata has a protococh of about the same dimensions as the material described here ( Ponder 1985: fig. 99 B). M. (M.) crassa is described from the Badenian of Poland, Austria, Hungary, and Romania. Glibert (1949) mentioned Manzonia costata falunica ( Morgan, 1915) from the Langhian –Early Serravallian of the Loire Basin, whereas Cossmann and Peyrot described Manzonia costata minuta ( Dollfus and Dautzenberg, 1886) from the Burdigalian of SW France. The species is not recorded from the Miocene of the Eastern Paratethys but appears along the Black Sea coasts during the Quaternary ( Iljina 1966). In the modern seas, M. (M.) crassa ranges from the Black Sea and the Mediterranean Sea and along the Atlantic coast as far north as Scandinavia ( Nordsieck 1972). Manzonia miocristata Sacco, 1895 from the Late Miocene of Italy differs by its more slender shell and by having fewer but more strongly developed axial ribs, which additionally differ by their stronger opisthocyrt course ( Ferrero Mortara et al. 1984: pl. 39: 8a–c).

Figures

Fig. 8. Two species of Manzonia (Alvinia) Monterosato, 1884 and two of Manzonia (Manzonia) Brusina, 1870. A. Manzonia (Alvinia) miocrassicosta (Sacco, 1895). Specimen (NHMW 2002z0030/0016) from the Badenian of Steinebrunn (A1). Lateral and apical view of the protoconch of the same specimen (A2, A3). The protoconch is terminated by a short sinusigera notch. Detailed view of the initial whorl of the same protoconch as in A3 (A4). The embryonic shell is demarcated from the subsequent larval shell by a well developed thickened rim. B. Manzonia (Alvinia) partschi (Hörnes, 1856). Specimen (NHMW 2002z0030/0017) from the Badenian of Baden/Sooss, Lower Austria (B1). Lateral and apical view of the protoconch of the same specimen as in B1 (B2, B3). The protoconch is terminated by a short, slightly thickened sinusigera notch. Detailed view of the initial whorl of the same protoconch as in B3 (B4). The embryonic shell is strongly sculptured and terminated by a slightly sinuous rim. C. Manzonia (Manzonia) crassa (Kanmacher in J. Adams, 1798), specimen (NHMW 2002z0030/0018) from the Badenian of Niederleis, Lower Austria. D. Manzonia (Manzonia) scalaris (Dubois, 1831). Specimen (NHMW 2002z0030/0019) from the Badenian of Steinebrunn, Lower Austria (D1). Lateral and apical view of the protoconch of the same specimen as in D1 (D2, D3). The protoconch is terminated by a well developed sinusigera notch. Detailed view of the initial whorl of the same protoconch as in D3 (D4). The transition to the larval shell is indicated by a thickened rim.