Zygopleuridae, Wenz, 1938

Ferrari, S. Mariel, 2009, Cosmopolitan Early Jurassic marine gastropods from west-central Patagonia, Argentina, Acta Palaeontologica Polonica 54 (3), pp. 449-461 : 452

Zygopleuridae ? gen. et sp. indet.

Fig. 3A .

Material.—MPEF−PI 1886, poorly preserved teleoconch.

Description.—Dextral, small−sized and high−spired shell, anomphalous and conical. Protoconch is not preserved and teleoconch consists of six convex whorls. The last two teleoconch whorls are considerably more expanded than the early whorls. Sutures are distinct. Shell is either externally smooth or the sculpture is not preserved. Base is convex and the aperture oval.

Dimensions.—MPEF−PI 1886: maximum height 9.8 mm; spire height 6.1 mm; maximum width 4.6 mm.

Remarks.—The Argentinean species may probably be a Zygopleuridae of the Azyga group. Mesozoic zygopleurids are generally characterized by a high−spired teleoconch with axial ribs (Nützel and Senowbari−Dayran 1999; Nützel and Erwin 2004) but there are some zygopleurids of the Azyga group having a smooth teleoconch and axially pleated protoconch ( Nützel 1998; Kaim 2004). Due to lack of protoconch in the specimen under consideration, crucial for a correct taxonomic assignment, this specimen is left in open nomenclature. The other possibilities are Pseudomelaniidae and Ampullinidae or even pyramidelloidean heterobranchs (compare Gründel and Kaim 2006; Hikuroa and Kaim 2007).

Figures

Fig. 3. Early Jurassic gastropods from Argentina A. Zygopleuridae? gen. et sp. indet., “El Córdoba” fossiliferous locality, Chubut Province. MPEF−PI 1886, latex cast of external mold in lateral view. B–D. Cryptaulax damborenae sp. nov., “El Córdoba” fossiliferous locality, Chubut Province. B. MPEF−PI 1878b, holotype, latex cast of external mold in lateral (B1, B2) and basal (B3) views, ornament detail (B4). C. MPEF−PI 1877, paratype, latex cast of external mold of incomplete teleoconch in apertural view. D. MPEF−PI 1872b, paratype, latex cast of external mold of incomplete teleoconch in lateral view. E. Cryptaulax cf. damboreneae sp. nov., Cerro Puchenque locality, Mendoza Province. MLP 18742, latex cast of external mold of incomplete teleoconch; adult teleoconch in lateral view. F–H. Cryptaulax nulloi sp. nov., “El Córdoba” fossiliferous locality, Chubut Province. F. MPEF−PI 1870, holotype, latex cast of external mold. Adult teleoconch in lateral view (F1), juvenile teleoconch in lateral view (F2). G. MPEF−PI 1861, paratype, latex cast of external mold in lateral and apertural view. H. MPEF−PI 1871, latex cast of external mold of incomplete teleoconch in lateral view (H1), and its ornament detail (H2). Scale bars 1 mm.