Anulifera chubutensis, Ferrari, 2013

Ferrari, S. Mariel, 2013, New Early Jurassic gastropods from west-central Patagonia, Argentina, Acta Palaeontologica Polonica 58 (3), pp. 579-593 : 585-587

Anulifera chubutensis sp. nov.

Fig. 3F–G .

2001 Zygopleura sp. Gründel; Gründel 2001: 54, pl. 4: 4.

Etymology: Referred to the Chubut province, where the material was found.

Type material: Holotype, SEGEMAR 25000 (cast MPEF−PI 4107), re−crystallized fragmentary teleoconch collected by Esther Wahnish; paratype, SEGEMAR 25001 (cast MPEF−PI 4108), re−crystallized fragmentary teleoconch collected by Esther Wahnish.

Type locality: Lomas Occidentales locality, Chubut province, Argentina .

Type horizon: Mulanguiñeu Formation, Lower Jurassic, Upper Pliensbachian, Lower Toarcian.

Dimensions.—MPEF−PI 4107: height 83.5 mm; width 43.2 mm.

Diagnosis.—Dextral, turriculate, large sized and high spired shell; juvenile teleoconch whorls flat; mature teleoconch whorls slightly convex; a spiral row of 18 nodes appear on mature whorls; base convex with irregular spiral keels; aperture holostomatous and oval; columellar lip thickened.

Description.—Dextral, anomphalous, turriculate, large sized and high spired shell. The protoconch is not preserved. The fragmentary teleoconch comprises three whorls; the juvenile teleoconch whorls are flat, becoming slightly convex toward the mature whorls. Last whorl is more expanded than the earlier whorls. The sutures are weakly incised. The shell is externally smooth or lacks a well developed ornament. Spiral elements are absent probably due to the poor preservation. An abapical spiral row of 18 conspicuous nodes borders the sutures on each teleoconch whorl. Weak opisthocline axial ribs appear from each node; but, collabral elements are not developed on the shell surface. The base is slightly convex, ornamented by weak and irregular spiral keels. The aperture is holostomatous and oval, with a thickened columellar lip.

Remarks.—The general shell morphology, the ornament pattern, consisting of conspicuous nodose rows on the teleoconch whorls, and the base with spiral furrows suggests an assignment to Anulifera (compare Nützel and Senowbari−Daryan 1999).

Anulifera chubutensis sp. nov. is the first occurrence of the genus in the Early Jurassic of South America. Zygopleura sp. recorded by Gründel (2001: 54, pl. 4: 4) from the Sinemurian of Chile most likely also belongs to Anulifera chubutensis . Pustulifer peruviana Haas, 1953 from the Upper Triassic of Peru (Haas 1953: 148, pl. 9: 20–24) is very similar to the species here described; however, the former species is bigger than A. chubutensis , has fewer nodes (ten/ twelve), and the mature teleoconch whorls are flat to slightly concave. Anulifera variabilis ( Zapfe, 1962) ( Zapfe 1962: 65, pl. 2:

http://dx.doi.org/10.4202/app.2011.0090

1–4; Nützel et al. 2010: 10, fig. 6.9–6.11), the type species of Anulifera from the Upper Triassic of Austria is very similar to the Chubutean species; Zapfe’s (1962) form, however, has less convex whorls, more developed spiral elements, and the base is angular and bordered by a strong spiral keel. Anulifera binodosa (Fallahi, Gruber, and Tichy, 1983) ( Nützel and Senowbari−Daryan 1999: 118, pl. 5: 3–8; Nützel et al. 2010: 10, fig. 6.1–6.6) from the Upper Triassic of Iran resembles A. chubutensis in shell size and general morphology; the Iranian species, however, has two nodose rows bordering the abapical suture, being the adapical nodes more developed than the abapical ones; and has many spiral striations or furrows and opisthocyrt growth lines on the shell surface. The last characters are not developed in the species here described. Zygopleura ? seminodosa Nützel and Senowbari−Daryan, 1999 ( Nützel and Senowbari−Daryan 1999: 113, pl. 4: 4, 5) from the Upper Triassic of Iran differs from the Chubutean species in being smaller, with flat to slightly concave whorls, sigmoidal growth lines on the shell surface, and smooth base. According to Nützel et al. (2010), Anulifera binodosa is very close related to A. variablilis . The authors suggested that it is actually possible that both species are synonyms and represent a single variable species.

Stratigraphic and geographic range.—Late Pliensbachian to Early Toarcian; Chubut province, Argentinean Patagonia

Figures

Fig. 3. Early Jurassic gastropods from Lomas Occidentales fossil locality. A–D. Pseudomelania feruglioi sp. nov. A. MPEF−PI 4090, paratype, adult teleoconch in lateral views (A1, A2). B. MPEF−PI 4091, paratype, adult teleoconch in lateral view. C. MPEF−PI 4096, juvenile teleoconch in lateral view. D. MPEF−PI 4089, paratype, adult teleoconch in apertural views (D1, D2). E. Pseudomelania sp. adult teleoconch in lateral views (E1, E2), basal views showing ornament details (E3, E4). F, G. Anulifera chubutensis sp. nov. F. SEGEMAR 25000 (MPEF−PI 4107), holotype, teleoconch in lateral (F1) and apertural (F2) views. G. SEGEMAR 25001 (MPEF−PI 4108), fragmentary teleoconch in lateral views (G1, G2). H. Globularia aff. catanlilensis (Weaver, 1931). MPEF−PI 4110, teleoconch in lateral (H1) and apertural (H2) views. Scale bars: A–E 3 mm, F–H, 10 mm.