Nerinea, Deshayes, 1827

Ferrari, S. Mariel, 2013, New Early Jurassic gastropods from west-central Patagonia, Argentina, Acta Palaeontologica Polonica 58 (3), pp. 579-593 : 590

Nerinea ? sp. 1

Fig. 4F .

Material.—MPEF−PI 4123; fragmentary re−crystallized teleoconch. LO 29 site from Lomas Occidentales locality, Chubut province, Argentina, Mulanguiñeu Formation, Lower Jurassic, Upper Pliensbachian, Lower Toarcian.

Dimensions.—MPEF−PI 4123: height 12.2 mm; width 5.6 mm.

Description.—Fragmentary, turriculate, high spired and small sized shell. The protoconch is not preserved. The teleoconch comprises 3.5 whorls; the outline of the whorls flanks is strongly concave; the sutural portion of the whorls is strongly angular and peripheral. Sutures are weakly incised. The ornament consists of a strong and peripheral spiral keel located in an adapical position on each whorl. The basal and apertural characters are not preserved.

Remarks.—According to Morris and Lycett’s (1850) diagnosis, the material here described shows the typical characters of Nerinea , such as a turriculate shell shape, conical or cylindrical, with a number of whorls and aperture subquadrate. However, due to lack of apertural, basal and columellar characters in the specimen under consideration, it is left in open nomenclature until a new material in better preserved conditions is available.

The South American nerineid, Nerinea sp. described by Bayle and Coquand (1851: 23, pl. 4: 8) from the Early Jurassic of Chile is similar to the species here described. Although the Chilean species does not show apertural characters and columellar folds, the authors suggested that their material belongs to Nerinea . The material designed by Jaworski (1925: 116) to Nerinea bathonica Rigeaux and Sauvage, 1869 from the Bathonian (Middle Jurassic) of Peru resembles Nerinea ? sp. 1 in general shell morphology and in lacking an ornament; but, the Peruvian species is larger than Nerinea ? sp. 1, and the concavity of the whorl flanks decreases on the mature whorls. Jaworski (1925), however, did not figure the Peruvian species. The Patagonian form is comparable to some members of Cossmannea Pchelintsev, 1927 described by Cox (1956) and Gründel (2001) from the Middle Jurassic (Bathonian–Callovian) of Peru and Chile, respectively. Cossmannea (Cossmannea) sp. 1 and Cossmannea (Cossmannea) sp. 2 described by Gründel (2001: 64, pl. 5: 3–6) from the Callovian (Middle Jurassic) of Chile differs from Nerinea ? sp. 1 in being larger. Cossmannea nascaensis described by Cox (1956: 1181, pl. 127: 4–6) and Cossmannea peruviana Cox (1956: 1182 , pl. 127: 7, 8), both from the Middle Jurassic of Peru, have more concave whorls and a more developed spiral peripheral keel than the Chubutean species, respectively. The specimen ascribed by Morris and Lycett (1850: 33, pl. 7: 6) to Nerinea (Trochalia) eudesii ( Eudes−Deslongchamps, 1842) from the Middle Jurassic of England resembles Nerinea ? sp.1. However, the English species has fine spiral lines and the sutures are bordered by a spiral keel. The specimen assigned by Morris and Lycett (1850: 35, pl. 7: 19) to Nerinea punctata Voltz, 1836 from the Middle Jurassic of England differs from the Chubutean species in having whorls with a more flattened outline and two or three spiral keels with nodose rows. Nerinea granulata (Phillips, 1829) ( Lycett 1863: 10, pl. 21: 12) from the Middle Jurassic of England differs from the species here described in having flatter whorls which are slightly contracted towards the base, and in having irregularly spaced spiral keels.

Figures

Fig. 4. Early Jurassic gastropods from Lomas Occidentales and Cerro La Trampa fossiliferous localities.A–C. Globularia cf. catanlilensis (Weaver, 1931). A. MPEF−PI 4112; teleoconch in lateral (A1, A2) and apertural (A3) views. B. MPEF−PI 4114; teleoconch in lateral (B1, B2) and latero−apical (B3) views. C. MPEF−PI 4116, teleoconch in lateral views (C1, C2). D. Globularia sp. MPEF−PI 4119; teleoconch in lateral (D1) and apertural (D2) views. E. Naricopsina? sp.; MPEF−PI 3560, teleoconch in latero−apical views (E1, E2). F. Nerinea? sp. 1. MPEF−PI 4123, fragmentary teleoconch in lateral views (F1, F2). G–I. Nerinea? sp. 2. G. MPEF−PI 4124, fragmentary teleoconch in lateral view. H. MPEF−PI 4125, fragmentary teleoconch in lateral view. I. MPEF−PI 4126, fragment of last teleoconch whorl in lateral view. Scale bars: A–D 10 mm, E–I 3 mm.