Pseudomelania sp.

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

Pseudomelania sp.

Fig. 3E .

Material.—MPEF−PI 4105 and 4506; fragmentary, re−crystallized teleoconchs. LO 29 site from Lomas Occidentales locality, Chubut province, Argentina, Mulanguiñeu Formation, Lower Jurassic, Upper Pliensbachian, Lower Toarcian.

Dimensions.—MPEF−PI 4105: height 25.2 mm; width 13.2 mm.

Description.—Dextral, anomphalous, turriculate, medium sized and high spired shell. The protoconch is not preserved. The fragmentary teleoconch consists of four straight to slightly convex whorls. Sutures are incised in a deep spiral furrow. The shell is smooth or lacks a well developed ornament, though on last whorl a weak abapical spiral keel may appear. The base is flat and ornamented by seven regularly spaced spiral keels. The aperture is not preserved.

Remarks.—The material shows the typical characters of Pseudomelania (according to the genus concept of Kaim 2004). However, due to lack of well preserved specimens, it is left in open nomenclature until more material is available.

Pseudomelania sp. together with Pseudomelania feruglioi sp. nov. are the first occurrences of the genus in the Early Jurassic marine deposits of Chubut province.

Pseudomelania sp. differs from P. feruglioi sp. nov. in having sutures deeply impressed in a spiral furrow, flat base with regularly spaced spiral keels, and lacks of adapical spiral keel on mature teleoconch whorls.

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.