Pseudomelania feruglioi, Ferrari, 2013

Ferrari, S. Mariel, 2013, New Early Jurassic gastropods from west-central Patagonia, Argentina, Acta Palaeontologica Polonica 58 (3), pp. 579-593 : 582-585

Pseudomelania feruglioi sp. nov.

Figs. 2F–I , 3A–D .

2001 Pseudomelania sp. 1 Gründel: 56, pl. 4: 5, 6.

2001 Pseudomelania ? sp. 2 Gründel: 56, pl. 4: 7.

2001 Pseudomelania sp. 4 Gründel: 57, pl. 4: 8, 9.

Etymology: Dedicated to Egidio Feruglio (1897–1954), who strongly contributed toward the geological and paleontological knowledge of the Patagonian Jurassic.

Type material: Holotype, MPEF−PI 4155, relatively well preserved teleoconch; paratypes, MPEF−PI 4087 to 4092, poorly preserved teleoconchs; MPEF−PI 4093 to 4104 , 4139 ; MLP 18507 and 18508; fragmentary and replaced teleoconchs.

Type locality: LO 28 and LO 29 sites from Lomas Occidentales locality; BET 33 site from Lomas de Betancourt locality, Chubut province, Argentina .

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

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

Dimensions.—See Table 1.

Diagnosis.—Dextral, anomphalous and turriculate shell; teleoconch comprises seven/ten whorls; juvenile teleoconch whorls slightly convex to flat; mature teleoconch whorls with a strong spiral keel on the upper portion; convex and smooth base; holostomatous and oval aperture.

Description.—Dextral, anomphalous, turriculate, high spired, and medium to large sized shell. The protoconch is not preserved. In the most complete specimens the teleoconch comprises seven/ten flat whorls; the earlier whorls of the teleoconch are slightly convex, becoming flat toward the mature whorls. Sutures are weakly incised in a spiral furrow. Ornament is poorly developed on the shell surface. The early teleoconch whorls are smooth. The mature ornament of the teleoconch stabilizes on the fifth whorl; a strong spiral keel appears on the upper portion of the each whorl. Some specimens show a second and weak spiral keel in an abapical position. The collabral ornament is not clearly developed. The base is convex and smooth, and lacks spiral and collabral elements. The aperture is holostomatous and oval, with a thick columellar lip.

Remarks.—The present material shows the characters which are typical of Pseudomelania (according to the genus concept in Kaim 2004). Most representatives of the genus are characterized by the presence of a thick and turriculate shell, with flat teleoconch whorls, and a poorly developed ornament pattern with strong spiral keels near the sutures.

The first mention of Pseudomelania in the Jurassic of Argentina may probably belong to Tornquist (1898), who described a specimen under the name of Cerithium postuliferum Tornquist, 1898 (172, pl. 10: 10) from the Early Jurassic of San Juan province. Tornquist (1898) considered C. postuliferum as closely related to Chemnitzia lonsdalei Morris and Lycett, 1850 ; thus, C. postuliferum may be a certain representative of Pseudomelania . Tornquist’s (1898) species share some features with Pseudomelania feruglioi sp. nov., including a high spired shell with poorly developed ornament; however, C. postuliferum has two lateral bumps located in an adapical and abapical position and separated by a medial depression. The latter character is not present in the material here described. Jaworski (1926b: 198, 199) described Pseudomelania aff. repeliana d’Orbigny, 1909 and Pseudomelania ? cf. bicarinata Wright, 1859 from the Early Jurassic of Mendoza province. P. aff. repeliana differs from the Chubutean species in lacking a spiral and adapical keel on the mature teleoconch whorls; moreover, the lateral portion of the whorls in P.? cf. bicarinata is slightly more concave than in P. feruglioi , and two strong spiral keels border the adapical and abapical sutures. However, these species were not figured by the author. Gründel (2001) described four species of Pseudomelania from the Jurassic of Chile, which resembles the Patagonian species. Three of these species treated by Gründel in open nomenclature are included here in the synonymy of P. feruglioi (see above). The remaining species, Pseudomelania sp. 3 ( Gründel 2001: 57. pl. 4: 13, 14) from the Toarcian (Early Jurassic) of Chile resembles P. feruglioi in lacking a collabral ornament and in having a convex base; but Gründel’s (2001) species has two adapical and abapical spiral keels on mature teleoconch whorls; the abapical one is bordered by a conspicuous nodose rows. The presence of spiral keel near the sutures gives to the whorl face a concave outline. The material described by Cox (1965: 147, pl. 24: 10) as Pseudomelania aspasia ( d’Orbigny, 1850) from the Middle Jurassic of Tanzania is similar to the species here described in general shell morphology and poorly developed ornament. However, the latter species differs in the absence of spiral keels near the sutures, and in having an oval aperture with a rounded anterior end and sharpened posterior end. The specimen assigned by Cox (1965: 148, pl. 24: 12) to Pseudomelania vittata (Phillips, 1829) from the Kimmeridgian (Upper Jurassic) of Tanzania differs from the Patagonian species in having two strong spiral keels on the last teleoconch whorl, which give the whorl surface a concave outline. Pseudomelania (Rhabdoconcha) wilderriensis Cox (1965: 151 , pl. 25: 10) from the Oxfordian (Upper Jurassic) of Kenya is similar to P. feruglioi in general shell morphology; but Cox’s (1965) species is larger, the teleoconch has more convex whorls, and a more developed ornament pattern consisting on fine spiral striations and prosocline growth lines. Collabral ornament is not clearly developed in P. feruglioi . Pseudomelania ? sp. Szabó (1983: 34, pl. 3: 10) from the Bajocian (Middle Jurassic) of Hungary has prosocline to slightly opistocline growth lines; these characters are not typical for the Chubutean species. Pseudomelania trochiformis (Piette, 1857) (Kaim 2004: 97, fig. 77) from the Middle Jurassic–Early Cretaceous of France and Poland is similar to P. feruglioi ; however, the European species is smaller, and lacks spiral ornament. Pseudomelania turbinata (Stoliczka, 1861) ( Szabó 2008: 97, fig. 90) from the Sinemurian (Early Jurassic) of Austria differs from the species here described in being smaller, in having more convex whorls, and fine and sigmoidal growth lines on the shell surface; P. feruglioi does not show sigmoidal growth lines. The specimens described by Hudleston (1887 –1896: 237, pls. 16: 9, 18: 1, 2, 21: 1) as Pseudomelania procera Eudes−Deslongchamps, 1842 from the Middle Jurassic of England are related to P. feruglioi ; but they have a more elongated spire, with a maximum height of 70–80 mm, and have fine growth lines on the shell surface. Pseudomelania coarctata Eudes−Deslongchamps, 1842 from the Middle Jurassic of England differs from the Patagonian species in having a more gradate shell and more developed collabral elements ( Hudleston 1887 – 1896: 242, pls. 18: 9, 19: 1). Pseudomelania lonsdalei Morris and Lycett (1850: 49 , pl. 7: 13; Hudleston 1887 –1896: 243, pl. 19: 2) from the Middle Jurassic of England differs from the Chubutean species in having a medial furrow on each teleoconch whorl. Pseudomelania remtsaensis Cox, 1969 from the Bathonian (Middle Jurassic) of India has more convex whorls than P. feruglioi ( Szabó and Jaitly 2004: 14, pl. 2: 1–5), while Pseudomelania calloviensis (Hébert and Eudes−Deslongchamps, 1860) from the Bathonian (Middle Jurassic) of India lacks spiral keels bordering the sutures ( Szabó and Jaitly 2004:

14. pl. 2: 9, 10). Stratigraphic and geographic range.—Lower Pliensbachian

(Early Jurassic) to Early Oxfordian (Late Jurassic); Andean region of South America, from northern−central Chile and Argentinean Patagonia.

Figures

Fig. 2. Early Jurassic gastropods from Lomas Occidentales and Cerro La Trampa fossiliferous localities. A. Lithotrochus humboldtii (von Buch, 1839), MPEF−PI 4127; teleoconch in lateral (A1, A2), latero−apical (A3), and apertural (A4) views. B. Lithotrochus cf. rothi Damborenea and Ferrari, 2008, MPEF−PI 3581; teleoconch in lateral (B1) and apertural (B2) views; apertural detail (B3); teleoconch in basal and apertural view (B4). C, D. Trochidae gen. et sp. indet. 1. C. MPEF−PI 4120, teleoconch in lateral views (C1, C2). D. MPEF−PI 4121, teleoconch in lateral view. E. Trochidae? gen. et sp. indet. 2., MPEF−PI 4122, teleoconch in lateral view. F–I. Pseudomelania feruglioi sp. nov. F. MPEF−PI 4155, holotype, juvenile teleoconch in apertural (F1) and oblique apertural (F2) views. G. MPEF−PI 4087, paratype, juvenile teleoconch in lateral view. H. MPEF−PI 4101, adult teleoconch in lateral view. I. MPEF−PI 4098, juvenile teleoconch in lateral view. Scale bars: A–E 10 mm, F–I 3 mm.

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.