Angulatella bizzarinii Nützel and Hausmann, 2021

Hausmann, Imelda M., Nützel, Alexander, Roden, Vanessa Julie & Reich, Mike, 2021, Palaeoecology of tropical marine invertebrate assemblages from the Late Triassic of Misurina, Dolomites, Italy, Acta Palaeontologica Polonica 66 (1), pp. 143-192 : 159-160

Angulatella bizzarinii Nützel and Hausmann sp. nov.

Fig. 15 .

1993 Protuba winkleri (Klipstein, 1894) ; Bandel 1993: pl. 4: 3.

ZooBank LSID: urn:lsid:zoobank.org:act:BEA466D7-1E46-4E41-B4EA-FE393C27B0D8

Etymology: After the palaeontologist Fabrizio Bizzarini for his excellent work on the fauna of the Cassian Formation.

Type material: Holotype PZO 12701 , specimen with larval shell and 4 teleoconch whorls from Misurina Landslide . Paratypes: PZO 12826 , specimen with larval shell and 4 teleoconch whorls ; PZO 12827 , relatively large specimen with 4 teleoconch whorls but lacking protoconch, from Lago Antorno .

Type locality: Misurina Landslide , near Cortina d’Ampezzo , northern Italy .

Type horizon: Cassian Formation; lower Carnian, Upper Triassic.

Material.— Eight specimens, all from bulk samples; 5 from Lago Antorno ( PZO 12826 , 12827 , 2 paratypes; PZO 12825 ,

3 specimens); 3 from Misurina Landslide ( PZO 12701 , holotype; PZO 12700 , 2 specimens); Italy, Carnian , Triassic .

Diagnosis.—High-spired, conical shell; teleoconch with two spiral keels on whorl face; upper keel at about mid-whorl; lower keel emerging at abapical suture; upper keel angulates whorl profile with a steep ramp between adapical suture and keel; shell axis of orthostrophic protoconch somewhat oblique to teleoconch axis; larval whorls with spiral keels which angulate larval whorls; spiral keels ornamented with minute tubercles.

Description.—Shell high-spired, conical; apical angle about 45°; shell with 6.5 whorls about 1.4 mm high, 0.8 mm wide

Fig. 15A ); teleoconch with two spiral keels on whorl face of earliest teleoconch whorls; upper keel at about mid-whorl; lower keel emerging at abapical suture; upper keel angulates whorl profile with a steep ramp between adapical suture and keel; ramp slightly convex to straight; whorl profile concave, parallel to shell axis between upper and lower keels; in later whorl the abapical spiral keel moves in an adapical direction; the latest preserved whorl has a rounded convex appearance with only slight angulations ( Fig. 15B ); at least early teleoconch whorls covered with micro-ornament of tubercles ( Fig. 15A 5 ), base convex, anomphalous ornamented with several weak spiral ribs; protoconch orthostrophic, consisting of about three whorls, 0.25 mm high, 0.22 mm wide; shell axis of protoconch somewhat oblique to teleoconch axis; initial whorl without visible ornament, with diameter of 0.12 mm; first larval whorl ornamented with two strong spiral keels; third spiral keel present on third protoconch whorls; spiral keels angulate larval whorls; spiral keels ornamented with minute tubercles; protoconch ends abruptly at sinusigera; sinus strengthened with a varix.

Remarks.— Bandel (1993: pl. 4: 3) illustrated a protoconch obviously representing Angulatella bizzarinii Nützel and Hausmann sp. nov. and identified it as “ Protuba winkleri (Klipstein, 1843) ”. However, Protuba Cossmann, 1912 , is a monotypic genus holding P. intermittens Kittl, 1894 , from the Cassian Formation. Bandel (1993) probably meant Promathildia winkleri Klipstein, 1894 . Promathildia winkleri is known from relatively large teleoconch fragments, its protoconch is unknown. It has a much stronger median spiral angulation and the whorls do not become more or less rounded convex in mature whorls so that species identity with our material can be excluded.

Stratigraphic and geographic range.—Only known from the Carnian, Upper Triassic; northern Italy (Cassian Formation).

Figures

Fig. 15. Caenogastropods Angulatella bizzarinii Nützel and Hausmann sp. nov. from Lago Antorno (A, B) and Misurina Landslide (C), northern Italy, Cassian Formation, Carnian, Upper Triassic. A. Paratype PZO 12826, specimen with preserved protoconch having bicarinate shell, in apertural view (A1); protoconch (A2–A5): A2, early whorls in lateral view inclucing bicarinate larval shell with axis oblique to teleoconch shell axis; A3, early whorls in oblique lateral view showing larval shell terminating at sinusigera; A4, close up of larval whorls with carinae ornamented with minute tubercles, in lateral view; A5, close up to show tuberculate micro-ornament on teleoconch whorl, upper portion shows sinusigera where larval shell end B. Paratype PZO 12827, relatively large specimen lacking protoconch, in lateral view. C. Holotype, PZO 12701, specimen with preserved protoconch having bicarinate shell, in apertural (C1) and apical (C3) views; C2, early whorls including bicarinate larval shell, in lateral view.

Fig. 5. Trochonematid gastropod Eunema badioticum Kittl, 1891, PZO 12796, from Lago Antorno, northern Italy, Cassian Formation, Carnian, Upper Triassic.In apertural (A1) and lateral (A2,A3) views;A4, detail of last whorl showing fine ornamentation including pits on upper angulation, in lateral view.