Laevitomaria periferialis ( Szabó, 1980 )

Szabó, János, 2017, Gastropods of the Lower Jurassic Hierlatz Limestone Formation, part 3. New pleurotomarioideans from the fauna of Hierlatz Alpe (Hallstatt, Austria), Fragmenta Palaeontologica Hungarica 34, pp. 9-48 : 41

Laevitomaria periferialis ( Szabó, 1980)

( Figs 134–136 )

1980 Pyrgotrochus periferialis sp. n. – SZABÓ, p. 62, pl. 3, fig. 6.

1987 Laevitomaria periferialis Szabó – CONTI & SZABÓ, p. 46.

2009 Laevitomaria periferialis Szabó – SZABÓ, p. 48, fig. 41.

Material – Two fragmentary specimens (GBA 2018/002/0011/01–02), representing the early teleoconch.

Measurements – Diameter 15mm (the figured one,GBA 2018/002/0011/01), 13 mm (GBA 2018/002/0011/02).

Description – The specimens have rather high conoidal shells of quite high whorls with feebly convex surface and slightly impressed suture. A prominently wide selenizone runs slightly below the midwhorl, its width is about 20% of the suture to suture distance.

On a small surface of a whorl, the ornament is well preserved; it consists predominantly of spiral threads, which are crossed by weak riblets above and below the suture. The subsutural ones diminish in short distance in abapical direction but the elements of the other row terminate at the rim of the selenizone. The selenizone has a median spiral thread and sparse, weak lunulae on the earliest visible whorl; the lunulae are lacking subsequently.

Remarks – Both specimens well correspond to the type material from the Bakony Mts. These are the first finds of Laevitomaria periferialis in the Hierlatz Alpe fauna; that is why they are remarkable.

Distribution – In the Bakony Mts, this species occurs in beds with mixed Obtusum to Ibex Zone fauna and in the Davoei Zone (Late Sinemurian to Early Pliensbachian). This interval and that of the deposition of the Hierlatz Limestone in the type locality area are partly contemporaneous.

Figures

Figs 131–139. Laevitomaria species.– 131–133.Laevitomaria? sp. (GBA 2018/002/0013).– 131– 132. Lateral view (×3.6 and ×1). – 133. Basal view (×3.6). – 134–136. Laevitomaria periferialis (Szabó, 1980) (GBA 2018/002/0011/01). – 134–135. Lateral view (×2 and ×1). – 136. Apertural view (×2). – 137–139. Laevitomaria sp. (GBA 2018/002/0012). – 137–138. Lateral view (×1 and ×3). – 139. Apical view (×3)