Foveolaria sp.

Szabó, János, 2016, Gastropods of the Lower Jurassic Hierlatz Limestone Formation, part 2. Some new archaic type slit-bearing components from the fauna of the Hierlatz Alpe (Hallstatt, Austria) and the Bakony Mts (Hungary), Fragmenta Palaeontologica Hungarica 33, pp. 3-30 : 25-26

Foveolaria sp.

( Figs 27–29 )

Material – Single early or small sized teleoconch without apical and peristomal parts; GBA 2017/001/0006.

Dimensions – Preserved height: 5.5 mm, preserved width: 5 mm, spiral angle: 65°.

Description – The available shell is a moderately high turbiniform one with conoidal outline and rather deeply impressed suture. The whorls are convex, initially almost evenly arched but the latest whorl has an obscure angulation that is blunted by the relatively wide, concave selenizone. The outer face is just slightly wider than the selenizone; it is abapically limited by a marked thread that gives also the abaxial rim of the base and the periphery of the shell. The base is subglobose as a whole and has a slightly convex wall; no trace of an umbilicus and no parts of the peristome has been found.

Predominant ornament consists of spiral threads both on the whorls and the base. On the ramp, two thin spiral threads appear on the earliest shell parts subsuturally and gradually strengthen; two thin threads are added along the adapical limiting thread of the selenizone on the latest available whorl. Two spiral threads are on the outer face. Between the peripheral (third) thread and the axis, dense, evenly spaced, simple spiral threads mean the ornament. The suture follows the first spiral thread adaxially from the peripheral one that is why the suture seems so impressed. The only belt with thin collabral threads is found between the suture and the adapical thread, limiting the selenizone on the latest whorl; granules are at the intersections of the threads. The growth lines are very fine, their form is slightly prosocline and prosocyrt between the suture and the selenizone, lunuliform within the selenizone, not observable on the outer face, and slightly prosocline and opisthocyrt on the base.

Remarks – The pair of spiral threads on the ramp resembles Foveolaria suemegensis n. sp.; however, in the similar sized shell part of that species, the ornament is different; it forms a network of evenly strong spiral and collabral threads. Moreover, the selenizone is lying in the plain of the ramp while angled to the ramp in Foveolaria sp. In this latter character, Foveolaria sp. is similar to Foveolaria globosa n. sp., which has more rounded whorls and base and a not concave outer face. Foveolaria conoidea n. sp. also has a selenizone, blunting the angulation of the whorl surface but the steep, flat-concave ramp and the less impressed suture distinguish it from Foveolaria sp.

Distribution – Within the Sinemurian to lowermost Pliensbachian interval (Lower Jurassic) of the Hierlatz Limestone Formation in Hierlatz Alpe, Hallstatt, Austria.

Figures

Figs 15–29. New species of Foveolaria n. gen. from the Sinemurian to lowermost Pliensbachian interval (Lower Jurassic) of the Hierlatz Limestone in the Hierlatz Alpe, Hallstatt, Austria. – 15–18. Holotype of Foveolaria bicarinata n. sp., GBA 2017/001/0003, all ×3.8. – 15. Dorsal view. – 16. Apical view. – 17. Basal view. – 18. Peristomal view. – 19–22. Holotype of Foveolaria conoidea n. sp., GBA 2017/001/0004, all ×4. – 19. Dorsal view. – 20. Apical view. – 21. Basal view. – 22. Peristomal view.– 23–26. Holotype of Foveolaria globosa n. sp., GBA 2017/001/0005, all ×4. – 23. Dorsal view. – 24. Apical view. – 25. Basal view. – 26. Peristomal view. – 27–29. Foveolaria sp., GBA 2017/001/0006, all ×4. – 27. Apertural view. – 28. Basal view. – 29. Dorsal view