Foveolaria globosa, Szabó, 2016

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 : 20-21

Foveolaria globosa n. sp.

( Figs 23–26 )

Type specimen – GBA 2017/001/0005.

Type locality – Hierlatz Alpe , Hallstatt ( Austria).

Type strata – Sinemurian to lowermost Pliensbachian (Lower Jurassic) Hierlatz Limestone .

Derivation of name – Globosa (Lat.) = globular; referring to the last whorl of the shell, providing the shell with subglobular shape.

Diagnosis – Subglobular shell with rounded whorls; both usual angulations of Foveolaria obscure. Selenizone blunting angulation at abapical rim of ramp, flat-convex outer face hiding other one at outer rim of base. Base subglobular with strongly convex wall and rather broad umbilicus. Ornament of collabral riblets and thin spiral threads on ramp, lunulae between strong limiting threads of selenizone, strong spiral threads on outer face, crossed by thin collabral threads, vanishing in abaxial belt of base. Base covered by quirinii type ridges. Growth lines prosocline-prosocyrt on ramp, prosocline-feebly prosocyrt on outer face and prosocline-feebly opisthocyrt on base.

Material – Single, damaged specimen of two whorls.

Dimensions – Width: 9 mm.

Description – Both angulations of the latest whorls, common in Foveolaria , are obscure on the available specimen, therefore the whorls have almost evenly arched surface. A rather wide selenizone is blunting the adapical angulation at the abapical rim of the ramp, and the flat-convex outer face almost fully hides also the second angulation at the outer rim of the base but the strongest spiral cord somewhat highlights it and gives the periphery. On the earlier whorl, this angulation is still clearly visible above the suture, which is impressed. The base itself is subglobular with a strongly convex wall and a rather broad phaneromphalus.

The ornament of the ramp on the last whorl in the available specimen consists of marked collabral riblets, which are equally strong along their full length and thin, dense spiral threads. Regularly repeating lunulae are present in the selenizone between strong boundary threads. Few (4) marked spiral threads are visible on the outer face; their strength increases and their interspaces widen in abapical direction. The strongest thread provides the periphery and the outer rim of the base; the suture is positioned slightly adaxially from this thread. The outer face is crossed by thin collabral threads, vanishing within the abaxial belt of the base; tiny granules are in the intersections. Quirinii type ridges cover the base. The growth lines are prosocline-prosocyrt on the ramp, prosocline-feebly prosocyrt on the outer face and prosocline-feebly opisthocyrt on the base.

Remarks – Two rounded angulations do not occur on late whorls of the shell in other species. The most similar, rather globose species is Foveolaria pinguis (J. A. Eudes-Deslongchamps, 1849) as figured by FISCHER & WEBER (1997) but its angulations and a subvertical outer face are present also on the latest whorl, furthermore, it has an ornament of granulate riblets, denser than in Foveolaria globosa n. sp.

The lack of globosity in the species, discussed in this paper, well distinguishes them from F. globosa , however, further details are added also in their descriptions.

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