Foveolaria kocsisi, 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 : 21-23

Foveolaria kocsisi n. sp.

( Figs 30–31 )

1980 Sisenna pinguis (Deslongchamps, 1849) – SZABÓ, p. 53, Pl. I, Fig. 1 .

2009 Wortheniopsis (Sisenna) aff. hierlatzensis Szabó, 2009 – SZABÓ, p. 34, Fig. 27C, D .

Type specimen – GGIH J.08.9.1.

Type locality – Kericser-dűlő , Lókút, Bakony Mts ( Hungary).

Type strata – Beds with Obtusum to Ibex Zones (Upper Sinemurian to Lower Pliensbachian, Jurassic) mixed fauna in Hierlatz Limestone.

Derivation of name – Dedicated to Lajos KOCSIS (Sümeg), leader worker of the collecting staff at the type locality.

Diagnosis – Gradate shell with whorls of flattish concave ramp and concave outer face. Suture impressed, running slightly below periphery. Base subglobular with convex wall and no or only narrow umbilicus. Concave selenizone between sharp threads. Ornament consisting of network from spiral and collabral threads with granules at intersection points on ramp and adapical part of outer face. Quirinii type spiral ridges on abapical belt of outer face and on base with short, riblet-like granules, aligned into seemingly continuous collabral threads.

Material – Two fragmentary specimens, one is shelly, the other is an inner mould with small shell fragments.

Dimensions – Preserved height: 11 mm; preserved width: 10 mm.

Description – The shells are gradate with clearly angulate whorls. The ramp is flattish but slightly convex just below the suture; its abapical rim is concave along the selenizone. The selenizone itself is moderately wide, concave between two sharp spiral cords; the abapical one just coincides with angulation of the whorl surface. The outer face is rather wide and its surface is nearly parallel to the axis but having also a feebly concave median belt. Its lower edge is slightly swollen next the rounded-angular periphery. The suture follows the abapically first spiral ridge from the peripheral one. The base is subglobular with convex wall, and it is seemingly anomphalous or possibly narrowly phaneromphalous. No peristome part can be observed in the available specimens; the growth lines indicate a prosocline outer lip with a rather deep sinus at the height of the inferred exhalant slit.

Collabral riblets and spiral threads intersect each other with granules on the ramp and the riblets weaken towards the selenizone. The shape of the spiral threads gradually changes into quirinii type ridges on the outer face in abaxial direction; only the latter ones are observed on the base. Instead of riblets, collabral threads are present on the outer face. Seemingly, they are continued also on the base but there the threads are actually composed of short riblets between pairs of the quirinii type ridges and are aligned as apparently continuous collabral threads; they are most conspicuous at the periphery. The selenizone bears dense lunulae.

Remarks – Both specimens are fragments of gradate shells of similar size; the inner mould one shows the conoidal-gradate outline. Though their size suggests early ontogenetic stage, the sharp angulation of the whorls and the dense lunulae seem to indicate nearly full-grown shells. The available information about the shell is satisfactory for the distinction of this species.

The shell fragments are most similar to Foveolaria hierlatzensis ( Szabó, 2009) but its larger shells are without angulation in the growth stage where the size is similar to that of Foveolaria kocsisi n. sp.; the position and morphology of the selenizone, and the ramp are also different. The selenizone lies clearly above the angulation in F. kocsisi n. sp. in the level of the ramp, however, it blunts the angulation in F. hierlatzensis , forms a third surface between the ramp and the outer face, and angled to both. The ramp is flattish concave in F. kocsisi n. sp. but convex in F. hierlatzensis .

Foveolaria jancsii ( Szabó, 2009) has convex ramp, and coeloconoidal shell with less markedly gradate outline, differently from F. kocsisi n. sp.

Distribution – Beds with mixed fauna of Obtusum to Ibex Zones (Upper Sinemurian to lowermost Pliensbachian), Kericser, Lókút, Bakony Mts, Hungary.

Figures

Figs 30–36. New species of Foveolaria n. gen.from the Bakony Mts, Hungary localities of the Hierlatz Limestone Formation. – 30–31. Holotype of Foveolaria kocsisi n. sp., GGIH J.08.9.1. from beds with Obtusum to Ibex Zones (Upper Sinemurian to Lower Pliensbachian, Lower Jurassic) mixed fauna in Hierlatz Limestone at Kericser-dűlő, Lókút, Bakony Mts, Hungary. – 30. The only preserved whorl and base parts, ×1. – 31. The same in ×3.5 magnification for the details. – 32–36. Holotype of Foveolaria suemegensis n. sp., GGIH J.08.8.1. from the (?)Upper Sinemurian (Lower Jurassic) Hierlatz Limestone of Mogyorósdomb, Sümeg, Bakony Mts, Hungary. – 32–33. Most informative surface parts of the monotype, ×1. – 32. Nearly parallel view to the inferable peristome plane, showing a short part of the outer lip below the suture. – 33. The shell from the opposite side. – 34. Weakening ornament of the early spire whorls, ×2.5. – 35. Magnified sample view of the obscure ornament on the ramp of the latest whorls, ×5.– 36. Networkornament of the early spire,×4.5

Figs 1–3. The peculiar “quirinii type” ridges, occurring in Wortheniopsis Böhm, 1895, Foveolaria n. gen. and some probably related forms. – 1. Copy of KITTL’s (1899, p. 14, Fig. 2) sketch. – 2. The ridges on the outer face and on the base of Wortheniopsis rakusi n. sp. – 3. The ridges on the base of Foveolaria conoidea n. sp.

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