Pseudonerinea? pseudomelaniformis, Gründel & Keupp & Lang & Nützel, 2022

Gruendel, Joachim, Keupp, Helmut, Lang, Fritz & Nuetzel, Alexander, 2022, Late Jurassic (Upper Kimmeridgian) Heterobranchia (Gastropoda) of the coral-facies of Saal near Kelheim and the viciniy of Nattheim (Germany), Zitteliana 96, pp. 179-221 : 179

Pseudonerinea? pseudomelaniformis sp. nov.

Plate 2: figs 1-7

Derivatio nominis.

For being similar to Pseudomelania Pictet & Campiche, 1862 in regard to shell shape.

Holotype.

SNSB-BSPG 2021 XV 23 (collection Lang).

Locus typicus.

Saal quarry near Kelheim.

Stratum typicum.

Upper Kimmeridgian.

Paratypes.

Thirty-three specimens from Saal, collection Lang: SNSB-BSPG 2021 XV 24-26, 183-212.

Additional material.

Three specimens from Saal, without type status (collection Lang).

Diagnosis.

Shell slender; spire high in relation to last whorl; whorl face straight with narrow ramp; weak spiral furrow present below ramp; aperture with distinct siphonal canal, two columellar, and one parietal plait.

Description.

The holotype is 22 mm high. The shell is slender, high-spired, and consists of many whorls. The whorl face is straight. The sutures are accentuated by a narrow ramp. The early whorls are poorly preserved, seemingly with two spiral cords near sutures and having a concave whorl face between the cords. Later whorls have a subsutural bulging spiral cord (weakly nodular?) that is demarcated by an abapical spiral furrow. This furrow is rarely distinct or frequently not visible at all probably due to preservation. No other ornament is present. The transition from whorl face to the strongly convex base is evenly rounded. The base has several, weakly defined, bulging spiral cords. It is anomphalous. The growth lines are indistinct; they are strongly curving backward adapically. The aperture is narrow with a weakly convex outer lip; parietal and columellar lip meet at an angle. The aperture has a distinct siphonal canal, a distinct parietal and two columellar plaits. The columellar plaits are commonly weak or not visible even in seemingly well-preserved specimens (variability or due to preservation).

Remarks.

It is possible that the studied material represent two species. The type species of Pseudonerinea lacks plaits. Therefore, the generic assignment of P.? pseudomelaniformis is tentative.

Relationships.

Phaneroptyxis fusiformis ( d’Orbigny) sensu Gemmellaro (1870), Blake and Hudleston (1877), Cossmann (1898), Loriol in Loriol and Koby (1895), and Fischer and Weber (1997) is less slender, has a higher last whorl in relation to spire height, a narrow umbilicus, and only a single columellar plait is visible. Cerithium pellati Loriol in Loriol & Pellat, 1874 is very similar but lacks plaits and the siphonal canal is less pronounced. Itieria melanioides Zittel, 1873 has only a single columellar plait as well as one parietal and one palatal plait; it lacks a siphonal canal, and its whorl face is weakly convex with impressed sutures. Phaneroptyxis sulejovensis Wieczorek, 1979 is larger, has a more pronounced ramp and deeper sutures, its base is demarcated by an edge, and it has a single columellar plait. Nerinea eichwaldiana d’Orbigny, 1845 has only a single columellar plait and a palatal plait; it lacks a ramp and the sutures are barely impressed. Phaneroptyxis grayensis Maire, 1927 is larger, its whorls are lower and increase more rapidly in width, and it has only a single columellar plait.

Figures

Plate 2. (1 - 7) Pseudonerinea? pseudomelaniformis sp. nov. (1 - 3) Holotype, SNSB-BSPG 2021 XV 23, Saal (collection Lang); (1) lateral view, height 22 mm; (2) aperture, height 8.5 mm; (3) base, width 6.5 mm. (4 - 5) Paratype, SNSB-BSPG 2021 XV 24, Saal (collection Lang); (4) lateral view, height 13.7 mm; (5) apex, height 2.8 mm. (6) Paratype, SNSB-BSPG 2021 XV 25, Saal (collection Lang), last whorl with aperture, height 10 mm. (7) Paratype, SNSB-BSPG 2021 XV 26, Saal (collection Lang); aperture, height 7 mm.