Serrettella gerberi ( Gründel, Keupp & Lang, 2017 ) Gründel & Nützel, 2024

Gründel, Joachim & Nützel, Alexander, 2024, Late Jurassic (Upper Kimmeridgian) gastropods from Saal near Kelheim (Germany, Bavaria), Zitteliana 98, pp. 19-72 : 19-72

Serrettella gerberi ( Gründel, Keupp & Lang, 2017) comb. nov.

Plate 3: figs 10–13

2017 Amphitrochus? gerberi n. sp. – Gründel, Keupp and Lang: 194, pl. 9, figs 6–9.

Material.

Saal, “ Fundort 1985, über Korallenstock, Sohle 2 ” (= locality 1985, above coral stock, level 2): 3 specimens, SNSB – BSPG 2016 XXI 1722 –1724, Saal, “ Fossilnest Sohle 3–4 ” (= fossil nest level 3–4): 1 specimen, SNSB – BSPG 2016 XXI 1725 .

Description.

The shell is broadly trochiform; largest specimen 14 mm wide; first approximately 2 whorls convex, without visible ornament (due to preservation?); whorl face of later whorls become straight, and sutures become inconspicuous; above abapical suture, a distinctive keel-like protruding spiral cord is formed, as well as 4 weaker ones between this cord and the adapical suture; whorl face slightly angulated by the keel-like spiral cord; as suture sinks, first one and then a second spiral cord become visible on penultimate whorl; both almost as strong as the keel-like spiral rib; transition from whorl face to the moderately convex base evenly rounded; 7–8 spiral cords on the base; all spiral cords densely covered with small pustules (not always clear due to preservation); aperture round with adapical canal; abapical edge of aperture broadly rounded.

Remarks.

In contrast to the description given by Gründel et al. (2017), the present material has only four additional, relatively strong spiral cords between the adapical suture and the keel-like spiral cord. Moreover, the base of the present material is completely covered with spiral cords. Based on the limited material available, it cannot be decided with certainty whether these differences indicate genuine morphological differences (in which case there would probably be two separate species) or whether they reflect intraspecific variation or are due to preservation.

Serrettella humbertina (Buvignier) sensu Gründel et al. (2020 a) has a subsutural spiral cord covered with stronger nodes, more than 4 weaker spiral cords between the adapical suture and the keel-like reinforced spiral cord, the nodes of the keel-like spiral cord increase in size during ontogeny. “ Serrettella nov. gen. humbertina (Buv.) ” sensu Fischer and Weber (1997) has a more concave whorl face between the keel and the adapical suture, and the keel-like spiral cord is higher on the whorl face. Trochus humbertina Buvignier, 1852 also has a row of reinforced subsutural nodes, the shell is higher in relation to the width and thus more slender.

Figures

Plate 3. (1) Caryomphalus globatus (Buvignier, 1843), SNSB – BSPG 2016 XXI 1713, lateral view, width 15 mm. (2, 3) Caryomphalus sp., cf. concavus Gründel, Keupp & Lang, 2017, SNSB – BSPG 2017 XXI 1717, lateral and basal views, height 14 mm, width 12 mm. (4) Proconulus? sp. 1 sensu Gründel, Keupp and Lang (2017), SNSB – BSPG 2016 XXI 1718, lateral and basal views, height 11 mm. (5–7) Nododelphinula oblonga sp. nov., holotype, SNSB – BSPG 2016 XXI 1721, lateral views, apertural and abapertural, basal view, width 26 mm. (8–9) Nododelphinula oblonga sp. nov., paratype, SNSB – BSPG 2016 XXI 1930, collection Lang, shell in lateral and dorsal view, width 27 mm. (10–12) Serrettella gerberi (Gründel, Keupp & Lang, 2017), SNSB – BSPG 2016 XXI 1722, lateral, basal views and aperture, width 13 mm. (13) Serrettella gerberi (Gründel, Keupp & Lang, 2017), locality 1985, above coral stock, level 2, SNSB – BSPG 2016 XXI 1723, lateral view, width 9.5 mm. (14, 15) Heliacanthus sp. 1, SNSB – BSPG 2016 XXI 1726, abapertural and apertural lateral views, height 12 mm.