Archaeotolithus doppelsteini, Schwarzhans & Keupp, 2022

Schwarzhans, Werner & Keupp, Helmut, 2022, Early teleost otolith morphogenesis observed in the Jurassic of Franconia, Bavaria, southern Germany, Zitteliana 96, pp. 51-67 : 51

Archaeotolithus doppelsteini sp. nov.

Plate 4, figs 2-4

Lapillus unbekannter 2021b Lapillus unbekannter Zuordnung - Keupp: fig. 9.3 D.

Etymology.

Named after Bernd Doppelstein (Berlin), who has intensely collected from the Buttenheim clay pit and provided the largest specimen of this species.

Holotype.

SNSB-BSPG 2022 IV 8 (Plate 4 , fig. 2), Clay pit near Buttenheim, upper Pliensbachian, Hawkerense subzone, EPH horizon.

Paratypes.

4 specimens same data as holotype (SNSB-BSPG 2022 IV 9, Plate 4 , figs 3-4).

Diagnosis.

OL:OH = 0.9-0.93; OH:OT = 2.8-3.6. Ventral rim deeply curved, middorsal angle with small process. Outer face with complex pattern of subvertical furrows.

Description.

Very high-bodied otoliths up to 3.25 mm in length (holotype 2.2 mm) with rounded ventral rim and rounded postventral angle. Middorsal angle with small projection. Anterior and posterior rims smooth, ventral rim regularly and coarsely crenulated.

Inner face moderately convex with distinct supramedian positioned sulcus. Dorsal margin of sulcus relatively well-defined, ventral margin gradational and indistinct. Sulcus anteriorly open and ventrally widened, posteriorly curved slightly downward and terminating close to rounded postventral angle. Distinction in ostium and cauda indistinct or with broad shallow ventral bend at junction; OsL:CaL notably variable, ranging from 0.7 to 1.2. Outer face flat, with set of opposing subvertical furrows on pre- and postventral fields, diminishing in intensity with size.

Discussion.

The relatively small holotype is well preserved whereas the large figured paratype (Plate 4 , fig. 4) has severe incrustations across much of the sulcus that obliterate part of its morphology. Archaeotolithus doppelsteini is readily distinguished from its congeners by its deep ventral rim, rounded postventral angle, and process of the middorsal angle. It differs from A. trigonalis in its higher body shape, expressed in the lower OL:OH ratio (0.9-0.93 vs. 1.05-1.12) and the different proportions of the ratio OsL:CaL (0.7-1.2 vs. 0.3-0.4). Furthermore, the ornamentation of the outer face differs from that observed in its congeners.

Figures

Plate 4. Otoliths of Archaeotolithus. fig. 1: Achaeotolithus bornholmiensis (Malling & Gronwall, 1909), from the late Pliensbachian of Buttenheim, holotype SNSB-BSPG 2022 IV 7, EPH horizon. figs 2 - 4: Archaeotolithus doppelsteini sp. nov., from the late Pliensbachian of Buttenheim, EPH horizon; 2: holotype SNSB-BSPG 2022 IV 8; 3 - 4: paratypes SNSB-BSPG 2022 IV 9. figs 5 - 7: Archaeotolithus trigonalis Stolley, 1912, from the late Pliensbachian of Buttenheim, EPH horizon, figured specimens SNSB-BSPG 2022 IV 12.