Leptolepis buttenheimensis, 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

Leptolepis buttenheimensis sp. nov.

Plate 2, figs 1-7

Leptolepis ornatus 2021b Leptolepis ornatus (Weiler, 1953) - Keupp: fig. 9.3 A,C.

Etymology.

Named after the type-locality Buttenheim near Bamberg, Franconia.

Holotype.

SNSB-BSPG 2022 IV 4 (Plate 2 , fig. 1), Clay pit near Buttenheim, upper Pliensbachian, Hawkerense subzone, EPH horizon.

Paratypes.

11 specimens: 10 specimens same data as holotype (SNSB-BSPG 2022 IV 5, Plate 2 , figs 2-5, 7), 1 specimen same location, Apyrenum subzone (SNSB-BSPG 2022 IV 6, Plate 2 , fig. 6).

Additional material.

48 specimens: same location as holotype , 45 specimens from the EPH horizon, 3 specimens from the Apyrenum subzone.

Diagnosis.

OL:OH = 1.55-1.75; OH:OT = 4.0-5.0. Rostrum length 37-45% of OL. Ventral rim of ostium shallow and fading, and ostium relatively narrow; OsH:CaH = 1.25-1.6.

Description.

Slender, thin otoliths up to 3.25 mm in length (holotype 2.65 mm). Ventral rim relatively shallow, regularly curved, deepest at or behind middle, and smooth to irregularly undulating. Rostrum very long, nearly half of otolith length. Dorsal rim behind ostial opening short, moderately elevated, broad and irregularly undulating. Posterior rim broadly rounded.

Inner face very slightly bent with distinctly supramedian sulcus. Ostium long, not expanding backward from rostrum and antirostral notch, about as long as cauda but separation poorly defined. Ventral margin of ostium indistinct, gradual, and shallow, resulting in relatively narrow ostium. Cauda very slightly flexed, terminating close to posterior tip of otolith. Dorsal depression very small, restricted to position above anterior part of cauda. No ventral furrow. Outer face flat to slightly concave with particularly thin and delicate rostrum, smooth dorsally and few indistinct furrows ventrally. Shallow umbo positioned near dorsal rim opposite to dorsal field of inner face.

Discussion.

Leptolepis buttenheimensis is readily recognized by its elongated shape, extremely long rostrum, and very thin and delicate structure. However, a few morphologically transitional specimens exist with L. normandica in specimens smaller than about 2.2 mm in length, which are not considered to be fully morphologically developed. Another distinctive feature is the shallow and fading lower margin of the ostium as seen in figures 1a, 2, 3a, 4a, 5 and 7a on Plate 2 . This development somewhat resembles otoliths of Leptoelops rhenanus (see below) where the lower margin of the ostium has become completely flattened and is level with the ventral margin of the cauda.

Leptolepis buttenheimensis is known only from the upper Pliensbachian of the type locality where it represents the second most common species.

Figures

Plate 2. Otoliths of Leptolepis buttenheimensis and L. steberae. figs 1 - 7 Leptolepis buttenheimensis sp. nov. from the late Pliensbachian of Buttenheim; 1: holotype SNSB-BSPG 2022 IV 4, EPH horizon; 2 - 7: paratypes SNSB-BSPG 2022 IV 5 - 6; 2 - 5, 7: EPH horizon; 6: Apyrenum subzone. figs 8 - 12: Leptolepis steberae sp. nov. from the Pliensbachian of Buttenheim, EPH horizon; 8: holotype SNSB-BSPG 2022 IV 13; 9 - 12: paratypes SNSB-BSPG 2022 IV 14.