Acanthoteuthis speciosa Münster, 1839

Klug, Christian, Hoffmann, René, Tischlinger, Helmut, Fuchs, Dirk, Pohle, Alexander, Rowe, Alison, Rouget, Isabelle & Kruta, Isabelle, 2023, ‘ Arm brains’ (axial nerves) of Jurassic coleoids and the evolution of coleoid neuroanatomy, Swiss Journal of Palaeontology (22) 142 (1), pp. 1-22 : 5

Acanthoteuthis speciosa Münster, 1839

( Fig. 2 )

Specimen HT 02/2, original of Klug et al., (2016, supplement, p. 8, figs. S4, S5).

Stratigraphy Lithographic Limestones, Beckeri-zone, Ulmense subzone, Rebouletianum horizon, uppermost Kimmeridgian.

Locality Öchselberg Quarry near Zandt, Bavaria ( Germany), Germany.

Description of arm crown Te entire specimen measures 440 mm from the tips of the arms to the apex of the rostrum. Te head foot-complex is exceptionally preserved, displaying statocysts with statoliths ( Klug et al., 2016, supplement), cephalic cartilage, body outline, jaws and the arms. Te arms are up to 120 mm long and nearly 300 hooks are discernible. Te arm hooks belong to the Acanthuncus morphotype and show the characteristic changes from the proximal to distal parts of the arm crown. Proximally, the hooks are small and almost straight, while those in the mid-section are much larger, strongly curved and have a large uncinus. Distally, they become shorter again. Between the hook rows, UV-photos ( Fig. 2a ) show fine phosphatized lines that run parallel to the hook rows. Tese lines are up to 1.5 mm wide and between 15 and about 70 mm long. Traces of about 10 such lines are visible particularly in the proximal half of the arms. Several are linked with the phosphatized surface surrounding the jaws.

Figures

Fig. 2 Acanthoteuthis speciosa MÜnster,1839, HT 02/2, latest Kimmeridgian,Öchselberg Quarry near Zandt, Bavaria (Germany). Figure modified after Klug et al., (2016, suppl. Fig. 5). a UV-photo by HT; b drawing after a