Mojsisovicsteuthis boeckhi ( Stürzenbaum, 1875 )

Košťák, Martin, Schlögl, Ján, Fuchs, Dirk, Havrila, Milan, Kolar-Jurkovšek, Tea, Vörös, Attila, Havelcová, Martina, Šurka, Juraj, Havrila, Jakub & Holcová, Katarína, 2024, Rare Middle Triassic coleoids from the Alpine-Carpathian system: new records from Slovakia and their significance, Swiss Journal of Palaeontology (19) 143 (1), pp. 1-19 : 8-12

Mojsisovicsteuthis boeckhi ( Stürzenbaum, 1875)

( Fig. 5 , A–Q; 6 ; 7 A–D )

Synonymy:

*1875 Atractites böckhi Stürzenbaum , p. 254, Tab. V, fig. 1.

1882 Atractites boeckhi (Stürzenbaum) . Mojsisovics, p. 302, pl. XCIII, figs. 12–13.

? 1914 Atractites böckhi Stürzenbaum. Smith , p. 138, pl. XCIV, figs. 20–21.

1915 Atractites Boeckhi Stürzenbaum, Diener , p. 18 (with additional/full synonymy).

1920 Atractites Boeckhi Stürzenbaum ; Büllow-Trummer, p. 65 (with additional synonymy).

1973 Mojsisovicsteuthis cf. M.? boeckhi ( Stürzenbaum, 1875) ; Rieber, p. 73–74, fig. 20, a–g.

? 1973 Mojsisovicsteuthis meneghinii ( Salomon, 1895) ; Rieber, p. 74, fig. 20, n–o.

? 1975 Ausseites bilhynicus Arthaber, 1915 ; Özdemir, p. 137, pl. 4, figs. 1–4.

2024 Mojsisovicsteuthis boeckhi . Pohle & Klug, XXXX

Studied material: A single specimen ( Fig. 5A–D ) from Harmanecká Cave—Kozelník ( GPS 48°48,582 ′ N 19°02,265 ′ E, Slovakia, No. KGP-KO-001; stored at Comenius University in Bratislava ). Five specimens from the type locality (Additional file 1: Table S 1) stored in the Mining and Geological Survey of Hungary in Budapest: including the holotype No. T.829 ( Fig. 5J–P ); specimens Nos T.3593, T.3206, T.3137 and two fragments referred to the taxon ( T.81, and T.371).

Description: The steinkern of the phragmocone fragment is 42 mm long and includes 7–8 chambers. Apical and apertural chambers are missing. The width (dimension of the flattened phragmocone) of the largest chambers measures 19 mm. The straight phragmocone appears longi- to orthoconic (apical angle 11–12°, Fig. 6 ). Thanks to a circular structure in the periphery of the smallest chamber determinable as the former position of the siphuncle, one can define the anatomical orientation. The phragmocone diameter is accordingly laterally compressed. Poorly defined remains of sutures, which are visible only on one side of the steinkern, are c. 4 mm apart implicating a ratio chamber length to chamber diameter of about 0.19. This suggests comparatively low chambers. Lateral lobes are perceptible. There is no evidence of preserved shell material. As mentioned above, the siphuncle is only slightly indicated in Slovakian specimen.

The material stored in the collections of Mining and Geological Survey of Hungary in Budapest provided unambiguous evidence of the siphuncle position ( Fig. 5G, H ) which lies in the narrow ventral side. The diameter of the siphuncle is ~ 1.3 mm (specimen No. T.3593, Fig. 5G, H ).

In specimens Nos T.3206 ( Fig. 7A ) and T.81 ( Fig. 7B ), the tubular final chamber is partly preserved. The preserved length measures 25 and 30 mm (Additional file 1: Table S1). In these specimens, a marked constriction of the last septum prior the final chamber is seen.

Comparing the specimen No. KGP-PO-0001 with the Hungarian material including the holotype, we observed stability in the phragmocone angle reaching 11–12°.

With the phragmocone diameter and the apical angle of 12°, one can calculate the maximum phragmocone length by the help of trigonometric laws [diameter/2 × sin (84)/sin (12/2)]. Accordingly, specimen T.3206 with a maximum phragmocone diameter of 37 mm had a phragmocone length of approx 180 mm (length of the final chamber is not known). Assuming a final chamber that reaches a similar length (in specimens with this part preserved, Fig. 6 ), the total shell length of this specimen was about 350 mm, which classifies it as a medium-sized coleoid.

Comparison: We exclude affinities to the order Phragmoteuthida , owing to the absence of a three-lobed proostracum and the presence of a longiconic (rather than brevi—or cyrtoconic) phragmocone. Despite our observation of an aulacoceratid-like final chamber, the overall phragmocone characteristics (dense chambers, apical angle, lateral lobus) also prevent a placement within the order Aulacoceratida .

Regarding chamber distance, the specimen from Slovakia resembles the holotype of M. convergens , the type species of Mojsisovicsteuthis . However, in M. convergens , the cross section is more circular or even almost circular, as figured in von Hauer (1847, pl. VII, fig. 2), later corrected by Mojsisovics (1902, Pl. XVI, fig. 1). The apical angle of the phragmocone in the dorso-ventral view is moreover significantly higher in M. convergens (20°).

The Slovakian specimen and the holotypes of M. boeckhi ( Stürzenbaum, 1875) and M. meneghinii ( Salomon, 1895, p. 195) share a laterally compressed phragmocone, but M. meneghinii differs from our specimen in a higher apical angle (16–19° according to Salomon, 1895) and more densely spaced chambers (0.13–0.17).

In terms of apical angle, our specimen is almost identical with the holotype of M. boeckhi ( Fig. 6 ). In addition, the Slovakian and the Hungarian specimens share a compressed phragmocone, a well developed lateral lobus, and a chamber distance ranging from 4 to 12 mm. The chamber distances just prior the final chanber are significantly constricted (in specimen T.81 ~ 3 mm).

Recently, Vörös et al. (2022) published record of cephalopod fauna from the Middle Anisian locality Akol Hill at Barnag ( Hungary) including specimen described as Mosjsisovicsteuthis sp. The specimen clearly differs from our material by having significantly more densely spaced septa.

Specimens similar to Slovakian specimen and referred to genus Ausseites ( Flower, 1944; rejected as nomen dubius by Mariotti et al., 2021) were figured by Özdemir (1975) from Ladinian/Carnian transition of Koaceli ( Turkey). A. bilhynicus ( Arthaber, 1915) resembles our specimen in shape, but the apical angle is higher in A. bilhynicus (~ 20–21°).

Remarks: The relatively large size (up to 30 cm) of the phragmocone ( Fig. 6 ) is comparable to larger specimens of aulacoceratids. The reconstruction of the length is based on the stability in the phragmocone angle in all ontogenetical stages studied.

Stratigraphy and palaeogeography: M. boeckhi is known from the Anisian—Ladinian strata of the Alpine-Carpathian-Dinaridic region (Trinodosus—Lomelli zones; Alma, 1926). Apart of the here described material, it is reported from Wettersteinkalk in Germany ( Reis, 1901), Austria ( Alma, 1926 —Schreyeralmkalke, Marmolatkalke; Schnetzer, 1934 —Muschelkalk), Italy (Marmolada— Salomon, 1895; Monte Clapsavon— Canavari, 1890), Montenegro ( Martelli, 1904),? Romania (Braşov, Ladinian, see on-line report: https://formatiunigeolo gice.igr.ro/formatiune/42), Hungary ( Stürzenbaum, 1875; Vörös, 1987, 2018), Bosnia and Herzegovina ( Kraus, 1916; von Hauer, 1888), Greece ( Renz, 1909), Bulgarian/ Romanian borders (Dobrudzha; Büllow-Trummer, 1920) and? Turkey (Koaceli—Ladinian/Carnian transition; Özdemir, 1975). Smith (1914) reported M. boeckhi from the Trinodosus Zone of North America. However, these old records (predominantly attributed to “ Atractites boeckhi ” or? Ausseites in the latter case) were not studied/verified by the authors of this article.

Crown Neocoleoidea Haas, 1997 (proostracum-bearing coleoids)

Figures

Fig. 5 Mojsisovicsteuthis boeckhi (StÜrzenbaum, 1875). A–D Specimen No. KGP-KO-001, upper Anisian, lower Illyrian, Harmanecká Cave—Kozelník, Slovakia.A Dorso-ventral view; B lateral view; C cross-section; D position of the siphuncle (s). E–H Specimen No. T.3593. E Dorso-ventral view; F lateral view; G, H Cross-section with position of the siphuncle (H. enlarged); I Cross-section of the apical part. J–P. Holotype No.T.829. Bakony (Hungary), Anisian, Reitzi Zone. J Original figure of StÜrzenbaum (1875), lateral view; K lateral view; L dorso-ventral view; M cross-section;N original figure of StÜrzenbaum (1875) with missinterpreted position of the siphuncle; O, P longitudinal section of the phragmocone with septa arrangement (partly seen).Q The largest specimen No.T.3137 in the lateral view.Scale bar equals 1 cm

Fig. 6 Mojsisovicsteuthis boeckhi (StÜrzenbaum, 1875)—the size reconstruction based on the phragmocone angle and size extrapolation.The largest specimen does not possess a“body chamber”, therefore, the approximated size may exceed 35 cm

Fig. 7 A–D, Mojsisovicsteuthis boeckhi (StÜrzenbaum, 1875), Bakony (Hungary), Anisian, Reitzi Zone. A Specimen No.T.3206 with preserved final chamber in lateral view. B Specimen No.T.81 with preserved final chamber in lateral view.The constriction of the last septum prior the final chamber is well seen in both specimens.C–D Specimen No.T.255. C lateral view; D detail of the septum attachment to the phragmocone wall. E–L Breviconoteuthis aff. breviconus, upper Anisian, lower Illyrian, Podhradie,Slovakia.E Ventral view; F, G lateral views demonstrating backwards inclined septa; H dorsal view; I, J cross section at the apical part; J position of the siphuncle; K, L micro-CT imaginations; K longitudinal section in lateral view; L longitudinal section in dorso-ventral view. Specimen No. KGP-PO-001. M Breviconoteuthis breviconus (Reis, 1907), original of Rieber (1974: Fig. 3), upper Anisian,Besano Formation, Monte San Giorgio, Switzerland. N, O. Zugmontites mojsisovicsi Reis, 1907, holotype, No. 1901-II-508, upper Anisian,Wettersteinkalk, Austria. N Lateral view; O dorso-ventral view. Scale bar equals 1 cm