Mojsisovicsteuthis Jeletzky, 1966

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 : 6-8

Genus Mojsisovicsteuthis Jeletzky, 1966

Type species: Orthoceras convergens von Hauer, 1847 ; p. 259, Tab. 7, figs. 1–2.

Diagnosis: Phragmocone longi- to orthoconic, medium-sized (up to 40 cm), laterally compressed, apical angle 10–20°, chamber length-to-diameter ratio 0.16–0.30, final chamber tubular (= proostracum absent), its relative length uncertain; sutures simple or with lateral lobes, septal necks short, prochoanitic?, connecting rings swollen; siphuncle at the ventral narrow side; sheath investment-like, smooth, rostrum solidum apparently absent.

Remarks: Despite an unusual set of characters, Jeletzky (1966) originally (and later authors such as Rieber, 1973 as well) placed the genus Mojsisovicsteuthis along with aulacoceratid belemnoids (see also Rieber, 1973). Prochoanitic septal neck as well as “conothecal growth lines” led them to this conclusion. Doyle (1990) placed Mojsisovicsteuthis to the family Xiphoteuthididae ( Naef, 1922) within Aulacoceratida Stolley, 1919. By contrast, Mariotti and Pignatti (1992) and Mariotti et al. (2021) excluded Mojsisovicsteuthis from the Aulacoceratida mainly owing to the absence of a rostrum proper and untypically dense (short) chambers. Pohle & Klug (2024) recently revisited the affinities of Mojsisovicsteuthis and concluded that the systematic affiliation are still puzzling. We follow this open nomenclature, because a tubular (ventrally closed) final chamber excludes this taxon from the Phragmoteuthida , whose members are typified by a ventrally opened final chamber. The overall mantle length in aulacoceratids and Mojsisovicsteuthis is difficult to estimate for the following reasons: (1) we do not know the proostracum in both taxa (if it was originally present) or its length. (2) large aulacoceratids s. l. are more than 50 cm long ( Mariotti & Pignatti, 1992)—but this length represents mainly the phragmocone. The largest size of the phragmocone within Mojsisovicsteuthis is estimated to be about 35 cm (see below).

Other species previously assumed to be close to Mojsisovicsteuthis convergens ( von Hauer, 1847) are M. elliptica ( Mojsisovics, 1871) , M. meneghinii ( Salomon, 1895) , M. subrotundus ( Salomon, 1895) , M. boeckhi ( Stürzenbaum, 1875) and Mojsisovicsteuthis ? n. sp. ( Jeletzky, 1966, Pl. 5, Fig. 1 ).

Stratigraphic and geographic occurrences: So far known from the Anisian (Middle Triassic) through the Hettangian (Lower Jurassic).

According to previous workers and their ambiguous samples, representatives of this rare genus are known from the Middle Triassic (Anisian to Ladinian) through the Lower Jurassic (Hettangian) of the Alpine region, Hungary, Indo-Pacific Region (Timor), with question mark also from British Columbia ( Jeletzky, 1966) and also other regions (see below— M. boeckhi ). In Slovakia (this report), it comes from dark-grey to black biodetritic limestones of the Ráztoka Limestone Member of Zámostie Limestone Formation, dated to lower Illyrian (upper Anisian), uppermost part of the Trinodosus Zone (Pseudohungaricum Subzone) —probably lowermost part of the Reitzi Zone (Felsoeoersensis Subzone?).

Figures

Fig. 1 Geographical position of the areas of interest (A, B) and close-up views of the satellite photo with precise localization of the studied outcrops in the village Podhradie (C), and near Dolný Harmanec (D). E Outcrop in the roadcut in the village Podhradie.The fossiliferous Bed 3 is outlined. Orange circles with acronyms TO represent the sampling points for the organic geochemistry