Ticinoteuthis Pohle & Klug 2024, gen. nov.
Creators: name: Pohle, Alexander
name: Klug, Christian
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Cephalopoda
Orthocerida
Orthoceratidae
Ticinoteuthis

description: Genus Ticinoteuthis gen. nov.
urn:lsid:zoobank.org:act: F7E76450-CFD4-4BCA-8D4E-7FF4D6D83094.
Etymology: Named after the Canton Ticino (Switzerland), where the type locality is situated.
Type species: Ticinoteuthis chuchichaeschtli gen. et sp. nov.
Included species: Only the type species.
Diagnosis: Small orthoconic (longiconic) phragmocone with slender expansion rate of about 5–9° and depressed cross section. Septa apparently inclined towards the venter in anterior direction. Siphuncle submarginal, probably with retrochoanitic septal necks. Neither primordial nor proper rostrum are known.
Remarks: Ticinoteuthis gen. nov. is similar to Mojsisovicsteuthis but differs in its depressed rather than compressed cross section, slenderer apical angle and apparently retrochoanitic instead of prochoanitic septal necks. For both Mojsisovicsteuthis and Ticinoteuthis gen. nov., a rostrum (or telum) is undocumented, which was interpreted by Jeletzky (1966) as primary absence. If this is the case, then they cannot be assigned to the Aulacoceratida, an approach that was already proposed by Mariotti and Pignatti (1992, 1993) and by the Treatise on Invertebrate Palaeontology (Mariotti et al., 2021). The absence of a rostrum may be taken as evidence to classify these taxa within the Phragmoteuthida, but representatives of this order are generally characterised by much larger apical angles and possess a typical three-lobed proostracum (Fuchs & Donovan, 2018). In contrast, Rieber (1973) described body chambers of Mojsisovicsteuthis, which is mutually exclusive with any proostracum. For T. chuchichaeschtli, it is unclear if a tubular body chamber or a proostracum was present, although the similarity to Mojsisovicsteuthis perhaps suggests a tubular body chamber as well. Thus, they do not fit any of the known Mesozoic coleoid orders or even families, implying that besides desperately needed new data, current family- or order-level definitions either need to be adjusted or new names to be established.
It is possible that “ Orthoceras ” styriacum Mojsisovics, 1873 from the Carnian of Austria belongs to the same group of species, perhaps even to Ticinoteuthis, as it has a similar expansion rate and cross section and further appears to agree with in the inclination of the septa. However, as the position of the siphuncle is unknown in “ O.” styriacum, it cannot be excluded that it represents a crushed trematoceratid.
Aulacoceratids differ in having a thick aragonitic rostrum, but their phragmocones generally expand more rapidly and are (sub-) circular in cross section. The only aulacoceratid with a similarly depressed cross section of the phragmocone is Miyagiteuthis, which further differs in having a strictly marginal siphuncle and less inclined septa (Mariotti et al., 2021; Niko & Ehiro, 2018).
Occurrence: Ticino, Switzerland; Middle Triassic (Anisian).
description: Published as part of Pohle, Alexander & Klug, Christian, 2024, Orthoceratoid and coleoid cephalopods from the Middle Triassic of Switzerland with an updated taxonomic framework for Triassic Orthoceratoidea, pp. 1-32 in Swiss Journal of Palaeontology (14) (14) 143 (1) on pages 20-21, DOI: 10.1186/s13358-024-00307-8, http://zenodo.org/record/12005092