Ticinoteuthis chuchichaeschtli, Pohle & Klug, 2024

Pohle, Alexander & Klug, Christian, 2024, Orthoceratoid and coleoid cephalopods from the Middle Triassic of Switzerland with an updated taxonomic framework for Triassic Orthoceratoidea, Swiss Journal of Palaeontology (14) 143 (1), pp. 1-32 : 21

Ticinoteuthis chuchichaeschtli gen. et sp. nov.

urn:lsid:zoobank.org:act:67,831,665-256E-476D-8690- 5C75A42D2F44.

Figure 3 A-G, 10C

Etymology: The Swiss German word “Chuchichäschtli” is a well-known shibboleth translating to small kitchen cupboard (standard German = Küchenschränkchen). This is a reference to the specimens being stored in a drawer in Zurich for many years.

Holotype: PIMUZ 39491 is the only specimen that shows the siphuncle and a partly preserved phragmocone and therefore selected as holotype.

Type locality and horizon: Point 902/Mirigioli, Meride, Ticino; middle Besano Formation, bed 112, secedensis zone, Illyrian, Anisian, middle Triassic.

Material: Two further specimens are preserved as internal moulds without trace of septa or siphuncle ( PIMUZ 39487 , 39,489 ) and seven further specimens are only preserved as external moulds ( PIMUZ 38652 , 38 , 655 , 39 , 488 , 39 , 490 , 39,492 – 39,494). Because of the poor preservation, we do not select these specimens as paratypes.

Diagnosis: As for genus, by monotypy.

Description: There are several specimens between bed 87–112 that are similar in cross section and apical angle, mostly preserved as external moulds. They range in the maximum lateral cross section from 6 to 20 mm and corresponding apical angles of 5–9°. The siphuncle is visible in only in the holotype, PIMUZ 39491, which also preserves a short part of the phragmocone. The phragmocone has a depressed cross section with a maximum lateral diameter of 8 mm and an expansion rate of 8.6°. It appears to have retrochoanitic septal necks and a relatively wide submarginal siphuncle ( Fig. 3B ). The septa are preserved as faint traces and are inclined towards the venter in anterior direction, with relative cameral length (RCL) of about 0.5. Further apicad, on the external mould, there are transverse lines, which could alternatively represent the septa, although they are more widely (> 1.0) and somewhat irregularly spaced. The preserved phragmocone is 12 mm long, while the entire specimen including external moulds is about 120 mm long.

Remarks: There are two potential traces of septa in the holotype, moderately long and inclined on the preserved phragmocone, and long and directly transverse on the apical part of the external mould. We think that the short, inclined traces are more likely to represent the septa, as they appear to be more regular and are preserved directly on the phragmocone. Mojsisovicsteuthis boeckhi (Stürzenbaum, 1875) has only a slightly higher apical angle, but as indicated by Mojsisivics (1882) and Hauer (1888), the siphuncle is situated on the narrower side of the cross section (see also Košťák et al., 2023), meaning that M. boeckhi has a compressed conch in contrast to the depressed T. chuchichaeschtli . Furthermore, the chambers are shorter in M. boeckhi , with only about 0.2 per conch diameter.

Occurrence: Ticino, Switzerland; Middle Triassic (Anisian).

Figures

Fig. 3 Ticinoteuthis chuchichaeschtli gen. et sp. nov. from the Besano Formation (Middle Triassic) of the Monte San Giorgio,Ticino,Switzerland and a co-occurring orthoceratoid for taphonomic comparison. A–D PIMUZ 39491, holotype, bed 112 A Lateral view.B Adapical view of preserved phragmocone,exposing the ventral position of the siphuncle. C Lateral view of preserved phragmocone,exposing faint traces of inclined septa.D Lateral view of adapical external mould, exposing potential traces of septa.E–G PIMUZ 39493, T.chuchichaeschtli gen. et sp.nov., bed 94. E Lateral view. F Enlarged view of longitudinal ribs. G Lateral view of counterpart. H PIMUZ 39060, bed 94, likely orthoceratoid with similar longitudinal ribs. Note the irregularity in these structures, suggesting that these represent a taphonomic artefact. Abbreviations: si =siphuncle, se =septa