Cycloplectoceras hinlopense Kröger & Pohle 2021, sp. nov.
Creators
- 1. Finnish Museum of Natural History, University of Helsinki, PO Box 44, FI- 00014 Helsinki, Finland.
- 2. Paläontologisches Institut und Museum, University of Zurich, Zurich, Switzerland.
Description
Cycloplectoceras hinlopense sp. nov.
urn:lsid:zoobank.org:act: 17CC19A8-797C-4718-AE09-C6DEEF037258
Fig. 41C–D
DiagnosisStrongly ribbed Cycloplectoceras with rapidly enlarging conch with WER of ca 3.7 and LER of ca 2, with adult size> 30 mm.
EtymologyFrom Hinlopen Strait, referring to the type region of this species.
Type materialHolotype Specimen FMNH-P30327; by monotypy.
Type locality and horizonFrom Profilstranda section, Ny Friesland, Svalbard, bed PO 131, 128 m above base of Olenidsletta Member, Blackhillsian, Floian.
DescriptionSpecimen FMNH-P30327 is a fragment of a phragmocone consisting of ca two whorls with a total diameter of 26 mm. The conch grows with a WER of 3.66 and a LER of 2. The whorl is 13 mm wide and high at a conch diameter of 26 mm and is slightly flattened on the lateral flanks and venter; a 0.3 mm deep imprint zone is present at the dorsum.
The conch is strongly annulated with ribs than run obliquely transverse across the flanks and forming a deep and broad ventral lobe. Prominent growth lines or striae are present, ca 8 per one millimetre, and are parallel to the ribs.
The siphuncular perforation has a diameter of 1.4 mm and is positioned at a distance of 1.3 mm from the venter (rSP = 0.1). The septal spacing is relatively narrow; where the conch is 22 mm in diameter the sutures have a distance of 2 mm apart over the venter.
RemarksThis specimen is assigned to Cycloplectoceras because it is a ribbed tarphycerid with rapidly enlarging whorls, both in whorl height and in whorl width. The conch cross section is nearly circular, similar as in known species of Cycloplectoceras. Pionoceras Ulrich et al., 1942 is another annulated tarphycerid with high WER and rapid growth of the whorl width. Pionoceras, however, differs in having broadly subtrapezoidal whorl cross sections and a very broad venter. The fragment described above is, however, relatively small, and ontogenetic growth changes are frequent among tarphycerid species, and especially among species of Pionoceras. It is therefore possible that this specimen represents a fragment of a larger individual, which if fully preserved would exhibit an adult morphology with an aspect of Pionoceras. More material is required to fully document the ontogeny, and consequently to further support the generic assignment of this species.
Cycloplectoceras hinlopense sp. nov. differs from C. miseri Ulrich, Foerste, Miller & Furnish, 1942 in being larger (the adult size of C. miseri is only 20 mm). The other known species of Cycloplectoceras, C. funatum Ulrich, Foerste, Miller & Furnish, 1942, has a smaller rate of increase in relative conch width (LER = ca 1.2, compare Ulrich et al. 1942: pl. 6 fig. 7) and is less strongly annulated.
Notes
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Linked records
Additional details
Biodiversity
- Collection code
- FMNH-P
- Family
- Tarphyceratidae
- Genus
- Cycloplectoceras
- Kingdom
- Animalia
- Material sample ID
- FMNH-P30327
- Order
- Tetrabranchia
- Phylum
- Mollusca
- Scientific name authorship
- Kröger & Pohle
- Species
- hinlopense
- Taxonomic status
- sp. nov.
- Taxon rank
- species
- Type status
- holotype
- Taxonomic concept label
- Cycloplectoceras hinlopense Kröger & Pohle, 2021
References
- Ulrich E. O., Foerste A. F., Miller A. K. & Furnish W. M. 1942. Ozarkian and Canadian cephalopods: Part I: Nautilicones. Geological Society of America Special Papers 37: 1 - 157. https: // doi. org / 10.1130 / SPE 37 - p 1