Vestinautilus kesslerae Korn & Klug 2023, sp. nov.
Creators
- 1. Museum für Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity, Invalidenstrasse 43, 10115 Berlin, Germany.
- 2. Paläontologisches Institut und Museum, Universität Zürich, Karl-Schmid-Strasse 4, 8006 Zürich, Switzerland.
Description
Vestinautilus kesslerae sp. nov.
urn:lsid:zoobank.org:act: 73A42507-23FD-4390-9DEE-8FC07C72A7BC
Fig. 9; Table 3
DiagnosisSpecies of Vestinautilus with thickly pachyconic, subevolute conch (ww/dm ~ 0.68; uw/dm ~0.38); whorl profile moderately depressed, oval (ww/wh ~1.75), venter broadly arched, ventrolateral shoulder subangular with three weak spiral ridges. Whorls not embracing, just touching the preceding one. Ornament with coarse growth-lines forming a moderately deep, broadly arched ventral sinus.
EtymologyNamed after Birgit Kessler (Berlin), who found the holotype.
Material examinedHolotype MOROCCO • Anti-Atlas, South-east of Gara el Itima, 31.5 km east-northeast of Taouz; Zrigat Formation; Kessler 2007 Coll.; illustrated in Fig. 9; MB.C.31287.
DescriptionHolotype MB.C.31287 is an entirely chambered steinkern specimen with 41 mm phragmocone diameter; it comprises one and a quarter whorl (Fig. 9). At the largest diameter of the specimen, the conch shape is thinly pachyconic and subevolute (ww/dm ~ 0.68; uw/dm ~0.38). The whorl profile is depressed (ww/ wh ~1.74) and has the shape of a symmetric oval. The coiling rate is very high (WER ~2.72) and the last whorl just touches the preceding one. The umbilical window has a diameter of 11.5 mm.
The initial chamber is bluntly cone-shaped with a length of 0.6 mm, a height of 2.0 mm and a width of about 4 mm. Very early in ontogeny, the whorl profile becomes depressed and already immediately after the protoconch, an angular ventrolateral shoulder is formed. This angular shoulder becomes more pronounced to form a spiral ridge, which is, at a conch diameter of 25 mm, accompanied by one less well-developed ridge on each side. The outer of these ridges fades out and is only barely visible at a conch diameter of 42 mm. Only some traces of the shell ornament are visible in the dorsal portion. They show coarse growth lines and three of them are arranged at a millimetre distance. They form a broadly arched ventral sinus.
The siphuncle has a subcentral position with a slight shift towards the venter. The suture line forms a wide and shallow external lobe, a very shallow and wide lateral lobe and a small, rounded internal lobe.
RemarksVestinautilus kesslerae sp. nov. has a somewhat marginal position in the morphological spectrum of the genus. It differs from the other species because of the combination of a number of conch and sculpture characters: the advolute conch shape even at a conch diameter of 40 mm, the comparatively weak development of only a few longitudinal ridges and the convex venter.
Notes
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Linked records
Additional details
Biodiversity
- Collection code
- MB
- Family
- Trigonoceratidae
- Genus
- Vestinautilus
- Kingdom
- Animalia
- Material sample ID
- MB.C.31287
- Order
- Nautilida
- Phylum
- Mollusca
- Scientific name authorship
- Korn & Klug
- Species
- kesslerae
- Taxonomic status
- sp. nov.
- Taxon rank
- species
- Type status
- holotype
- Taxonomic concept label
- Vestinautilus kesslerae Korn & Klug, 2023