Liroceras karaouii, Korn & Klug, 2023

Korn, Dieter & Klug, Christian, 2023, Early Carboniferous coiled nautiloids from the Anti-Atlas (Morocco), European Journal of Taxonomy 885, pp. 156-194 : 180-181

publication ID	https://doi.org/ 10.5852/ejt.2023.885.2199
publication LSID	lsid:zoobank.org:pub:8432EEFF-391F-4778-81F6-14F3F6ECAA5F
DOI	https://doi.org/10.5281/zenodo.8222737
persistent identifier	https://treatment.plazi.org/id/2EDCD119-FDE9-426A-9547-A89E8AA520F4
taxon LSID	lsid:zoobank.org:act:2EDCD119-FDE9-426A-9547-A89E8AA520F4
treatment provided by	Felipe
scientific name	Liroceras karaouii
status	sp. nov.

Treatment

Liroceras karaouii sp. nov.

urn:lsid:zoobank.org:act:2EDCD119-FDE9-426A-9547-A89E8AA520F4

Fig. 17 View Fig ; Table 7 View Table 7

Diagnosis

Species of Liroceras with thickly pachyconic, subinvolute conch (ww/dm ~0.75; uw/dm ~0.25), whorl profile moderately depressed (ww/wh ~ 1.65) with broadly rounded venter and subangular umbilical margin. Coiling rate very high (WER ~ 2.65), whorls very weakly embracing (IZR ~0.17). Suture line nearly straight.

Etymology

Named after Driss Karaoui (Hassilabied), the collector of the specimen.

Material examined

Holotype MOROCCO • Anti-Atlas, region south-west of Rissani ; basal Mougoui Ayoun Formation; Karaoui Coll.; illustrated in Fig. 17 View Fig ; PIMUZ 39515 View Materials .

Description

Holotype PIMUZ 39515 is a corroded, desert-polished specimen with a phragmocone diameter of about 46 mm ( Fig. 17 View Fig ). It is fully septate and has about 22 chambers in the last volution. It is, at 46 mm in conch diameter, thickly pachyconic and subinvolute (ww/dm=0.77; uw/dm=0.25) with a strongly depressed, reniform whorl profile (ww/wh=1.65), a very small whorl overlap zone (IZR= 0.17) and a very high coiling rate (WER ~ 2.65). The whorl profile is crescent-shaped and widest at the subangular umbilical margin. The umbilical wall is flattened and slightly oblique. The suture line extends nearly linearly across the flanks and venter.

Remarks

Liroceras karaouii sp. nov. differs from L. vermis sp. nov. in the subangular umbilical margin and in the slightly wider umbilicus (uw/dm ~ 0.25 in L. karaouii but only uw/dm ~ 0.20 in L. vermis ). This shape of the umbilicus is also the most important distinguishing character from the other species of the genus. The pronounced umbilical margin in L. karaouii can be seen as a plesiomorphic character, which transforms from the possible evolutionary lineage from Bistrialites to Liroceras .