Paraliroceras macrogaster, Korn & Hairapetian, 2025

Korn, Dieter & Hairapetian, Vachik, 2025, Late Permian nautiloids from Baghuk Mountain (Central Iran), European Journal of Taxonomy 1019, pp. 1-76 : 56-58

publication ID

https://doi.org/10.5852/ejt.2025.1019.3071

publication LSID

lsid:zoobank.org:pub:E24EBF4A-9FE2-47E4-A656-E1698F88BB41

DOI

https://doi.org/10.5281/zenodo.17227795

persistent identifier

https://treatment.plazi.org/id/03E487D4-FFEC-4939-FD8E-5FB18732F8D3

treatment provided by

Plazi

scientific name

Paraliroceras macrogaster
status

sp. nov.

Paraliroceras macrogaster sp. nov.

urn:lsid:zoobank.org:act:

Fig. 26 View Fig ; Table 20 View Table 20

Diagnosis

Species of Paraliroceras with thinly globular, subinvolute conch (ww/dm ~ 0.86; uw/dm ~ 0.23), moderately depressed whorl profile (ww/wh ~1.90) and very high coiling rate (WER ~2.35) at a conch diameter of 60 mm. Whorl profile with broadly arched venter and flanks, narrowly rounded umbilical margin, flattened and steep umbilical wall and moderately wide imprint zone ( IZR ~ 0.22). Without sculpture. Suture line with very shallow and wide external, lateral and umbilical lobes.

Etymology

From the Greek ‘μακρός’=‘large’ and ‘γαστήρ’= ‘abdomen’; because of the broadly rounded flanks and venter.

Type material

Holotype

IRAN – Esfahan Province • Baghuk Mountain ; Hambast Formation, Araxoceras beds ( early Wuchiapingian); 2011; Korn et al. leg.; illustrated in Fig. 26A–C View Fig ; MB.C.32141 .

Paratype

IRAN – Esfahan Province • 1 specimen; Baghuk Mountain ; same data as for holotype; illustrated in Fig. 26D–F View Fig ; MB.C.32142.

Description

Holotype MB.C.32141 is a fully chambered, incomplete specimen with a conch diameter of 62 mm, in which the right side is incomplete. Some conch dimensions can thus only be reconstructed ( Fig. 26A View Fig ). The conch is thinly globular and subinvolute (ww/dm ~ 0.87; uw/dm =0.22) with a very high coiling rate (WER= 2.39) and a moderately deep whorl overlap ( IZR =0.23). The whorl profile is moderately depressed (ww/wh ~ 1.91) with a broadly convex venter that merges continuously with the flanks. The umbilical margin is narrowly rounded and pronounced; the umbilical wall is steep and almost flat ( Fig. 26B View Fig ). The suture line shows very broad and shallow lobes on venter, flanks and umbilical wall ( Fig. 26C View Fig ). The last volution possesses 15 phragmocone chambers without an indication of crowding (CLI=24). The siphuncle has a dorsocentral position.

Paratype MB.C.32142 is almost completely chambered and, with a conch diameter of 60 mm ( Fig. 26D– E View Fig ), has very similar conch parameters to the holotype. The umbilical margin is slightly more rounded and the suture line has a slightly deeper external lobe ( Fig. 26F View Fig ). The last volution of the phragmocone has about 15 chambers (CLI=24).

Remarks

Paraliroceras macrogaster sp. nov. with its pronounced, narrowly rounded umbilical margin makes a separation from the other late Permian representatives of the family Liroceratidae rather easy. Paraliroceras macrogaster has a very similar conch to P. kazanicum , but differs from P. kazanicum (with IZR = 0.15 and WER = 2.80) in the higher whorl overlap rate of the whorls ( IZR = 0.22) and the lower coiling rate (WER=2.35).

MB

Universidade de Lisboa, Museu Bocage

Kingdom

Animalia

Phylum

Mollusca

Class

Cephalopoda

SubClass

Nautiloidea

Order

Nautilida

SubOrder

Liroceratina

SuperFamily

Liroceratoidea

Family

Liroceratidae

Genus

Paraliroceras

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