Pseudaganides aquitanense Branger, 2024, n. sp.
Creators: name: Branger, Patrick
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Cephalopoda
Nautilida
Pseudonautilidae
Pseudaganides
Pseudaganides aquitanense

description: Pseudaganides aquitanense n. sp.
(Fig. 11C-E)
urn:lsid:zoobank.org:act: 5A8D33FE-BD65-41CC-BF14-5DE1E26B3B19
DIAGNOSIS. — Small nautilus, maximum diameter 60 mm, shell rather compressed with an oval section except on the body-chamber where the venter flattens. Umbilicus closed. Suture lines with a wide but shallow lateral lobe.
ETYMOLOGY. — From the name of the region Nouvelle Aquitaine where all the specimens of this new species have been collected
TYPE MATERIAL. — Holotype. France • 1 specimen (adult); Nouvelle-Aquitaine, Aiffres; [46°18’07”N, 0°26’07”W]; Retrocostatum Zone; Upper Bathonian; Patrick Branger leg.; MBAN; 2023. PB.N96 (Fig. 10C).
Paratype. France • 1 specimen; Nouvelle-Aquitaine, Niort, Buffevent quarry (POC0009); [46°20’28”N, 0°30’21”W]; Retrocostatum Zone; bed 8b; Upper Bathonian; Patrick Branger leg.; MBAN; 2023. PB.N124 (Fig. 11E).
OTHER SPECIMENS EXAMINED. — France • 2 specimens; Nouvelle-Aquitaine, La Crèche, Champs-Albert; [46°21’08”N, 0°17’58”W]; Retrocostatum Zone; Upper Bathonian; Patrick Branger leg.; MBAN; 2023.PB.N106, 2023.PB.N125.
TYPE LOCALITY AND STRATUM TYPICUM. — Until now, Pseudaganides aquitanense n. sp. has only been collected from the Upper Bathonian, Retrocostatum Zone, where it seems restricted. The holotype is from Aiffres.
MEASUREMENTS. — See Table 5.
DESCRIPTION
Small Pseudaganides, the smallest among Bathonian and Callovian species (Fig. 10), 58 to 61 mm diameter for full grown shells. Inner whorl section is oval, the venter flattens, just slightly rounded before the end of the phragmocone where it is limited by well-marked angulated shoulders that disappear close to the aperture as the shell widens. The umbilicus is closed, boarded by a rounded edge. Maximum width is situated on the dorsal part, close to the umbilicus. Suture line (Fig. 4E) draws a true S, the lateral lobe is wide but not very deep with P/L around 30%. The latero-dorsal saddle is visible for the first time in this lineage on the whole shell. On the holotype (Fig. 11C), the two last septa of the phragmocone are approximated indicating the adult stage.
REMARKS
Pseudaganides aquitanense n. sp. is the only Pseudaganides that have been found within Upper Bathonian strata with certainty. Presently, the only cited Pseudaganides of this age was Pseudaganides subbiangulatus. This Bathonian placement should be now revised because of several major differences with Pseudaganides aquitanense n. sp., the size and shape of the suture lines that is more folded on Pseudaganides subbiangulatus shells and, above all, because of the age attributed to the P. subbiangulatus collected in our study area (see below). Pseudaganides aquitanense n. sp. differs mostly from Antaganides fournieri n. gen., n. sp. by its suture lines that shows a sigmoidal profile at any growth stage. The sizes of the two species are similar, about 60 millimeters at adult stage. Antaganides fournieri n. gen., n. sp. can be interpreted as the probable ancestor of Pseudaganides aquitanense n. sp. and Pseudaganides buffeventi n. sp. The latter is a larger and younger species with a clearly open umbilicus.
description: Published as part of Branger, Patrick, 2024, Antaganides n. gen., a new genus of Middle Jurassic nautiloid, ancestor of Pseudaganides Spath, 1927, with discussion on the phyletic origin of the family Pseudonautilidae, pp. 471-493 in Geodiversitas 46 (14) on page 482, DOI: 10.5252/geodiversitas2024v46a14, http://zenodo.org/record/13884433