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

description: Pseudaganides crechensis n. sp.
(Figs 12C1-C3; 13C)
urn:lsid:zoobank.org:act: 9DEFECCC-BA77-49A1-BA95-AEAB23E26268
DIAGNOSIS. — Small nautilus, maximum diameter 75 mm, shell rather compressed with a subrectangular section except on the body-chamber where the sides are a little more rounded. Umbilicus clearly open. Suture lines with a wide and rather deep lateral lobe.
TYPE MATERIAL. — Holotype. France • 1 specimen (adult); Nouvelle-Aquitaine, La Crèche, Champs-Albert; [46°21’08”N, 0°17’58”W]; base of the Gracilis Zone, Prahecquense Subzone; Lower Callovian; Patrick Branger leg.; MBAN; 2023.PB.N107 (Fig. 12C1-C3).
OTHER SPECIMENS EXAMINED. — France • 1 specimen (adult); same data as holotype; 2023.PB.N132 • 2 specimens (young shells almost newly hatched); same data as holotype; 2023.PB.N142, 2023.PB.N143 • 1 specimen; Nouvelle-Aquitaine, Niort, Buffevent quarry (POC0009); [46°20’28”N, 0°30’21”W]; base of the Gracilis Zone, Prahecquense Subzone; Lower Callovian; Patrick Branger leg.; MBAN; 2023.PB.N75.
TYPE LOCALITY AND STRATUM TYPICUM. — The holotype of Pseudaganides crechensis n. sp. (Fig. 12C1-C3) has been sampled from the base of the Gracilis Zone, Prahecquense Subzone, Lower Callovian, in La Crèche.
MEASUREMENTS. — See Table 7.
ETYMOLOGY. — The species is named based on La Crèche (Deux-Sèvres), the city where four of the five known specimens were collected.
DESCRIPTION
Pseudaganides crechensis n. sp. is a small sized and compressed nautilus, maximum diameter observed is 75 mm on the biggest specimen (2023.PB.N75). The section is oval on the embryonic shell, then subrectangular until the end of the phragmocone where it widens. The body-chamber looks more rectangular at the adult stage because of the presence of angular but not sharp ventral shoulders. Flanks are slightly rounded with a maximum width at one third of the height. At the beginning of the body-chamber, the outer part of the flank is a little depressed. The venter, rounded at first, flattens from the end of the phragmocone to the aperture. The umbilicus is clearly open (u> 0.10), funnel like, with rounded sides. The lateral lobe of the suture line (Fig. 4F) is well marked, (P/L = 0.43 to 0.47). The ventral lobe is shallow, P/L = 0.23 on the type specimen. The two young shells show some ontogenetic elements. The hatching size, indicated by the existence of the nepionic constriction (Landman 1988), corresponds to 1 cm in diameter. At that size the shell shows a cross-hatched ornament of fine growth lines and perpendicular lirae (Fig. 13C). The aperture, very well-preserved on the type specimen (Fig. 12C1-C3), is typical of Pseudaganides with straight lateral borders and a well-marked ventral sinus.
REMARKS
Pseudaganides crechensis n. sp. presents the same size than Pseudaganides buffeventi n. sp. The two species differs mainly from their umbilicus that is open on Pseudaganides crechensis n. sp. whereas it is closed on Pseudaganides buffeventi n. sp.
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 pages 483-484, DOI: 10.5252/geodiversitas2024v46a14, http://zenodo.org/record/13884433