Antaganides grulkei, Branger, 2024

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, Geodiversitas 46 (14), pp. 471-493 : 480

Antaganides grulkei n. gen., n. sp.

(Fig. 11A, B)

urn:lsid:zoobank.org:act:6971C0AB-C1CA-44EF-8109-2E5D67A2D8BD

Nautilus cf. fuscus – Lissajous 1923: 48, pl. II, fig. 2-2a.

DIAGNOSIS. — Small sized nautilus, maximum diameter 65 mm, shell rather compressed on the last whorl with an oval section except on the body-chamber where the venter flattens. Umbilicus closed. Suture lines with a wide and shallow lateral lobe.

ETYMOLOGY. — Antaganides grulkei n. gen., n. sp. is dedicated to Wolfgang Grulke, Sherborne, United Kingdom, who made a worldwide promotion for nautiloids studies through his magnificent book “ Nautilus , the Beautiful Survivor ” ( Grulke 2016). Doing this work, he gave us the opportunity to meet or to discuss with most of the specialists of the world.

TYPE MATERIAL. — Holotype. France • 1 specimen (complete); Nouvelle-Aquitaine , Sainte-Éanne , near la Mothe-Saint-Héray, les Hauts-de-Rochefort quarry ( NAQ0021 ); [46°23’30”N, 0°07’55”W]; Base of the Progracilis Zone, Orbignyi Subzone; Middle to Upper Bathonian; Patrick Branger leg.; MBAN; 2023. PB.N97 (Fig. 11A, B).

OTHER SPECIMENS EXAMINED. — France • 1 specimen (complete); same data as holotype; 2023.PB.N133 • 1 specimen (complete, body-chambers poorly preserved); Nouvelle-Aquitaine, La Crèche, Champs-Albert; [46°21’08”N, 0°17’58”W]; base of the Retrocostatum Zone; Upper Bathonian ; Patrick Branger leg.; MBAN; 2023.PB.N134.

TYPE LOCALITY AND STRATUM TYPICUM. — Antaganides grulkei n. gen., n. sp. has been mostly encountered within the Middle Bathonian of the Submediterranean Realm where it appears at the base of the Progracilis Zone, Orbignyi Subzone. The holotype has been found there, in les Hauts-de-Rochefort quarry. It persists until the Upper Bathonian, at the base of the Retrocostatum Zone where the youngest specimens have been found. In Burgundy, the nautilus figured as Nautilus cf. fuscus ( Crick, 1898) byLissajous (1923) also comes from the upper part of the Middle Bathonian, “ Arbustigerum Zone” (that corresponds to Morrisi and Bremeri Zones [ Mangold et al. 2012]).

MEASUREMENTS. — See Table 4.

DESCRIPTION

The holotype (2023.PB.N97; Fig. 11A, B) and the specimen 2023.PB.N133 are rather well preserved samples. They only reach a small size, a little more than 6 cm, at the adult stage. 2023.PB.N134 is a young one with a diameter of 42 mm, The shell is always compressed with dorsal sides slightly rounded showing a maximum width at about two third height. Then, the lateral-ventral sides flatten and converge. The ventral part, rounded on the inner whorls, flattens on the body-chamber, boarded by angular but not sharp shoulders. The umbilicus is very small, funnel-shaped. The lateral lobe of the suture line ( Figs 4D ; 9 ) is well marked (P/L <30%) whereas the ventral lobe is very shallow.

REMARKS

Antaganides grulkei n. gen., n. sp. is a very close species to the contemporary Antaganides fournieri n. gen., n. sp., comparing size and shape of the shell. In comparison, the umbilicus is funnel-like in one case and deep and boarded by subvertical sides for the other. The lateral lobe of the suture line also shows differences, especially close to the umbilicus where the suture line is more retrosiphonate in A. fournieri n. gen., n. sp. than on A. grulkei n. gen., n. sp.

Figures

FIG. 4. — Suture lines of Antaganides n. gen. and Pseudaganides Spath, 1927: A, Antaganides cf. erycinus (Tagliarini,1901), n. comb., 2023.PB.N117; B, Antaganides sauvageti n. gen., n. sp. 2023.PB.N64; C, Antaganides fournieri n. gen., n. sp., 2023.PB.N105; D, Pseudaganides aquitanense n. sp., 2023.PB.N96; E, Pseudaganides buffeventin. sp.,2023.PB.N76; F, Pseudaganides crechensisn. sp., 2023.PB.N107; G, Pseudaganides subbiangulatus (d’Orbigny,1850),2023. PB.N73, Patina Zone; H, Pseudaganides subbiangulatus, 2023.PB.N112, Anceps Zone.

FIG. 9. — Ratio “P/L” of the depth of the width of the lateral lobe compared with its width among the different species of Antaganides n. gen. and Pseudaganides Spath, 1927.