Zelandites pujatoi, Raffi & Olivero & Milanese, 2019

Raffi, María E., Olivero, Eduardo B. & Milanese, Florencia N., 2019, The gaudryceratid ammonoids from the Upper Cretaceous of the James Ross Basin, Antarctica, Acta Palaeontologica Polonica 64 (3), pp. 523-542 : 538-539

Zelandites pujatoi sp. nov.

Fig. 9H− J.

ZooBank LSID: urn:lsid:zoobank.org:act:11FB9232-8BEB-4252-8F0F-2D85943BBAF1

Etymology: In honor of General Hernán Pujato (1904–2003) founder of the Antarctic Institute.

Holotype: CADIC PI 543 , specimen (D 29 mm) with complete phragmocone and incomplete body chamber (Fig. 9H)

Type locality Redonda Point, southeast of the James Ross Island, Antarctica.

Type horizon: Early Campanian (Cretaceous), Member II, Rabot Formation, Ammonite Assemblage 6 Natalites spp. Group 2.

Material. — Six internal molds, preserving patches of the shell and including the phragmocone and part of the body chamber ( CADIC PI 190 , 543–547 ). From type locality and horizon .

Diagnosis. —Small shell, strongly involute (U ~22 %) and fairly compressed whorl section. Neanoconch with up to seven ribs, young stages with weak prorsiradiate lirae accompanied by at least 8 slightly flexuous constrictions that project aperturally on the venter.

Description. —Involute shell with fairly compressed section (Wb/Wh ~0.74; Table 6). The umbilicus is small with a short umbilical wall and a slightly rounded umbilical shoulder. Subparallel flanks with gentle ventrolateral shoulder and slightly sharp venter. Neanoconch with up to seven strong ribs. As the diameter increases the ornamentation becomes much finer, almost imperceptible to the naked eye and in addition to the lirae, there are more than 8(?) well-defined slightly flexuous constrictions that in the venter form a slight aperturall projection.

Remarks.— Zelandites pujatoi Raffi and Olivero sp. nov. is similar to Zelandites kaiparaensis Marshall, 1926 and Zelandites inflatus Matsumoto, 1959 in its style of ornamentation. Z. kaiparaensis has fine lirae and more than 8 constrictions per whorl, but the constrictions are rectiradiate across the venter. Z. inflatus also has slightly flexuous constrictions but are more spaciate than those in Z. pujatoi . In addition, our new species differ from both in the strong ornamented neanoconch and in the greater degree of involution (~22% of the shell diameter).

Z. varuna , recorded in Antarctica ( Macellari 1986), has two or three constrictions per whorl and these are strongly incised in the flanks but disappearing toward the venter.

Stratigraphic and geographic range. —Early Campanian of the Rabot and Santa Marta Formations, Ammonites Assemblage 6 Natalites spp. Group 2, James Ross Island, Antarctica.