Chloephaga sp.

Agnolín, Federico L., Álvarez Herrera, Gerardo P. & Tomassini, Rodrigo, 2024, Pleistocene record of Chloephaga Eyton, 1838 (Anseriformes: Anatidae) in the Argentine Pampas, with the description of a new species, Comptes Rendus Palevol 23 (18), pp. 241-255 : 250-251

Chloephaga sp.

( Fig. 10 A-E)

REFERRED MATERIAL. — PV-UNS-394, right humerus lacking proximal end.

A B C D

E

STRATIGRAPHIC PROVENANCE AND AGE. — Facies Sp, Lower Section of the San José Sequence. Middle Pleistocene.

DESCRIPTION AND COMPARISONS

PV-UNS-394 belongs to a very small representative of Chloephaga , probably the smaller of the genus. It is similar in proportions and humeral curvature to other species of the genus. The distal end of the humerus shows lateral and medial margins subvertically oriented, whereas they are somewhat divergent in the other species. The ring surrounding the facet for the collateral dorsal ligament is poorly defined, as occurs in C. rubidiceps and C. poliocephala , whereas in C. picta this facet is delimited by a prominent subcircular bony rim. In posterior view, such a rim is less evident in PV-UNS-394 than in other species. The anterior articular ligament is almost subvertically oriented, as occurs in C. poliocephala , whereas in C. picta and C. rubidiceps it is distally oriented.

REMARKS

PV-UNS-394 shows differences in size and anatomical features with respect to the extant species of the genus Chloephaga . Besides, although there are no comparable skeletal elements, the specimen shows a much smaller size than what could be inferred for the extinct C. dabbenei n. sp. Based on these points, it is considered that this specimen probably corresponds to a new species of Chloephaga .