Redescription and palaeoecological significance of the bryozoan Hippoporidra patagonica (Pallaroni, 1920) in the San Julián Formation (late Oligocene) of Santa Cruz province, Argentina

PÉREZ, L. M.; GRIFFIN, M.; PASTORINO, G.; LÓPEZ-GAPPA, J.; MANCEÑIDO, M. O.

ALCHERINGA

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2015 vol. 39 p. 1 - 7

0311-5518

Hippoporidra is a cheilostome bryozoan that predominantly encrusts gastropod shells inhabited by hermit crabs. The genus has a Pan-Atlantic distribution and its fossil record ranges from Eocene to Holocene times. The species Cellepora patagonica Pallaroni, 1918 is here transferred to the genus Hippoporidra and its autozooids and avicularia are described for the first time based on scanning electron microscopy. H. patagonica can be distinguished from the remaining species of the genus by the peculiar shape of its interzooidal avicularia and the morphology of its orifice, which is semicircular, with straight proximal border. In addition, its adventitious avicularia are often located on a suboral umbo. The record of Hippoporidra patagonica (Pallaroni, 1918) in facies from the Gran Bajo Member of the San Julián Formation (late Oligocene) in Patagonia validates the presence of this genus in the southern tip of South America and supports a Pan-Atlantic distribution during Cainozoic times.