Taxonomic status of some species of Aspidostomatidae (Bryozoa, Cheilostomata) from the Oligocene and Miocene of Patagonia (Argentina)

LÓPEZ-GAPPA, JUAN; PÉREZ, LEANDRO M.; GRIFFIN, MIGUEL

JOURNAL OF PALEONTOLOGY

PALEONTOLOGICAL SOC INC

Año: 2018 vol. 92 p. 432 - 441

0022-3360

The bryozoan genus Aspidostoma Hincks, 1881 has been regarded as the only representative of the AspidostomatidaeJullien, 1888 inArgentina to date. Its type species, Aspidostoma giganteum (Busk, 1854), is presently distributed in the Magellanic Region (Argentinaand Chile) and has been recorded in Oligocene and Miocene fossil deposits ofSanta Cruz and Chubut, respectively. New material from San Julián (lateOligocene), Monte León (early Miocene), Chenque (early to middle Miocene), andPuerto Madryn (late Miocene) formations suggests, however, that A. giganteum is not represented in the fossil record. Material fromPuerto Madryn Formation previously regarded as A. giganteum is here recognized as Aspidostoma roveretoi newspecies. Aspidostoma ortmanniCanu, 1904 is revalidated for the speciesfrom the San Julián Formation. Aspidostoma armatum new species and Aspidostoma tehuelche new species are introduced for material from the MonteLeón and Chenque formations, respectively. Aspidostoma incrustans Canu, 1908, from the early Miocene, is redescribed. Melychocella Gordon and Taylor, 1999, which differs from Aspidostoma in having vicarious avicularia and lacking a median ridgeand a quadrangular process proximal to the opesia-orifice, is so farrepresented by three Paleogene species from the Chatham Islands (Southwest Pacific). The material fromMonte León allowed us to transfer Aspidostoma flammulum Canu, 1908 to Melychocella, resulting in the new combination Melychocella flammula (Canu, 1908). Melychocella biperforata new species is described from the lower Miocene Monte León and Chenqueformations. The presence of Melychocella in the Neogene ofPatagonia extends its geographic distribution and its temporal range.