New productide brachiopods (Productoidea) from the Carboniferous of Ixtaltepec Formation, Oaxaca, Mexico

From the Santiago Ixtaltepec area, in Oaxaca State, southern Mexico, 11 species of productoid brachiopods, including a new genus and five new species, are described. Semicostella sp., Antiquatonia sp., Keokukia? sp., Inflatia inflata, Reticulatia cf. R huecoensis, Buxtonia websteri, Weberproductus donajiae n. gen. n. sp., Dictyoclostus transversum n. sp., Inflatia coodzavuii n. sp., Buxtonia inexpletucosta n. sp., and Flexaria magna n. sp. were collected from eight stratigraphic levels of the Ixtaltepec Formation. The presence of Semicostella sp., Keokukia? sp. and Inflatia inflata in the basal strata, Units 1 to 3, of the formation indicate a Visean-Serpukhovian (Late Mississippian) age. Reticulatia cf. R huecoensis and Buxtonia websteri, found in Units 6 to 8, confirm the Pennsylvanian age for upper strata of the Ixtaltepec Formation. Inflatia and Flexaria are present in the uppermost beds of the formation so it is possible to extend their upper stratigraphic range to the Middle Pennsylvanian. All these taxa also occur in the United States Midcontinent, suggesting that during the Carboniferous the epicontinental sea extended at least to central Mexico.