Upper Jurassic (Upper Tithonian) radiolaria from the Taman Formation, east-central Mexico

Upper Tithonian (Upper Jurassic: Zone 4) Radiolaria of the Taman Formation represent a very abundant and highly diversified Northern Tethyan fauna. Thirteen families (one new), forty-four genera (ten new), and one hundred and seventy-two species level taxa (fifty-six new) are documented herein. Biostratigraphically important taxa present in this assemblage include Acanthocircus dicranocanthos, Vallupus hopsoni, Bivallupus, Parvicingula excelsa, and Perispyridium. The distinctive Jurassic "marker" Perispyridium rapidly decreases in abundance towards the top of Subzone 4 beta and does not occur in Subzone 4 alpha. Curiously, the Taman radiolarian fauna is poor in Mirifusus and completely lacks Ristola altissima, R. procera, Eucyrtidiellum ptyctum, and Sethocapsa(?) cetia, which are common, distinctive upper Tithonian elements elsewhere. This radiolarian fauna is associated with ammonites, calpionellids, and pectenacids. It includes Kossmatia-Durangites assemblage and lower part of Substeueroceras-Proniceras assemblage of Imlay (1980). Furthermore, the base of Zone 4 corresponds closely to the first occurrence of hyaline calpionellids. The radiolarian assemblage is correlated with radiolarian faunas in other areas, such as the Cape Verde Basin (East Atlantic) and Oman. Additionally, a new genus (Loopus, Family Pseudodictyomitridae), described herein from the Taman, bridges the correlation of Tithonian between North America and Japan.; Characteristically, abundant and diversified Vallupinae (Pantanelliidae) occur in the Taman (Zone 4). This subfamily reached its acme of development during late Tithonian. Five genera (two new) and twenty-three species (seven new) of the Vallupinae are illustrated. Because of their distinctiveness, limited range, and wide distribution, many taxa of Vallupinae are useful for global biostratigraphic correlation in upper Tithonian.; Acaeniotylidae, n. fam., is established here to include tuberculate spumellarians common in Upper Jurassic and Lower Cretaceous. Acaeniotylids possess one fragile medullary shell connected to the cortical shell by secondary radial beams; the medullary shell is rarely preserved. Prior to this study, diversified morphotypes had been lumped under genus Acaeniotyle Foreman. Four acaeniotylid genera (three new) are established herein, and sixteen species level taxa (seven new) are illustrated. The proposed taxonomic scheme will aid in understanding the phylogeny and biostratigraphic value of this family.; The following families, illustrated herein, are also common in the Taman (Zone 4): Hagiastridae (three new genera), Patulibracchiidae, Hsuidae, Parvivaccidae, Parasaturnalidae (Acanthocircus), Epitingiidae (Perispyridium), Archaeodictyomitridae, Pseudodictyomitridae (one new genus), Syringocapsidae, Xiphostylidae, and Ultranaporidae (Napora).