Lower Tithonian mono- and dicyrtid Nassellaria (Radiolaria) from the Solnhofen area (southern Germany) Author Dumitrica, Paulian Institut de Géologie et Paléontologie, BFSH 2, UNIL, CH- 1015 Lausanne (Switzerland) Paulian. Dumitrica @ igp. unil. ch umitrica@igp.unil.ch Author Zügel, Peter Geologisch-Paläontologisches Institut, Johann Wolfgang Goethe-Universität, Senckenberganlage 32 - 34, D- 60054 Frankfurt am Main (Germany) zuegel @ em. uni-frankfurt. de. text Geodiversitas 2003 25 1 5 72 journal article 10.5281/zenodo.5372196 1638-9395 5372196 8BF4D0FF-F247-4B92-B327-0D647B01C386 Family TERTONIIDAE n. fam. TYPE GENUS . — Tertonium n. gen. RANGE . — Lower Pliensbachian-Tithonian. DIAGNOSIS. — Dicyrtid nassellarians with small cephalis and large conical thorax. Thorax with an indefinite number of circumferential ridges separated by two or more rows of alternate pores. Initial spicule with MB, A, V, two L, two l, and D. L and l sometimes prolonged outside test wall. REMARKS This family is erected to define a group of Jurassic species resembling somehow the Parvicingulidae Pessagno, 1977 by the presence of circumferential ridges separated by rows of transverse pores, but differing from them in that these ridges do not correspond to internal planiform partitions which are missing. The large postcephalic segment is therefore interpreted herein as representing a single chamber – the thorax. This group of species seems to predominantly occur in the Kimmeridgian-Tithonian. Hull (1997: 174 , pl. 51, figs 1, 2, 20) illustrated two undetermined and undescribed species from this interval in California, and Kiessling (pers. comm.) found a species in the lower Tithonian of the Antarctic Peninsula. A species assignable to this family was also illustrated by Takemura (1986) , Hattori (1989) , and Yao (1997) as Parvicingula (?) obesa Takemura, 1986 from probably Bajocian manganese concretions ( Unuma echinatus Zone ) of Japan , and a specimen assignable to Toritenum n. gen. was found by us in the very rich material from the lower Pliensbachian of Turkey partly studied by De Wever (1982) .