New Records of Ordovician Ostracodes from Two Genera of the Family Egorovellidae Schallreuter
- PDF / 1,197,571 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 2 Downloads / 179 Views
Records of Ordovician Ostracodes from Two Genera of the Family Egorovellidae Schallreuter L. M. Melnikova* Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow, 117647 Russia *e-mail: [email protected] Received December 16, 2019; revised January 24, 2020; accepted January 24, 2020
Abstract—Based on published data and material from several Ordovician sections of the Siberian Platform and northeastern Russia housed in the Paleontological Institute of the Russian Academy of Sciences, the ostracode family Egorovellidae Schallreuter, 1966 is revised. The family is of great importance for biostratigraphic correlation. The diagnosis of the genus Bodenia V. Ivanova, 1959 is clarified and two new species, B. signata sp. nov. and B. densistriata sp. nov. are described. Two species previously included in Bodenia are removed from the genus and assigned to the family Richinidae: B. aechminiformis is designated as the type species of the new genus Bodeniella gen. nov. and B. anonyma is assigned to the Siberian genus Angarallina Melnikova, 2020. Two new species of the genus Egorovella, E. porilamellata sp. nov., and E. insperata sp. nov., are also described. Keywords: Ostracodes, family Egorovellidae, Ordovician, Siberian Platform DOI: 10.1134/S0031030120060052
INTRODUCTION The study of ostracodes from V.A. Ivanova’s collection (Paleontological Institute, Russian Academy of Sciences, PIN RAS), from the Ordovician deposits of the Podkamennaya Tunguska, Moyero, and Kulyumbe rivers (Siberian Platform), as well as Kalychan Creek (northeastern Russia) allowed the species composition of some genera of the family Egorovellidae Schallreuter, 1966 to be clarified. According to the classification adopted in the “Prakticheskoe rukovodstvo” (1990), which I follow, this family includes three genera: Egorovella V. Ivanova, 1959, Bodenia V. Ivanova, 1959 and Egorovellina Kanygin, 1965. However, it should be noted that in a later work (Schallreuter et al., 1999), nine genera were included: in addition to the three above, Curvilobella V. Ivanova, 1968 [=subgenus E. (Curvilobella) V. Ivan., 1968, which was raised to the rank of genus], Valentella Neckaja, 1973 (a junior synonym of the genus Sibiritella Kanygin, 1967), Debonia Schallreuter, Kanygin et Hinz-Schallreuter, 1999, Fissebonia Schallreuter, Kanygin et Hinz-Schallreuter, 1999, Lenatella Melnikova, 1976, and Nicolina Kolosnitsyna, 1984. This family composition was mainly based on a particular type of dimorphism that Schallreuter et al. (1999) stated was possessed by all of these genera and called ‘egorovellid’. However, this point of view cannot be supported, since the genera Debonia, Fissebonia, Lenatella, and Nicolina do not have one of the main criteria for egorovellids, namely, ridge-like lobes are not developed on
the lateral surface. The authors explained the absence of ribbed lobes in these genera by stating that egorovellids underwent evolutionary changes that led to the reduction of lobes and furrows, as, for example, in the nonsulcate genus Lenatella. The studi
Data Loading...
