Rissoa, Desmarest, 1814

Kowalke, Thorsten & Harzhauser, Mathias, 2004, Early ontogeny and palaeoecology of the Mid-Miocene rissoid gastropods of the Central Paratethys, Acta Palaeontologica Polonica 49 (1), pp. 111-134 : 113-114

Rissoa and Alvania in the Middle Miocene Paratethys

The evolution and development of Rissoa and Alvania during the Early Miocene of the Central Paratethys are largely unknown. This probably reflects poor preservation because the contemporaneous faunas of the Atlanto−Mediterranean Region yielded a considerably more diverse fauna (Sacco 1895; Cossmann and Peyrot 1919). Three species each are described from the Eggenburgian (early Early Miocene) of Austria and Bavaria ( Steininger 1963; Hölzl 1973) and from the Carpathian (late Early Miocene) of the Korneuburg Basin in Lower Austria (Harzhauser 2002).

Badenian (early Middle Miocene) faunas, however, indicate a marked increase in diversity.

Representatives of Rissoa display their acme in the Central Paratethys during the Badenian. Aside from the discussed species Rissoa turricula , R. clotho and R. acuticosta , additional taxa are described in the literature: R. sulzeriana Risso, 1826 , R. sobieskii Friedberg, 1923 , Turboella conoidea Baluk, 1975 , T. dilemma (Boettger, 1906) , T. hebes (Boettger, 1906) , T. johannae Boettger, 1901 , T. inconspicua Aldrovandi, 1648 (invalid name), T. podhorcensis ( Friedberg, 1923) , T. perparva ( Friedberg, 1923) , and T. dubiosa ( Friedberg, 1923) . The validity of these literature−based species may be debatable in certain cases. Rissoa turricula is the only species distributed throughout the Central Paratethys. Sarmatian representatives were described as Rissoa soceni Jekelius, 1944 , R. banatica Jekelius, 1944 , R. certa Svagrovský , R. gracilis Svagrovský , R. mucronata Svagrovský , and R. rugosa Svagrovský ( Svagrovský 1971) . This high number of taxa probably reflects oversplitting. In fact most of the ”species” may represent morphs of Rissoa turricula (cf. discussion in the systematic part). In the Eastern Paratethys, representatives of Rissoa are still mentioned from the Maeotian— Rissoa subinflata ( Andrusov, 1890) , R. ventricosa ( Desmarest, 1814) , and R. subangulata ( Andrusov, 1890) (Iljina et al. 1976) .

Twenty−eight species of Alvania are described from the Badenian of the Central Paratethys. In addition to the species described in this paper there occur: Alvania (Alvania) alta Bałuk, 1975 , A. (A.) brachia Boettger, 1901 , A. (A.) helenae Boettger, 1901 , A. (A.) productilis Boettger, 1906 , A. (A.) sublaevigata Boettger, 1906, A. (A.) tenuicosta Bałuk, 1975 , A. (A.) trochiformis Csepreghy−Meznerics, 1950 , A. (A.) holubicensis Friedberg, 1923 , and A. (A.) veliscensis Reuss, 1867 . Further species mentioned in the literature are: Alvania (Alvinia) alexandrae (Boettger, 1901) , A. (Alvinia) convexispira (Boettger, 1901) , A. (Alvinia) ellae (Boettger, 1901) , A. (Alvinia) hungarica ( Bohn−Havas, 1973) , A. (Alvinia) kowalewskii ( Bałuk, 1975) , A. (Alvinia) subzetlandica (Boettger, 1901) , Alvania (Acinus) reticulata ( Montagu, 1803) , Alvania (Arsenia) punctura ( Montagu, 1803) , Alvania (Turbona) giselae (Boettger, 1901) , Alvania (Turbona) subclavata (Boettger, 1906) , and Alvania (Turbona) subcrenulata ( Schwartz von Mohrenstern, 1864) . The subgeneric affiliation of these taxa was not checked within the frame of this paper.

The maximum diversity was achieved during the Early Badenian, as represented by the extraordinarily rich faunas of Korytnica ( Poland), Coştei, and Lăpugiu ( Romania). At that time the diversity of Alvania seems to have been considerably lower in the Eastern Paratethys, where only Alvania (Alvania) gontsharovae Iljina, 1993 and Alvania (A.) montagui Iljina, 1993 (non Payraudeau, 1826) were described from the Tarkhanian to Konkian of southern Russia /Eastern Paratethys ( Iljina 1993).

None of the manifold Badenian Alvania spp. passes the Badenian/Sarmatian boundary in the Central or the Eastern Paratethys. Whilst the environments of Lake Pannon (cf. Harzhauser et al. 2002) in the former Central Paratethys excluded any resettlement by Alvania during the Late Miocene, at least two species managed to enter the Eastern Paratethys in the contemporaneous Maeotian: Alvania (A.) montagui ( Payraudeau, 1826) , Alvania pseudalvania pseudalvania ( Andrusov, 1905) , and Alvania pseudalvania raricostata Iljina, 1976 from Southern Russia and Ukraine (Iljina et al. 1976).