Mesoleptostrophia (Mesoleptostrophia) Harper and Boucot, 1978

Musteikis, Petras & Cocks, L. Robin M., 2004, Strophomenide and orthotetide Silurian brachiopods from the Baltic region, with particular reference to Lithuanian boreholes, Acta Palaeontologica Polonica 49 (3), pp. 455-482 : 464

Mesoleptostrophia (Mesoleptostrophia) Harper and Boucot, 1978

Remarks.—The type species of this long−lived genus, which lasted from the Aeronian to the Middle Devonian, is M. (M.) kartalensis from the Emsian of Turkey. Species attributed to the genus from Baltica include Mesoleptostrophia (M.) filosa (J. de C. Sowerby, 1839) , originally described from the Wenlock of England, but identified by Bassett and Cocks (1974: 15) from the Wenlock and Lower Ludlow of Gotland, and “ Leptostrophia? filosa ?” lata Holtedahl, 1916, from the Wenlock of the Oslo Region, Norway ( Harper and Boucot 1978: 68). Rubel et al. (1984) listed Leptostrophia compressa from the East Baltic without giving details of any localities—the species is known only from the Aeronian and Telychian of Wales and the Welsh Borderland ( Cocks 1967). Sokolskaya (1954: 40) also described and illustrated forms which she determined as Rafinesquina compressa ( Davidson, 1871) from the Aeronian Raikküla Beds of Estonia, but without figuring interiors—these forms may possibly be true Mesoleptostrophia , but their identification as R. compressa cannot be confirmed. Gagel (1890: 43) erected Strophomena lindströmi from the glacial erratic boulders of the north German plain, but without illustrating interiors: its age and generic affinity are unknown, and therefore we treat the species as a nomen dubium. However, Sokolskaya (1954) identified and illustrated what she determined as S. lindströmi from the Aeronian Raikküla Beds of Estonia, but again she did not illustrate interiors—from the pictures of the exteriors her specimens appear more likely to be attributable to the orthotetoid Coolinia . In the Lithuanian boreholes we have identified Mesoleptostrophia (M.) sp. ( Fig. 5G) from the Birštonas Formation (Sheinwoodian and Homerian) in east Lithuania, the top of the Jūrmala (Telychian), Riga and Gėluva formations (Sheinwoodian and Homerian) in central Lithuania, and the Dubysa, Rusnė, Mituva, Pagėgiai (Gorstian and Ludfordian) formations and the Šilalė Beds of the Minija Formation (Lower Pridoli) in west Lithuania (Appendix).