Megavitrina, Ruud, A. Bank, Henk P. M. G Menkhorst & Eike Neubert, 2016

Ruud, A. Bank, Henk P. M. G Menkhorst & Eike Neubert, 2016, Descriptions of new and little-known land snail taxa from Turkey, and establishment of a new genus (Gastropoda, Pulmonata: Lauriidae, Enidae and Vitrinidae), Basteria 80 (1), pp. 5-30 : 25-26

Megavitrina gen. nov. ( Figs 21-23 )

Type species. – Megavitrina imperatoria spec. nov. (by original designation).

Diagnosis. – Shell big (maximum diameter> 13 mm), orthostyl, with a closed umbilicus because of a reflexed (thickened) columellar peristome, and with a lacking membranous margin. Especially characteristic for the genus is the presence of 2 to 3 prominent growth interruptions.

Derivatio nominis. – Named after the large size of the two currently known species when compared to the Vitrinidae taxa living in continental Europe.

Differentiation. – Taxa of Arabivitrina have a more dome-shaped, subglobose shell, and lack the characteristic prominent growth interruptions.

Remarks. – It is well known that in some areas vitrinids occur with a relatively large shell, i.e, a shell with a maximum diameter above 11 mm. These areas are Macaronesia (Madeira, Canary Islands), Saudi Arabia, Yemen, and the eastern part of Africa. From a geographical point of view, the below discussed species of Lebanon and Turkey are most closely related to those of Saudi Arabia, i.e. Arabivitrina. Neubert (1998: 449) already discussed the new genus in the context of Arabivitrina, and stated that a separate genus should be introduced, but postponed it “until preserved specimens are available for anatomical research”. Unfortunately, no such material has become available in the meanwhile. Since shell morphology prohibits the assignment of libanica and imperatoria into Arabivitrina or any other genus, we decided to make a new genus name available, despite the lack of anatomical data.

A marked feature of the new genus is the presence of 2 to 3 very marked growth interruptions; it can also be seen at the inside of the aperture as a radially arranged, whitish, callus. As far as we known, this is a unique feature in the Vitrinidae . The robustness of the growth interruptions can be compared with those seen in the genus Eopolita Pollonera, 1916 (family Oxychilidae ).

Figures

Figs 21 - 23. Megavitrina from Turkey and Lebanon. 21, Megavitrina imperatoria spec. nov., holotype NMBE 548324 (D = 16.2 mm), Turkey, Vil. Adıyaman, under rocks on top of the Nemrud Dağ, 2150 m. 22 - 23, Megavitrina libanica (Germain, 1911), MNHN (D = 15.3 mm), labelled as “ Beyrouth? ”. All photographs Bochud & Neubert, × 5.