Turbonilla s.l. sp. 4, Risso, 1826

Thivaiou, Danae, Harzhauser, Mathias & Koskeridou, Efterpi, 2019, Early Miocene Gastropods from the Felli Section (Proto-Mediterranean Sea NW Greece), Geodiversitas 41 (8), pp. 323-366 : 357

Turbonilla s.l. sp. 4

(Fig. 9 D1-D3)

MATERIAL EXAMINED. — Sample F11: AMPG ( IV) 2586-2593 (eight incomplete specimens).

DIMENSIONS. — Maximum height: 1.85 mm; maximum width: 0.75 mm.

DISTRIBUTION. — Early Miocene. Proto-Mediterranean Sea: Greece (this paper).

DESCRIPTION

Elongated, turreted shell, apex missing. Longest teleoconch recovered bears six almost flat whorls; sutures linear, faintly impressed; axial sculpture consists of 6-7 flat almost orthocline ribs, spaces between ribs are smooth. Base smooth; aperture sub-rectangular, columellar fold moderately developed, outer lip straight.

REMARKS

This is the largest species of Turbonilla , with a maximum width of 0.75 mm; all of the shells recovered are incomplete. Some type A protoconchs recovered could be attributed to this species although not with certainty (incomplete specimens with only one teleoconch whorl). The ribs have a curved and opisthocline structure (not sigmoidal) which is more prominent in the first teleoconch whorls.

Since the present material is incomplete it cannot be attributed with certainty to a species, although it shares many similarities with T. ( Turbonilla ) gastaldi auct. (non Semper, 1861) (A.W. Janssen 1984; Landau et al. 2013) in terms of sculpture and shape of the aperture. It differs from T. spiculoides in having less inflated whorls and a flatter axial sculpture. Turbonilla cf. superstructa Boettger, 1907 from the Serravallian of Turkey ( Landau et al. 2013) has a comparably elongated shell yet with more convex whorls.

Acknowledgements

This research was supported by SYNTHESYS project FR- TAF-6608. Valuable comments were provided by Dr Pierre Lozouet (Muséum national d’Histoire naturelle, Paris) and Luc Dolin (Civray-de-Touraine, France). Special thanks to Mr Nikos Baharidis for suggesting sampling locations.The authors are grateful to Dr Andreas Kroh (Natural History Museum Vienna) and Dr Paolo G. Albano (University of Vienna) for acquisition of SEM photographs; Lilian Cazes (Muséum national d’Histoire naturelle, Paris) for acquisition of UV photographs. Finally, we thank Bernard M. Landau and Stefano Dominici for their constructive comments that helped improve the quality of the manuscript.

This work is part of the Ph.D. thesis of Danae Thivaiou, P.I. Efterpi Koskeridou.

Figures

FIG. 9. — A1-A3, Turbonilla (s.l.) sp. 1, AMPG(IV) 2580; B1-B3, Turbonilla (s.l.) sp. 2, AMPG(IV) 2583; C1, C2, Turbonilla (s.l.) sp. 3, AMPG(IV) 2584; D1-D3, Turbonilla (s.l.) sp. 4: D1, AMPG(IV) 2586 (SEM image); D2, D3, AMPG(IV) 2687. Scale bars: 500 µm.