Sigaretotrema exclathratum ( Sacco, 1891 )

Sigaretotrema exclathratum ( Sacco, 1891)

Figs 2Q View FIGURE 2 , 58C View FIGURE 58 1 –C View FIGURE 1 4 View FIGURE 4 , 59B View FIGURE 59

Sigaretus clathratus Récluz—Hörnes 1856: 515 , pl. 46, fig. 28 [ non Sinum clathratum ( Gmelin, 1791) View in CoL ].

Sigaretus clathratus Récl.— Schaffer 1912: 167 , pl. 54, figs 17–18 [ non Sinum clathratum ( Gmelin, 1791) View in CoL ].

* [ Sigaretotrema michaudi View in CoL ] exclathrata Sacc.— Sacco 1891: 97 [for Sigaretus haliotoideus sensu Hörnes 1856 View in CoL : pl. 46, fig. 28]. non Sinum michaudi exclathrata ( Sacco 1891) — Hölzl 1958: 214, pl. 19, fig. 8 [? = Sinum sp. ].

Type material. Holotype, NHMW 2013 View Materials /0053/0001, SL: 18.5 mm, MD: 19.8 mm, locality unknown, most probably from the Austrian part of the Vienna Basin, Badenian (Middle Miocene), see below for discussion on locality; illustrated in Hörnes (1856: pl. 46, fig. 28) and Schaffer (1912: pl. 54, figs 17–18), Figs 2Q View FIGURE 2 , 58C View FIGURE 58 1 –C View FIGURE 1 4 View FIGURE 4 , 59B View FIGURE 59 .

Revised description. Small, moderately fragile, auriculate shell of two teleoconch whorls, wider than high ( SL /MD = 0.9). Protoconch depressed of 1.5, weakly convex whorls, diameter ~750 μm. Spire broadly conical, with weakly convex whorls; apical angle 110°. Suture narrowly incised. Periphery far below mid-whorl (~24%). Sculpture of first teleoconch whorl of 12 narrow, convex spiral cords separated by interspaces of subequal width. Slightly weaker secondary and tertiary cords intercalated on last whorl. Spiral cords weakly wavy on early whorls, slightly granulose due to interruptions by growth lines on last whorl; becoming weak with flattish tops towards aperture. Last whorl strongly expanding, with very broad, weakly convex subsutural ramp, convex periphery placed mid-whorl. Last whorl attaining 96% of total height. Base broadly convex with distinct spiral sculpture of narrow, convex primary and secondary cords; growth lines weak. Aperture wide, ovate, strongly prosocline, attaining 76% of total height. No parietal callus. Columellar callus forming broad rim, narrowing umbilicus to deep, narrow chink (~5%). Basal lip and outer lip thin. No color pattern preserved.

Discussion. The holotype was described by Hörnes (1856) and Schaffer (1912) from the mid-Burdigalian locality Gauderndorf ( Austria) in the North Alpine-Carpathian Foreland Basin. The good preservation, however, excludes this provenance and the shell was most probably misplaced. Shells from Gauderndorf are usually leached and chalky. We assume that it derived from a Badenian (Middle Miocene) locality in the Vienna Basin. As already stated by Robba et al. (2016) Sigaretotrema exclathratum ( Sacco, 1891) differs from Sigaretotrema michaudi ( Michelotti, 1847) , from the Rupelian to Burdigalian of Italy, in having a protoconch of only 1.5 whorls (instead of three), a less globose teleoconch with a more expanding last whorl, a wider aperture, and a narrower umbilicus. The depressed, flattish protoconch and obtuse apex distinguish Sigaretotrema exclathrata also from Sigaretotrema vindobonense nov. sp., which is larger, has fewer secondary spiral cords and more regular sculpture. Sigaretotrema deshayesi ( Michelotti, 1847) , from the Early Miocene of the Colli Torinesi ( Italy), differs in its more globose shell, narrower aperture and wider umbilicus ( Robba et al. 2016: pl. 14, figs 7–8).

Paleoenvironment. Unknown.

Distribution in Central Paratethys. Unknown, most probably Badenian (Middle Miocene) of the Vienna Basin.