Trigonostoma exgeslini ( Sacco, 1894 )

Harzhauser, Mathias & Landau, Bernard, 2012, A revision of the Neogene Cancellariid Gastropods of the Paratethys Sea 3472, Zootaxa 3472, pp. 1-71 : 58

Trigonostoma exgeslini ( Sacco, 1894)

Figs 3W, 11A 1–A 3, 11B 1–B 3

Cancellaria Geslini Bast. —Hörnes 1854: 320, pl. 35, figs. 3a–c [non Cancellaria Geslini Basterot, 1825 ].

Cancellaria (i. Trigonostoma ) Geslini Bast.— Hoernes & Auinger 1890: 277 [non Cancellaria Geslini Basterot, 1825 ].

Trigonostoma ampullaceum Brocc. — Friedberg 1914: 250, pl. 15, fig. 13 [non Voluta ampullacea Brocchi, 1814 ].

Cancellaria (Gulia) Geslini forma exgeslini Sacco, 1894: 22 .

Cancellaria (Trigonostoma) exgeslini Sacco — Sieber 1936: 85.

Cancellaria (Trigonostoma) spinifera Grat. — Csepreghy-Meznerics 1950: 58, pl. 3, fig. 13 [non Scalptia spinosa ( Grateloup, 1827) ].

Cancellaria (Trigonostoma) spinifera Grateloup (1832) 1845 — Strausz 1966: 377, pl. 45, fig. 14 [non Cancellaria spinosa Grateloup, 1827 )].

Cancellaria (Trigonostoma) gradata Hörnes — Kókay 1966: 9, fig. 10.

Trigonostoma exgeslini Sacco, 1894 — Bałuk 1997: 45, pl. 15, figs 6–7.

non Cancellaria (Trigonostoma) exgeslini Sacco — Csepreghy-Meznerics 1950: 58, pl. 3, fig. 16 [?= Cancellaria imbricata

Hörnes, 1854].

Type material. NHM Vienna ( Austria); see below for details .

Studied material. 2 spec. Grund ( Austria) NHMW 1868 /0001/0229; 4 spec. Lăpugiu de Sus ( Romania) NHMW 1875 /0009/0027.

Illustrated material. Fig. 3W: Lăpugiu de Sus ( Romania), height: 24.9 mm, width: 16.7 mm, NHMW 1878 / 0009/0027. Figs 11A 1–A 3: syntype illustrated in Hörnes (1854, pl. 35, figs 3a–c), Grund ( Austria), height: 36.4 mm, width: 24.4 mm, NHMW 1868 / 0001/0229. Figs 11B 1–B 3: Grund ( Austria), height: 28.9 mm, width: 25.0 mm, NHMW 1868 /0001/0229.

Description: A very characteristic species with moderately high and gradate spire, which starts with a cancellate sculpture and regularly convex whorls grading rapidly into strongly scalate, nearly straight-sided whorls with wide spaced axial ribs and narrower spiral cords. The growth of the last two whorls is strongly allometric resulting in a rapidly widening sutural shelf, which is ornamented by wide spaced, prominent, prosocline axial ribs. The spiral cord at the sharply angulated shoulder is slightly raised and forms the outer rim of the sutural shelf. The last whorl contracts rapidly below the shoulder causing a nearly trigonal, conical outline. The allometric growth is also expressed by a rapidly widening and very deep umbilicus. A weak, oblique third fold may appear rarely below the two prominent columellar folds. The lecithotrophic type protoconch consists of about 2.25 whorls and a mediumsized nucleus.

Discussion. This morphology has little in common with the more elongate, less angulated and narrowly umbilicate Gulia geslini ( Basterot, 1825) , as described by Cahuzac et al. (2004). Thus, the separation from that French Burdigalian species as proposed by Sacco (1894) is fully justified.

Only Trigonostoma pseudoumbilicare Peyrot, 1928 , from the Early Miocene of the Aquitaine Basin, is reminiscent of T. exgeslini . It differs, however, in its low spire, broad shell, wider umbilicus and the convex last whorl.

Distribution. Paratethys —Badenian: Polish–Carpathian Foredeep ( Poland: Korytnica); North Alpine Foreland Basin ( Austria: Grund); Vienna Basin ( Austria: Steinebrunn, Bad Vöslau); Eisenstadt–Sopron Basin ( Austria: Forchtenau); Pannonian Basin ( Hungary: Hidas, Herend), Transylvanian Basin ( Romania: Lăpugiu de Sus). Proto – Mediterranean Sea —Late Serravallian–Early Tortonian: Karman Basin ( Turkey, BL collection).