Trigonostoma extractrix ( Boettger, 1906 )

Harzhauser, Mathias & Landau, Bernard, 2012, A revision of the Neogene Cancellariid Gastropods of the Paratethys Sea 3472, Zootaxa 3472, pp. 1-71 : 56

Trigonostoma extractrix ( Boettger, 1906)

Figs 6E 1–E 2

Discohelix (Pseudomalaxis) extractrix Boettger, 1906: 138 .

Ps. extractrix Boettger —Cossmann 1915: 143, pl. 12, figs 25–26. [within chapter Pseudomalaxis s. stricto]

Pseudomalaxis extractrix (Boettger) — Zilch 1934: 219, pl. 7, fig. 23.

non Trigonostoma (Trigonostoma) extractrix ( Boettger, 1906) — Janssen 1984a: 20, pl. 2, fig. 16, pl. 6, fig. 4 [=?].

non Trigonostoma (Trigonostoma) extractrix ( Boettger, 1906) — Janssen 1984b: 260, pl. 66, figs 6–7 [=?].

non Trigonostoma (Trigonostoma) extractrix ( Boettger, 1906) — Wienrich, 2001: 516, pl. 107, fig. 2 [=?].

non Trigonostoma (Extractrix) extractrix ( Boettger, 1906) — Moths & Tüxen, 2008: 106, pl. 9, fig. 1 [=?].

non Trigonostoma (Extractrix) extractrix ( Boettger, 1906) — Moths et al. 2010: 77, pl. 22, fig. 4 [=?].

Type material. SMF Frankfurt ( Germany); see below for details .

Illustrated material. Figs 6E 1–E 2: specimen illustrated in Zilch (1934, pl. 7, fig. 23), Lăpugiu de Sus ( Romania), width: 5.2 mm (paralectotype, SMF XII 2576 b) .

Discussion. This species is the type species of Extractrix Korobkov, 1955 . The status of this genus is questionable. Its species form a morphological but not necessarily a monophyletic group and may simply represent uncoiled species of Trigonostoma .

Ronald Janssen (Senckenberg Museum, Frankfurt; pers comm.) stated that the only well preserved specimen from the original suite of Boettger (1906) was borrowed by Cossmann, who illustrated the specimen in his Paléoconchologie Comparée in 1915. This specimen was never returned to Frankfurt. Erroneously, Zilch (1934) treated this specimen as holotype, although it was clearly a syntype. Therefore, it has to be considered as lectotype (ICZN 74.6), whilst the fragmentary specimen, illustrated by Zilch (1934) and herein, is a paralectotype.

A.W. Janssen (1984 a, 1984b) considers also the Burdigalian–Langhian shells from the North Sea Basin to be conspecific with Extractrix extractrix . The North Sea specimens, however, are slender, with high whorls and their flanks are less steeply inclined. Judging from the illustrations, the aperture of the North Sea species is higher and the Paratethyan species lacks the strong spines on the angulation. Therefore, we suggest separating both taxa at species level. The Burdigalian Trigonostoma protrigonostoma ( Sacco, 1894) differs from both species in its “normally” coiled early spire and the very prominent axial ribs and spines.

Distribution. This species is extremely rare and known so far only from the early Badenian of the Transylvanian Basin.

Paratethys —Badenian: Transylvanian Basin: Romania (Lăpugiu de Sus).