Clausilioides palatalis, 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 : 19

Clausilioides palatalis spec. nov. ( Figs 12-13 )

Type locality & type material. – Turkey, Vilayet Artvin, 4.3 km NE. Narlık, 400 m (41.0022° N 41.7697° E), H.P.M.G. Menkhorst leg., 6.ix.2010. Holotype NMBE 544676, paratypes NMBE 544677/1, HMK/5+4 juveniles.

Diagnosis. – A small, turreted, Clausilioides species with a prominent palatal fold that can be seen in the aperture as it almost reaches the peristome.

Description. – Shell dextral, turreted in outline, with a narrow, slit-like umbilicus. The 10.2-11.6 whorls are moderately convex with a moderately deep suture. Teleoconch with irregular, fine, oblique striae; there are no spiral striae. Shell rather thin, translucent, glossy, uniformly corneous coloured, with a whitish band behind the peristome. Aperture rounded, horny yellowish on the inside, peristome reflected and well thickened by a labial callus (which is mostly slightly coloured). Columellar and palatal insertion connected by a well developed parietal callus; it thickens even more at both ends. The parietal callus generates at the palatal end a subangularis , which is connected to the palatal insertion of the peristome by a mostly weakly developed callus. There is a broad, indistinct thickening at the position of the palatalis superior. The oblique columellar ledge reaches to about halfway of the columellar side of the aperture. There is a prominent palatal fold in the last whorl which is visible as a well delineated whitish band through the shell. It is fully visible in the aperture, as it stops closely in front of the thickened labial callus of the palatal peristome. The palatal fold reaches into the last part of the penultimate whorl, or stops in between the insertion of the columellar and palatal peristome. Interestingly, the palatal fold is partially enlarged towards the penultimate whorl, forming a ridge-like structure.

Measurements (n = 5). – H = 8.2-10.3 (mean 9.1); LWH = 3.3-3.5 (mean 3.4); HM = 2.0-2.2 (mean 2.1); LWD = 2.2-2.4 (mean 2.3); LWM = 2.2-2.6 (mean 2.4); MD = 1.7-1.8 (mean 1.7); NW = 10.2-11.6 (mean 10.7).

Localities. – Vilayet Artvin: type locality (see above); rocks 1.5 km N. Narlık (40.9993°N 41.7829°E) (HMK/1).

Derivatio nominis. – Named after the palatal fold in the aperture, a rather unique character in the Enidae .

Differentiation. – Clausilioides berendinae has a fusiform shape (not turreted), it has different dimensions, the columellar ledge is curled and more prominent, the parietal callus is more prominent, the aperture is generally more oval, and the palatal fold does not run to the peristome and does not show a ridge-like structure. Clausilioides filifer ( Fig. 11) is more fusiform in outline, but most importantly, the palatal fold is located deep in the last whorl, and can therefore hardly been seen in the aperture (see also Lindholm, 1913: 22 "in der Mündung nur bei sehr schiefen Einblick sichtbar"). It is not known whether the palatal fold in C. filifer has a ridge-like structure.

Remarks. – Clausilioides filifer has been described on the basis of a single shell which was picked from deposition of the Çoruh Nehri near Kapandidi. This is most likely Maradidi in Georgia, located a few km north of the Turkish border (see also under Multidentula squalina acutior ). It is not known whether the species actually lives in Georgia, or whether the shell has been transported from Turkey by the Çoruh river. The holotype of C. filifer has been figured by Sysoev & Schileyko (2009: fig. 23F). We have seen three specimens of C. filifer collected in the Vilayet Artvin, crossing Artvin/Şavşat/Demirkent, 17 km towards Yusufeli, near the suspension bridge over the Çoruh Nehri (Neubert leg.).

Figures

Figs 10 - 13. Clausilioides taxa from Turkey. 10, Clausilioides berendinae spec. nov., holotype NMBE 544672 (H = 15.1 mm), Turkey, Vil. Artvin, 1 km W. Ardanuç. 11, Clausilioides filifer (Lindholm, 1913), NMBE 544602 (H = 9.9 mm), Turkey, Vil. Artvin, crossing Artvin / Şavşat / Demirkent, 17 km towards Yusufeli, near suspension bridge over the Çoruh Nehri, leg. Neubert, 4. v. 1993. 12 - 13, Clausilioides palatalis spec. nov., holotype NMBE 544676 (H = 10.2 mm), Turkey, Vil. Artvin, 4.3 km NE. Narlık.