Turritus Westerlund, 1883

Zallot, Enrico, Kamchev, Panche, Schilthuizen, Menno, Fehér, Zoltán, Mattia, Willy De & Gittenberger, Edmund, 2024, Cochlostoma Jan, 1830 revised: an overview of the subgenus Turritus Westerlund, 1883 and its species (Caenogastropoda, Cochlostomatidae), European Journal of Taxonomy 927, pp. 1-163 : 15-16

Subgenus Turritus Westerlund, 1883

Type species

Pomatias stossichi Hirc, 1881 (subsequent designation Wenz, 1923: 1781).

Diagnosis of the subgenus

The conical shell varies from 5.4 to 10.4 mm in height and has from 6.3 to 10 whorls, it is always ribbed, either spotless or with marked spots. The umbilicus is either hidden by an inwardly curved columellar lobe or visible. The protoconch is initially smooth and after 1.2–1.5 whorls finely ribbed. The columella is either solid or hollow. The operculum is thin, almost transparent and flexible. In the female genitals, the pedunculus of the bursa copulatrix and the seminal receptacle are superficial. The angle between the pedunculus of the bursa copulatrix and the distal oviduct is less than 45 degrees. In the male genitals, the penis is situated close to the right eye and has an internal spermiduct.

Differential diagnosis

Morpho-anatomical features which allow to distinguish Turritus from the other Cochlostoma subgenera (see also Zallot et al. 2015: 78):

• from Auritus : the operculum is thin and transparent in Turritus , with more or less developed concretions in Auritus ( Fig. 12A ). The protoconch is dull and strong in Turritus ; it is translucent and fragile in Auritus ;

• from Eupomatias Wagner, 1897: in the female genitals of Eupomatias, the proximal oviduct always runs over the apex of the elongated seminal receptacle, never as such in Turritus ( Fig. 12B );

• from Lovcenia : the protoconch is smooth in the first 1.5–2 whorls in Turritus , only the first 0.5 whorl in Lovcenia ( Fig. 12C );

• from Wagneriola Zallot et al., 2015 : the seminal receptacle is moved dorsally and there is a ventralanterior connection of the pedunculus to the bursa copulatrix in Wagneriola , never as such in Turritus ( Fig. 12D );

• from Cochlostoma s.s. and Clessiniella Zallot et al., 2015 : in the female genitals, the pedunculus is connected apically to the bursa copulatrix in Clessiniella and Cochlostoma s.s., never apical in Turritus ( Fig. 12E ).

No known morpho-anatomical features allow to distinguish with certainty the subgenus Dalfreddia Zallot et al., 2015 from Turritus ; however, they resolved in well-separated clades in the molecular analysis (see Fig. 11 ).

Distribution ( Fig. 13 )

The subgenus inhabits only rocky limestone soils. It is widespread along the Italian and Balkan peninsulas. It inhabits the most eastern and western parts of the Alps. West of the Alps, it is found in the southern coastal mountains of France and Spain. It inhabits the two main islands of the western Mediterranean, Sardinia and Sicily. One African species on the coast of Algeria probably also belongs to this subgenus. Clade A seems to be restricted to the Balkan and Italian Peninsulas and it is also present on the two main islands (Sicily and Sardinia) of the western Mediterranean Sea. It may be, however, that a species of this clade inhabits the south coast of France (see remarks in C. (T.) macei ( Bourguignat, 1870)) . Clade B is present both on the Balkan and Italian peninsulas. It is also found on the most western and eastern sides of the Alps and in the south coastal mountains of France and Spain. It is missing from the most parts of the Alps, which are inhabited on the calcareous south side by species of Eupomatias, Clessiniella and Dalfreddia ; it is not living in the Puglia region in South of Italy either, which is inhabited by species of Auritus (except on the Gargano peninsula which does not host, despite the favourable environment, populations of Cochlostoma ).

Remarks

No morphological synapomorphies of Turritus are known, but its monophyly is supported in the molecular phylogenetic analyses ( Zallot et al. 2015). Recognizing a species purely morphologically is often impossible without geographical information and molecular data. For this reason, classical dichotomous keys based on morpho-anatomical character states will not be presented.

Clade A

Note to clade A

In an unresolved polytomy at the root of clade A there are morphologically and anatomically almost indistinguishable taxa, namely the Slovenian C. (T.) stussineri ( Wagner, 1897) , in the currently accepted taxonomy as a subspecies of C. (T.) gracile (Pfeiffer, 1849) , C. (T.) patulum ( Draparnaud, 1801) for the South of France and, in a small area of the Central Appennine, populations referred to in the Appendix as NFS064.

Figures

Fig. 12. Morpho-anatomical features which allow to distinguish Turritus Westerlund, 1883 from other subgenera of Cochlostoma Jan, 1830.

Fig. 11. Maximum Likelihood consensus tree based on H3. Bootstrap support of the nodes is indicated.

Fig. 13. Distribution of the samples by clade: yellow =clade A; red = clade B; white =unknown clade.