Turricaspia lyrata (B. Dybowski & Grochmalicki, 1915)

Neubauer, Thomas A., Velde, Sabrina van de, Yanina, Tamara & Wesselingh, Frank P., 2018, A late Pleistocene gastropod fauna from the northern Caspian Sea with implications for Pontocaspian gastropod taxonomy, ZooKeys 770, pp. 43-103 : 43

Turricaspia lyrata (B. Dybowski & Grochmalicki, 1915) Fig. 12A-K

Turricaspia lyrata *1915 Micromelania (Turricaspia) spica Eichw. var. lyrata nov. var.; B. Dybowski & Grochmalicki: 117, pl. 2, fig. 18.

Turricaspia lyrata 1915 Micromelania (Turricaspia) spica Eichw. var. incisata nov. var.; B. Dybowski & Grochmalicki: 117, pl. 2, fig. 19.

Turricaspia lyrata 1915 Micromelania (Turricaspia) spica Eichw. var. striata nov. var.; B. Dybowski & Grochmalicki: 117, pl. 2, fig. 20.

Turricaspia lyrata 1917 Micromelania (Turricaspia) spica Eichw. var. lyrata nov. var. - B. Dybowski & Grochmalicki: 17, pl. 3, fig. 25.

Turricaspia lyrata 1917 Micromelania (Turricaspia) spica Eichw. var. incisata nov. var. - B. Dybowski & Grochmalicki: 18, pl. 3, fig. 26.

Turricaspia lyrata 1917 Micromelania (Turricaspia) spica Eichw. var. striata nov. var. - B. Dybowski & Grochmalicki: 18, pl. 3, fig. 27.

Turricaspia lyrata 1969 Pyrgula [( Turricaspia )] Pyrgula lirata [sic] (Dyb. et Gr.). - Logvinenko & Starobogatov: 365, fig. 362 (2).

Turricaspia lyrata 2006 Pyrgula lirata [sic] (B. Dybowski et Grochmalicki, 1915). - Kantor & Sysoev: 101, pl. 46, fig. E.

Turricaspia lyrata 2016 Pyrgula lirata [sic] (B. Dybowski et Grochmalicki, 1915). - Vinarski & Kantor: 240.

Material.

562 specimens ( RGM 1309802 , RGM 1309825 , RGM 1310209 , RGM 1310213 , RGM 1310214 , RGM 1310216 , RGM 1310218 -1310220, LV 201512 , LV 201513 ) .

Type material.

Lectotype: ZIN 4552 /1 (specimen illustrated by B. Dybowski and Grochmalicki 1915, 1917), designated by Logvinenko and Starobogatov (1969), illustrated by Kantor and Sysoev (2006: pl. 46, fig. E).

Type locality.

Caspian Sea (no locality specified).

Dimensions.

7.68 × 2.59 mm ( RGM 1310213, Fig. 12A-C ); 7.99 × 2.42 mm ( RGM 1310220, Fig. 12D ); 7.34 × 2.28 mm ( RGM 1310214, Fig. 12E ); 7.54 × 2.50 mm ( LV 201512, Fig. 12F ); 6.87 × 2.43 mm ( LV 201513, Fig. 12G-I ); 7 × 2.52 mm ( RGM 1310218, Fig. 12J ).

Description.

Slender elongate shell of up to 9 whorls. Protoconch large, measuring about 485 µm in diameter; it forms bulbous cap on top of shell and comprises 1.25 whorls; surface weakly granulate, with striae on last 0.25 whorls; nucleus low, broad, ca. 170 µm in diameter; P/T transition very distinct, marked by sharp growth cessation. Teleoconch whorls low to moderately convex, often flattened or with straight-sided upper half, which creates spruce-like morphology. Sometimes, very weak and thin bulge appears below suture, producing faintly stepped spire. Most shells bear very low and somewhat irregular spirals, but expression varies considerably concerning its onset (mainly starts on lower whorls), strength (faint traces to distinct but blunt keels) and number of elements (one keel near base to several keels spread across whorl profile). Expression of sculpture varies in most specimens throughout ontogeny, which creates uneven, rugged appearance. Aperture comparatively small, in most cases regularly ovoid and weakly inclined, covering up umbilicus entirely or leaving very thin opening; peristome simple. Growth lines strongly sigmoidal, with prosocline upper third and opisthocline lower two-thirds.

Discussion.

This species can be distinguished from its congeners in its large, bulbous protoconch and the typical, somewhat irregular sculpture. It is consistently larger, more massive and on average bears much stronger sculpture than co-occurring T.? spica . The varieties " Micromelania (Turricaspia) spica var. incisata " and " M. (T.) spica var. striata " introduced by B. Dybowski and Grochmalicki (1915) only differ in the depth of the suture and the expression of the teleoconch sculpture, respectively. Given the variability of these features, we consider both of them synonymous with T. lyrata . Already Logvinenko and Starobogatov (1969) considered Micromelania incisata and Turricaspia lyrata synonymous and, as first revisers, chose Turricaspia lyrata as the valid name of the species. The variety " M. (T.) spica var. lLittorinimorphasa " B. Dybowski & Grochmalicki, 1915 might also be a synonym of this species. However, the apex of the specimen illustrated in B. Dybowski and Grochmalicki (1915, 1917), which contains diagnostic characters, is not preserved. Nevertheless, Micromelania striata and Micromelania lLittorinimorphasa are certainly not synonymous with T. andrussowi as suggested by Logvinenko and Starobogatov (1969). That species differs from T. lyrata in the much slender whorls with spruce-like, near straight-sided profile.

Distribution.

Endemic to the Caspian Sea (after Logvinenko and Starobogatov 1969, it occurs in the western part of the middle and southern Caspian Sea at a depth of 25-50 m; mind however that these authors used a slightly different concept of the species).

Figures

Figure 12. Pyrgulinae. A-C Turricaspia lyrata (B. Dybowski & Grochmalicki, 1915), RGM 1310213 D T. lyrata, RGM 1310220 E T. lyrata, RGM 1310214 F T. lyrata, LV 201512 G-I T. lyrata, LV 201513 J T. lyrata, RGM 1310218 K T. lyrata, RGM 1309802.