Bittium tulskajense Iljina, 1993

Bittium tulskajense Iljina, 1993 View in CoL

Figs 22A–J View FIGURE 22

Bittium digitatum Zhizhchenko— Zhizhchenko 1936 View in CoL : pl. 20, fig. 18 [non Bittium digitatum Zhizhchenko, 1934 View in CoL ].

? Turbonilla (Strioturbonilla) bulgarica sp. nov. — Manolov 1960: 304, pl. 2, figs 10–20.

Sandbergeria View in CoL (?) sp.— Özsayar 1977: 62, pl. 10, fig. 4.

* Bittium (Semibittium) multiliratum tulskajense L. Iljina , subsp. nov. — Iljina 1993: 69, pl. 8, figs 22–25.

Bittium (Semibittium) multiliratum tulskajense L. Il’jina, subsp. nov.— Iljina 1994: 36, pl. 1, fig. 9.

Bittium multiliratum tulskajense L. Ilyina— Goncharova et al. 2014: 251 , pl. 4, fig. 10.

Bittium multiliratum tulskajense Iljina, 1993 — Ilgar 2015: 69, text fig. 5(A), fig. 16.

Bittium reticulatum View in CoL ( da Costa, 1778)— Ilgar 2015: 69, text fig. 5(A), fig. 34 [non Bittium reticulatum View in CoL ( da Costa, 1778)]. Bittium multiliratum tulskajense L. Iljina— Guzhov 2015: 84 .

Bittium tulskajense L. Iljina, 1993 View in CoL — Guzhov 2022: 12, pl. 1, figs 1–14, pl. 2, figs 1–11, pl. 3, figs 6–8.

Type material. Holotype, PIN 4450 View Materials /184, SL: 7 mm, 2.6 MD: mm, Belaya River ( Russia), early Chokrakian, Middle Miocene, Figs 22C View FIGURE 22 1 –C View FIGURE 1 2 View FIGURE 2 .

Illustrated material. PIN 5794 View Materials /1, SL: 6.1 mm, MD: 2 mm, Shirvanskaya ( Russia), Tarkhanian, Middle Miocene, Fig. 22A View FIGURE 22 . PIN 5794 View Materials /7, SL: 5.8 mm, MD: 1.9 mm, Kutais ( Russia), Tarkhanian, Middle Miocene, Fig. 22B View FIGURE 22 . PIN 5794 View Materials /10, SL: 7.5 mm, MD: 2.1 mm, Shirvanskaya ( Russia), early Chokrakian, Middle Miocene, Figs 22D View FIGURE 22 1 –D View FIGURE 1 2 View FIGURE 2 . PIN 5794 View Materials /16, SL: 8 mm, MD: 2.4 mm, Belaya River ( Russia), early Chokrakian, Middle Miocene, Fig. 22E View FIGURE 22 . PIN 5794 View Materials /14, SL: 10.9 mm, MD: 3.4 mm, Belaya River ( Russia), early Chokrakian, Middle Miocene, Fig. 22F View FIGURE 22 . PIN 5794 View Materials /20, SL: 8.6 mm, MD: 2.7 mm, Mount Bryk ( Russia), early Chokrakian, Middle Miocene, Fig. 22G View FIGURE 22 . PIN 5794 View Materials / 12, Belaya River ( Russia), early Chokrakian, Middle Miocene, Figs 22H View FIGURE 22 1 –H View FIGURE 1 2 View FIGURE 2 . PIN 5794 View Materials /18, SL: 7.6 mm, MD: 2.4 mm, Otradnaya ( Russia), early Chokrakian, Middle Miocene, Fig. 22I View FIGURE 22 . PIN 5794 View Materials /37, SL: 7.5 mm, MD: 2.1 mm, Malyi Kamyshlak (Crimea), early Chokrakian, Middle Miocene, Fig. 22J View FIGURE 22 .

Revised description. Small to medium sized, slender conical shell of up to 12 teleoconch whorls, attaining 11–13 mm in height; apical angle 19–25°. Protoconch of 2.5 convex and probably smooth whorls, terminating in sinusigera (dp = 270 μm). Early teleoconch whorls bicarinate, convex; later whorls straight-sided, occasionally with weak angulation slightly above abapical suture. Suture shallow, narrowly incised. Beginning of first teleoconch whorl with two spiral cords placed mid-whorl and partly visible suprasutural cord. First secondary cord appears just below suture at end of same whorl. Second secondary cord appears below first secondary on third whorl. Later, secondary cords appear between these secondary and two upper primary cords. Axial sculpture subobsolete, represented in some specimens by indistinct swellings over ribs, its appearance strongly varies among intraspecific morphs. Later whorls weakly convex to nearly straight-sided with 6–9 weak, flattened primary and secondary spiral cords and threads separated by narrower to broader interspaces depending on number of spiral cords. Weak varices may developed on two last whorls. Last whorl weakly convex or rarely with faint peribasal angulation, moderately constricted, attaining 35–42% of total height, with rarely developed varices. Base with two widely spaced peribasal cords, not strengthened, four or five further cords over base and fasciole.Aperture ovate, moderately wide. Columella excavated. Columellar callus forming narrow rim. Anal canal indistinct. Outer lip thin with shallowly sigmoidal margin in lateral view. Siphonal canal very short and wide.

Synonyms. Turbonilla (Strioturbonilla) bulgarica Manolov, 1960 , from the Chokrakian of Bulgaria, might be the same species. In this case Bittium bulgaricum ( Manolov, 1960) would have priority over Bittium tulskajense Iljina, 1993 . Turbonilla (Strioturbonilla) bulgarica is reminiscent of shells described by Guzhov (2022) as shortlived ecological morph ‘ pseudodigitatum ’ of Bittium tulskajense . The whereabouts of the type material of Turbonilla (Strioturbonilla) bulgarica Manolov, 1960 is unknown and the illustrations do not illustrate the protoconch, which would be crucial for the placement in Turbonilla . Therefore, we refrain from synonymizing both species for now until new material of Turbonilla (Strioturbonilla) bulgarica becomes available.

Discussion. The variability of this species and its morphological evolution was discussed in detail by Guzhov (2022: 12). Bittium tulskajense Iljina, 1993 was established as subspecies of the coeval Bittium multiliratum Brusina, 1877 [= Bittium turritella ( Eichwald, 1851) ], which occurred in the Central Paratethys Sea. It differs from B. turritella in its more slender, more conical spire, the faintly angulated last whorl, the less incised suture and the weaker but more numerous flattened spiral cords that are not as clearly delimited as in B. turritella .

Paleoenvironment. Shallow marine, inner neritic based on the associated fauna (own data A.G.).

Distribution. Tarkhanian and early Chokrakian of the Eastern Paratethys Sea.

Eastern Paratethys. Tarkhanian (Middle Miocene): Turkey: Arabadurağı (Sinop District); Ciscaucasia : Damanka, Khadyzhensk, Kutais, Shirvanskaya (Krasnodar Krai, Russia); Transcaucasia : Naguru ( Georgia) ( Guzhov 2022). Early Chokrakian: Turkey: Cape Bayram, Cape Carta (location named as Carta-Burnu in Goncharova et al. 2014), Cape Bayram, Ordu (Sinop District) (hoc opus); Crimea: Bondarenkovo, Lake Chokrak, Malyi Kamyshlak, Skelya, Yuzmyak, Cape Zyuk; Ciscaucasia : Belaya, Fars and Kurdzhips rivers, Semikolennyi (Adygea), Novo-Kuvinsk (Karachay-Cherkessia), Otradnaya, Khadyzhensk, Kutais, Rubaily, Shirvanskaya (Krasnodar Krai), Mount Bryk, Yaman-Dzhalga (Stavropol Krai, Russia); Transcaucasia : Dzhgali ( Georgia); Transcaspian Region: Chelyungkyr Plateau ( Turkmenistan) ( Goncharova et al. 2014; Guzhov 2022; hoc opus).