Bittium agibelicum ( Zhizhchenko, 1936 )

Bittium agibelicum ( Zhizhchenko, 1936) View in CoL

Figs 3A–F View FIGURE 3

* Newtoniella dertobicarinata Sacco var. agibelica n. var. — Zhizhchenko 1936: 214, pl. 21, figs 31–33.

Newtoniella dertobicarinata Sacco var. agibelica Zhizhchenko— Strachimirov 1953: 71 , pl. 16, figs 14–15.

Newtoniella dertobicarinata Sacco var. agibelica Zhizhchenko— Volkova 1955: 49 , pl. 22, figs 12–13.

Newtoniella dertobicarinata Sacco var. agibelica Zhizhchenko— Zhizhchenko 1959: 253 , pl. 16, figs 32–34.

Newtoniella dertobicarinata Sacco var. agibelica Zhizhchenko— Zelinskaya et al. 1968: 165 , pl. 40, figs 13–14.

Newtoniella dertobicarinata agibelica Zhizh.— Bidzinashvili 1971: 52 , pl. 1, fig. 17.

Newtoniella dertobicarinata Sacco var. agibelica Zhizhchenko, 1936 — Volkova 1974: 91, pl. 11, figs 12–13.

Newtoniella dertobicarinata agibelica Zhizh.— Bidzinashvili 1975: 108 , fig. 8.

Bittium agibelicum (Zhizh.) View in CoL —Nevesskaya et al. 1986: 94.

Bittium (Bittium) kamyshlakense L. Iljina View in CoL , sp. nov. — Iljina 1993: 67, pl. 8, fig. 12 [non Iljina 1993 = figs 10–11].

Bittium (Bittium) kamyshlakense View in CoL L. Il’ina sp. nov.— Iljina 1994: 35, pl. fig. 8 [non Iljina 1993 = fig. 7].

Bittium View in CoL (?) agibelicum ( Zhizhchenko, 1936) View in CoL — Iljina 1993: 71, pl. 9, figs 1–3.

Cerithidium agibelicum ( Zhizhchenko, 1936) — Ilgar 2015: 69, text fig. 5(A), fig. 19.

Bittium agibelicum (Zhizhchenko) View in CoL — Guzhov 2015: 84.

Bittium agibelicum ( Zhizhchenko, 1936) View in CoL — Guzhov 2022: 23, pl. 4, figs 9–10, pl. 5, figs 7–16.

non Newtoniella dertobicarinata var. agibelica Zhizhchenko— Strachimirov 1960a: 287 , pl. 59, figs 27–30 [= Bittium orientale

( Andrussow, 1911)]. non Newtoniella dertobicarinata Sacco— Urbaniak 1974: 38 , pl. 3, fig. 9, pl. 19, fig. 13 [= Bittium sp. ]. non Newtoniella dertobicarinata agibelica Zhizh.— Kókay 1985: 94 , pl. 9, figs 14–15 [= Theodiscella biseriata ( Friedberg,

1914)].

Type material. Holotype, TSNIGR 171/11330 (former number 42183), illustrated in Zhizhchenko (1936, pl. 21, fig. 31), SL: 5.5 mm, MD: 2.2 mm, Fig. 3A View FIGURE 3 . Paratypes stored in TSNIGR Museum: 172/11330, illustrated in Zhizhchenko (1936, pl. 21, fig. 32); 173/11330, illustrated in Zhizhchenko (1936, pl. 21, fig. 33). All types from Lugovoe (formerly Agibel’) (Crimea), early Chokrakian, Middle Miocene.

Illustrated material. PIN no. 5794/69, SL: 8.4 mm, MD: 3 mm, Belaya River ( Russia), Figs 3B View FIGURE 3 1 –B View FIGURE 1 2 View FIGURE 2 . PIN 5794/68, Belaya River ( Russia), Middle Miocene, lower Chokrakian, Fig. 3C View FIGURE 3 . PIN, no. 5794/54, SL: 5.9 mm, MD: 1.9 mm, ravine Semikolennyi ( Russia), Fig. 3D View FIGURE 3 . PIN no. 5904/33, SL: 16.8 mm, MD: 4.8 mm, Cape Carta ( Turkey), Figs 3E View FIGURE 3 1 –E View FIGURE 1 2 View FIGURE 2 . PIN no. 5794/71, SL: 8.3 mm, MD: 2.5 mm, Cape Tarkhan (Crimea), Figs 3F View FIGURE 3 1 –F View FIGURE 1 2 View FIGURE 2 .

Additional material. See Guzhov (2022: 25).

Revised description. Small, slender shell of 8–13 teleoconch whorls, typically 9–12 mm, rarely up to 16–17 mm in height; apical angle 20–25°. Protoconch low conical of 2.5 smooth convex whorls. Teleoconch whorls with steep, very broad, slightly concave subsutural ramp, marked angulation slightly below mid-whorl and distinct constriction at abapical suture. Suture linear, weakly incised. Adapical spiral cord more prominent, placed slightly below mid-whorl, second cord midway between adapical cord and suture; third, weak spiral cord appearing just above suture. Axial ribs only on early teleoconch whorls, reduced to subobsolete ridges on later whorls; 14–17 on last whorl. Axial ribs indicated by small, spirally elongated tubercles on spiral cords. Microsculpture of spiral rows of tiny pustules in spiral interspaces visible only on early teleoconch whorls. Later whorls only with indistinct microscopical spiral threads in spiral interspaces, tiny pits over cords. Last whorl strongly constricted, 35–38% of total height. Varices usually absent; occasionally one or two weak varices may appear on last one or two whorls; rarely, three varices may occur on last whorl. Base weakly convex, delimited by two prominent, widely spaced peribasal cords; two or three spiral cords over fasciole. Aperture low, wide ovate. Columella excavated. Columellar callus forming thin, narrow rim. Anal canal narrowly V-shaped. Outer lip thin. Siphonal canal short, very wide.

Discussion. The species probably derived from Bittium rossicum sp. nov. during the earliest Chokrakian ( Guzhov 2022). Bittium agibelicum differs from Bittium nabokovorum nom. nov., B. orientale ( Andrussow, 1911) (early Chokrakian) and B. badzoshviliae sp. nov. (early Maeotian) in its more slender, elongated shell with broad smooth subsutural ramp. This species was discussed in detail by Guzhov (2022).

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

Distribution. Restricted to the early Chokrakian of the Eastern Paratethys Sea.

Eastern Paratethys. Early Chokrakian (Middle Miocene): Turkey: Cape Bayram, Cape Carta, Ordu (Sinop District) (hoc opus); Bulgaria: Samotino ( Strachimirov 1953); Crimea: Bulganak, Lake Chokrak, Malyi Kamyshlak and Skelya sections, Cape Tarkhan, Yuzmyak place near Leninskoe, Cape Zyuk; Ciscaucasia : Khadyzhensk (Krasnodar Krai); Belaya and Fars rivers, ravine Semikolennyi (Adygea); Novo-Kuvinsk (Karachay-Cherkessia), Vorovskolesskoe (Stavropol Krai, Russia); Transcaucasia : Grmagele, Inashauri, Kinoti ( Georgia) ( Iljina 1993, Guzhov 2022, hoc opus).