Hemicerithium caucasicum, Harzhauser & Guzhov & Landau, 2025

Hemicerithium caucasicum sp. nov.

Figs 66A–F View FIGURE 66

Cerithium (Hemicerithium) banaticum (Boettger, 1901) — Iljina 1993: 82, pl. 10, figs 16–18 [non Hemicerithium banaticum ( Boettger, 1902) View in CoL ].

Type material. Holotype. PIN 5904 View Materials /66, SL: 14 mm, MD: 7 mm, Cape Carta ( Turkey), early Chokrakian, Figs 66A View FIGURE 66 1 –A View FIGURE 1 2 View FIGURE 2 . Paratypes. PIN 5904 View Materials /67, SL: 12.8 mm, MD: 5.6 mm, Malyi Kamyshlak (Crimea), early Chokrakian, Fig. 66B View FIGURE 66 . PIN 5904 View Materials /68, SL: 8.5 mm, MD: 4.8 mm, Lake Chokrak (Crimea), early Chokrakian, Fig. 66C View FIGURE 66 . PIN 5904 View Materials /69, SL: 6.4 mm, MD: 3.6 mm, Belaya River ( Russia), early Chokrakian, Figs 66D View FIGURE 66 1 –D View FIGURE 1 2 View FIGURE 2 . PIN 5904 View Materials / 70, Belaya River ( Russia), Middle Miocene, early Chokrakian, Fig. 66E View FIGURE 66 . PIN 5904 View Materials / 71, Arabadurağı ( Turkey), Middle Miocene, Tarkhanian, Fig. 66F View FIGURE 66 .

Type locality. Cape Carta ( Turkey, Sinop District) .

Type stratum. Sandy aleurite.

Age. Middle Miocene, early Chokrakian (Langhian).

Etymology. Referring to the occurrence of this species in the Caucasus region.

Diagnosis. Small, moderately slender conical shell with bicarinate early teleoconch whorls and convex later whorls, with strongly reduced axial sculpture; spiral sculpture of two close-set primary spiral cords and numerous delicate secondary cords and threads.

Description. Small (12–14 mm), conical shell of nine to ten teleoconch whorls; apical angle 32–40°. Protoconch of 2.5 convex and smooth whorls, with deep sinusigera (dp = ~320 μm). First spiral cord appears at mid-whorl from beginning of teleoconch, forming keel on first three to four teleoconch whorls. Second spiral cord appears half whorl later, attaining strength of first cord after fourth whorl. Subsequent whorls bicarinate, with two prominent cords; adapical placed mid-whorl, except for last 2–2.5 whorls with convex periphery. Numerous close-set secondary spiral cords and threads of variable strength, separated by narrow grooves. Axial sculpture strongly reduced, visible on early teleoconch whorls as narrow swellings around first spiral cord, only occasionally reaching across entire whorl. Last whorl evenly convex, attaining ~50% of total height, densely covered by cords variable in thickness, often with the two primary spiral cords slightly more prominent. Base convex, covered by slightly weaker and more wide-spaced cords. Aperture wide, ovate. Columella excavated. Columellar callus forming narrow rim. Anal canal indistinct. Outer lip thin, smooth. Siphonal canal short, very wide.

Discussion. This species was identified by Iljina (1993) as Hemicerithium banaticum ( Boettger, 1902) , which has a comparable outline, but differs in its much stronger varices and undulating suture. Hemicerithium caucasicum sp. nov. is reminiscent of H. evae ( Boettger, 1902) , from which it differs in its reduced axial sculpture, the prominent primary spiral cords, and the convex whorls. Iljina illustrated subadult shells (1993: pl. 10, figs 16, 18) with a single small figure of probably adult shell (pl. 10, fig. 17).

This species is frequently found in coarse grained shallow water sediment of the Eastern Paratethys, but the shells are usually fragmented (own data A.G.). Therefore, complete, fully grown shells are rare and little information on its morphological variability is available.

Paleoenvironment. Shallow marine, inner neritic (own data A.G.).

Distribution. Tarkhanian and early Chokrakian of the Eastern Paratethys.

Eastern Paratethys. Tarkhanian (Middle Miocene): Turkey: Arabadurağı (Sinop District) (hoc opus); Ciscaucasia : Damanka, Khadyzhensk, Kutais, Shirvanskaya (Krasnodar Krai, Russia) ( Iljina 1993; hoc opus). Chokrakian (Middle Miocene): Turkey: Cape Carta (Sinop District) (hoc opus); Crimea: Lake Chokrak, Leninskoe (place Yuzmyak), Malyi Kamyshlak, section Skelya, Cape Tarkhan, Cape Zyuk; Ciscaucasia : Belaya, Fars and Kurdzhips rivers, ravine Semikolennyi (Adygeya), Kutais, Shirvanskaya (Krasnodar Krai), ravine Yaman-Dzhalga (Stavropol Krai, Russia); Transcaucasia : Dzhgali ( Georgia) ( Iljina 1993; hoc opus).