Astyris sarmatica ( Kojumdgieva, 1969 )

Harzhauser, Mathias & Landau, Bernard M., 2021, The Columbellidae (Gastropoda, Buccinoidea) in the Miocene Paratethys Sea — striking diversity of a negelected group, Zootaxa 5025 (1), pp. 1-75 : 59-61

Astyris sarmatica ( Kojumdgieva, 1969)

Figs 4G, 18A 1 –A 2

Columbella scripta Bell. — Laskarev 1903: 113, pl. 5, figs 24–25 [non Linnaeus, 1758].

Columbella scripta Bell. — Schaffer 1908: 50 [non Linnaeus, 1758].

Mitrella (Mitrella) cf. scripta (Linne) — Papp 1954: 50, pl. 9, fig. 19 [non Linnaeus, 1758].

Columbella (Mitrella) scripta L.— Moisescu 1955: 213, pl. 20, figs 12–14 [non Linnaeus, 1758].

Mitrella scripta (Bell.) — Boda 1959: 622, 718, pl. 29, figs 3–5 [non Linnaeus, 1758].

Mitrella scripta L.— Roshka 1964, pl. 2, figs 13–14.

Mitrella (Mitrella) bittneri Hoernes & Auinger — Kühn & Schaffer 1960: 75 [non Hoernes & Auinger, 1880].

Mitrella (Mitrella) scripta sarmatica subsp. n. — Kojumdgieva 1969: 115, 132, pl. 38, figs 10–13, pl. 39, figs 1–2.

Mitrella (Mitrella) scripta (Bellardi, 1849) — Švagrovský 1971: 379, pl. 66, figs 1–5 [non Linnaeus, 1758].

Mitrella (Mitrella) bittneri Hörn. et Auing. — Papp 1974: 349, pl. 2, fig. 26 [non Hoernes & Auinger, 1880].

Mitrella bittneri (Hoernes & Auinger) — Harzhauser & Piller 2010: 194 [non Hoernes & Auinger, 1880].

Mitrella sarmatica Kojumdgieva, 1969 —Harzhauser et al. 2017: 73, 104.

Type material. Holotype: Lipen at Mikhailovgrad ( Bulgaria), SL: 9.5 mm, MD: 4.1 mm, illustrated by Kojumdgieva (1969, pl. 38, figs 10a–b). We were not able to trace the whereabouts of this specimen.

Illustrated material. NHMW 2020/0156/0001, SL: 7.6 mm, MD: 3.1 mm, Kronberg ( Austria), illustrated by Papp (1954, pl. 9, fig. 19), Figs 4G, 18A 1 –A 2 .

Revised description. Shell small, fusiform, with weakly incised suture. Protoconch large, paucispiral of about two convex whorls. Teleoconch of six whorls, diameter increasing abapically. Early teleoconch whorls convex; convexity decreasing on later whorls, with periphery in abapical third of whorls. Last whorl moderately inflated, convex, rounded at periphery, moderately constricted at base. Shell surface smooth except for weak, broad spiral cords on siphonal fasciole. Aperture ovate. Outer lip thin, without denticles. Anal canal hardly developed. Siphonal canal moderately long, wide, shallow notched at tip. Columellar callus forming sharply delimited callus rim, detached from base; no columellar denticles. No parietal callus. Outer lip thin without denticles.

Shell measurements and ratios. SL: 7.6 mm, MD: 3.1 mm, AA: 41°, SL/MD: 2.4, AL/AW: 3.2, LWH/AH: 1.3.

Discussion. A thin outer lip and the lack of apertural dentition in columbellids is usually a sign of subadult state. However, all specimens illustrated in the literature show these same features, so we can say with relative certainty that a thickened lip and apertural dentition were lacking in adult specimens of this species. Therefore, shape and apertural features are reminiscent of Astyris H. Adams & A. Adams, 1853 . Cossmann (1901: 238) designated the extant A. rosacea ( Gould, 1840) as type species, which has a biconic shell profile, with paucispiral protoconch, moderately high and wide spire and spire whorls, which increase in convexity during ontogeny. Astyris rosacea is characterized by a wide and simple aperture with thin columellar callus and thin outer lip without dentition. Unfortunately, Cossmann (1901) included also the Pliocene Astyris communis ( Conrad, 1862) in his diagnosis of the genus, which has a thickened outer lip with eight prominent denticles within (Whitfield 1864: 110). Similarly, deMaintenon (2019: 169) provided a diagnosis based on several species, but emphasized that Astyris species are ‘typically lacking labial or parietal denticles or heavy callosities’ and stressed that most species have a paucispiral protoconch. The Paratethyan species agrees in these features with Astyris . Extant Astyris species occur in cold waters ( deMaintenon 2019), whereas A. sarmatica occurred in warm temperate waters. An occurrence in warm temperate waters, however, is also documented for an Astyris species from the Tortonian of northwestern France ( Landau et al. 2019). Alternatively, the Sarmatian species might represent a case of paedomorphosis of a Mitrella , in which adult species did not form apertural dentition. Such development could have been triggered by the environmental deterioration at the Badenian/Sarmatian boundary. Thus, our generic placement is tentative.

This species is one of the few examples of the marine relict fauna, which survived the Badenian-Sarmatian Extinction Event ( Harzhauser & Piller 2007). Initially, it was identified with the extant Mitrella scripta ( Linnaeus, 1758) (e.g., Laskarev 1903) from which it differs in its smaller size and wider apical angle and contracted base. Later, Kühn & Schaffer (1960) and Papp (1974) identified the Sarmatian species with Mitrella bittneri ( Hoernes & Auinger, 1880) , which was originally described from the Badenian of Steinebrunn ( Austria). Astyris sarmatica , however, differs from “ Mitrella ” bittneri in its much larger protoconch and the thin outer lip, which lacks denticles. Kojumdgieva (1969) separated the Sarmatian shells as distinct subspecies Mitrella scripta sarmatica . Similarity to the extant Mitrella scripta ( Linnaeus, 1758) is superficial and Astyris sarmatica differs in its simple outer lip and the squatter profile. In profile A. sarmatica is very similar to M. inflatula ( Millet, 1865) from the Atlantic upper Miocene of NW France, but the French species is even squatter and has well-developed denticles on both the columella and outer lips.

The extant Astyris rosacea and A. amiantis Dall, 1919 are reminiscent of A. sarmatica but differ in their more globular last whorls and shorter spires (see Dall 1919, deMaintenon 2019). Astyris sp. , from the Tortonian of northwestern France, differs from A. sarmatica in its much more slender shape and twisted siphonal canal (see Landau et al. 2019: pl. 14, fig. 1).

Palaeoenvironment. Recorded from inner to middle neritic clays and coastal sand (own data).

Distribution in Central Paratethys. A rather rare species, which is restricted to the Volhynian part of the Sarmatian. Geographically it seems to be confined to the western part of the Sarmatian Paratethys Sea. Sarmatian (middle Miocene): Vienna Basin: Nexing, Kronberg, Poysdorf 1 well ( Austria), Vienna /Hernals, Vienna /Heiligenstadt ( Papp 1954; Kühn & Schaffer 1960; Harzhauser & Piller 2010; Harzhauser et al. 2017), Trkmanec, Skalica, Plavecká Peter ( Slovakia) ( Švagrovský 1971); Eisenstadt-Sopron Basin: Wiesen ( Austria) ( Papp 1954); Carpathian Foredeep: Kuncha at Tiofipol ( Ukraine) ( Laskarev 1903), Moldavia ( Roshka 1964); Făget Basin: Bujtur ( Romania) ( Moisescu 1955); Dacian Basin: Lipen, Plewen, Medehevtzi, Mikhailovgrad, Rakevo, Krivodol, Gelatin ( Bulgaria) ( Kojumdgieva 1969).

Figures

FIGURE 1. A. Map of central and south–eastern Europe, representing the area that was partly covered by the Central Paratethys Sea. The white insert corresponds to the area that is restored in the palaeogeographic map below. B. Paleogeography of the Middle Miocene Paratethys Sea showing the most important sedimentary basins (NAFB: North Alpine Foreland Basin, E–Sopr B: Eisenstadt–Sopron Basin).

FIGURE 2. Measurements for shell morphology and whorl profiles. SL: shell length, MD: maximum diameter, AA: apical angle, LWH: last whorl height, AH: aperture height. AL: aperture length. AW: aperture width.

FIGURE 18. A1–A2. Astyris sarmatica (Kojumdgievam 1969), NHMW2020/0156/0001, Kronberg (Austria). 8 B. Asytris? agenta Harzhauser & Kowalke, 2002, NHMW2001z0058/0001, holotype, St. Margarethen (Austria). C2–C2. Astyris? agenta Harzhauser & Kowalke, 2002, NHMW2001z0059/0001a, paratype, St. Margarethen (Austria).