Cirsotrema dertonense ( Sacco, 1891 )

Harzhauser, Mathias & Landau, Bernard M., 2025, The Epitoniidae (Gastropoda, Epitonioidea) of the Miocene Central Paratethys Sea-an overwhelming diversity, Zootaxa 5630 (1), pp. 1-142 : 40-42

publication ID	https://doi.org/10.11646/zootaxa.5630.1.1
publication LSID	lsid:zoobank.org:pub:89462472-D932-4255-880F-C6EF15220A31
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treatment provided by	Plazi
scientific name	Cirsotrema dertonense ( Sacco, 1891 )
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Cirsotrema dertonense ( Sacco, 1891)

Figs 14D–E View FIGURE 14 , 15F View FIGURE 15

* [ Scalaria ] C [irsotrema]. pumiceum var. dertonense Sacc.— Sacco 1891: 55 , pl. 2, fig. 41.

Scalaria (Cirsotrema) pumicea Brocc. var. dertonensis Sacco— Boettger 1902: 85 .

Cirsotrema dertonense Sacco— Cossmann 1912: 183 , pl. 5, figs 18–19.

Cirsotrema pumiceum Brocc. var. dertonensis Sacco— Friedberg 1938: 84 , text-fig. 21.

Scala (Cirsotrema) pumicea ( Brocchi, 1814) — Bałuk 1975: 174 (pars), pl. 21, fig. 10 [non Cirsotrema pumicea ( Brocchi, 1814) View in CoL ].

[ Cirsotrema pumiceum ( Brocchi, 1814) View in CoL ] var. dertonense Sacco— Ferrero Mortara et al. 1984: 48 .

Type material. Lectotype (designated herein), BS.030.08.029, SL: 16 mm, MD: 8.7 mm, Stazzano ( Italy), Tortonian (Late Miocene), stored in the Museo Regionale di Scienze Naturali Torino ( Italy), illustrated in Sacco (1891: pl. 2, fig. 41).

Illustrated material. NHMW 1997 View Materials /0178/0971a, SL: 7.8 mm , MD: 4.3 mm, Bad Vöslau ( Austria), Figs 14D View FIGURE 14 1 – D View FIGURE 1 2 View FIGURE 2 , 15F View FIGURE 15 . NHMW 2010 View Materials /0004/0523a, SL: 8.3 mm , MD: 4.3 mm, Bad Vöslau ( Austria), Figs 14E View FIGURE 14 , 15H View FIGURE 15 .

Revised description. Shell medium-sized, robust, broad, markedly scalate (apical angle ~40°), weakly coronate. Protoconch incomplete, high conical, last protoconch whorl with weak mid-whorl angulation. Teleoconch of five whorls, with broad, shallow, weakly concave subsutural ramp, strongly angled at shoulder forming periphery, weakly convex and constricted below. Suture deeply impressed, fenestrate. Sculpture of broad, prominent, close-set, prosocline, foliaceous varices, not aligned axially, separated by narrow interspaces (~16: ~18: 20; partly amalgamated). Varices on later teleoconch whorls often touching or amalgamating, forming spongiose, crisscross surface pattern on varix tops. Later whorls with two very prominent varices per whorl with dense sculpture, weakly coronate and bearing low spine at shoulder, with barely visible interspaces. Last whorl attaining 50% of total height, with prominent basal angulation delimited by broad, flattened peribasal cord, slightly concave basal disc, varices weakening on base. Fasciole short, broad with very prominent growth lines. Aperture subcircular. Columella concave. Outer lip strongly thickened by varix, basal lip broad. Columellar callus and parietal callus delicate. Peristome duplex. No umbilicus.

Discussion. Cirsotrema dertonense ( Sacco, 1891) differs from the Pliocene to Recent Atlanto-Mediterranean Cirsotrema pumiceum ( Brocchi, 1814) in its stockier, more markedly scalate shell and the conspicuous internal crisscross pattern of the varices (see Landau et al. 2006: 40 for C. pumiceum ). Cirsotrema sallomacense de Boury in Cossmann, 1912, from the Langhian of France, might be a closely related species, which differs in its much broader and higher spire whorls (see Cossmann 1912, pl. 6, fig. 13). Cirsotrema bourgeoisi de Boury in Cossmann, 1912, from the Middle and Late Miocene of France, is very similar and differs from C. dertonense mainly in the more prominent lamellae on the subsutural shelf and the more regular, fenestrate sculpture (see Landau et al. 2018: pl. 29, figs 1–2).

Paleoenvironment. Occurrences in the Baden Formation of the Vienna Basin suggest middle to outer neritic settings in up to 250 m water depth ( Kranner et al. 2021) .

Distribution in Central Paratethys. Badenian (Middle Miocene): Polish-Ukrainian Fore-Carpathian Basin: Niechobrz ( Poland) ( Friedberg 1938); Korytnica Basin: Korytnica ( Poland) ( Bałuk 2006); Vienna Basin: Baden, Bad Vöslau ( Austria) (hoc opus); Făget Basin: CoŞteiu de Sus ( Romania) ( Cossmann 1912).

Proto-Mediterranean Sea. Tortonian (Late Miocene): Po Basin: Stazzano ( Italy) ( Sacco 1891).