Cirsotrema nudum, Harzhauser & Landau, 2025

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 : 47-48

publication ID	https://doi.org/10.11646/zootaxa.5630.1.1
publication LSID	lsid:zoobank.org:pub:89462472-D932-4255-880F-C6EF15220A31
persistent identifier	https://treatment.plazi.org/id/03D787A4-FFCB-FFCB-FF3F-F9AAFEEE9188
treatment provided by	Plazi
scientific name	Cirsotrema nudum
status	sp. nov.

Treatment

Cirsotrema nudum sp. nov.

Figs 15J View FIGURE 15 , 18D–F View FIGURE 18

Type material. Holotype, NHMW 2020 View Materials /0138/0360a, SL: 6.5 mm, MD: 3.0 mm, Figs 18D View FIGURE 18 1 –D View FIGURE 1 2 View FIGURE 2 . Paratypes, NHMW 2020 View Materials /0138/0360b, SL: 13.0 mm , MD: 7.8 mm, Grund ( Austria), Figs 18E View FIGURE 18 1 –E View FIGURE 1 2 View FIGURE 2 . NHMW 2007 View Materials /0086/0166, SL: 9.7 mm , MD: 6.2 mm, Grund ( Austria), Figs 15J View FIGURE 15 , 18F View FIGURE 18 1 –F View FIGURE 1 2 View FIGURE 2 .

Type locality. Grund ( Austria), North Alpine-Carpathian Foreland Basin .

Type stratum. Grund Formation.

Age. Middle Miocene, early Badenian (Langhian).

Etymology. From nudus (Latin for naked), referring to the comparatively reduced sculpture.

Diagnosis. Small, robust, very broad, somewhat scalate shell with marked shoulder, relatively narrow varices, narrowing on slightly concave subsutural ramp, sharp basal angulation.

Revised description. Shell small, robust, very broad, somewhat scalate (apical angle ~35–44°). Protoconch unknown. Teleoconch of more than five whorls. Teleoconch whorls with broad, moderately shallow, weakly concave subsutural ramp, marked shoulder angulation delimiting periphery placed just above mid-whorl, constricted below. Suture deeply impressed, largely obscured by varices. Sculpture of prominent, close-set, relatively narrow, weakly prosocline, internally lamellose varices not strictly aligned axially (~13: ~21: 16), narrowing over subsutural ramp. Later whorls with up to three prominent varices per whorl. Interspaces with about four, very weak spiral cords. Last whorl attaining ~50% of total height, with prominent basal angulation delimited by broad peribasal cord, basal disc slightly concave, 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 and parietal callus forming narrow, continuous rim, detached from base. Peristome duplex. No umbilicus.

Discussion. Cirsotrema nudum sp. nov. is reminiscent of Cirsotrema dertonense ( Sacco, 1891) in its somewhat scalate outline but differs from that species in its much weaker varices, which lack the complex, internal crisscross structure. Cirsotrema microperforata sp. nov. has broader varices with flat crests and a characteristic microperforate surface. Moreover, C. microperforata lacks protruding varices on the last whorl.

Paleoenvironment. At the locality Grund channels formed in middle to outer neritic environments and were filled, with allochthonous assemblages uniting coastal-mudflat faunas with inner neritic ones (Zuschin et al. 2005; Roetzel 2009). The preservation suggests that the shells of Cirsotrema nudum sp. nov. belonged to the inner neritic assemblages.

Distribution in Central Paratethys. Badenian (Middle Miocene): North Alpine-Carpathian Foreland Basin: Grund ( Austria).