Potamides fraterculus (Mayer, 1878)

Harzhauser, Mathias, Guzhov, Aleksandr & Landau, Bernard, 2023, A revision and nomenclator of the Cainozoic mudwhelks (Mollusca: Caenogastropoda: Batillariidae, Potamididae) of the Paratethys Sea (Europe, Asia), Zootaxa 5272 (1), pp. 1-241 : 70-72

Potamides fraterculus (Mayer, 1878)

Figs 8A–H

* Cerithium fraterculus Mayer — Mayer 1878b: 173, pl. 4, fig. 1

Cer [ithium]. fraterculus Mayer — Hilber 1879b: 125.

Cerithium Brenneri n. f.— Handmann 1883b: 167.

Cerithium Ĥllesense n. f.— Handmann 1883b: 168.

Cerithium pyramidella n. f.— Handmann 1883b: 168.

[ Cerithium ] Brenneri Handm.— Handmann 1888: 40.

[ Cerithium ] Ĥllesense Handm.— Handmann 1888: 40.

[ Cerithium ] pyramidella Handm. — Handmann 1888: 40.

Cerithium Ĥllesense Handmann—Handmann 1889: 62.

Potamides (Bittium) Hartbergensis Hilber nova forma — Hilber 1891: 239, figs 7, 8, 9.

Potamides (Bittium) Hartbergensis Hilb. var. Schildbachensis Hilb.— Hilber 1891: 241, fig. 10.

Potamides (Bittium) Hartbergensis Hilb. var. L̂ffelbachensis Hilb.— Hilber 1891: 241, fig. 11.

Potamides (Bittium) Hartbergensis Hilb. var. Dominici Hilb.— Hilber 1891: 241, fig. 12.

Potamides (Bittium) Hartbergensis Hilb. var. Rüdti Hilb.— Hilber 1891: 242, figs 13–14.

Cerithium hartbergensis Hilb. — Kolesnikov 1935: 226, pl. 28, figs 18–21.

Pirenella fraterculus (Mayer) — Sieber 1937: 481, pl. 25, D7, 8.

Bittium fraterculus (Mayer) — Papp 1954: 44, pl. 7, figs 1–8.

Bittium hartbergense hartbergense (Hilber) — Papp 1954: 45, pl. 7, figs 9–14.

Bittium hartbergense rüdti (Hilber) — Papp 1954: 45, pl. 7, fig. 15.

Bittium hartbergense schildbachense (Hilber) — Papp 1954: 45, pl. 7, figs 16–20.

Bittium hartbergense schildbachense Hilb. — Strausz 1954: 98, pl. 2, fig. 29.

Potamides hartbergensis extortus var. ssp .— Kókay 1954: 37, pl. 2, figs 2a–d.

Pirenella hartbergensis rüdti Hilber, 1891 — Strausz 1955a: 197, pl. 8, fig. 135.

Pirenella hartbergensis Hilber, 1891 — Strausz 1955a: 73, 197, pl. 8, figs 136–138.

Pirenella hartbergensis schildbachensis Hilber, 1891 — Strausz 1955a: 199, pl. 8, figs 139–153.

Pirenella hartbergensis Hilber , forma aberrans— Strausz 1955b: 202, pl. 12, fig. 20.

P [otamides]. fraterculus (May.) — Sieber 1958: 136.

P [otamides]. hartbergensis hartbergensis (Hilb.) — Sieber 1958: 136.

P [otamides]. hartbergensis rüdti (Hilb.)— Sieber 1958: 136.

P [otamides]. hartbergensis schildbachensis (Hilb.)— Sieber 1958: 136.

Pirenella hartbergensis hartbergensis (Hilber) — Boda 1959: 618, pl. 26, fig. 15.

Pirenella hartbergensis schildbachensis (Hilber) — Boda 1959: 619, pl. 26, fig. 16.

Pirenella hartbergensis rüdti (Hilber) — Boda 1959: 618, pl. 26, figs 17–22.

Pirenella hartbergensis extorta (Kókay) — Boda 1959: 619, pl. 27, figs 1–3.

Potamides hartbergensis extortus Kókay 1954 — Boda 1964: 132.

Potamides (Pirenella) hartbergensis Hilber, 1891 – Strausz 1966: 156, pl. 7, figs 4–7.

Potamides (Pirenella) hartbergensis ruedti Hilber, 1891 – Strausz 1966: 157, pl. 7, fig. 8.

Potamides (Bittium) hartbergensis schildbachensis Hilber, 1891 — Strausz 1966: 157, pl. 7, figs 9–13.

Pirenella hartbergensis ruedti ( Hilber, 1891) —Hinculov in Iliescu et al. 1968: 127, pl. 30, figs 9a–b.

Pirenella fraterculus (Mayer) — Plǎmǎdealǎ 1970: 133, pl. 10, figs 7–22.

Bittium hartbergense (Hilber, 1897) — Švagrovský 1971: 348, pl. 60, figs 1–5.

Bittium hartbergense hartbergense (Hilber) — Papp 1974: 345, pl. 7, figs 7–12.

Bittium hartbergense rüdti (Hilber) — Papp 1974: 408, pl. 7, fig. 13.

Bittium hartbergense schildbachense (Hilber) — Papp 1974: 346, pl. 7, figs 14–18.

P [otamides]. hartbergensis — Lozouet 1986: 16.

Potamides hartbergensis ( Hilber, 1891) — Harzhauser & Kowalke 2002: 68, pl. 9, figs 1–4.

Potamides hartbergensis (Hilber) — Harzhauser & Piller 2009: 194.

non Pirenella hartbergensis schildbachensis (Hilber) — Kókay 1966: 42, pl. 4, fig. 8 [= Theodisca theodisca ( Rolle, 1856) ].

Type material. Lectotype designated herein: ETH 27009 (Nr. 3140), SL: 8.3 mm, MD: 2.9 mm, ETH Z̧rich ( Switzerland), Fig. 8F. Paralectotype: ETH 27009 (Nr. 3140), SL: 14.4 mm, MD: 4.0 mm, ETH Z̧rich ( Switzerland), Fig. 8G. The lable of the syntype-lot mentions six specimens of which four are still preserved. Of these, the specimen selected as lectotype might represent the specimen illustrated by Mayer (1878) .

Type locality. Hauskirchen ( Austria) .

Stratigraphy. Middle Miocene, Sarmatian (Volhynian).

Illustrated material. UMJG &P 4634, SL: 12.9 mm, MD: 4.5 mm, Universalmuseum Joanneum Graz ( Austria), lectotype of Potamides (Bittium) hartbergensis dominici Hilber 1891 , illustrated in Hilber (1891: 241, fig. 12), Figs 8E. UMJG &P 4630, SL: 12.7 mm, MD: 4.3 mm, Universalmuseum Graz ( Austria), lectotype of Potamides (Bittium) hartbergensis Hilber 1891 , illustrated in Hilber (1891: pl. 1, fig. 7), Figs 8A 1 –A 2. UMJG &P 4637, SL: 12.4 mm, MD: 3.9 mm, Universalmuseum Joanneum (Graz, Austria), lectotype of Potamides (Bittium) hartbergensis loeffelbachensis Hilber 1891 , illustrated in Hilber (1891: 241, fig. 11), Figs 8B 1 –B 2. UMJG &P 4635, SL: 11.5 mm, MD: 3.6 mm, Universalmuseum Joanneum (Graz, Austria), lectotype of Potamides (Bittium) hartbergensis ruedti Hilber 1891 , illustrated in Hilber (1891: 242, fig. 14), Figs 8D 1 –D 2. UMJG &P 200.158, SL: 13.5 mm, MD: 5.3 mm, Universalmuseum Joanneum (Graz, Austria), lectotype of Potamides (Bittium) hartbergensis schildbachensis Hilber 1891 , illustrated in Hilber (1891: 242, fig. 10), Figs 8C 1 –C 2. NHMW, St. Margarethen ( Austria), Sarmatian (Bessarabian), illustrated in Harzhauser & Kowalke (2002), Fig. 8H.

Studied material. 1 spec., NHMW 1999z0004/0025, Hauskirchen ( Austria) , illustrated in Sieber (1937: pl. 25, fig. D8); 1 spec., NHMW 1999z0004/0025, Hauskirchen ( Austria) , illustrated in Sieber (1937: pl. 25, fig. D7); 2 spec., NHMW 1859/0045/0357, Oberpullendorf ( Austria) ; 6 spec., NHMW 1860/0001/0274, Holič ( Czech Republic) .

Revised description. Small, moderately slender shell of about 12 teleoconch whorls; apical angle ~20–27°. Protoconch of about 1.5 strongly convex, smooth whorls. Transition to teleoconch marked by slightly thickened rim and onset of two weak spiral cords and delicate axial threads. Adapical spiral cord separated from suture by broad subsutural ramp with faint spiral threads. Axial ribs appear on third teleoconch whorl, forming tiny beads at intersections with spiral cords. Third spiral cord appears on subsutural ramp around 5–6 th teleoconch whorl. Spiral cords separated by narrowly incised spiral grooves, with broad, subquadrate beads on later teleoconch whorls. Beads of abapical spiral cord usually most prominent, coinciding with weakly angulated periphery. Rare, fourth spiral cord appears above abapical suture on late adult whorls. Suture distinctly incised, slightly wavy. Last whorl moderately constricted with convex base, covered by about four further weak spiral cords. Sculpture of last whorl often reduced. Aperture wide, ovoid. Columella concave, smooth. Columellar callus moderately thickened, moderately broad, separated from base by narrow chink or adapically fully attached to base. Anal canal indistinct. Outer lip convex, weakly thickened. Siphonal canal moderately incised, distinctly deflected to the left.

Synonyms. Several subjective synonyms of Potamides fraterculus have been described for Paratethyan occurrences. Most were established by Hilber (1891) from a few quarries at Hartberg ( Austria) in the Styrian Basin. Of these, Potamides (Bittium) hartbergensis dominici Hilber, 1891 and Potamides hartbergensis loeffelbachensis Hilber, 1891 are morphologically rather close to P. fraterculus differing mainly by a slightly more angulated periphery. Potamides (Bittium) hartbergensis ruedti Hilber, 1891 represents a slender morph with small beads. Potamides hartbergensis Hilber, 1891 and Potamides hartbergensis schildbachensis Hilber, 1891 represent shells with prominent axial ribs and a reduced spiral grove separating the lower two spiral cords. Similarly, Potamides hartbergensis extortus Kókay, 1954 lacks a spiral groove between the abapical spiral cords resulting in blunt axial ribs. In addition, it has a prominent spiral groove below the adapical spiral cord. Cerithium brenneri Handmann, 1883 , Cerithium hoellesense Handmann, 1883 and Cerithium pyramidella Handmann, 1883 , all from Ĥlles in Austria, are most likely also synonyms of P. fraterculus , based on the brief descriptions in Handmann (1883b). As Handmann (1883b) did not illustrate these species and because the type specimens are lost, we consider these taxa nomina dubia.

Discussion. Potamides fraterculus is a small, slender Potamides , which displays considerably variability concerningsculpture.Thespiralgroovebetweenthetwoabapicalspiralcordsmaybedeep( fraterculus /loeffelbachensis - morphs) or nearly absent (schildbachensis -morph) and the beads may be very prominent ( hartbergensis -morph) or small and isolated (ruedti -morph). Potamides hartbergensis ( Hilber, 1891) was accepted as full species by many authors (e.g., Papp 1954, 1972; Strausz 1966; Harzhauser & Kowalke 2002). Papp (1954) considered Potamides fraterculus and Potamides hartbergensis to form a lineage with P. fraterculus being restricted to the Ervilia Zone (Volhynian) evolving into P. hartbergensis in the Sarmatimactra Zone (Bessarabian) . Papp (1954) distinguished P. fraterculus based on the smaller and more delicate shell from the larger, more robust P. hartbergensis . The presence of both morphologies in the Sarmatimactra Zone of St. Margarethen ( Austria) ( Harzhauser & Kowalke 2002) and the Bessarabian of the Moldavian Platform ( Plǎmǎdealǎ 1970) does not support this hypothesis.

Potamides hartbergensis is the name-giving species for the Potamides hartbergensis assemblage as defined by Harzhauser & Kowalke (2002), which occurred on littoral mudflats and ponds under fluctuating salinities. The animals could stand considerably evaporation as documented by stable isotope data ( Latal et al. 2004). For the sake of clarity we recommend to change the name of this assemblage into Potamides fraterculus assemblage.

Distribution. Potamides fraterculus was an endemic species in the Sarmatian Paratethys Sea but is not described so far east of the Moldavian Platform. Badenian occurrences are based on misidentifications (e.g., Kókay 1966).

Central Paratethys. Sarmatian, Volhynian (Middle Miocene): Vienna Basin: Hauskirchen, Hautzendorf, Ĥlles, Nexing, Vienna /Heiligenstadt, ( Austria) ( Harzhauser & Piller 2009), Čejč, Bílovice u Uherského Hradiště, Strážnice ( Czech Republic) ( Švagrovský 1971), Skalica, Holič ( Slovakia) ( Švagrovský 1971); Pannonian Basin: Várpalota, Herend–Márkó ( Kókay 1966, Strausz 1955 a, 1966), Cserhát Mountains: Bér ( Hungary) ( Boda 1959). Mehadia Basin: Valea Bela Reca, Valea Răduliţei ( Romania) (Hinculov in Iliescu et al. 1968); Sarmatian, Bessarabian (Late Miocene): Styrian Basin: Hartberg, L̂ffelbach, Schildbach, Totterfeld, Grillberg at Hartberg ( Austria) ( Hilber 1891); Eisenstadt-Sopron Basin: St. Margarethen, Wiesen ( Austria), Fertőrákos, Sopron ( Hungary) ( Harzhauser & Kowalke 2002, Papp 1974).

Eastern Paratethys. Sarmatian, Volhynian (Middle Miocene): Moldavian Platform: Calfa, Chişinău, Doibani, Oxentea, Rîbnița ( Moldova) ( Simionescu & Barbu 1940; Plǎmǎdealǎ Bursuc, FloreȘti, Năpadova, MolochiȘul, Rezina, Rîbnița, Severinovca ( Moldova) ( Kolesnikov 1935; Plǎmǎdealǎ 1970); Sarmatian, Bessarabian (Late Miocene): Moldavian Platform: Calfa, Chişinău, Doibani, Oxentea, Rîbnița ( Moldova) ( Simionescu & Barbu 1940; Plǎmǎdealǎ 1970).