Bulletin of the Mizunami Fossil Museum, no. 36 (2010), p. 1–11, 2 pls., 2 figs. © 200, Mizunami Fossil Museum Decapod crustaceans from the type area of the Helvetian Stage (lower Miocene) in the Bern area, Switzerland René H. B. Fraaije1, Ursula E. Menkveld-Gfeller2, Barry W. M. van Bakel1,3, and John W. M. Jagt4 1Oertijdmuseum De Groene Poort, Bosscheweg 80, NL-5283 WB Boxtel, the Netherlands <[email protected]> 2 Naturhistorisches Museum der Burgergemeinde Bern, Bernastraße 15, CH-3005 Bern, Switzerland <[email protected]> 3Nationaal Natuurhistorisch Museum (Naturalis), P.O. Box 9517, NL-2300 RA Leiden, the Netherlands <[email protected]> 4Natuurhistorisch Museum Maastricht (SCZ), de Bosquetplein 6-7, NL-6211 KJ Maastricht, the Netherlands <[email protected]> Abstract Material collected recently from temporary excavations at the Belpberg near Bern, in the type area of the – now obsolete – Helvetian Stage, allows new data on decapod crustacean faunules from the Upper Marine Molasse of Burdigalian (early Miocene) age to be presented. The comparatively rare and rather poorly preserved, yet fairly diverse, assemblages comprise two thalassinideans (Pestarella sp., Ctenocheles sp.), an indeterminate paguroid anomuran, as well as three species of brachyuran, Glebocarcinus helveticus n. sp., Portunus sp. and Necronectes? sp. The present material documents fossil representatives of the genera Pestarella Ngoc-Ho, 2003 and Glebocarcinus Nations, 1975 from Europe for the first time. Key words: Crustacea, Decapoda, Miocene, Burdigalian, Upper Marine Molasse, Switzerland, new species Introduction which were referred to as the Belpberg Beds. Initially, these included a wider range of lithostratigraphic units (Rutsch, 926), but in modern The Upper Marine Molasse unit at the Belpberg, south of Bern terminology (Rutsch & Schlüchter, 973), the Belpberg Beds (sensu (Switzerland; see Fig. ), of early Miocene (Burdigalian) age, was laid stricto) comprise only the ‘Muschelsandstein beds’, ‘Petrefactenlager’ down in the perialpine Molasse Basin (Pfister & Wegmüller, 994), and ‘Utzigen Beds’ (Fig. 2). The decapod crustacean faunules described in the transitional area between the western Paratethys (Rhône Basin, below originate from these ‘restricted’ Belpberg Beds. Gruner (200) France) and the central Paratethys in the east. Distinguished within characterised the lithology of the Belpberg Beds sensu stricto as a fine- the series of Burdigalian age in the study area, the type area of the to medium-grained sandstone, rich in mica, with intercalated marly Helvetian Stage (now obsolete), are the Sense Beds at the base of the layers and/or conglomerates. Rapid facies changes are typical, and the Upper Marine Molasse, the Belpberg Beds and, finally, the Niedermatt thickness of the Belpberg Beds sensu stricto varies between 250 and 300 Beds (Gruner, 200) (Fig. 2). metres; the unit shows a tendency to decrease in thickness towards the Ever since Ritter (742), the fossil-rich Belpberg Beds have featured northeast. Interpretations of sedimentary settings by Schoepfer (989) prominently in a number of palaeontological and geological studies. B. and Pfister & Wegmüller (994) suggest deposition within a storm- Studer (825), Bachmann (867) and Kissling (890) described fossil influenced delta front, ranging into protected shallow-water, prodelta faunas from the area around Bern and also noted decapod crustacean bay environments. remains. At the time, Rutsch (928) presented the most thorough Gruner (200) dated these beds as middle Burdigalian. For a more palaeontological and geological study of the Belpberg strata. More detailed discussion on the age of the Belpberg Beds, and on the recently, bivalve and gastropod faunas from the Belpberg Beds (sensu ‘Helvetian Stage’, reference is made to Harzhauser et al. (2003), while a stricto) have been described in detail by Pfister & Wegmüller (994, more general overview of the lithostratigraphy and palaeogeography of 998, 999, 2000, 200, 2007a, b), echinoids by Kroh & Menkveld- the Swiss Molasse was presented by Berger et al. (2005a, b). Gfeller (2006), bryozoans by Vávra & Pfister (in press) and balanoid In Miocene Molasse strata of Switzerland, decapod crustaceans are cirripedes by Carriol & Menkveld-Gfeller (in press). comparatively rare. The first to record such from the Upper Marine As far as decapod crustaceans are concerned, T. Studer (892, Molasse was Mayer-Eymar (872); unfortunately, he failed to provide 896, 898), Rutsch (928) and Bachmayer & Rutsch (962) recorded descriptions and illustrations of this material. New ‘Helvetian’ taxa several species from different localities at the Belpberg. It should be named by him are: Astacus lucernensis, Cancer rietmanni and Lupea noted that their material came from the fossil-rich sediments in the area dubia. The first two possibly came from the Helvetian proper, in the 2 R. H. B. Fraaije et al. area between Rotsee and St. Gallen, while the last-named is of unknown NMBE Ho 2) described another new species from the Belpberg near provenance, but possibly came from the ‘Aargauer Molasse’ near St. Bern, Macropipus gruneri, and revised species described by T. Studer. Gallen. Already two decades later, the whereabouts of these specimens Here we add two specifically indeterminate species of thalassinidean, a were unknown (T. Studer, 892); the names have subsequently been single indeterminate paguroid anomuran and three species of crab, one considered to be nomina nuda by Bachmayer & Rutsch (962, p. 676) of which is new. and rightly so. T. Studer erected three new species of crab from the type To denote the repositories of specimens illustrated or referred to area of the Helvetian Stage, south of Bern, as follows: below, the following abbrevations are used: MNHN, Muséum national d’Histoire naturelle, Paris; NMBE, Naturhistorisches Museum Bern, Bern. Dorippe fankhauseri T. Studer, 1892 (p. 6, pl. 1, figs. 1–4), from the ‘Petrefactenlager’ at Hohburggraben, Belpberg [see also Material studied Bachmayer & Rutsch, 1962, pl. 2, fig. 1]; holotype is a carapace (NMBE Ho 1); In 2003, the Naturhistorisches Museum Bern sent on loan to the 2. Portunus kisslingi T. Studer, 1892 (p. 8, pl. 1, figs. 5–7), collected ex senior author, the twenty-five best-preserved decapod crustacean situ, but probably from the ‘Petrefactenlager’ at Marchbachgraben, remains (out of c. 00 specimens) collected subsequent to publication Belpberg [see also Bachmayer & Rutsch, 1962, pl. 2, fig. 2]; of the paper by Bachmayer & Rutsch (962). The new material was holotype is a right major cheliped (NMBE Ma 2); collected from the localities Aarwald, Cheergraben, Chramburgwald 3. Atelecyclus tiechei (T. Studer, 1898) (p. 1, pl. 1, figs. 1–6) [= A. tièchi and Hohburggraben at the Belpberg near Bern (Fig. ). The decapod T. Studer, 1896, p. xii, nomen nudum], from the ‘Tapeslager’ at crustaceans from the Burdigalian Upper Marine Molasse at the Belpberg Marchbachgraben, Belpberg [see also Bachmayer & Rutsch, 962, originally were part of the A. Klee and B. Hostettler collections, and pl. 1, fig. 1]; lectotype is a partial carapace (NMBE Ma 1). some came from excavations executed by NMBE staff at other localities More than sixty years later, Bachmayer & Rutsch (1962, p. 678, pl. 3, at the Belpberg (Fig. ). The preservation of these remains is rather poor figs. 1, 2; holotype is a female carapace with major chelipeds preserved, Aare A Aare 2 3 Kiesen 4 Münsingen A 2 3 Kiesen 4 Münsingen 1 N 1 study area N study area Plateau Molasse: UpperPlateau Freshwater Molasse: Molasse (OSM) basal thrust of the thrusted and folded Plateau Molasse Upper Freshwater Molasse (OSM) basal thrust of the Upper Marine Molasses (OMM) thrusted and folded Belpberg Beds s.l. 1-4 LocalitiesPlateau Molasse and Niedermatt Beds Upper Marine Molasses (OMM) UpperBelpberg Marine Beds s.l.Molasses (OMM) A1-4 = OberbalmLocalities Senseand Niedermatt Beds Beds Upper Marine Molasses (OMM) A = Oberbalm Sense Beds 10 km 10 km Fig. 2. Simplified geological map of the study area, showing the various localities which yielded the decapod crustacean material described herein; 1 – Chramburgwald; 2 – Hohburggraben; 3 – Aarwald; 4 – Cheergraben (modified after Pfister & Wegmüller, 1994; Kellerhalset al., 999). Miocene decapods from Switzerland 3 Niedermatt Beds (della Valle 1965) Sädel Conglomerate (Rutsch 1928) Utzigen Beds ) (Gerber 1926) M with M O Muschelsandstein ( (Rutsch 1926) e s Belpberg Beds s and a sensu stricto l Belpberg Beds "Petrefactenlager" o (Rutsch & Schlüchter 1973) M sensu lato (Studer 1825) e n (Rutsch 1926) Upper Muschelsandstein i r a (Gerber 1926) M and/or r e Conglomerate with Oysters p p Bütschelbach Conglomerate U (Rutsch 1967) and/or Lower Muschelsandstein (Gerber 1926) Sense Beds (Rutsch 1967) Fig.Fig. 2. 2 Lithostratigraphy of the Upper Marine Molasse in the study area, with pertinent references (modified from Gruner, 200). on account of intense ‘decalcification’, which has left only ‘powdery Discussion: Ngoc-Ho (2003, p. 475) erected the genus Pestarella casts’ in a silty to sandy matrix. This state of preservation also explains to accommodate five extant callianassine shrimps, three European why specific identification is difficult, if not impossible, in particular of (Mediterranean) in distribution, one from Senegal and one from South thalassinidean and brachyuran taxa. Africa. The European species occur mainly in intertidal to subtidal, muddy bottoms. Our assignment of the Belpberg form to this Recent genus is based on the