Geologia Croatica 63/1 27–53 14 Figs. 4 Tabs. Zagreb 2010 27 Gosavisiphon gen. nov. based on Halimeda paucimedullaris SCHLAGINTWEIT & EBLI, 1998: a remarkable macroalga (Udoteaceae?) from the Late Cretaceous of the Northern Calcareous Alps, (Austria and Germany), with affi nites to Late Palaeozoic and Late Triassic phylloids Felix Schlagintweit Lerchenauerstr. 167, D-80935 München, Germany; ([email protected]) doi: 10.4154/gc.2010.02 GeologiaGeologia CroaticaCroatica AB STRA CT The new genus Gosavisiphon with the type-species Halimeda paucimedullaris SCHLAGINTWEIT & EBLI, 1998, tentatively referred to the Udoteaceae, is described from the Late Cretaceous (Middle/Late Cenomanian-Santonian) of the Branderfl eck Formation and the Lower Gosau Subgroup of the Northern Calcareous Alps (Austria, Germany). It is a plurimillimetric to pluricentimetric marine, hard-substrate dwelling macroalga, with membraneous and partly fused plates and an internal siphonaceous construction but lacking a real medullary zone. Although some thallus de- tails are still unknown, Gosavisiphon gen. nov. can, from a strictly morphological point of view, directly be compared with the Late Palaeozoic and Upper Triassic phylloid algae. Gosavisiphon gen. nov. is the fi rst fossil record of a platy siphonal alga in the Cretaceous, since the Late Triassic Ivanovia triassica REID. The monotypic taxon is most prob- ably endemic to the Northern Calcareous Alps where it dwelled in protected, terrestrially infl uenced lagoonal envi- ronments attaching to hard substrates, (metazoan skeletons, rudistid shells). Based on fi ndings of the cylindrical Halimeda? aff. johnsoni PAL and another taxon described as Halimeda sp. with typically fl attened ovate segments, some considerations on the segment-morphological phylogenetic evolution of Halimeda LAMOUROUX are pro- vided. Halimeda species with discoidal-fl attened segments, that can morphologically be compared with extant spe- cies, are not known prior to the Turonian. Forms possessing cylindrical segments date further back, but can not di- rectly be compared morphologically with modern counterparts, thus placing doubts on the existence of long-lasting methusalemi species by uniting extant and fossil species, as proposed by both botanists and palaeontologists in re- cent times. Keywords: Calcareous algae, taxonomy, Bryopsidales, Halimedaceae, Udoteaceae, phylloid algae, Phylogeny, Upper Cretaceous, Northern Calcareous Alps 28 Geologia Croatica Geologia Croatica 63/1 1. INTRODUCTION calcareous algae were reported from different localities (e.g. In the area of the Northern Calcareous Alps (NCA), Late Ju- SCHLAGINTWEIT & WEIDICH, 1991; SCHLAGINTWEIT, rassic to Early Cretaceous convergence and nappe stacking 1992). The subsequent marine transgression affecting the were followed by extensional exhumation and subaerial ex- higher nappe units started during the Turonian with the tec- posure of large parts of the orogen (e.g. RATSCHBACHER tonosedimentary cycle of the Gosau Group that unconform- et al., 1989). Within the northern part of the NCA, namely ably overlies mainly Triassic and Jurassic sediments. The the Lechtal Nappe, the transgressive sedimentary cycle of Alpine Gosau Group can roughly be subdivided into a lower the Branderfl eck Formation started in the Lower Cenoma- subgroup with neritic shelf lithologies, and an upper sub- nian with breccias, conglomerates and orbitolinid sandston- group consisting of deeper water facies (WAGREICH & es, followed succesively by deeper water lithologies (e.g. FAUPL, 1994) (Figs. 1A–B). From Turonian to Campanian GAUPP, 1982; WEIDICH, 1984). From Turonian marls, oli- times, a variegated, mixed siliciclastic-carbonate succession stolites of Late Cretaceous shallow water limestones with up to more than 2000 metres thick accumulated in a wide A BC Fi gu re 1: A) Simplifi ed tectonic map of the Eastern Alps with the major occurrences of the Gosau Group (in black) (see WAGREICH & FAUPL, 1994). Oc- currences of calcareous algae described in the present paper (yellow circles; for the distribution of individual taxa see Table 1): 1 Krumbachalm, Branden- berg, Tyrol; 2 Pletzachalm, Tyrol; 3 Lattengebirge, Salzburg, 4 Eisenbach, Lake Traunsee, Upper Austria 5 Rußbach-Pass Gschütt-Gosau (Gosau type-area), 6 Weißwasser-Unterlausa, Lower Austria, 7 Gams, Lower Austria. B) Lithostratigraphic subdivision of the Gosau Group of the type area (from WAGREICH & DECKER, 2001); asterix marks the position of the fi ndings of Gosavisiphon in the area of Gosau (locality Hofergraben) and Pass Gschütt-Rußbach (local- ity Randobach). C) The village of Gosau (780 m altitude) with the Dachstein Mountains in the background; view towards the south. White arrow points to the Hofergraben. 29 Felix Schlagintweit: Gosavisiphon gen. nov. based on Halimeda paucimedullaris SCHLAGINTWEIT & EBLI, 1998: a remarkable macroalga... Geologia Croatica spectrum of terrestrial to neritic palaeoenvironments (Lower discovered in various outcrops of the Lower Gosau Sub- Gosau Subgroup; WAGREICH & FAUPL, 1994). Deposition group (Fig. 1A, from west to east). The last taxon was also of the Lower Gosau Subgroup was terminated, from Santo- observed in olistolites of the Branderfl eck Formation. Brief nian to Campanian times, by deepening into bathyal to abys- informations on geographical setting, microfacies and asso- sal depths (WAGREICH & FAUPL, 1994). The area around ciations of the algal-bearing samples and stratigraphy are the village of Gosau (Upper Austria) and Russbach (Salzburg) given for each locality. Occurrences of the described taxa represents the type locality of the Gosau Group (Fig. 1C). The are summarized in Table 1. lithostratigraphic division of the Gosau type area still used to- day is that from WEIGEL (1937) with modifi cations in the last decades (WILLE-JANOSCHECK, 1966; WEISS, 1977; Table 1: Summary of the investigated sample localities with respect to the WAGREICH, 1988; WAGREICH & DECKER, 2001) (Fig. occurrence of the described calcareous algae. 1B). The present occurrences (Fig. 1A) only represent the ero- sional remnants of a former wider distribution; preservation is often due to faulting or deposition in synse di mentary active small basins (WAGREICH & DECKER, 2001). Species Localities Krumbachalm Pletzachalm Lattenberg Eisenbach Randobach Hofergraben Weißwasser Noth-Klamm In the Lower Gosau Subgroup, calcareous algae, mainly Dasycladales and Halimedaceae, were reported from la go onal Halimeda? aff . johnsoni limestones, rudistid limestones, and marly limestones, inter- Halimeda sp. calated within marly successions of Middle Turonian to Up- Gosavisiphon paucimedullaris per Santonian age (e.g. HÖFLING, 1985; SCHLAGINT- WEIT, 1991, 1992, 2004; SCHLAGINTWEIT & LOBITZ ER, 2003a). For an inventory of calcareous green algae of the Lower Gosau Subgroup see SCHLAGINTWEIT (2004). The 2.1. Lower Gosau Subgroup alga Halimeda paucimedullaris was described by SCHLAG- INTWEIT & EBLI (1998) from the Pletzachalm section in Krumbachalm area, Brandenberg (locality 1 in Fig. 1). the Sonnwend Mountains, Tyrol. It also occurs in the Lat- The outcropping limestones of the Lower Gosau Subgroup tengebirge (Salzburg), Weißwasser-Unterlausa (Lower Au- are located at the northern part of the Brandenberg Gosau, a stria) and Pass Gschütt-Gosau (e.g. SCHLAGINTWEIT & larger erosional remnant of the Gosau Group located in Ty- LOBITZER, 2003b). New material from the Gosau of Gams, rol, about 10 km west of Wörgl (e.g. Fig. 2 in SANDERS, Styria, and the reinvestigation of material already published, 1998). especially that from the Hofergraben near Gosau, resulted in Microfacies and associations: Halimeda? aff. johnsoni the recognition of morphological and microstructural details PAL occurs in bioclastic packstones with corals, rudistids, that differ suffi ciently from the genus Halimeda LAMOUR- OUX, to warrant establishment of a new genus of the order echinoderms, gastropods, calcareous algae (green algae and Bryopsidales with the generic name Gosavisiphon gen. nov. red algae), including Permocalculus (Pyrulites) theresien- and the new combination Gosavisiphon paucimedullaris steinensis SCHLAGINTWEIT & SANDERS, and benthic (SCHLAGINTWEIT & EBLI), described in this paper. foraminifera (textulariids, and arenaceous encrusting taxa). The Krumbachalm area is also the type-locality of Acan- thochaetetes? krumbachensis (SENOWBARI-DARYAN et. 2. SAMPLE LOCALITIES AND MATERIAL STUDIED al., 2004). Halimeda sp., Halimeda? aff. johnsoni PAL and Gosavisi- Stratigraphy: Upper Turonian to Coniacian (SANDERS, phon paucimedullaris (SCHLAGINTWEIT & EBLI), were 1998 and SANDERS & PONS, 1999 for details). Fi gu re 2: Stratigraphic distribution of Halimeda? johnsoni PAL, Halimeda sp. and Gosavisiphon paucimedullaris (SCHLAGINTWEIT & EBLI) in the Late Cre- taceous Lower Gosau Subgroup of the Northern Calcareous Alps supplemented with literature data. It is most likely that Halimeda sp. has a larger strati- graphic distribution, than the two Middle-Late Turonian occurrences (see Tab. 1). The dashed dark-grey line in Halimeda? johnsoni refers to a possible synonymy with Boueina pygmaea PIA. For comparison, the distribution of the "phylloid algae" and the genus Halimeda are indicated (see Tab. 3 and de- tails in the text). 30 Geologia Croatica Geologia Croatica 63/1 Pletzachalm (locality 2 in Fig. 1). The Pletzachalm section Stratigraphy: Middle Turonian (based on calcareous nan- near Kramsach (Fig. 1 in SCHLAGINTWEIT & EBLI, 1998, nofossils). for exact location),