Lindbergia 35: 33–39, 2012 ISSN 0105-0761 Accepted 11 May 2012 Pyramidula tetragona (Brid.) Brid. rediscovered in Fennoscandia and new to Norway Torbjørn Høitomt, Leif Appelgren, Niklas Lönnell, Kåre Arnstein Lye and Kristian Hassel T. Høitomt ([email protected]), Stiftelsen BioFokus, Gaustadalléen 24, NO-0149 Oslo, Norway. – L. Appelgren, Ambio miljørådgivn- ing AS, Godesetdalen 10, NO-4034 Stavanger, Norway. – N. Lönnell, PO Box 25195, SE-750 25 Uppsala, Sweden. – K. A. Lye, Dept of Ecology and Natural Resource Management, Norwegian Univ. of Life Sciences, PO Box 5003, NO-1432 Ås, Norway. – K. Hassel, NTNU Museum of Natural History and Archaeology, NO-7491 Trondheim, Norway. The threatened moss Pyramidula tetragona is rediscovered in Fennoscandia and found for the first time in Norway. The species has recently been classified as regionally extinct both in Sweden and Finland, and it is thus highly sur- prising that we can present four new localities from southeast Norway. All localities are or have been influenced by agriculture through grazing or cereal crop production. The distribution of Pyramidula tetragona Brid. (Brid.) is duction may take place by small red rhizoidal tubers. In confined to the Western Palearctic and Nearctic ecozones. Sweden the species is found mainly from April to May and It seems to avoid the northernmost areas, and in Sweden it from October to November (Lönnell 2002), and a similar has not been recorded north of Limes norrlandicus (about pattern is also reported from Hungary (Papp et al. 2000). 60°N in Uppland), and the distribution is southern to It thus seems that under favourable conditions P. tetragona southeastern in Fennoscandia. The distribution in the is able to develop mature sporophytes twice a year. To fully West Palearctic region is wide, but it seems to avoid the understand how this can take place we need to study the most extreme oceanic areas. In North America it has only phenology of P. tetragona in more detail. Especially the been found in more continental areas. (Fig. 1). timing of fertilisation in relation to sporophyte develop- The ecology of Pyramidula tetragona is seemingly quite ment is of importance. In much of the distribution area wide. In North America it is most commonly found on of Pyramidula tetragona, the summer is quite warm and mineral soil in grasslands, less often in forests or on river dry and not suitable for growth and reproduction. There- banks (Goffinet 2007). Also in Europe the ecology of the fore it must have a rapid growth of gametophyte, rapid species is varying from grassland with dry mineral soils maturation of gametangia as well as rapid sporophyte de- (Papp et al. 2000, Kara et al. 2008) to moist clay in arable velopment. In periods of unfavourable conditions, such as fields (Krusenstjerna 1945). Lönnell (2002) and Halling- drought or frost, it probably survives as spores or tubers bäck (2010) describe the ecology based on the old Swedish in the diaspore bank. Since neither the large spores nor collections as a pioneer on disturbed rather base rich clay, the underground tubers are well adapted for long distance and mainly growing in fallow fields. Associated species in dispersal, the life strategy of Pyramidula tetragona is best Sweden were Fissidens taxifolius, Pleuridium subulatum, described as an annual shuttle (sensu During 1992). This Tortula truncata and Riccia sorocarpa. From Hungary Papp strategy relies upon a habitat that reoccurs at irregular in- et al. (2000) list Bryum argenteum, Bryum capillare, Man- tervals, but at the same location, and the duration of the nia fragrans, Phascum cuspidatum, Riccia sorocarpa and favourable habitat may be short. The disturbance agent is Weissia longifolia as associated species. man-made in the cases where it is growing in arable land Pyramidula tetragona is autoicous and frequently found (ploughing etc.), while animal trampling or other natural with sporophytes (Fig. 2). The spores are large, 45–72 µm disturbance factors may dominate in grasslands. Climatic in diameter, and nearly smooth. Specialised asexual repro- conditions are critical for a species with such a short time © 2012 The Authors. This is an Open Access article. 33 Figure 1. World distribution of Pyramidula tetragona (after Lönnell 2002). span for completing its life cycle, and even short periods of Methods drought at a critical time may hamper fertilisation. Papp et al. (2000) demonstrates large between-years variation in As part of the Norwegian Species Initiative project Bryo- above-ground populations at two localities in Hungary. phytes of poorly known habitats we conducted field in- Since P. tetragona is naturally very rare in all Europe- ventories of bryophytes of arable land, focusing on areas an countries where it is recorded, the species is listed as where we have little knowledge of the bryophyte flora and vulnerable (VU) on the European red list for bryophytes where the potential for new records of poorly known spe- (ECCB 1992), and it is also included in the Bern Con- cies is high. The Oslofjord area (southeastern Norway) is vention Appendix I for strictly protected flora species one of our focus areas, and within this area 12 regions were (The list contains only 13 species of Musci). Addition- chosen for further investigation. The regions visited were ally the species is included in many national red lists, e.g. chosen in order to cover the geographical variation in the Finland, Serbia and Montenegro, Sweden, Hungary and area and to get a representative sample of habitats. During Switzerland (Sabovljevic et al. 2004, Schnyder et al. 2004, September to November 2011 four regions were visited: Gärdenfors 2010, Papp et al. 2010, Rassi et al. 2010). In Østfold, Oslo, Romerike and Ringerike. Investigations of Sweden P. tetragona has been found in some 10–15 locali- the bryophyte flora of the cultural landscape were mainly ties (Lönnell 2002, Hallingbäck 2010), but the last record focused on cereal crop fields and pastures, but occasion- is from the county of Uppland, in 1943. The species has ally other open habitats like roadsides and open calcareous been actively searched for at many of the old localities and soils were included. The selection of localities was mainly other presumably suitable localities, but with negative based on old herbarium records, bedrock and soil quality outcome (Lönnell 2002, 2004). Consequently P. tetrago- and altitude. In each region the main goal was to visit a na is listed as regionally extinct (RE) in the Swedish red number of sites representative for the cultural landscape list (Gärdenfors 2010). The situation is much the same in in the area. Exposure, substrate texture, moisture, and pH Finland, where it also is classified as RE in the latest red were factors that were taken into consideration. list (Rassi et al. 2010). We have not been able to verify Two of the four regions investigated, the central parts whether P. tetragona occurs in Denmark; some authors of Østfold and Romerike, are dominated by acidic soils. In report it (Nyholm 1989) while others do not (Lönnell Ringerike and Oslo, the investigations were focusing on 2006). Thus the situation for the species in Fennoscandia calcareous soils. Both Ringerike and Oslo are a part of the seemed rather critical prior to the new discoveries from Oslo Rift with limestone formed in the Cambrian, Ordo- southeastern Norway. vician and Silurian periods (Moen 1998). Most lowland 34 Figure 2. A dense tuft of Pyramidula tetragona with sporophytes at the locality on Storøya in Hole municipality. Photo: TH 2011. areas in the Oslo Rift are strongly influenced by humans, Results and the cultural landscape contains a wide variety of po- tentially interesting bryophyte habitats. Pyramidula tetragona was found in four of 30 localities Pyramidula tetragona was discovered in Ringerike and investigated in the Ringerike (3) and Oslo (1) regions. Oslo. All together, approximately 30 sites were investigat- The localities are restricted to the Oslo Rift with base rich ed in these two regions. According to Moen (1998), the bedrock. lowland areas of both Oslo and Ringerike are situated in the boreonemoral zone. The mean annual precipitation in Oslo (station Blindern) is 763 mm (Table 1). The Ring- Description of new localities erike area (station Hole, only precipitation measuring) is slightly drier, with a mean annual precipitation of 520 mm (Table 1). The mean annual temperature is almost simi- 1) Buskerud, Hole, near the farm Nøstret lar in the two regions, 5.7°C in Oslo (station Blindern) Pyramidula tetragona was found in the upper, northwest- and 4.7°C in Ringerike (station Hønefoss) (Table 1). This ern margin of a stubble field with cereal crops, gently slop- marginal temperature difference is mainly caused by lower ing towards southeast. The field margin borders towards winter temperatures in Ringerike. a narrow tongue of forest that stretches into arable land. The nomenclature follows Hill et al. (2006) for mosses The forest mainly consists of deciduous trees, e.g. Acer and Söderström et al. (2002) for liverworts. Threat status platanoides, that had shed its leaves onto the area where of red listed species in Norway is according to Hassel et P. tetragona was growing. The locality is exposed to the al. (2010). sun from morning until mid day, but the forest shades the 35 Table 1. Precipitation (mm) and temperature data (°C) for the last normal period (1961–1990) and 2011 (Norwegian Meteorological Institute 2011). Only the growing season (April–November) is included.