A new population of Hammarbya paludosa, a rare orchid typical of peat bogs, has been discovered in Cinque Valli (Valsugana, Roncegno municipality, province of Trento). In Italy, this species was previously known only in one other locality in the province of Bolzano, near Anterselva/Antholz (Rasun-Anterselva/Rasen-Antholz municipality).

Flora of Italy, Trentino-Alto Adige/Südtirol region

Hammarbya paludosa (L.) Kuntze (≡ Malaxis paludosa (L.) Sw.) is a tiny circumboreal orchid (Meusel et al. 1965). This species is typical of peat bogs and characteristic of the alliance Rhynchosporion albae W.Koch (Oberdorfer 2001). Hammarbya paludosa was discovered for the first time in Italy in 1979 by Franco Pedrotti in the Bolzano province, near Anterselva (Rasun-Anterselva municipality) in a small population with 15-20 individuals (Pedrotti 1980). In this site, there are currently very few individuals, which do not flower every year (Perazza and Lorenz 2013).

On June 18^th 2014, during a field trip aimed at investigating some potentially interesting bogs, a small population of H. paludosa was discovered in Cinque Valli, on the southern side of Lagorai, Valsugana (municipality of Roncegno; WGS84: ca. 46°3'N 11°22'E; MTB: 9934/1). At the time of discovery, we observed a dozen plants, about half of them at the beginning of flowering. A plant was collected and deposited in the herbarium of the Museo Civico di Rovereto (ROV, acc. n. 67391). The plants were in full anthesis a month later, as documented by Giorgio Perazza with photos taken on July 19^th 2014. One year later 10 flowering and about 20 sterile plants were counted by A. Bertolli, G. Tomasi and R. Vettori. This finding was already mentioned by Perazza in GIROS (2016) for the province of Trento without the exact location.

In the province of Trento this species was not found with certainty earlier. The only indication is found in a letter dated November 10^th 1992 by A. J. B. Brilli-Cattarini (botanist in Pesaro who died in 2006) to F. Prosser, where the former informed that his collaborators in Berne found H. paludosa in Sphagnum samples collected in two localities of Val di Fassa (see Perazza 1993). However, investigation at these two sites, namely the High Val San Pellegrino and Val di Grepa, and considerations about the ecology of the species, led Perazza and Decarli Perazza (2005) to consider these records as erroneous. In any case, specimens of H. paludosa from the localities cited by Brilli-Cattarini are not present in the herbarium PESA (L. Gubellini, in litt.).

Among the species so far assessed for the Red List of the Italian Flora (Rossi et al. 2013), H. paludosa is considered Critically Endangered (CR). The total number of fertile individuals, including the Cinque Valli station, occurring in Italy remains below 50; thus, following criterion D of the IUCN guidelines (IUCN 2012), the category should remain unchanged. In the Red List of the flora of the province of Bolzano (Wilhalm and Hilpold 2006), the species had also been assessed as Critically Endangered. Finally, H. paludosa should be also be added, again as Critically Endangered, in the Red List of the flora of the province of Trento (Prosser 2001).

Hammarbya paludosa, despite its ecological and phytogeographical significance, is not part of the species mentioned in the annexes of the Council Directive 92/43/EEC and in the Berne Convention. However, it is protected in the province of Trento based on Annex A of the regulation following the provincial law L.R.11/2007, which includes all wild Orchidaceae with the exception of the most common ones.

While the Anterselva population is inside a Natura 2000 area (Torbiera di Rasun/Rasner Möser), the Cinque Valli population is not in a protected area. Here H. paludosa grows in its typical environment, on Sphagnum mounds, in a restricted zone. The inconspicuous aspect of the plant, its delicate environment of growth, the absolute rarity in Italy and the desirability for photographers are factors that expose the population of H. paludosa to trampling damage. For this reason exact coordinates of the site of occurrence are omitted.

The population of H. paludosa nearest to Cinque Valli is Anterselva, which is over 100 km in a straight line to the northeast (see Fig. 2). Pedrotti (1980) considered the latter as the only station on the southern side of the Alps, interpreting it as a relict. This should apply even more to the Cinque Valli population, being even more southern. Other rare bog species were also found in the province of Trento in recent years, such as Carex buxbaumii Wahlenb., Carex chordorrhiza L.f. and Eriophorum gracile W.D.J.Koch ex Roth (Bertolli and Prosser 2011).

Figure 1. 

Hammarbya paludosa (L.) Kuntze photographed in Cinque Valli (province of Trento, Roncegno municipality) on July 19^th 2015 (photo by A. Bertolli).

Figure 2. 

Distribution map of Hammarbya paludosa (L.) Kuntze in the Alps (dotted line) after the MTB-grid (see Ehrendorfer and Hamann 1965). The data are drawn from the following sources: https://www.infoflora.ch/it/ (accessed 24.06.2016) for Switzerland; Bettinger et al. (2013) for Germany; Griebl (2013) for Austria, with integrations by H. Niklfeld and K. Zernig (in litt.); Jogan (2001) for Slovenia. Dots: confirmed after 1950 ca.; crosses: not confirmed after 1950 ca.

The considerable altitude of the population of Cinque Valli, which is located at ca. 1400 m a.s.l., should also be highlighted. This may be the highest altitude reached by this species in the Alps and one of the highest in Europe; Dusak and Prat (2010) reported 1400 m as the maximum elevation in France, while for Bulgaria the maximum altitude reported is 1500 m (Peev et al. 2011).

The discovery of a second site of H. paludosa in Italy can raise some optimism about the chances of survival of this species in our country. The absence of protection of the Cinque Valli site is undoubtedly a problem, especially because it lies several kilometers away from the nearest Natura 2000 area.

We thank Giorgio Perazza (Fondazione Museo Civico di Rovereto) for critical reading of the text, Leonardo Gubellini (Centro Ricerche Floristiche Marche) for searching H. paludosa in herbarium PESA, Harald Niklfeld (University of Vienna) and Kurt Zernig (Museum Joanneum, Graz) for providing Austrian distribution data.