Cryptogamie, Bryologie, 2017, 38 (3): 231-251 © 2017 Adac. Tous droits réservés The moss genus Zygodon (Orthotrichaceae) in Poland – distribution, ecological preferences and threats Adam STEBEL a*&Jan ŻARNOWIEC b aDepartment of Pharmaceutical Botany, Medical University of Silesia in Katowice, Ostrogórska 30, 41-200 Sosnowiec, Poland bDepartment of Ecology and NatureProtection, University of Bielsko-Biała, Willowa 2, 43-309 Bielsko-Biała, Poland Abstract – The moss genus Zygodon Hook. &Taylor (Orthotrichaceae) is represented by five species in Poland, namely: Z. dentatus (Limpr.) Kartt., Z. gracilis Wilson, Z. rupestris Schimp. ex A.W.H.Walth. &Molendo, Z. stirtonii Schimp. and Z. viridissimus (Dicks.) Brid. Their current distribution in Poland is reviewed and mapped, and lists of their localities are presented. The ecological preferences, altitudinal limits, reproduction and threats for each species are shortly discussed. Akey for determination of these species is given. Bryophyta /Central Europe /moss diversity /epiphytes /phytogeography /protected mosses INTRODUCTION The genus Zygodon Hook. &Taylor includes small to medium-sized acrocarpous mosses forming light to dark green cushions, tufts, or rarely mats on trunks and branches of trees, logs, rarely on base-rich rocks, walls or on concrete. Brotherus (1925) placed in Zygodon 112species, and in the only world monograph Malta (1924, 1926) listed 77 species. Currently,itisbelievedthat the genus encompasses between 50 (Smith, 2004) and about 90-91 species (Crosby et al., 1999; Vitt, 2014). Zygodon is represented in the floras of both hemispheres in warm and temperate climates, but the highest species diversity is in the tropics and subtropics. The real species richness within this genus is most probably lower,because modern taxonomic revisions show,that anumber of species have been described repeatedly under various names. For example, Calabrese (2006) described one new species and accepted 12 taxa from 20 known from South America, the names of the remainder being reduced to synonymy.For Australasia and Australia, six species are recognised (Lewinsky,1990; Lewinsky-Haapasaari &Ramsay,2012), and in the moss flora of North America five species and two varieties (Z. viridissimus (Dicks.) Brid. var. rupestris Lindb. and Z. viridissimus var. dentatus Limpr., frequently considered as * Corresponding author: [email protected] doi/10.7872/cryb/v38.iss3.2017.231 232 A. Stebel &J.Żarnowiec separate species) are mentioned (Britton, 1908; Vitt, 2014). Düll (1985a) revised European specimens of Zygodon,and new conceptualisations of the genus are represented in the modern Floras (e.g. Lewinsky-Haapasaari, 1998; Smith, 2004). In total, nine species and one variety are now recognised from Europe (Hill et al., 2006; Garcia et al.,2006), of which five species are represented in Poland (Ochyra et al., 2003; Stebel et al. in Blockeel et al.,2007). The aims of this paper are to address the following: (i)what is the present diversity of Zygodon in Poland? (ii) what is their geographical distribution? (iii) what is their altitudinal range? (iv) what are their habitat preferences? and (v) is their occurrence in Poland threatened? MATERIALS AND METHODS All available collections of Zygodon from Poland (over 80 specimens) from the following herbaria: KRAM, LBL, OSTR, POZG, SOSN, WA,and WRSL, were re-examined. Additional field research during the last few years was also conducted and collected specimens are housed in the herbarium SOSN. The overwhelming majority of localities known from the literature were revisited. In earlier papers, especially from northern Poland, information about the occurrence of Z. viridissimus s.l. is presented (e.g. Koppe, 1931; Dietzow,1938). Because of the lack of specimens, these data have not been included in the analysis. All information about habitat, altitude, and others, was included in adata base. The data gathered during fieldwork and the information contained on herbarium labels formed the basis for description of the ecological preferences of these taxa. For microscopic examination, dried plants were soaked in water and permanent slides of leaves, sections and propagula were mounted in Hoyer’s solution (Anderson, 1954), and the species have been distinguished on the basis of morphological characters. All measurements were obtainedfrom wet plants and/or from prepared slides mounted in Hoyer’s solution. Morphological and anatomical details were drawn with the aid of aNikon Eclipse E200 compound microscope and Nikon Y-IDT drawing tube. The distributions of the individual taxa have been presented as dot maps. The signatures of sites were split into five time phases. Analysis of species occurrence was undertaken using five time periods to show historical trends for individual taxa over the last decades. For each species the list of known stations are presented. For literature based records the bibliographical information is included. New findings and localities not known from literature are marked with an asterisk. For allocation of individual species to each threat category the latest IUCN criteria (IUCN, 2012 – second edition of version 3.1, first published in 2001) have been used, with recommendations for estimating threatened taxa (IUCN Standards and Petitions Subcommittee, 2014) and Guidelines for application of IUCN Red List criteria at regional and national levels (IUCN, 2010), adapted for bryophytes (Hällingbäck et al.,1998; Hodgetts, 2015). Some species elaborated in this paper,including Zygodon dentatus (Limpr.) Kartt.,Z.rupestris Schimp. ex A.W.H.Walth. &Molendo and Z. stirtonii Schimp.are treated at alower taxonomic rank, mainly as varietes of Z. viridissimus (e.g.Düll, 1992;Frey et al.,2006; van der Pluijm, 2012; Vitt, 2014), but, following Karttunen (1984), Smith (2004)and Hill et al. (2006),weview them as separate species. Zygodon in Poland 233 RESULTS In Poland, five species of Zygodon occur,namely: Z. dentatus, Z. gracilis, Z. rupestris, Z. stirtonii and Z. viridissimus.All belong to sect. Zygodon and subg. Zygodon.They are small acrocarpous mosses forming loose turfs or soft cushions on trunks and branches of trees, more rarely on calcareous rocks, on light-shaded walls and on concrete. Their main features are erect, simple or branched stems; lanceolate to linear-lanceolate leaves with and acute apex; margins entire or denticulate towards the apex and plane or recurved below; costa vanishing below the leaf apex or rarely excurrent; lamina cells quadrate, rounded-hexagonal to ovate; upper lamina cells papillose; and rectangular,smooth, translucent basal lamina cells. In leaf axils are frequently present ovoid to ellipsoidal gemmae. Polish Zygodon taxa are dioicous but in all examined materials only twice were afew archegonia observed (in Z. rupestris and Z. viridissimus). Also twice, in the same species, immature and broken sporophytes were noted. Key for identification Polish species of Zygodon 1. Margin of upper leaves toothed towards apex; plants without gemmae, only on limestone rocks.......................................................................................Z. gracilis 1. Margin of leaves entire or,particularly in young leaves, denticulate near apex; plants with gemmae, growing mainly on bark of trees.......................................2 2. Gemmae without cross-walls ....................................................... Z. rupestris 2. Gemmae with cross-walls ..............................................................................3 3. Margin of younger leaves usually denticulate near apex; gemmae with curved cell-walls...............................................................................................Z. dentatus 3. Margin of leaves entire; gemmae with almost straight cell-walls.......................4 4. Costa distinctly widened in leaf apex, excurrent in asharp, stout point ....... .........................................................................................................Z. stirtonii 4. Costa not widened in leaf apex, percurrent or subpercurrent......................... .................................................................................................. Z. viridissimus Asurvey of species Zygodon gracilis Wilson Figs 1-5, 38 Plants (1.0-)1.5-3.5(-5.0) cm high, forming brownish to yellowish-green to dark-green tufts. Leaves lanceolate to oblong-lanceolate,pointed, contorted and incurved when dry,spreading to recurved when moist. Margin of the upper leaves sharply serrate towards the apex, entire below.Costa stout, ending below or in the apex. Mid-lamina cells rounded-hexagonal, thick-walled, (4-)7-9(-10) µmwide with (1-)2-4 clavate papillae. Fertile plants not observed in Polish material. General distribution. — Zygodon gracilis occurs sporadically in the Carpathians and frequently in the Alps (Düll, 1985a, b; Frey et al.,2006; Meinunger &Schröder,2007; Müller,2005). Elsewhere it is reported from mid-west Yorkshire in England (Proctor &Blockeel,2014a), British Columbia in North America and from one locality in Guatemala in Central America (Vitt, 2014), but Central American plants apparently belong to Z. campylophyllus Müll.Hal. (Allen, 1994). 234 A. Stebel &J.Żarnowiec Zygodon in Poland 235 Extent of distribution and altitudinal range in Poland. — Previously reported from Poland under the name Zygodon gracilis var. alpinus (Schimp.) Grav. (Lisowski, 1960a, 1962). The species is known from only one locality in Dolina Kościeliska valley situated in the western part of the Tatras at