Pylaisia polyantha (Hedw.) Bruch, Schimp. & W. Gümbel, Bryol. Eur.

1. Pylaisia polyantha (Hedw.) Bruch, Schimp. & W. Gümbel, Bryol. Eur. View in CoL 5: 89 (fasc. 46-47. Monogr. 3). — Leskea polyantha Hedw., Sp. Musc. Frond. 229. 1801.

Figs. 6–9 View Fig View Fig , 14 View Fig B-F, 15A-D, 34D,E.

Note on taxonomy. Pylaisia polyantha is usually considered to be a most widespread species of the genus in more northern part of temperate zone of the Holarctic, including North America ( Arikawa, 2014), Europe (Hodgetts & Lockhart, 2020), East Europe and North Asia ( Ignatov et al., 2006), whereas in Mexico, China and Japan it is rarer than other species. Molecular phylogengetic analysis based on rbc L showed a genetic differentiation between Asian and European populations of P. polyantha ( Arikawa & Higuchi, 2003) , and we confirmed this based on nuclear ITS and IGS markers ( Figs. 1–4 View Fig View Fig View Fig View Fig ). For plants from Asian Russia with julaceous habit Arikawa (2004) suggested the name P. curviramea Dixon , applied to a species described from Central China which remained little known for its morphology and distribution before this study of Arikawa.

The present study confirmed this in general. Plants from Europe, Arctic Siberia and North America belong to one group of haplotypes, and in this region P. polyantha is less polymorphic comparatively with South Siberia and Russian Far East. Asian plants differ from European ones, but they were found to be not homogeneous ( Fig. 4 View Fig ). The outstanding morphological variation in Asian P. polyantha was noted as early as by Lindberg (1872), who described from Bureya River (Amur River tributary) var. homomalla Lindb. (later synonymized by Arikawa (2004) with P. steerei ), and subsequently Lindberg & Arnell (1890) added, also from Yenissey River, var. brevifolia Lindb. & Arnell and var. julacea Lindb. & Arnell , which descriptions fit well P. curviramea .

Morphological differentiation of P. steerei and P. curviramea from P. polyantha is supported in general by IGS nuclear molecular marker ( Figs. 2–3 View Fig View Fig ), although ITS haplotype network illustrates an imperfect segregation and three samples with P. steerei morphotype were found having core ITS haplotype of P. polyantha ‘ orientalis ’ ( Fig. 4 View Fig ).

Siberian plants of P. polyantha are very variable and can not be differentiated morphologically from Europe- an plants, and therefore they are treated here within P. polyantha , excluding morphologically different P. steerei and P. curviramea . Also, P. polyantha is treated here excluding haplotypes from the eastern regions of Russia that were (1) resolved monophyletic in molecular phylogenetic analyses; (2) have small but stable distinctions in leaf and spore sizes. They are accepted as a separate species, Pylaisia coreana .

Description. Plants small to medium-sized, yellowish- to dark-green, sometimes brownish. Stem and branches straight or only indistinctly curved, densely foliate; leaves straight to indistinctly homomallous and turned outwards substrate. Stem leaves 1.1–1.5(–1.7) ×0.5–0.6(–0.7) mm, ovate to ovate-lanceolate, gradually narrowed into a long acumen, slightly rounded to insertion; margins entire or serrulate above; median laminal cells 35–70(–90)×5–6(–7) µm, alar cells subquadrate, forming slightly elongate triangular or subquadrate group 10–15 cells long and 5–6 cells wide. Branch leaves somewhat smaller. Capsules cylindrical, 1.5–1.8 mm long without operculum. Operculum high conic to conic-rostrate. Peristome forming high conus when dry. Exostome teeth 250–300 µm long above the mouth, dorsal plates smooth below, papillose above; endostome 300–350 µm above the mouth, not adherent to exostome, segments narrow or broad, not or slightly perforated along keel, slightly papillose. Spores (10–)11–16(–18) µm.

Variation and differentiation. The morphological differences between two main genetic entities of P. polyantha , i.e. between mainly European and Asian ‘ orientalis ’ group of haplotypes is difficult to present without special extensive morphometric study, as both are very widespread and very variable. In Figs. 7–8 we can only show a relatively higher variation in Asian population by comparison of leaf shape of sequenced plants. In each collection one of the best developed shoot was used for illustration of two stem leaves taken below stem apex and above part where branches already elongate, and one branch leaf. This comparison shows that Asian plants are somewhat larger, have leaves more abruptly tapered to acumen and with a larger difference between stem and branch leaves. Of course, this illustration cannot pretend to any completeness: e.g., Arikawa (2004) illustrated stem leaves from the type of P. polyantha of 2.0 mm long, whereas in Russia we never saw stem leaves longer than 1.7 mm. However, with some hesitation we present this comparison, which generally agree with our observations on numerous other collections from Russia, showing at the same time differentiation that unlikely may be interpreted as a basis for taxa delimitation.

The differentiation in peristome structure between these two groups of haplotypes is discussed below separately, with comparison with other species of Pylaisia polyantha -complex ( Figs. 14–16 View Fig View Fig View Fig ).

The distinction between P. polyantha and P. coreana is discussed under that species.

Distribution: In European Russia P. polyantha occurs almost throughout its territory, except islands of Arctic Ocean and tundra areas. It is rare in Kola Peninsula, xeric areas near Caspian Sea, otherwise it is ubiquitous species, growing on various trees. Due to the fact that Populus is widely used in cultivation in cities and along roads, Pylaisia polyantha , which is especially common of Salix and Populus trunks, is an abundant species in almost all climatic zones.

Besides Salicaceae , Pylaisia polyantha is not rare in boreal forests on Betula trunks, while in broad-leaved forest zone it may grow on hardwood trees ( Tilia , Quercus, Acer , etc.), growing on them sporadically in Central

13 14 15 17 19 20 22 23

Fig. 7. Pylaisia polyantha s. str.: 1–3: P6, OK445, Poland; 4–6: P10, AY528881 View Materials , Russia, Moscow; 7–9: P5, OK435, Russia, Dagestan; 10–12: P7, OK832, Russia, Perm Territory; 13–15: P1, OK2725, Russia, Taimyr; 16–19: P2, OK2741, U.S.A., Alaska; 19–21: P4, OK2809, Canada, Ontario; 22–24: P3, OK2742, U.S.A., Michigan. 1–2, 4–5, 7–8, 10–11, 13–14, 16–17, 19–20, 22– 23: stem leaves; 3, 6, 9, 12, 15, 18, 21, 24: branch leaves. Scale bar: 1 mm for all.

European Russia, but rarely in the Caucasus, where it is more strictly associated with Salicaceae . Also throughout its range it occasionally grows on fresh logs (including decorticated wood of Picea ) and on rocky susbstrates, both natural (e.g. granites, schists and other metamorphic rosks) and man-made (concrete, various roof materials, old woody walls and fences in more or less wet places, etc.).

The above characteristics of habitats and overall distribution of Pylaisia polyantha s.l. pertains the Asiatic Russia as well. The northernmost localities are in Arctic in Taimyr Region and at the mouth of Lena River.

Selected specimens examined: (in addition to Table 1): WEST EUROPE: FINLAND: Lieto, Aurajoki River, Ignatov & Ignatova 10-1018 (MW9078580). POLAND : Warmian-Masurian Voivodeship, Nature reserve “Springs” on the Lyna river , Seregin et al. M-3109 (MW9061553). BULGARIA : Western Stara- Planina , Vidin Province, Nature Park “Belogradchik Cliffs”, Seregin M-1135 (MW9061554). EUROPEAN RUSSIA : Kaluga Province, Borovsk Distr., Satino , 26 Jul. 1998 Maksimova s.n. (MW9061610) ; Ryazan Province: Oksky State Reserve, Lakash sttl., 25 Oct. 1995 Volosnova s.n. (MW9061598) ; Vladimir Province: Gus-Khrustalny Distr., Nikulino Village, Seregin M-2582 (MW9061577); Suzdal Distr. , Smolino Village , 29 Apr. 2006 Seregin M-1493 (MW9061584) ; Tver Province: Nelidivo Distr., Tsentralno-Lesnoy Nature reserve , 26 Jul.1994 Kuraeva s.n. (MW9061592) ; Kostroma Province, Kologriv Distr., Varzengskoe forestry, 6 Jul. 2005 Tikhonova D 12m (MW9061595) ; Moscow Province, Odintsovo Distr., Zvenigorod biostation, 4 Jul. 2009 Obukhova s.n. (MW9061653) ; Arkhangelsk Province, Primorsky Distr., Onezhsky peninsula, Bolshoe Paranino Lake , 16 Aug. 2015 Korotkov 11 (MW9061706) ; Komi Republic, North Urals, Pechoro-Ilychsky Reserve , Seregin M-3678 (MW9061705) ; Vologda Province, Kirillov Distr., National Park “Russian North”, Vognema settl., Karmazina 207-04 (MW9061704) ; Kirov Province, Nagorsky Distr., Nurgush Nature Reserve , 25 May 2017 Bakka 162 (MW9114694) ; Perm Province: Krasnovishersk Distr., Vishersky Nature Reserve, 9 Jul. 1995 Bezgodov 524 (MW9061733); Basegi Nature Reserve , Vilva River , 8 Jun. 1994 Ignatov & Bezgodov 223 (MW9061737) ; Chelyabinsk Province, Troitsky Forestry , 14 Jul. 1989 Bezgodov 47 (MW9061809) ; Orenburg Province, Buzuluksky Distr., Buzukuksky Forest , 4 Jul. 2000 Kalmykova s.n. (9061804) ; Tatarstan Republic, Volzhsko-Kamsky Nature reserve , Saraly, Ignatov & Ignatova 05-2021 (MW9061773); Republic of Mordovia, Bolshebereznikovsky Distr., Simkino Village , 26 Jul. 1994 Filin s.n. (MW9061765) ; Uljanovsk Province, Sakhchinskoe Forestry , 1973 Kurnaev s.n. (MW9061768) ; Penza Province, Penza Distr., Zasechnoe Settl. , 2 Aug. 2008 Kobozeva 21 (MW9061771) ; Lipetzk Province, Dankov Distr. , Polibino Settl., Seregin M-3033 (MW9061781) ; Voronezh Province, Khopersky State reserve , 25 Apr. 1982 Popova s.n. (MW9061777) ; Tambov Province, Gorelovskoe forestry, 11 Aug. 2926 Samsel 472a (MW9061779) ; Karachaevo-Cherkessian Republic, Teberda Nature Reserve, Ignatov & Ignatova 05-3676 (MW9061797); Republic of North Ossetia, Ardon River valley, Nizhny Unal Settl. , 1 Sept. 1997 Petrunina s.n. (MW9061801) .

ASIAN RUSSIA: Altai Republic: Maima, flood valley of Katun River, 18 Jul. 1993 Ignatov 35/23 (MHA9047324); Ongudai Distr., Malyj Yaloman, 30 Jul. 1991 Ignatov & Ignatova 25/6 (9047329); Teletzkoe Lake , Bele, 3 Jul. 1989 Ignatov 0/ 79 (MHA9047326); Kurkure Range, Kayakkatuyaryksky Creek basin, 6 Jul. 1991 Ignatov 8/293 (MHA9047325). Irkutsk Province, Ust-Ilimsk Distr. , Ust-Ilimsky reservoir, 8 Aug. 2007 Seregin et al. M-2009 (MHA9047273). Zabaikalsky Territory, Kyra Distr. , “Gornaya Step” Reserve, 31 Aug. 2005 Afonina 7805 (MHA9130452). Republic of Sakha / Yakutia: Momsky Distr. , Ulakhan-Chistai Range, Tirekhtyakh River middle course, Mramornaya Mt. , Ignatov & Ignatova 18-1480 (MHA 9028262); Tomponsky Distr. , a creek, right tributary of Sakkyryr River , Ignatov & Ignatova 17-636 (MHA9025874; Tomponsky Distr. , Suntar-Khayata Range, right bank of Kyurbelyakh Creek , Ignatov & Ignatova 15-183 (MHA9047648); same place, Sukhaya Creek , Ignatov & Ignatova 15-98 (MHA9047649); Tomponsky Distr. , Sette Daban Range, Okraina Ridge between Ulakh and Nadezhda Creeks, Ignatov & Ignatova 16-1083 (MHA9022767); Khangalassky Distr. , Ulakhan Keteme Creek , Ignatov & Ignatova 16-208 (MHA9021791). Amurskaya Province: Tukuringra Ridge, left bank of Gilyui Bay between Lugerkan and Tabuneika Rivers, Dudov 2016_Br_0725 (MW9079158); same place, cape of Zeya reservoir between Razvedochny and Sukhoy Gulfs, Dudov 2016_Br_0732 (MW9079153); same place, left side of Motovaya River vally, Dudov 2016_Br_0721 (MW9079659). Khabarovsk Territory: Verkhnebureinsky Distr. , Bureinsky State Reserve , Levaya Bureya River near Kolbond’o Creek mouth, Iwatsuki 60553 (MHA9130436); Okhotsk Distr. , Urak River , 15 Sep 1952 Rozenberg s.n. (MW9061906); Sovgavan Distr. , Botchi Reserve , Kluych Dlinny , Ignatov & Ignatova 13-452 (MHA9047650). Primorsky Territory : Partizansk Distr. , Kamenisty Creek (south of Olkhovaya Peak ), Ignatov et al. 06-2448 (MW9061539); Vladivostok area , Bolshaya Sedanka Creek , Ignatov et al. 06-3349 (MW9061905); Partizansk Distr. , Lozovyj Range , Chandolaz Mt. , Ignatov 07-63 (MW9061902). Sakhalinskaya Province : Sakhalin, Tymovsk Distr. , Chamginsky Pass , Ignatov 06-493 (MW9061907) ;