Pylaisia coreana Nog., J. Hattori Bot. Lab.

2. Pylaisia coreana Nog., J. Hattori Bot. Lab. 12:

32, f. 12. 1954.

Figs. 10 View Fig , 14A View Fig , 34F View Fig .

Note on taxonomy. Pylaisia coreana was described by Noguchi (1954) who compared it with P. sublaevidens Toyama, but later Noguchi (1984) synonymized P. sublaevidens with P. polyantha , without any discussion about P. coreana . Arikawa (2004) placed P. coreana to the synonymy of P. polyantha , but P. sublaevidens to the synonymy of P. obtusa (which well fits the illustrations of Toyama, 1938). Pylaisia coreana was described by Noguchi as having small plants, with leaves 1–1.2× 0.3–0.35 mm, narrow laminal cells, 55–70×4–5.5 µm, and small spores, 10–13 µm; these characters exactly fit specimens from eastern part of Russia, which were found in a separate moderately supported clade. Therefore we apply the name P. coreana to the species of this clade.

The above mentioned quantitative characteristics of Pylaisia coreana are not totally exceptional in P. polyantha , but small spores are known in European populations of P. polyantha , while P. polyantha ‘ orientale ’ has spores 12–18(–20) µm, i.e. is consistently different from P. coreana . The distinctions in peristome structure are discussed below.

Description. Plants small, light- to yellowish-green. Stem and branches straight, moderately densely foliate; leaves straight to indistinctly homomallous and turned outwards substrate. Stem leaves 0.6–1.1× 0.2–0.4 mm, lanceolate, rarely ovate, gradually narrowed into a long or short acumen, slightly rounded to insertion; margins entire or serrulate above; median laminal cells 35–75×4–5 µm, alar cells subquadrate, few, forming small, slightly elongate triangular group to 10 cells long and 5 cells wide. Branch leaves somewhat smaller and narrower. Capsules cylindrical, 1.4–1.7 mm long (without operculum). Operculum conic to conic-rostrate. Peristome forming high conus when dry.Exostome teeth 250 µm long above the mouth, dorsal plates smooth below, and slightly papillose above; endostome to 300 µm above the mouth, not adherent to exostome, endostome segments narrow, not perforated along the keel, slightly papillose. Spores 9–12(–13) µm.

Differentiation and variation. In the whole range of P. polyantha –complex, P. coreana might be difficult to differentiate from some smaller morphs of the European group of haplotypes, especially from plants described as P. suecica , that was characterized by leaves up to 1.2 mm long and spores 8–10 µm ( Limpricht, 1895). Currently, however, P. suecica is considered as a form of P. polyantha (and putatively of the European group of haplopytes). A sympatric plants of Asian P. polyantha however usually have larger plants with leaves 1.2–1.5 mm long and spores 12–14 µm, as probably most importantly, the exostome to 300 µm and endostome to 350 µm long, whereas in P. coreana exostome is to 250 µm and endostome to 300 µm long, and less papillose than in P. polyantha ‘ orientalis ’.

Among the samples referred here fo P. coreana , the most strongly dissimilar in morphology are Kamchatkan plants ( Fig. 10 View Fig : 37–40: Cr9). Its leaves are very short and broad, resulting in julaceous habit similar to that of P. curviramea , but their narrow leaf cells and short peristome agree with its affinity to P. coreana , suggested from molecular phylogenetic analysis. We interpret such morphs as a result of an impact of severe environmental conditions, especially exposure to strong winds.

Distribution. Kamchatka,EastYakutia,AmurskayaProvince, Khabarovsk and Primorsky Territories, Sakhalin.

Selected specimens examined: RUSSIA: East Siberia, Republic Sakha ( Yakutia ), Ust-Maya Distr. , left bank of Yudoma River , 2 km downstream Shchel Creek mouth, 8 Sep 2000 Ivanova s.n. (Bryophyta Sibiriae Exsiccata Fasc. I #48 (as P. steerei ), MHA9130433); Primorsky Territory: Sudzhukhinsky Reserve , 27 Sept. 1944 Zhudova 164 (MW9061904); Anuchino Distr. , Anuchino, Ignatov & Ignatova 13-1411 (MHA9130450) .