Pylaisia curviramea Dixon, Rev. Bryol.

4. Pylaisia curviramea Dixon, Rev. Bryol. View in CoL , n.s. 1:

186. 1928.

Figs. 13 View Fig , 16 View Fig , 34C View Fig .

Note on taxonomy. Arikawa (2004) found that P. polyantha from Asian Russia and, specifically, collections from Bureya River Basin differ from European P. polyantha by rbc L sequences, and also found that these plants are identical by morphology with Pylaisia curviramea described from Central China.

The present analysis found specimens of this species homogeneous by applied DNA markers, posing only a question on its differentiation from P. steerei . However, these species are distinct morphologically when plants are well developed: P. steerei looks as Hypnum cupressifirme or miniature Calliergonella lindbergii , whereas optimally developed P. curviramea has short and broad leaves, dense foliage and curved branches, which make these plants more similar to Entodon challengeri (Paris) Cardot than to any Pylaisia species ( Fig. 13 View Fig ). Less developed plants are still conspicuous due to imbricate, strongly concave leaves.

Description. Plants looks medium sized due to tumid foliage, despite its leaves are shorter than in many other species of Pylaisia , yellowish- or brownish-intense green. Stems and branches usually curved, occasionally straight, densely terete foliate; leaves straight or with slightly curved subapical part, in the latter case forming a homomallous apsect. Stem leaves 0.7–1.0× 0.3–0.5 mm, ovate to broadly ovate, shortly narrowed to apex, slightly rounded to insertion; margin entire or serrulate above, median laminal cells rhomboidal, 20–45×5–6 µm, alar cells subquadrate in a rather expanded elongate group to 15 cells long and 7 cells wide. Branch leaves somewhat smaller. Capsules cylindrical, 1.5–2.0 mm long (without operculum). Operculum conic. Peristome forming high conus when dry. Exostome teeth 300 µm long above the urn mouth, dorsal plates smooth below, papillose above; endostome to 350 µm above the mouth, not adherent to exostome, endostome segments narrow, more or less perforated along keel, moderately papillose. Spores 12–15(–16) µm.

Differentiation and variation. A considerable variation in leaf size and shape between sequenced specimens of P. curviramea from Asian Russia is shown in Fig.13 View Fig . The record of Pylaisia curviramea from Kamchatka is based on plants with a julaceous habit, but with slightly concave leaves and short, not curved branches. DNA sequence data place this specimen within P. coreana (specimen Cr9, OK217, Fig. 10 View Fig : 37–40).

Distribution. Pylaisia curviramea is known from several areas in Russia; it usually grows in abundance. There are numerous collections (and observations in the field) in valleys of the left side tributaries of Amur River – Zeya and Bureya Rivers, in their middle courses which experience regular great floodings. An extensive population of P. curviramea was also found in Baikal Lake surroundings. Pylaisia curviramea , as it is circumscribed here, occurs in Yakutia, Irkutsk Province, Amurskaya Province, and Khabarovsk Territory.

Specimens examined: Khabarovsk Territory: Chegdomyn Settl., on street of the settlement, Ignatov 97-1284 (MHA9130435); Amurskaya Province : Norsky Nature Reserve , valley of Nora River near cordon “Sorokaverstny”, 30 Jun. 2010 Bezgodov 17 (MHA9130451); same place, island at the mouth of Meun River , 11 Jul 2010 Bezgodov 397 (MHA9047653) .