Pylaisia stereodontoides Broth. & Yasuda ex Ihsiba, Classif. Mosses

11. Pylaisia stereodontoides Broth. & Yasuda ex Ihsiba, Classif. Mosses Japan 92. 1932.

Figs. 32 View Fig , 33 View Fig , 34K View Fig .

Description. Plants small to medium-sized. Stems creeping, branches straight or slightly curved, rather densely foliate; leaves erect-spreading when dry, slightly homomallous. Stem leaves 1.3–1.7× 0.4–0.45 mm, ovate-lanceolate, gradually or moderately abruptly narrowed into narrow acumen, gradually rounded to insertion; margins subentire; median laminal cells 30–65×5–6 µm, alar cells subquadrate, form triangular alar group 10–14 cell long and 6–8 cells wide. Branch leaves markedly differentiated, smaller, narrowly ovate-lanceolate. Inner perichaetial leaves erect to reflexed, long. Capsules oblong-cylindrical. Operculum conic, with short, obtuse beak. Capsules ovoid-cylindrical. Operculum long-rostrate. Peristome in dry state forms low conus due to adherence of its elements. Exostome teeth ca. 230 µm long above the mouth, long acuminate, dorsal plates smooth below, slightly papillose above; endostome totally adherent to exostome theeth, fragmentary. Spores 14–25 µm.

Differentiation: Pylaisia stereodontoides can be recognized from other species occuring in the Russian Far East by combination of only slightly homomallous leaves with narrow acumina, triangular alar group formed of rather large cells, long cylindrical capsules and low conic peristome due to fragmentary endostome totally adherent to exostome teeth. Pylaisia subcircinata and P. obtusa have smaller, subquadrate alar group consisting of smaller, often dark-colored cells, and less strongly modified endostomes. Shape of alar group in leaves of P. stereodontoides is more similar to P. polyantha , but this species is readily recognized from it due to high-conic, free endostome with wide, keeled segments and exostome teeth usually incurved into the urn mouth between endostome segments.

Distribution: Arikawa (2004) reported P. stereodontoides only from Japan (Hokkaido and eastern Honshu) and Korea. In Russia it is known from several localities in Primorsky Territory. It was also reported (as P. intricata ) from Judish Autonomous District (Cherdantseva, 2007) and south of Khabarovsk Territory (Lazarenko, 1941), but we haven’t seen specimens.

Specimens examined: RUSSIA: Primorsky Territory: Khasansky Distr., Kedrovaya Pad’ Reserve, 16 Sept. 1958 Cherdantseva s.n. (ex VLA, MHA); Lazovsky Reserve , Petrov Island , 25 Aug. 1986 Cherdantseva (s.n. ex VLA, MHA); Ussurijsky Nature reserve , upper course of Artyomovka River , Ignatov 08-217 (MW9061983); Ussurijsky Nature Reserve , Komarovka Creek , Ignatov & Ignatova 06-3522 (MW9061984); Lazovsky Distr. , Lazovsky Reserve , 1 Jul. 2008 Dudov s.n. (MW9061986); Partizansk Distr. , Lozovy Range, Chandolaz Mt. , Ignatov et al. 13-1887 (MHA9047654); Chuguevka Distr. , ridge S of Pravaya Sokolovka Creek, I gnatov 07-603 (MHA9130443); Vladivostok area , Bolshaya Sedanka Creek , Ignatov et al. 06-3361 (MHA9130448); Terney Distr. , surroundings of Taiga village , Galanina & Yakovchenko Pr-430-1-11 (MHA9130449); Okeanskaya Station , Markovsky Peninsula, 6 Sept. 1931 Popov s.n. (MHA9047212) .

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Despite Pylaisia is a not very large genus, a number of misinterpretations of species was rather great, which at least partly may be explained by a difficulty in presenting species characters. Habitually many species are recognizable at once. Thus we provide the species habit comparison in Fig. 34 View Fig , where all Russain species are shown at the same magnification.