Pylaisia obtusa Lindb., Contr. Fl. Cryptog. Asiae

Ignatova, E. A., Kuznetsova, O. I., Shafigullina, N. R., Fedosov, V. E. & Ignatov, M. S., 2020, The genus Pylaisia (Pylaisiaceae, Bryophyta) in Russia, Arctoa 29 (1), pp. 135-178 : 171-174

10. Pylaisia obtusa Lindb., Contr. Fl. Cryptog. Asiae 257. 1872.

Figs. 29–31 , 34L .

Description. Plants small to medium-sized. Stem and branches curved, rather densely foliate; leaves homomallous, turned outwards substrate. Stem leaves 1.1–1.5 × 0.4–0.5 mm, ovate to ovate-lanceolate, gradually or moderately abruptly narrowed into narrow acumen, gradually and slightly rounded to insertion; margins subentire; median laminal cells 40–60×4–6 µm, alar cells subquadrate, form compact subquadrate to triangular or occasionally transversely elongate alar group, 7–10 cells long and 12 cell wide. Branch leaves smaller, narrowly ovate-lanceolate. Inner perichaetial leaves erect to reflexed, long. Capsules oblong-cylindrical. Operculum conic, with short, obtuse beak. Peristome forming high conus when dry. Exostome teeth 230–260 µm long above the mouth, dorsal plates smooth below, papillose above; endostome up to 300 µm above the mouth, adherent to exostome only at base; segments bifid; endostome moderately papillose. Spores 15–22 µm.

Differentiation: Pylaisia obtusa is habitually similar to P. subcircinata , and these species were often confused in herbarium collections. Their distinctions are described in comments to the latter species. Combination of markedly differentiated stem and branch leaves, stem leaves with ovate base and narrow acumen, small, subquadrate alar group, obtuse opercula and bifid endostome segments is unique for this species.

Distribution. Pylaisia obtusa is the commonest species of the genus in Sakhalin; it is also known from Kuril Islands and Kamchatka. In Japan it occurs only on Hokkaido ( Arikawa, 2004). Our molecular data also suggest the presence of this species in Alaska.

Specimens examined: RUSSIA: Sakhalinskaya Province: Kuril Islands: Kunashir, Mysovoy Cape , Ignatov 06-1822 (MHA9029876); Iturup Island , Bogatyr Range , Stokap Volcano , Bakalin K-23-19-07a (ex VLA, MW9061988); Sakhalin: near Yuzhno-Sakhalinsk Town , Bolshevik Mt. , 18 Aug 2009 Pisarenko op03713 (MHA9130437); Tymosvky Distr. , Kamyshovy Range, Kamyshovy pass, 5 Sept. 2009 Pisarenko op03716 (MHA9130438); Dolinsky Distr. , Sokol, Ignatov & Teleganova 06-598 (MHA9130439); Anivsky Distr. , Bystraya River , 7 Sep 1966 Ardeeva (Cherdantseva) s.n. (MHA9130440) .

Figures

Fig. 29. Pylaisia obtusa (O1, OK211, Russia, Sakhalin). 1, 3: capsules; 2, 9: habit, dry; 4–6: stem leaves; 7: upper laminal cells; 8: basal laminal cells; 10–12: branch leaves; 13: median laminal cells. Scale bars: 5 mm for 9; 2 mm for 1–3; 1 mm for 4–6, 10–12; 100 µm for 7–8, 13.

Fig. 30. Pylaisia obtusa (all specimens from Russia). 1–3: O12, OK813, Sakhalin; 4–6: O2, OK225, Sakhalin; 7–9: O8, OK441, Sakhalin; 10–12: O6, OK433, Sakhalin; 13–15: O10, OK810, Sakhalin; 16–18: 013, OK811, Sakhalin; 19–21: O7, OK434, Sakhalin; 22–24: O4, OK226, Dakhalin; 25–27, O11, OK812, Sakhalin; 28–29: O9, OK443, Kuril Islands, Shikotan; 31– 32: O5, OK2795, Kuril Islands, Kunashir; 33–34: O3, OK2748, Sakhalin. 1–2, 4–5, 7–8, 10–11, 13–14, 16–17,19–20, 22–23, 25, 26, 28–29, 31, 33: stem leaves; 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 32, 34: branch leaves. Scale bar: 1 mm for all.

Fig. 31. Peristome of Pylaisia obtusa under SEM (A–F) and light (G) microscopes, showing endostome segments split into two branches distally and rather moderate adherence to exostome teeth. A–F: from Sakhalin, Pisarenko, 20.VIII.2012, op I448 (MHA), G from O4, Sakhalin, Ignatov & Teleganova 06-268 (MHA).

Fig. 34. Habit of the Russian species of the genus Pylaisia. A: P. bezgodovii, OK212; B: P. steerei, OK212; C: P. curviramea, Irkutsk, OK2682; D: P. polyantha, Moscow, P10; E: P. polyantha, haplotype‘orientalis’, Altai, OK2729; F: P. coreana, Yakutia, OK2722; G: P. camurifolia, Kurils, OK209; H: P. condensata, OK446; I: P. brotheri, OK2799; J: P. subcircinata, OK830; K: P. stereodontoides, OK2811; L: P. obtusa, OK226. Scale bar: 1 mm for all.