Isotheciastrum subdiversiforme (Broth.) Ignatova, Fedosov & Ignatov

Isotheciastrum subdiversiforme (Broth.) Ignatova, Fedosov & Ignatov View in CoL , comb. nova — Isothecium subdiversiforme Broth., Hedwigia View in CoL 38: 237. 1899.

Plants slender, rigid, pale green, slightly glossy. Secondary stems erect to ascending, to 2–5 cm long, dendroid, irregularly to subpinnately branched; stipe short; attenuate flagelliform branches absent. Secondary stem leaves erect-spreading when dry and wet, 1.3–1.5× 0.6– 0.7 mm, ovate-lanceolate, widest at mid-leaf, acuminate, moderately concave; costa single, stout, gradually narrowing, occasionally forked, extending to 2/3–3/4 the leaf length; margins sharply serrate in upper 1/3–1/2, serrulate almost to the base; upper laminal cells 20–30×8–10 µm, slightly flexuose, thick-walled, eporose; median laminal cells sublinear, 25–45×7–8 µm, not flexuose, thick-walled, weakly porose; basal laminal cells long rectangular, 30–50×7–8 µm, thick-walled, weakly porose; alar group small to medium sized, well delimited, consisting of isodiametric, irregular in shape, thick-walled, dark colored cells. Branch leaves similar to secondary stem leaves but smaller. Dioicous. Setae 1.0– 1.5 cm, flexuose. Capsules inclined, asymmetric, narrowly oblong-cylindric, brown. Exostome teeth 500–600 µm long, striolate below, papillose above; endostome basal membrane low, segments perforated, cilia 1–2, short. Spores 12–17 µm. Calyptra occasionally with few hairs at base.

Distribution and ecology. This species is widespread in Japan and is also known from Taiwan and southern provinces of China. It is not found in Russia yet; we consider it as a provisionary species which can be found in South Kuril Islands. Grows on humus or rocks, rarely on tree bases.

Specimens examined: Japan, Kyushu: Kagoshima Prefecture, Ohnami Lake in Kirishima Range , 31°56’N, 131°22’E, Ignatov & Ignatova 98-619 ( MW9046234 ) GoogleMaps ; Miyazaki Prefecture, Inohae Valley north of Nichinan , 31°40’N, 130°51’E, Ignatov & Ignatova 98-589 ( MW9046235 ) GoogleMaps ; same place, Ignatov & Ignatova 98-580 ( MW9046237 ) ; Miyazaki, Minaminaka, Kitago , IV.1946 Noguchi & Hattori, Musci Japonici Ser. 1 (1947), #6 ( MW9046236 ) .

Differentiation. Isotheciastrum subdiversiforme can be easily recognized due to a unique combination of morphological characters, i.e, erect-spreading leaves with acuminate apices and strongly dentate upper margins, and asymmetric, inclined capsules.

Dolichomitriopsis S. Okamura, Bot. Mag. (Tokyo)

25: 66. 1911.

Type: Dolichomitriopsis crenulata S. Okamura

The genus is characterized by ovate-lanceolate or oblong-ovate leaves, mainly acuminate, except for the type speciesof the genus which has leaves with widely obtuse apices. Other diagnostic characters of the genus include (1) erect, symmetric capsules; (2) calyptra extending to the middle of capsule; (3) annulus persistent (consisting of small cells); (4) exostome teeth evenly and densely papillose; (5) endostome basal membrane low, segments not perforated, cilia lacking.

Dolichomitriopsis crenulata S. Okamura, Bot. Mag.

(Tokyo) 25: 66. 3. 1911.

Plants medium-sized, yellowish-green, slightly glossy, forming loose tufts. Secondary stems ascending, to 5 cm long, irregularly branched, stipe indistinct; branches occasionally flagelliform-attenuate. Secondary stem leaves imbricate when dry and wet, 1.6–1.8(–2.0)×0.8–1.0 mm, oblong-ovate or obovate, widest at 1/3–2/3 the leaf length, widely obtuse, strongly concave; costa single, stout, gradually narrowing, occasionally forked, extending to 2/3– 4/5 the leaf length; margins widely incurved, crenulate or almost entire in upper 1/2, slightly uneven below; upper laminal cells vermiform, 20–30×8–10 µm, thick-walled, eporose; median laminal cells sublinear, flexuose, forming oblique rows, 35–50×6–7 µm, with moderately thickened walls, eporose; basal laminal cells sublinear, 40– 55×8–9 µm, thick-walled, eporose or indistinctly porose; alar group small to medium-sized, well-delimited, consisting of isodiametric, irregular in shape, thick-walled, dark colored cells. Branch leaves similar to secondary stem leaves but smaller.

Dioicous. Gametangia and sporophytes unknown in Russia. [Perichaetia on secondary stems. Setae flexuose when dry, 5–7 mm long. Capsules erect, symmetric, oblong-cylindric, smooth, brown. Annulus consisting of small cells. Exostome teeth ca. 300 µm long, papillose throughout; endostome basal membrane low. Spores 10– 13 µm].

Distribution and ecology. This species was considered as an endemic of Japan (Hokkaido, Honshu). It is newly reported from Russia, South Kuril Islands, Iturup Island. It was collected in dwarf-shrub & herb dominat- ed tundra in place with late snow melting, in crevices between boulders.

Specimen examined: Russia, Sakhalinskaya Province, Iturup Island, Bigatyr Range NW-faced macroslope, Bakalin K-16-45-07 (MHA9038397).

Differentiation. In leaf shape (oblong-ovate, widely obtuse, strongly concave) and imbricate foliage D. crenulata is similar to Dolichomitra cymbifolia ; however, leaf margins are indistinctly crenulate in D. crenulata vs. strongly and irregularly dentate in the latter species. D. crenulata was also confused with Dolichomitriadelphus hakkodense ; the differences between these two species include strongly vs. moderately concave leaves; oblong-ovate or obovate vs. ovate leaf shape; widely vs. narrowly obtuse leaf apices; and indistinctly crenulate vs. serrulate upper leaf margins.