Dolichomitriadelphus hakkodensis (Besch.) Ignatova, Fedosov & Ignatov.

Dolichomitriadelphus hakkodensis (Besch.) Ignatova, Fedosov & Ignatov. View in CoL — Isothecium hakkodense Besch., Ann. Sci. Nat., Bot. View in CoL , sér. 7, 17: 371. 1893.

Plants robust, yellowish-green, glossy. Secondary stems erect to ascending, to 5 cm long, dendroid, irregularly branched; stipe short; attenuate flagelliform branches absent. Secondary stem leaves imbricate when dry and wet, 1.3–1.5× 0.7–0.9 mm, ovate, widest at 1/6–1/3 the leaf length, obtuse or bluntly acute, concave; costa single or forked, thin, extending to 1/2–3/4 the leaf length; margins serrulate in upper 1/2, entire below; upper laminal cells 15–20×6–7 µm, moderately thick-walled, slightly

Dolichomitriopsis Dolichomitriadelphus Isotheciastrum Pseudisothecium Isothecium

Plant size medium to large medium to large

Branching irregular irregular

Foliage julaceous or not julaceous

Foliage density loose to dense loose to dense

Leaf shape ovate ovate

Leaf concavity rather strong rather strong

Leaf apex acuminate acute

Leaf margin serration weak weak

Alar group moderate poor

Costa long long

Cells elongate elongate

Cell walls thick and porose thin

Capsule erect slightly inclined

Annulus persistent persistent

Exostome teeth below papillose striolate

Cilia 0 1-2

Calyptra smooth smooth medium medium to large small to large irregular to pinnate irregular to pinnate irregular not julaceous julaceous or not julaceous or not loose loose, rarely dense dense, rarely loose ovate-lanceolate ovate to triangular ovate to obovate moderately strong strong to weak rather strong narrow acute acute to acuminate short acuminate strong strong weak moderate moderate to conspicuous moderate long long long elongate elongate or short elongate thick thick thick strongly inclined sl-str inclined erect or inclined persistent deciduous deciduous striolate striolate striolate

1-2 1-3 0-1

with few hairs smooth smooth Tripterocladium small pinnate not julaceous loose to dense ovate-lanceolate weak narrow acute weak moderate short elongate thick inclined deciduous striolate

1-2

?

Bryolawtonia medium pinnate subcomplanate loose ovate weak acute strong moderate long short thick deciduous striolate

1-2

smooth flexuose, eporose; median laminal cells linear, 40–60×5– 7 µm, with moderately thickened walls, porose; basal laminal cells elongate rectangular, 30–40×6–7 µm, with moderately thickened walls, porose; alar group small, weakly delimited, consisting of rectangular cells. Branch leaves similar to secondary stem leaves but smaller. Dioicous. Gametangia and sporophytes not seen in specimens from Russia. [Setae 0.8–1.2 cm, curved or flexuose. Capsules inclined, oblong, symmetric or slightly asymmetric. Exostome teeth ca. 600 µm long, striolate below, papillose distally; basal membrane low, segments narrowly perforated, cilia 1–2, short. Spores 12–15 µm.]

Distribution and ecology. This species occurs in Japan (Hokkaido, Honshu) and in South Kuril Islands in the Russian Far East. In Russia it grows at altitudes 200- 500 m, on rocks and cliffs along streams.

Specimens examined: Russia, Sakhalinskaya Province , Kunashir Island , Ruruj Mt., NW-faced slope, Dal’nij Creek, 44°28'N, 46°06', 250 m alt., Ignatov 06-1284 ( MHA9038396 About MHA ); same place, 500 m alt., Ignatov 06-1188 ( MHA9038398 About MHA ) .

Differentiation. The distinction from Dolichomitriopsis crenulata is discussed under this species. Other species of Dolichomitriopsis from the Russian Far East have leaves with attenuate apices, while leaf apex in D. hakkodense is obtuse, rounded or, rarely, bluntly acute. D. hakkodense was also confused with Dolichomitra cymbifolia due to imbricate foliage and strongly concave leaves with rounded-obtuse apices; however, they can be recognized by ovate vs. wide elliptical leaves and upper leaf margins serrulate vs. irregularly dentate.