Campylopus gracilis (Mitt.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1870

Campylopus gracilis (Mitt.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1870 View in CoL –71: 427 (Gen. Sp. Musc. 1: 131). 1872. — Dicranum gracile Mitt., J. Proc. Linn. Soc., Bot., Suppl. 1: 17. 1859. Fig. 5

Plants in loose tufts, light green, glossy. Stems 1–2 cm, forked. Leaves (4–)5–7× 0.35–0.5 mm, erect when wet, appressed when dry, narrowly lanceolate, ending in a very long, slightly flexuose, concolorous, serrate subula; costa very broad, occupying 3/4–4/5 of leaf width, long-excurrent, in transverse section with ventral hyalocysts of the same size as following guide cells and somewhat smaller substereids forming massive band on a dorsal side, with dorsal surface ribbed due to protruding cells; distal and median laminal cells 20–37×6–8 µm, rectangular or elongate-rhomboidal, with oblique transverse walls, basal laminal cells 30–55×8–15 µm, rectangular, hyaline and translucent, along margins well differentiat- ed, narrower, forming a border extending to mid-leaf; alar cells sharply hyaline, thin-walled, forming inflated

The genus Campylopus in Russia 215 group, projecting into the costa; basal laminal cells hyaline, thin-walled, long-rectangular. Specialized asexual reproduction unknown. Sporophytes not seen in collections from Russia.

B 5 mm A C D E 100 µm 1 mm F G H I

Differentiation. In having combination of a very broad costa bearing substereids with longitudinal ribs on dorsal side and short cells in upper portion of the leaf lamina, C. gracilis can resemble the only one another Rus-

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sian Campylopus , C. subulatus . Although in most manuals C. subulatus is treated as having costa that occupies a half of the leaf base width, this character is very variable, and plants with broader costae may occur; moreover, basal laminal cells in C. subulatus usually are hyaline, not forming well delimited, inflated alar groups, but, according to Frahm & Vitt (1978), this species possesses well-differentiated group, composed of reddishbrown, inflated alar cell. However, a combination of very wide costa and inflated hyaline alar group projecting into the costa occurs only in C. gracilis . One more remarkable trait of this species is a rather well differentiated narrow cells, forming a border in a basal leaf portion.

Distribution and ecology. Campylopus gracilis is an oceanic species with a disjunctive distribution, largely associated with western coasts of Eurasia ( UK, south-western part of Norway, the Alps) and North America (British Columbia). In addition, this species occurs in Asia: in China and neighbouring areas of Sino-Himalayan Region within Nepal, India, Myanmar and Thailand. A single Russian collection originates from the middle part of Khabarovsk Territory ( Fig. 9 View Fig ), where the species was found in subalpine belt at elevation of about 1500 m, on humus in cliff crevice (for details see Pisarenko et al., 2022). DNA-barcoding supports an identification based on morphology, although an Asian specimen has somewhat different sequences from the European ones.