Campylopus pyriformis (Schultz) Brid., Bryol. Univ.

Campylopus pyriformis (Schultz) Brid., Bryol. Univ. View in CoL 1: 471. 1826. — Dicranum pyriforme Schultz, Prodr. Fl. Starg. Suppl. 73. 1819. Fig. 7 View Fig

Plants in loose tufts, light to bright green. Stems 0.2– 2.5 cm, simple or forked. Leaves 3–4× 0.3–0.45 mm, erect-spreading, slightly contorted to flexuose when dry, occasionally falcate, from lanceolate base gradually narrowed into a long concolorous, canaliculate subula with few blunt teeth near apex; costa filling 1/3–1/2 of leaf width, excurrent, in transverse section with large ventral hyalocysts, guide cells and rather small and lax group of substereids on dorsal side, smooth or nearly so on dorsal surface; distal and median laminal cells 15–25×7–9 µm, thick-walled, elongate-rectangular; basal laminal cells 45–65×8–15 µm, translucent, thin-walled, quadrate to rectangular, along margins in 2–3 rows narrower, alar cells not differentiated. Specialized asexual reproduction absent. Sporophytes unknown in Russia.

Differentiation. Campylopus pyriformis differs from other Campylopus species in Russian flora in having combination of substereids rather than stereids on transverse section of costa, not differentiated alar groups, and concolorous, short-quadrate basal cells of leaf lamina. In addition, C. pyriformis has smooth dorsal surface of costa – the trait shared with only one species, C. schimperi . From the later species C. pyriformis differs in growth in loose, not tomentose tufts (vs. very dense, tomentose) and concolorous basal leaf portion. Due to having leaves with the costae smooth on dorsal side, C. pyriformis may be confused with representatives of several other Dicranoid mosses.

Campylopus pyriformis View in CoL is a very polymorphic species, so the traits useful for its identification in several areas do not work in the other ones. For instance, both Europen and North American plants of C. pyriformis View in CoL have leaves with very long, subulate acumina, which is not neccessary the case of plants from Kamchatka. At the same time, the molecular data proved that the plants from southern Kamchatka represent C. pyriformis View in CoL s.l. Except Kamchatka, this species was reported from Kaliningrad Province ( Ignatov et al., 2006, Dolnik & Napreenko, 2007) and Iturup Island ( Bakalin et al., 2019). Although Dolnik & Napreenko (2007) noticed C. pyriformis View in CoL as a common species on sandy dunes of Kuronian Spit, no specimens are available from that area for checking. Report of the species from Iturup Island ( Bakalin et al., 2019) is based on misidentification of Dicranella cf. heteromalla View in CoL , which resembles C. pyriformis View in CoL in having leaves with very wide costae, guide cells opening on the ventral side of the costa, smooth dorsal surface of costa and concolorous, short rectangular laminal cells at leaf base. To differentiate such Dicranella View in CoL specimens from Campylopus View in CoL , transverse sections of costa in middle portion of leaf should be checked. In Campylopus View in CoL , hyalocysts form ventral surface of costa throughout its length, while in Dicranella View in CoL leaf cross section in the middle part of leaf shows ventral stereids and ventral epidermis.

Distribution and ecology. Broadly circumscribed, C. pyriformis has a worldwide distribution with most records concentrated in Europe and in moderate climate of south hemisphere. Few currently known North American populations are considered as a result of rather recent dispersal from South America. The species was also reported from several provinces of China, including Jilin in north-east of the country close to the Russian border. According to Frahm (2007), C. pyriformis usually grows on eroded soil, including acidic sand; however, specimens from Kamchatka Peninsula available for our study originated from the thermal fields of southern Kamchatka ( Fig. 9 View Fig ), where it grew together with C. atrovirens , C. subulatus and C. umbellatus ( Ignatova & Samkova, 2006) .

Specimens examined: RUSSIA: Kamchatsky Territory: Ust’-Bol’sheretsky Distr., vicinity of Pauzhetka settl., eastern Pauzhetskoe thermal field, Samkova 9-10 ( MW9027886 , MW9027888 ) (with C. umbellatus ); the same area, ca. 500 m southward Pauzhetskaya geothermal powerplant, upper thermal field, 01.VIII.2006 Samkova #13-4 ( MW9027887 ) .