Weissia planifolia Dixon, Rev. Bryol.

Ignatova, E. A., Fedorova, A. V., Kuznetsova, O. I. & Ignatov, M. S., 2024, Notes on the genus weissia in russia focused mainly on the species from asian russia, Arctoa 33 (1), pp. 50-60 : 55-57

Weissia planifolia Dixon, Rev. Bryol. , n. s. 1: 179. f. 1. 1928. — Trichostomum planifolium (Dixon) R.H. Zander, Bull. Buffalo Soc. Nat. Sci. 32: 92. 1993. Fig. 2 .

Plants in small, dense or lax patches, yellowish-green. Stems 1–2(–4) mm long. Leaves crispate when dry, erect-spreading to patent when moist, 1.1–2.5×0.25–0.45 (–0.5) mm, with length:width ratio 4–8:1, becoming longer distally, lanceolate to oblong-lanceolate, canaliculate distally, margins almost plane in midleaf, narrowly incurved in the upper third or near apex, apices slightly cucullate, base slightly widened; costa strong, 50–70 µm wide at base, excurrent into short mucro, in transverse section with one row of guide cells, ventral band of 1(2) layers of substereids, dorsal band of 2–4 layers of stereids, ventral epidermis differentiated, dorsal epidermis not or slightly differentiated, cells on dorsal surface of costa linear or elongate rectangular, smooth or with scarce papillae in middle part; cells in the middle and upper part of lamina quadrate, thin-walled, 9–12×9–12 µm, with 3–4 papillae per cell, papillae low, simple and bifid, obscuring cell walls; basal laminal cells rectangular, smooth, yellowish or hyaline, with moderately thickened walls, 30–80×11–15 µm. Autoicous. Perichaetial leaves similar to upper stem leaves. Setae 5–9 mm, pale yellowish. Urns 0.7–1.1 mm long, light-brownish, cylindrical, not or weakly narrowed to the mouth. Exothecial cells thin-walled. Annuli differentiated, persistent, opercula falling off, low conic, with long, narrow, straight or oblique beaks ca. 0.5 mm long. Peristome well developed, teeth erect or erect-spreading when dry, subobtuse at tips, 50–90 µm long, reddish-brown or brownish, densely papillose. Spores 16–20 µm.

Distribution and ecology. This is the most frequent species of Weissia in the southern Russian Far East ( Amur Province, south of Khabarovsk and Primorsky Territories, and South Kuril Islands). In grows on soil banks along roads, in dry Quercus mongolica forests on slopes, in ravines, at edges of arable fields, and in flood-valley stands (willow, poplar, and alder).

H I J

Differentiation. Weissia planifolia is recognized by having leaves with almost plane or weakly and narrowly incurved margins in distal part; long and thin setae; and well developed, erect or slightly spreading, reddish-brown peristome teeth. In some specimens, costa is weakly papillose on dorsal surface in mid-leaf. This character is considered as diagnostic for the Japanese species W. deciduifolia K. Saito ( Trichostomum deciduifolium (K. Saito) R.H. Zander ); however, its costa is much denser papillose, and its leaves are strongly deciduous. The distinctions of W. planifolia from W. controversa var. controversa include weakly and narrowly vs. tightly and widely incurved leaf margins, and from W. controversa var. sachalinensis in weaker incurved leaf margins and small- er spores (16–20 µm vs. (19–)21–25 µm).

Weissia controversa var. sachalinensis Ignatova &

Ignatov, var. nova. Fig. 3 .

Diagnosis. The new variety differs from the type variety by narrower incurved upper leaf margins and larger spores, (19–)21–25 µm vs. 16–20 µm.

Type: Russia, Sakhalin Island, Korsakovo District , Tonino-Anivsky Peninsula , outskirts of Novikovo Settlement , 46°21’N, 143°22’E, 10 m alt. N-faced rock outcrops along a stream. 15.IX.2009. Coll O. Yu. Pisarenko op03797. Holotype MHA9102705 , isotype NSK2003797 .

Etymology. The name of variety points its distribution in Sakhalin Province of Russia ( Sakhalin and Kuril Islands).

Plants in small, more or less dense patches, yellowish-green. Stems 1–2(–4) mm long. Leaves crisped when dry, erect-spreading when wet, 1.4–2.2× 0.25–0.35 mm, becoming larger distally, lanceolate to linear-lanceolate, with margins narrowly but strongly incurved in distal halves, slightly cucullate distally, with slightly widened bases; costa 35–50 µm wide at base, excurrent into a short mucro, smooth dorsally, ventral stereid band 1–2- layered, dorsal stereid band 2–3-layered, dorsal epidermis not differentiated; upper and median laminal cells quadrate and shortly transverse rectangular, moderately thick-walled, 6–9×9–11 µm, papillae 3–4(–5) per cell,

I

G

100 µm

L M

low, simple and bifid, obscuring cell walls; basal laminal cells rectangular, smooth, yellowish or hyaline, with moderately thickened walls, 25–60×8–11 µm. Autoicous. Perichaetial leaves similar to upper stem leaves. Setae 3–4 mm, yellowish to light brownish when mature. Urns 0.7–1.2 mm long, light-brown, cylindrical, weakly narrowed to the mouth. Exothecial cells thin-walled. Annuli differentiated, opercula falling off, low conic and with narrow, straight or oblique beaks ca. 0.5 mm long. Peristome well developed, peristome teeth erect when dry, lanceolate, obtuse, 90–100 µm long, reddish-brown, densely papillose. Spores (19–)21–25 µm.

Distribution and ecology. The variety is known only from Sakhalin, Shikotan, and Kunashir Islands (see specimen data in Appendix 1). It was collected on rock outcrops along a stream, on small rocks under high grasses and in rock crevices at sea coast. The type variety was also reported to grow occasionally on rock substrates, but more frequently it grows on various soil banks.

Differentiation. The distinctions from the type variety are given in the diagnosis. Another Far Eastern species with narrowly incurved leaf margins and well developed peristome is W. planifolia ; it differs by having leaves with wider, subobtuse apices, weaker incurved leaf margins, longer setae ( 5–9 mm vs. 3–4 mm), and small- er spores (16–20 µm vs. (19–)21–25 µm).

Figures

Fig. 2. Weissia planifolia (from Russia, Primorsky Territory: A–I: Partisansk Distr., Olkhovaya Mt., Ignatov & Ignatova 06- 2861, MHA9102668; K–T: Khasansky Distr., Ryazanovka, Ignatov s.n., MHA9111946). A, M: habit, dry; B, L: habit, wet; C–D, P: leaf transverse sections; E, N: upper leaf cells; F, K: peristome teeth; G, O: mid-leaf cells; H–I, Q–S: leaves; J, T: basal leaf cells. Scale bars: 3 mm for B; 2 mm for A, L–M; 1 mm for H–U, Q–S; 100 µm for C–G, J–K, N, O–P, T.

Fig. 3. Weissia controversa var. sachalinensis (from holotype). A: habit, wet; B: peristome teeth; C–E: leaf transverse sections; F: upper leaf cells; G: mid-leaf cells; H–K: leaves; L: habit, dry; M: basal leaf cells. Scale bars: 2 mm for A, L; 1 mm for H–K; 100 µm for B–G, M.