Anoectangium, Schwagr., Sp. Musc. Frond. Suppl.

Ignatov, M. S., Kuznetsova, O. I. & Ignatova, E. A., 2024, Once again on the genus Anoectangium (Pottiaceae, Bryophyta) in Russia, Arctoa 33 (1), pp. 1-8 : 6

ANOECTANGIUM Schwägr., Sp. Musc. Frond. Suppl. 1(1): 33. 1811.

Type species: A. compactum Schwägr. (= A. aestivum (Hedw.) Mitt. )

Plants in dense or loose tufts, yellow-green in upper part, brownish below. Stems 0.5–4 cm, weakly branched, usually moderately tomentose, rounded-triangular in transverse section, with more or less strong central strand, weak sclerodermis, hyalodermis absent. Leaves distantly or densely arranged, straight or contorted and twisted when dry, erect-spreading when wet, uneven in size along the stem, forming alternating zones of smaller and larger leaves, ovate, ovate-lanceolate or oblong-lanceolate, with not differentiated or differentiated base, occasionally constricted above base, widest below or above midleaf, acute or acuminate, strongly keeled, narrowly grooved along costa ventrally; margins plane, entire or slightly crenulate at leaf base, sometimes uneven proximally; costa strongly projecting abaxially, ending few cells below apex, percurrent or shortly excurrent, with only dorsal stereid band, dorsal and ventral epidermis, occasionally ventral epidermis absent and guide cells exposed, ventral surface cells elongate, smooth, dorsal surface cells elongate, smooth proximally, slightly to strongly papillose distally; lamina unistratose, distal and median laminal cells subquadrate, densely papillose, papillae low and wide, bifid, rarer loosely papillose, basal laminal cells short rectangular, shorter to the margins, smooth. KOH laminal reaction yellow. Specialized asexual reproduction rare, by multicellular gemmae on rizhoids in leaf axils. Dioicous. Gametangia and sporophytes terminal on short lateral branches. Perichaetial leaves convolutesheathing, ovate-acuminate. Setae yellow-brownish. Urns yellow-brown, with red rim, elliptic, smooth and glossy, exothecial cells rectangular, thin-walled, annulus of two rows of slightly vesiculose cells, peristome absent. Spores 12–16 µm, finely papillose. Opercula with long oblique beak.

KEY TO IDENTIFICATION OF ANOECTANGIUM SPECIES IN RUSSIA

1. Leaves lanceolate to oblong lanceolate, (1.0–) 1.5– 2.5 mm long, often constricted above base ............. ..................................................... A. stracheyanum

— Leaves ovate-lanceolate to oblong-lanceolate, 0.8– 1.2(–1.8) mm long, not constricted above base .... 2

2. Leaves incurved when dry, distantly arranged, stem exposed at places; leaves widest below midleaf ...... .............................................................. A. aestivum

— Leaves contorted when dry, densely arranged, stem not exposed; leaves widest at or above midleaf ...... ........................................................... A. laetevirens