Orthotrichum gigantosporum Lewinsky

Lara, Francisco, San, Raúl D., Román, León, Alicia, Draper, Isabel & Garilleti, Ricardo, 2021, New data on Orthotrichum gigantosporum Lewinsky (Orthotrichaceae, Bryophyta), a widespread northern Andean-Patagonian endemic moss, Cryptogamie, Bryologie 20 (12), pp. 169-179 : 171-174

Orthotrichum gigantosporum Lewinsky

( Figs 2 ; 3 )

Lindbergia 14: 183 [1988(1989)].

Orthotrichum macrosporum Lewinsky hom. illeg. Lindbergia 10: 91. figs 150-161. ( Lewinsky 1984 [1985]). — non O. macrosporum Müll. Hal., Nuovo Giornale Botanico Italiano , n. s. 5: 185 ( Müller 1898).

TYPE. — Argentina. Rio Negro: Bariloche, Pampa del Toro, road to Lago Steffen; 41°31’S, 71°28’W; Rahn 4593 p.; 27.II.1979. holo- C.

DESCRIPTION

Plants

Up to 0.8(-1.7) cm tall, in lax or rarely compact irregular tufts or patches, up to 2 cm in diameter, frequently mixed with other species, olive green to brownish below.

Stems

Rounded-pentagonal in section, with all cells thick walled, orange to deep red, the 1(-2) external rows smaller with narrow lumina; axillary hairs scarce, of 1 short slightly coloured basal cell and 1-2 elongated hyaline distal cells.

Rhizoids

Mostly in basal parts of stems, scattered in median and upper branches, reddish, smooth.

Leaves

Erect to erect-appressed when dry, scarcely sinuose but frequently loosely and irregularly oriented, when moist patent to spreading, ovate-lanceolate to lanceolate with oval base, more or less concave, lamina narrowly triangular, slightly carinate, (0.8-)1.0-1.5 × 0.2-0.3 mm; leaf apex acute to acuminate, frequently ending in a row of up to 7 cells; costa single, ending well below apex to subpercurrent, 25-50 µm wide at base and at mid-leaf; leaf margins entire to papillose-crenulate, usually completely plane, sometimes finely and irregularly recurved in part of their length; lamina unistratose throughout; upper and median leaf cells (6-)10-15(-16) × (6-)10-15(-20) µm, isodiametric or somewhat elongate or oblate, with moderately thickened walls, with (1-)2(-3) simple papillae on both surfaces; basal cells (10-)15-40(-50) × 5-10 µm, mostly rectangular, sometimes fusiform, with thin to moderately thickened smooth or somewhat nodulose walls, towards margins usually shorter, short rectangular to quadrate. Brood bodies not seen.

Cladautoicous.

Perigonia

Bud-shaped, terminal on branches and main axes; perigonial leaves (0.2-)0.3-0.7(-1.2) mm long.

Perichaetial leaves

Similar to vegetative leaves, somewhat larger, (0.9-)1.1-1.9(- 2.1) × 0.2-0.4(-0.5), with a longer ovate base that reaches ²�₅ to ½ leaf.

Vaginula

Cylindric to oblong, 0.4-0.6 mm long, strongly hairy, with hairs up to more than 1 mm long, 1(-2)-seriate, barely papillose.

Calyptra

Mitrate, conic-oblong, 1.3-1.5 mm long, yellowish to orange with a dark orange beak, naked, plicate, almost smooth to papillose at plicae.

Seta

(1.1-) 1.5-2.7 mm long.

Capsule

Exserted, ovoid when moist, urceolate to pyriform and constricted below mouth when dry, unribbed except near mouth or very faintly in the upper half, (1.1-)1.2-1.5(-1.8) mm long, including a 0.3-0.5 mm long neck, gradually narrowing to seta; exothecial cells rectangular, yellowish, arranged in vertical sinuous lines with external walls thickened; exothecial bands differentiated in the distal part of urn, orange tinted, of (2-)3(-4) rows of enlarged cells with extra-thickened walls, extending 130-200 µm from mouth, 2 rows weakly differentiated beyond, sometimes up to the middle of the capsule; stomata immersed, almost to completely covered by well differentiated exothecial cells, located in the upper half of capsule, not reaching urn base nor mouth vicinity.

Operculum

350-550 µm in diameter, shortly rostrate, convex, with a broad reddish basal rim.

Peristome

Double; small basal remnants of prostome sometimes present; exostome of 8 pairs of teeth, completely splitting into 16 or some pairs remaining after hygrometric movements, reflexed to revolute when dry, yellowish to light orange, (190-)220- 330 µm long; outer peristomial layer (OPL) densely papillose throughout; exostomial primary peristomial layer (PPL) finely ornamented, with vertical lines and some intercalated papillae in basal part, papillose at apex; endostome of 16 segments, lanceolate, relatively broad, with margins frequently irregular, the intermediate ones more slender, paler and somewhat shorter than teeth, united by a thin connecting membrane of 2-3 cell rows tall, the upper cell row papillose like the segments; endostomial PPL faintly carinate, finely ornamented with vertical or oblique lines, usually papillose, centred on the cell surface; inner peristomial layer (IPL) biseriate in main segments, uniseriate to partially biseriate in intermediate segments, densely covered with tall papillae, becoming low in distal part.

Spores

Unicellular, (27-)30-50(-55) µm, yellowish brown, spherical to ellipsoidal, verrucose, the largest spores sparsely ornamented after the verrucae are partially detached.

Figures

FIG. 2. — Orthotrichum gigantosporum Lewinsky: A, habit; B, mature capsules with exostome teeth both in pairs and divided, compare with the peristome in E; C, calyptra; D, mature operculated capsule;E, mature capsule with exostome teeth completely divided in 16; F, vegetative leaf;G, setae of two capsules showing the vaginula hairs protruding from the perichaetial leaves; H, operculum beginning its dehiscence from the capsule; I, vegetative leaf base; J, apicule of a single row of cells in a vegetative leaf. A-C, E, H, from Garilleti 2016-199a; D, G, I, from Garilleti 2016-198a; F, J, from Garilleti 2016-177. Scales bars: A, 1 mm; B-E, G, 0.5 mm; F, 0.2 mm; H, 0.25 mm; I, 100 µm; J, 50 µm.

FIG. 3. — Orthotrichum gigantosporum Lewinsky: A, peristome showing the endostome in first plane, note the teeth pair on left joined by the tip; B, detail of the exothecium with the short exothecial bands shining in polarized light; C, operculum; D, spores; E. upper and lateral view of stomata. A, B, E, from Garilleti 2016- 198a; C, from Lara s.n. 30-12-2005; D, from Garilleti 2016-236g. Scale bars: A-C, 50 µm; D, E, 30 µm.