Monographs Details: Orthotrichum araucarieti Müll.Hal. ex Broth.
Authority: Buck, William R. 1987. Bryostephane Steereana: A Collection of Bryological Papers Presented to William Campbell Steere On The Occasion of His 80th Birthday. Mem. New York Bot. Gard. 45: 1-749.
Family:Orthotrichaceae
Description:Species Description - Plants in loose tufts or as single plants, to 3 cm tall, olive-green or green above, brown below; rhizoids sparse. Stems regularly branched below each perichaetium. Leaves spreading when moist, erect and appressed when dry, but with the apical leaves somewhat flexuose, from ovate bases long or short acuminate, 2.9-3.3 x 0.5-0.6 mm; costa ending some distance below the apex; margins entire, revolute except for the extreme apices and bases; apices acuminate; basal leaf ceUs 22-44 × 5-9.5 iim, regular, rectangular with thick, nodose, porose walls; cells slightly diflferentiated in the basal leaf comers; upper leaf cells 7.5-11 × 4.5-8 µm, rounded isodiametric to slightly elongate, thick-walled, with 1-2 low, single or branched papillae per cell. Goniautoicous. Perichaetial leaves slightly differentiated with somewhat longer points. Capsules immersed or emergent, cylindric, furrowed in the upper half when dry; exothecial cells differentiated into eight bands above, below the mouth with a few rows of small isodiametric cells; stomata superficial, numerous, surrounded by radiating cells, in upper and central parts of capsules; peristomes double, low preperistomes sometimes present; exostome teeth eight, recurved or revolute when dry, orange, evenly and finely papillose; endostome segments eight, lanceolate to triangular, almost or as tall as the exostome mostly of two rows of cells, with larger and more distant papillae. Spores globose, 26-29 µm, finely and evenly papillose, brownish. Calyptrae large, conic or conic-oblong, only slightly plicate, pale yellowish with red-brown apex with comal hairs reaching over the top.

Discussion:Type: BRAZIL. Santa Catarina: Serra Geral, 1890, Ule Bryotheca Brasiliensis 20 (lectotype H, chosen here; isotypes C, FH, JE, M, NY.

Illustrations: Figures 163-172.

Variation: The plants from Uruguay match well with the Brazilian populations. In both the spores vary to some extent in size within the same capsule probably due to uneven maturation. Also the hairiness of the calyptra is more or less pronounced.

Diflferentiation: Orthotrichum araucarieti seems related to O. pycnophyllum, but diflfers in having immersed or emergent capsules with eight endostome teeth and exostome segments. It might be mistaken for O. laxifolium, but this taxon has naked calyptrae and thin-walled almost isodiametric exothecial cells.

Note: Sehnem (1978) reported O. verrucosum from southem Brazil. According to the protologue this taxon has 16 anastomosing, irregular endostome segments, and the lectotype from H has shortly exserted capsules. These characters are not shared by Sehnem's voucher specimens, which belong to O. araucarieti. The spores are reported by Sennem (1978) to be 15-20 µm in diameter. The present study shows sizes to 29 µm. are not unusual. The strong diflferentiation between perichaetial leaves and ordinary stem leaves as indicated by Sehnem was not observed either. Usually the ordinary leaves are longer pointed than shown by Sehnem.

Distribution:Brazil South America| Uruguay South America|