Isopterygiopsis Moss

Isopterygiopsis pulchella

Isopterygiopsis pulchella (Hedw.) Z. Iwats., J. Hattori Bot. Lab. 63: 450. 1987. Leskea pulchella Hedw., Spec. Musc. Frond. 220. 1801; Isopterygium pulchellum

(Hedw.) A. Jaeger, Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1876-77: 441. 1878. Type: Scotland, no collector cited (holotype: G!).

Hypnum magellanicum Müll. Hal., Flora 68: 425. 1885, hom. illeg.; Isopterygium fuegianum Besch., Miss. Sci. Cape Horn, Bot. 5: 301. 1889 (new name for Hypnum magellanicum); Plagiothecium magellanicum (Besch.) Paris, Index Bryol. 963. 1896. Type: Chile, Clarence Is., S. Holl Bay, Hariot 63 (holotype: BM!; isotype?: H!). Syn. nov.

Plagiothecium leptoplumosum Dusén, Rep. Princeton Univ. Exp. Patagonia, Botany 8: 100. 1903; Isopterygium leptoplumosum (Dusén) Cardot, Wiss. Erb. Schwed. Südpolar-Exp. 4(8): 178. 1908. Type. Chile, Patagonia, Río Chico, Hatcher s.n. (holotype: S!; isotype: NY!). Syn. nov.

Plants in thin to dense mats, glossy, light green to yellowish green. Stems to 2 cm long, 1–2 mm wide, simple or irregularly branched; hyalodermis present but somewhat indistinct from the 1 to several layers of inner thick-walled cortical cells. Asexual reproductive bodies 30–60 μm long, rarely present, cylindrical or fusiform, clustered in leaf axils on stems and branches, green to yellowish green, composed of 2–5 smooth cells. Leaves 0.5–1.5 mm long, 0.2–0.4 mm wide, flaccid, close or sometimes distant, erect-spreading, occasionally secund, often appearing distichous, subconcave, smooth, lanceolate to slenderly ovate-lanceolate, symmetric, gradually long-acuminate; margins plane to erect throughout, entire or sometimes minutely serrulate, often with 1–2 cells distinctly serrulate in alar region; costa none or short and double; median cells 47–122 × 5–7 μm, smooth; alar cells differentiated only on margins, 1–3 quadrate to short-rectangular cells, sometimes lacking. Autoicous. Setae 1–2 cm long, red to reddish brown; capsules 0.5–2.5 mm long, subcernuous to cernuous, rarely erect, straight to subarcuate, oblong to ovoid, contracted below the mouth when dry; operculum conic to conic-apiculate; annulus present, deciduous, of 2–3 rows of cells. Spores 9–14 μm in diameter.

Distribution and ecology: Infrequent; Mexico, Chile, and Argentina (Figures 8, 10); on soil, in crevices of rock cliffs, and on rotting tree trunks at 150–3650 m and sometimes higher.

Discussion: Isopterygium fuegianum Besch. and I. leptoplumosum (Dusén) Cardot are considered here as new synonyms of I. pulchella. No important differences could be found for maintaining either species as separate taxa from I. pulchella. Even Dusén and Bescherelle stated

that their new species were very similar to I. pulchella when they described them.

Isopterygiopsis pulchella is recognized by the erect-spreading, sometimes secund, lanceolate to slenderly ovate-lanceolate, gradually acuminate, nondecurrent leaves with entire or minutely serrulate margins, the long (47–122 μm) and narrow (5–7 μm), smooth, median leaf cells, the alar regions undifferentiated or sometimes with 1–3 short-rectangular to quadrate cells on the margins, the occasional presence of cylindrical to fusiform, 2–5-celled brood bodies clustered in the leaf axils and the autoicous sexual condition.

Bryologists may sometimes have difficulty placing I. pulchella into Isopterygiopsis because the stem hyalodermis cells of I. pulchella are not as distinctly enlarged and thin-walled as those of the type species of the genus, I. muelleriana. However, the other important features distinguishing the genus Isopterygiopsis and placing I. pulchella within it are present, i.e., lack of pseudoparaphyllia, presence of cylindrical or fusiform propagula, and papillose rhizoids in the leaf axils.

Specimens examined: MEXICO. Mpio. Toluca, Parque Nacional Nevado de Toluca, NW slopes of Nevado de Toluca volcano, 3650 m, 19°08'N, 99°47'W, Buck 28203 (NY); Mt. Orizaba, Sep 1908, Purpus s.n. (FH). CHILE. Bío-Bío Region: Bío-Bío Prov., National Park Lake Laja, Los Barros Military Base, 1500 m, 37°27'S, 71°09'W, Ireland & Bellolio 34124 (CONC, MO, US). Magellanes Region: Antártica Chilena Prov., Communa Cabo de Hornos, Parque Nacional Alberto de Agostini, E end of Isla Gordon, S side of Punta Divide on Brazo Sudoeste of Beagle Channel, 54°58'S, 69°08'W, Buck 47943 (NY); Clarence Is., Hariot 63 (BM); Patagonia, Río Chico, Hatcher s.n. (NY, S); Patagonia, Aysén, Dusén 584 (FH, H, M, NY); Río Aysén, 22 Feb 1897, Dusén s.n. (M); Punta Arenas, Thaxter 161 (FH), Dusén 63 (H); ˜35 km from Puerto Natales, inside Cueva de Milodon, Kuc 117 (CANM). ARGENTINA. Dept. Ushuaia, Camino de ascenso al Glaciar Le Martial, ˜900–1200 m, 54°46'S, 68°29'W, Schiavone & Ochyra 6908, Musci Fuegiani Exsiccati 48, (MO); Tierra del Fuego australis, Valle del Río Pipo, 300 m, 54°46'S, 68°20'W, Roivainen 1352 (NY); Arroyo Grande, 150 m, 54°47'S, 68°17'W, Roivainen 2095 (MO, NY); E Glaciar Martial, Kuc 107 (CANM); Santa Cruz, in valley above Río Santa Cruz, Jan 1905, Dusén s.n. (H); Lago Argentino, Dusén 5684 (NY).