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Isopterygium affusum Mitten 1869

Comprehensive Description

provided by Smithsonian Contributions to Botany
Isopterygium affusum

Isopterygium affusum Mitt., J. Linn. Soc., Bot. 12: 499. 1869. Type: Brazil. Taruma River, Spruce 1059 (lectotype: NY!, designated by Iwatsuki and Crosby, 1979); isolectotype: BM!); Prov. Ceara, Sierra de Araripe, Gardner 106c (synype: BM!).

Isopterygium herminieri Schimp. ex Besch., Ann. Sci. Nat. Bot. sér. 6,3: 256. 1876. Type: Guadeloupe. In rivers or streams, Herminier s.n. (holotype: BM!; isotype: NY!).

Ectropothecium submersum Broth., Bih. Kongl. Svenska Vetensk.-Akad. Handl. 26 Afd. 3(7): 48. 1900; Isopterygium submersum (Broth.) Broth., Nat. Pflanzenfam. 1(3): 1081. 1908. Type: Brazil. Mato Grosso: Macoco River, Lindman 502 (holotype: H!; isotype: BM!).

Plagiothecium fontigenum Müll. Hal., Hedwigia 40: 58. 1901; Isopterygium fontigenum (Müll. Hal.) W. R. Buck & Ireland, Fl. Neotrop. 50: 19. 1989. Type: Brazil. Santa Catarina: Serra do Oratorio, Ule 521 (lectotype: H!, designated by Buck and Ireland, 1989).

Isopterygium aquaticum H. Rob., Bryologist 67: 453. 1964, hom. illeg., non Dixon 1922; Isopterygium irelandii H. Rob., Bryologist 70: 43. 1967. Type: Honduras. Dept. Francisco Morazán, Río Agua Amarilla, NE slopes of Cerro de Uyuca, Morton 7566 (holotype: US!).

Plants in thin, loose masses, yellow-green to green. Stems up to 10 cm long, 1.5–3.5 mm wide, complanate-foliate, simple or irregularly branched. Asexual reproductive bodies lacking. Leaves flaccid, close, complanate, erect-spreading, smooth, usually wrinkled and contorted when dry, 1–3 mm long, 0.4–1.0 mm wide, ovate-lanceolate to ovate, symmetric or often asymmetric, acuminate to long-acuminate; margins plane, serrulate above, entire below; costa none or weak, short and double;

median cells smooth, 66–118 × 5–7 μm; alar cells weakly differentiated, rectangular or rarely quadrate, in small groups with 1–2 cells on margins. Autoicous or rarely dioicous. Setae brown to reddish brown, 1.5–2.2 cm long; capsules inclined, 1.0–1.2 mm long, ovoid to ellipsoid, somewhat contracted below the mouth when dry; operculum obliquely short-rostrate; peristome teeth up to 0.2 mm long. Spores only seen immature.

Distribution and ecology: Honduras, Guadeloupe, Venezuela, and Brazil (Figures 12, 14, 15); an aquatic species on rocks in and beside rivers and streams, near waterfalls, or occasionally at bases of tufts of grasses and sedges in marshes, occurring at altitudes of 430–1460 m.

Discussion: The aquatic habit helps to identify this species since the other Latin American taxa, except Isopterygium acutifolium, are terrestrial. Its distinguishing

morphological features are the large plants, stems to 10 cm long, 1.5–3.5 mm wide, leaves ovate-lanceolate to ovate, symmetric to asymmetric, acuminate, flaccid, close, erect-spreading, strongly wrinkled and contorted when dry, 1–3 mm long, alar regions weakly differentiated, 1–2 rectangular or rarely quadrate cells on margins, setae 1.5–2.2 cm long, capsules rarely produced, ovoid to ellipsoid, inclined, contracted below the mouth when dry, 1.0–1.2 mm long.

Iwatsuki and Crosby (1979) considered this species synonymous with I. tenerifolium. However, the aquatic habitat of I. affusum and its larger leaves, often up to 3 mm long, and shorter setae, 1.5–2.2 cm long, distinguish these two closely related species. The differences are rather minor, and it is possible that additional specimens of the two species may, indeed, prove that they are synonymous.

Specimens examined: HONDURAS. Francisco Morazán: El Quebracho, above El Zamorano, ˜950 m, Standley 353 (F); region of Agua Amarilla, above El Zamorano, ˜780 m, Standley & Williams 13 (F), 900–1100 m, Standley et al. 5047 (BM, F), 5044, 5050 (F); near Joya Grande, on road from El Zamorano to Suyapa, 1200–1350 m, Standley & Molina R. 4511 (F). WINDWARD ISLANDS. Guadeloupe: Known only from type collection of I. herminieri. VENEZUELA. Bolívar: Morichal cercano al conuco de Odremán, Santa Elena, Gran Sabana, Tamayo 3068 (FH, US). BRAZIL. Amazonas: Taruma Alta, 5 km N of Manaus-Itacoatiara road, near Manaus, Griffin 283-A (CANM, F, MEXU, MO, NY, SP); between Manaus and Sao Gabriel, along shores of Rio Curicuriari and Igarapé Branco (Rio Cariua) from Rio Curicuriari to Cachoeira de Bôto (Cachoeira Piraiauara), 0°20'S, 66°55'W, Buck 2549 (CANM, NY). Goiás: Region of the Chapada dos Veadeiros, 4 km N of Veadeiros, Dawson 14745 (CANM); region of the southern Serra Dourada, 20 km E of Formoso, Dawson 14888 (CANM). Mato Grosso: Serra do Roncador, ˜86 km N of Xavantina, 550 m, Irwin et al. 16370 (NY). Minas Gerais: Mpio. Santa Bárbara, Serra do Espinhaço, Parque Natural do Caraça, trail from Santuário do Caraça to Pico da Carapuça, 1300–1460 m, 20°02'S, 43°30'W, Buck 26686 (NY); between Serro and Datas, Diamantina, Frahm 1421, 1499 (MO); ˜15 km SE of Datas, Vital 7568 (CANM); National Park Serra de Itatiaia, 1950 m, Schäfer-Vervimp & Vervimp

9571 (NY). Pará: Serra do Cachimbo, Base Aérea do Cachimbo and vicinity, along bank of Rio Braço Norte, ˜20 km N of border of Mato Grosso, 430–480 m, Reese 16169 (MICH, NY, US), 16193 (MICH), 16197, 16418 (MICH, NY). Santa Catarina: Serra Geral, Ule 1197 (H). São Paulo: Icem County, Vital DV-1826 (CANM). São Paulo: Mpio. Guapiara, Serra Paranapiacaba, Fazenda Intervales, ˜800 m, ˜24°16'S, 48°25'W, Vital & Buck 20436 (NY).
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bibliographic citation
Ireland, Robert Root and Buck, William R. 2009. "Some Latin American Genera of Hypnaceae (Musci)." Smithsonian Contributions to Botany. 1-97. https://doi.org/10.5479/si.0081024X.93