Taxonomy of the Carex atropicta Complex (Cyperaceae) in South America

Abstract

Three similar species of Carex sect. Atratae subsect. Atropictae (subsect. nov.) occur in South America, which together may be known as the Carex atropicta complex. All three, similar in habit, grow south of the Tropic of Capricorn, with C. atropicta occurring primarily in Patagonia and Tierra del Fuego, C. malmei in west-central Argentina and adjacent parts of Chile, and C. monodynama (comb. et stat. nov.) in central Argentina. The new subsection is distinguished by: stigmas 2 (infrequently 3); plants commonly with a solitary spike (except in C. atropicta where they are occasional); and margins of the perigynia ciliate-scabrous (but in C. monodynama sparingly so), more or less winged, and generally with a lightcolored strip of varying length that extends from the beak toward the base. Habitats for the three species include moist to wet meadows, swamps, marshes and marshy pasturelands, depressions in moist grassland, grassy hillsides, ravines, banks of streams, and coastal flats bordering the sea. Carex L., with an estimated 1500 to 2000 species, is well represented in both hemispheres, but sectional representation can vary greatly from one hemisphere to another. For instance, sect. Atratae (Kunth) Christ is strongly developed in the mountains and cooler regions of the Northern Hemisphere, particularly in North America and Eurasia (e.g., Charkevicz 1988; Chater 1980; Hermann 1970; Mackenzie 1935; Murray 1969), but is poorly represented in the Southern Hemisphere (Kiikenthal 1909). Previous authors (Barros 1935, 1947; Hauman and Vanderveken 1917; Kalela 1940; Kiukenthal 1899,1909; Leveille 1915; Marticorena and Quezada 1985) have recognized from one to three species, and a varying number of infraspecific taxa, of sect. Atratae in South America. Discrepancies abound regarding their distributions. Also, some validly published names (Kalela 1940) applicable to the South American members of sect. Atratae have not been taken into account by recent authors (e.g., Barros 1947, 1969). In this paper, which is the third in a series of sectional revisions of the Carex flora of South America (Wheeler 1987, 1989b), I treat the South American members of sect. Atratae. As treated here, three species of sect. Atratae occur in South America (table 1): C. atropicta Steudel, C. malmei Kalela, and C. monodynama (Griseb.) G. Wheeler (comb. et stat. nov.). Because the South American members of sect. Atratae differ morphologically in some respects from their counterparts in the Northern Hemisphere, they are here placed in subsect. Atropictae G. Wheeler (subsect. nov.). All members of the new subsection occur south of the Tropic of Capricorn, and only one, C. atropicta, extends as far south as Tierra del Fuego. Habitats include moist to wet meadows, swamps, marshes and marshy pasturelands, depressions in moist grassland, grassy hillsides, ravines, banks of streams, and coastal flats bor-