Chaptalia ignota Burkart, Physis

Pasini, Eduardo & Ritter, Mara Rejane, 2012, New record of Chaptalia ignota Burkart (Asteraceae) for the Brazilian flora, Phytotaxa 65 (1), pp. 1-6 : 1-5

Chaptalia ignota Burkart, Physis 11: 102 (1932). ( Figs. 1 and 2 )

Herbs perennial, 30–45 cm tall, roots dark brown. Leaves rosulate, sessile; blade membranaceous, discolorous, oblanceolate to lanceolate, 7–19 x 1–3 cm, base attenuate, margin crenate-dentate, sinuate-dentate, dentate, irregularly dentate, or smooth; apex subacute. Inflorescences monocephalous, scapigerous; scapes 12–43 cm long, tomentose, with leafy bracts; bracts 5–16, subulate, tomentose. Capitula radiate, heterogamous, nodding at anthesis; involucre conical to campanulate, 1–3 x 1.7–4 cm; involucral bracts 4–5-seriate, imbricate, subulate, green, abaxial surface tomentose, apex acute to acuminate, dark red.

Florets trimorphic; outer florets pistillate, uniseriate, ca. 18, corollas ligulate–bilabiate, abaxial lip liguliform, white to pink, 4–6.6 mm long, apex irregularly 3-lobed; adaxial lip irregularly bifid, occasionally absent, tube 4.5–8.3 mm long; style 8.4–10.3 mm long, style lobes 1–1.6 mm long; middle florets pistillate, ca. 40, corollas filiform, tube 4.5–5.7 mm long; style 7.5–8.3 mm long, exserted, style lobes 1.3–1.6 mm long; inner florets bisexual, ca. 10, corolla tubulose-bilabiate, whitish, abaxial lip 1.5–2.5 mm long, apex 3-lobed, adaxial lip bifid, 1.5–2.3 mm long, tube 5.5–9.2 mm long; style 8.7–9.6 mm long, style lobes 0.7 mm long, papillose above bifurcation; anther thecae 3.6–4.8 mm long, apex obtuse, base of pollen sacs caudate, 1.3–2.2 mm long. Cypsela narrowly fusiform, 13.8–23.8 mm long, including slender beak 8.2–16.0 mm long, 5–8-ribbed, with trichomes densely distributed, pappus uniseriate, setose.

Distribution and ecology: —Native to South America, distributed in Argentina (provinces of Buenos Aires, Entre Rios, and Corrientes) and Uruguay. In Brazil, only known from Rio Grande do Sul ( Fig. 2 ), from the pampean biogeographical province of Cabrera & Willink (1973), municipality of Aceguá. Information about the ecology of this species is sparse; Burkart (1944) noted the distribution area but did not provide details regarding habitat and phenology. We therefore emphasize the importance of field expeditions to better understand the distribution, demography and ecology of C. ignota . However, our field observations and label information of herbarium specimens suggests that the species inhabits wet or dry, flat or gently rolling grasslands. It also can be found in disturbed areas such as roadsides with exposed soil.

Phenology: —Flowering and fruiting from October to November (pers. obs. and label information of herbarium specimens).

Conservation status: —Although the species is widely distributed in Argentina and Uruguay, we emphasize its restricted occurrence in Rio Grande do Sul. In this state, according to the IUCN (2010), the species is considered to be critically endangered (CR B2b(ii)—the estimated area of occupancy is less than 10 km 2, and the field observations indicate a continuing decline of habitat quality; D—the size of the observed population was less than 50 mature individuals). Therefore, C. ignota should be included in the Official List of Threatened Species of Rio Grande do Sul’s Flora.

Specimen examined: — BRAZIL. Rio Grande do Sul: Aceguá, 31º34’97.2’’S, 54º08’39.0’’W, em beira de estrada, campo limpo, úmido, de plano à suave ondulado, 7 November 2010, fl., fr., E . Pasini 469 ( ICN) .

Aditional specimens examined: — ARGENTINA. Buenos Aires: Buenos Aires, San Isidro, 2 April 1933, fl., fr., A . Burkart 5597 ( SI); Corrientes: Sauce , Chacra El Timbó, 3 km N de Sauce, 22 October 1977, fl., O . Ahumada et al. 1335 ( CTES); San Lisso Palmar, Estación Herlitzka , 26 September 1945, fl., Z . Ibarrola 3324 ( CTES); Entre Rios: Colón, Calera Barquín, s.d., fr., A . Pozzi s.n. ( SI 115700); Concepción del Uruguay , 17 October 1949, fl., fr., A . Burkart 17966 ( SI); Concordia, ruta 14 a Concordia , Arroyo Isletas, 21 September 1961, fl., A . Burkart 22793 ( SI); Crespo , 2 November 1970, fl., A . Burkart & N . Troncoso 28085 ( SI); Diamante , 15 May 1964, fl., fr., A . Burkart et al. 25518 ( SI); Gualeguaychú , ruta 12, 14 km al S de Gualeguaychú, 30 September 1970, fl., fr., A . Burkart & N . Troncoso 28115 ( SI); Paraná, camino al Paracao , 31 October 1962, fl., A . Burkart et al. 23847 ( LP, SI); Puerto Cupalén , 22 December 1941, fl., E. G . Nicora 3371 ( SI) .

URUGUAI. Cerro Largo: Rio Negro, Estancia Palleros , January 1941, fl., fr., G . Aragone & B . Rosengurtt 4598 ( LP) .

According to Burkart (1944), Chaptalia ignota belongs to the section Leria Burkart (1944: 6) . The species in this section are robust herbs, with long inflorescence scapes and foliaceous involucral bracts. Although the species is easy to recognize, it is morphologically close to C. arechavaletae Hieronymus (1904: 14) , C. integerrima ( Vellozo 1831: 8) Burkart (1944: 6) and C. sinuata Baker (1884: 6) , from which it can be distinguished by the oblanceolate to lanceolate leaves with crenate-dentate margins vs. ovate-lanceolate leaves ( C. sinuata ) or leaves with denticulate or smooth margins ( C. integerrima ) or more strongly crenatedentate margins ( C. arechavaletae ).

Figures

FIGURE 1. Chaptalia ignota. A. Habit (E. Pasini 469, ICN). B. Outer pistillate floret. C. Middle pistillate floret. D. Inner bisexual floret. E. Cypsela. F. Detail of cypsela. B-F: (Burkart et al. 23847, SI). Illustration by Edson Luís de Carvalho Soares.

FIGURE 2. Chaptalia ignota. A, B. Habit. C. Detail of crenate-dentate leaf. D, E. Detail of scape and pappus. F. Grassland habitat at site, municipality of Aceguá, Rio Grande do Sul State, Brazil. Photo credits: A, B, C, D, F, G, H by E. Pasini and E by Gerard Ernst Overbeck.