Chromolaena callilepis (Baker) King & Robinson (1970c: 199)

Christ, Anderson Luiz & Ritter, Mara Rejane, 2019, A taxonomic study of Praxelinae (Asteraceae-Eupatorieae) in Rio Grande do Sul, Brazil, Phytotaxa 393 (2), pp. 141-197 : 150-153

2.1. Chromolaena callilepis (Baker) King & Robinson (1970c: 199) .

Eupatorium callilepis Baker (1876: 285) . Osmia callilepis Schultz-Bipontinus ex Baker (1876: 285) nom. nud. pro syn. Lectotype (designated by Christ & Ritter 2018: 112):— BRAZIL. s.l., s.d., F. Sellow 570 (P! [00742345], isolectotype B, probably lost, Field Museum Berlin Negative 16220!)

= Eupatorium polyanthum Baker (1876: 285) , non Wallich (1831: 109) nom. nud., nec Schultz-Bipontinus ex Baker (1876: 279) nom. nud. pro syn. (= Eupatorium subserratum Gardner (1847: 440)) . Osmia polyantha Schultz-Bipontinus ex Baker (1876: 285) nom. nud. pro syn. Lectotype (designated by Freire & Ariza Espinar 2014b: 334):— URUGUAY. Rio Negro, April 1867, J.E. Gibert 226 (K! [K000373090]).

= Eupatorium callilepis var. oligocephalum Grisebach (1879: 168) . Eupatorium paucicapitulatum Hieronymus (1897: 756) . Lectotype (designated by Freire & Ariza Espinar 2014b: 334):— ARGENTINA . Entre Rios: Concepción del Uruguay, April 1877, P.G. Lorentz 583 (CORD! [CORD0006402], isolectotypes CORD! [CORD000064], B, probably lost, Field Museum Berlin Negative 16322!) ( Fig. 5A–E , 6A–C ).

Subshrubs, up to 1.5 m tall, erect, xylopodium absent, branched only in capitulescence; stems glabrous to puberulous, eglandular, leafy until capitulescence. Leaves 2.7–8 × 0.4–1.6 cm, opposite, petiolate, 3-veined, leaf blade lanceolate to linear, papyraceous to chartaceous, apex acute, base attenuate to rounded, margins entire to serrate, adaxial surface glabrous to strigose, eglandular, abaxial surface glabrous to strigose only on veins, glandular, margins ciliate or eciliate, petioles 0.4–1.2 cm long, glabrous, eglandular. Primary capitulescences corymbose. Secondary capitulescences corymbose or paniculate, axis glabrous to puberulous, eglandular, bracteate, bracts 0.8–4.8 × 0.2–0.5 cm, petioles 0.2–3.3 mm long, glabrous, eglandular. Capitula pedunculate; peduncles 0.6–1.8 cm long, puberulous, eglandular, involucres campanulate, 6.2–8.7 × 4.1–5.7 mm, involucral bracts 30–40, 5–6-seriate, outer ovate to oblong, 2.3–2.4 × 1.2–1.9 mm, apex rounded to cuneate, citrine to vinaceous, eciliate, glabrous to rare puberulous, eglandular or rarely glandular, recurved, abaxial surface citrine, 3–5-veined, glabrous, inner oblanceolate to spatulate, 6.4–7.5 × 0.7–1.1 mm, apex rounded, lilac to pink, petaloid, eciliate, glabrous, eglandular, slightly recurved to erect, abaxial surface citrine, 2–3-veined, glabrous, receptacles epaleate or rarely paleate, palea 0–1, linear, 6.2 × 0.5 mm, 1-veined, apex pink, abaxial surface stramineous, eciliate, eglandular. Florets 40–60, corollas 3.9–4.6 × 0.5–1 mm, lilac, lobes glabrous, glandular. Cypselas obconical, 2.9–3.4 × 0.4–0.6 mm, 5–6-ribbed, ribs and sinuses glabrous to glabrescent, eglandular, pappus setae ca. 31–38, white, 4–4.7 mm long.

Distribution: — Argentina , Brazil, Paraguay and Uruguay ( Cabrera 1996). In Brazil, it is recorded only in Rio Grande do Sul. In Rio Grande do Sul, it occurs in the physiographic regions of Campanha and Depressão Central ( Fig. 7 , triangles).

Habitat: —Grasslands of the Pampa biome, preferably in humid soils or close to rivers or streams.

Phenology: —Flowers from the end of summer to the beginning of autumn, with a flowering peak in March and April.

Etymology: —Greek kallos (beauty) and lepis (scales), with reference to the inner involucral bracts with showy, colorful apices, named ‘petaloid’ in this work for their similarity to petals.

Comments: — Chromolaena callilepis is a neglected species due to the inconstant treatments it received in the different studies it has appeared. It is also considered a very rare species in Rio Grande do Sul, known from the last 30 years from a single locality near the frontier with Uruguay.

We disagree with Freire & Ariza Espinar (2014b) in respect to their treatment of E. polyanthum and E. paucicapitulatum as synonyms of C. ivifolia . Mainly the inner involucral bracts with petaloid apices in C. callilepis can easily tell the two species apart, a character absent in every other species of Chromolaena found in Rio Grande do Sul. Chromolaena callilepis also bears more florets in its capitula and has a more lax capitulescence than C. ivifolia . The indumentum of stems and leaves is also useful to distinguish between the two species. Chromolaena squarrosoramosa also bears some superficial similarity to C. callilepis , but can also be differentiated by the inner involucral bracts with non-petaloid apices and by the indumentum of the leaves and stems.

Chromolaena callilepis is probably endemic to the Pampa biome, given its overall geographic distribution.

Specimens examined: — BRAZIL: Rio Grande do Sul:Dom Pedrito:Ponche Verde [31°16’21,9’’S 54°50’44,9’’W], 11 April 2008, Schneider, A. A. 1595 (ICN). Porto Alegre: Vila Nova, 19 March 1942, Augusto, I. s.n. (ICN19065). São Gabriel: Fazenda Santa Cecília, January 1944, Rambo, B. s.n. (PACA25610). São Jerônimo: Margem do Rio Jacuí, 23 March 1983, Hagelund, K. 14523 (ICN)

Figures

FIGURE 5A–E: Chromolaena callilepis. A. Fertile branch. B. Capitulum. C. Involucral bracts. D. Floret. E. Palea. F–J: Chromolaena christieana. F. Fertile branch. G. Capitulum. H. Involucral bracts. I. Floret. J. Peduncle.

FIGURE 6A–C: Chromolaena callilepis. A. Primary capitulescence. B. Leaves. C. Capitula. D–F: Chromolaena christieana. D. General view. E. Primary capitulescence. F. Leaves. Credits:Angelo Schneider (A) and Anderson Christ (B–F).

FIGURE 7: Distribution of C. callilepis (triangles) and C. christieana (circle) in Rio Grande do Sul.