Chromolaena latisquamulosa (Hieronymus) King & Robinson (1970c: 202)

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 : 173-176

2.9. Chromolaena latisquamulosa (Hieronymus) King & Robinson (1970c: 202) .

Eupatorium rhinanthaceum var. latisquamulosum Hieronymus (1897: 759) . Eupatorium latisquamulosum (Hieron.) Malme (1933: 34) . Neotype (designated by Christ & Ritter 2018: 113):— BRAZIL. Paraná: Lago, 14 December 1904, P. Dusén 3227 (S! [S-R-8995]). ( Fig. 17A–E , 18A–C )

Subshrubs, up to 40 cm tall, decumbent, rarely erect, xylopodium present, branched from base or only in capitulescence; stems strigose to puberulous, rarely glabrescent, eglandular, leafy only in lower half, then aphyllous or near-aphyllous in upper half, rarely leafy until capitulescence. Leaves 0.6–2.8 × 0.4–2 cm, opposite, petiolate, 3-veined, leaf blade orbicular to ovate, membranaceous to chartaceous, apex acute to rounded, base rounded, sometimes cuneate, margins crenate to serrate in apical half, entire in basal half, adaxial surface glabrous, eglandular, abaxial surface glabrous to puberulous only on veins, eglandular, margins ciliate, petioles 0.9–3.8 mm long, puberulous, rarely glabrous, eglandular. Primary capitulescences corymbose. Secondary capitulescences corymbose; axis puberulous, eglandular, bracteate or ebracteate; bracts 0.4–0.8 × 0.2–0.3 cm, petioles 1.5–1.6 mm long, puberulous, eglandular. Capitula sessile to subsessile, peduncles up to 0.4 cm long, puberulous, eglandular, involucres cylindrical to campanulate, 4.8–6.2 × 2.2–3.3 mm, involucral bracts 13–19, 5–6-seriate, outer ovate to oblong, 1.9–3 × 0.8–1.9 mm, apex cuneate to obtuse, rarely rounded or truncate, vinaceous, ciliate, puberulous, eglandular or rarely glandular, slightly recurved, abaxial surface stramineous to citrine, 3–5-veined, glabrescent to puberulous, inner linear, 4.3–5.5 × 0.7–1.2 mm, apex acuminate to rounded, vinaceous, non-petaloid, ciliate, glabrescent to puberulous, eglandular, slightly recurved to erect, abaxial surface stramineous to vinaceous, 3-veined, glabrous, receptacles epaleate or rarely paleate, palea 0–1, linear, 5 × 0.3 mm, 1-veined, apex and abaxial surface stramineous, ciliate, eglandular. Florets 9–14, corollas 3.2–4.4 × 0.4–0.8 mm, lilac, lobes glabrous, eglandular. Cypselas obconical, 2–2.7 × 0.4–0.8 mm, 5–8-ribbed, ribs setuliferous, sinuses glabrescent to setuliferous, eglandular, pappus setae ca. 25–40, stramineous, 3.7–5.3 mm long.

Distribution: — Brazil, in the states of Paraná, Rio Grande do Sul, Santa Catarina and São Paulo. In Rio Grande do Sul, it occurs in the physiographic regions of Campos de Cima da Serra and Encosta Inferior do Nordeste ( Fig. 19 , triangles).

Habitat: —Highland grasslands in Atlantic Forest biome, in general in sites with shallow or rocky soils.

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

Etymology: —Latin latus (broad) + squamulosus (diminutive of squamosus: bearing scales). The specific epithet is a reference to the width of the involucral bracts, which would be broader than those of E. rhinanthaceum .

Commments: — Chromolaena latisquamulosa is a species typical of highland grasslands in Southern Brazil. It can be easily recognized by its usually orbicular leaves, with rounded bases and apices and crenate margins, glabrous or almost glabrous and eglandular in the abaxial surface.

Despite not being particularly rare in the field, this species is considered neglected due to its absence from the studies of a number of authors. Despite appearing in the taxonomic treatments of Barroso (1950) and Esteves (2001), no other study makes reference to this species, and all the examined specimens were misidentified as C. ascendens or C. congesta . This species is also considered part of the “ Chromolaena congesta group”. It differs from the other species of the complex by the shape and indumentum of the leaves and involucral bracts and by the absence of glandular hairs in the abaxial surface of the leaves.

It is notable that this species was very often misidentified with E. ascendens var. parcisetosum (and, by extension, C. ascendens ). Most of the examined specimens of C. latisquamulosa collected in Rio Grande do Sul were identified as C. ascendens , a species that does not occur in the state, or as E. ascendens var. parcisetosum , which is considered, in our study, a synonym of C. squarrulosa . Chromolaena latisquamulosa and C. ascendens are similar only in the shape of the leaves, differing in the indumentum of leaves and stems, size of the capitula, number of florets, indumentum of cypselas and general characters of the involucral bracts. Chromolaena latisquamulosa and E. ascendens var. parcisetosum share the usually decumbent habit and the indumentum of stems and leaves. However, it is clear that there is a strong morphological continuum between E. ascendens var. parcisetosum and the typical morphotypes of C. squarrulosa ¸ which compelled us to synonymize the former under the latter (see the comments under C. squarrulosa for further detail on this matter). Thus, C. squarrulosa can be distinguished from C. latisquamulosa mostly due to the involucral bracts with a tomentose indumentum and squarrose apices, usually with glandular hairs.

There is some uncertainity about the occurrence of this species in Argentina , but it still appears in Freire & Ariza Espinar (2014b) as a synonym of C. elliptica . We disagree with this synonymy, mostly due to the morphological discontinuities between both species (despite both being part of the C. congesta group): C. elliptica differs from C. latisquamulosa by the elliptic leaves, the indumentum of stems and leaves, the presence of glandular hairs in the abaxial surface of the leaves, the indumentum and shape of the involucral bracts and the indumentum of the cypselas.

Specimens examined: — BRAZIL: Rio Grande do Sul: Bom Jesus: Fazenda Caraúna , 02 February 1937, Dutra , J. 1461 ( ICN) ; Serra da Rocinha, 30 January 1976, Matzenbacher, N. I. 409 ( ICN). Cambará do Sul: Itaimbezinho , 14 February 1946, Rambo, B. s.n. ( PACA32117 ) ; para São Francisco de Paula , February 1948, Rambo, B. s.n. ( PACA36243 ) ; Itaimbezinho , 21 February 1951, Rambo, B. s.n. ( PACA50078 ) ; 20 February 1953, Rambo, B. s.n. ( PACA53952 ) ; 12 February 1956, Rambo, B. s.n. ( PACA59248 ) ; 03 April 1958, Schultz, A. R. 1651a ( ICN) ; 03 February 1973, Lindeman, J. C. & Porto, M. L. s.n. ( ICN21225 ) ; 28 March 1975, Matzenbacher, N. M. s.n. ( ICN43608 ) ; Faxinal , March 1986, Sobral, M. et. al. 5014 ( ICN) ; a 10 km do centro, 24 March 1999, Longhi-Wagner, H. et. al. 6058 ( ICN) ; Parque Nacional dos Aparados da Serra [29°02’S, 50°08’W], 27 January 2005, Kerber, K. T. B. 115 ( PACA) ; 10 December 2010, Pasini, E., Schneider, A. A., Dal Ri, L. & Baumhardt, E. 823 ( ICN) ; 29 April 2017, Christ, A. L. 441 ( ICN) ; estrada para o Parque Nacional dos Aparados da Serra, 05 December 2017, Christ, A. L. 479 ( ICN). Canela: caminho a São Francisco de Paula , a 12km de Canela, Krapovickas, A. et. al. 44678 ( MBM). São Francisco de Paula : Fazenda Englert, January 1944, Buck, P. s.n. ( PACA11641 ) ; Tainhas , 17 February 1946, Rambo, B. s.n. ( PACA32117 ) ; s.l., 10 February 1979, Hagelund, K. 12655 ( ICN) ; Josafá , April 1984, Sobral, M. 2996 ( ICN) ; Tainhas , 20 January 2000, Wasum, R. 410 ( HUCS) ; Pró-Mata, 30 November 2004, Freitas, E. M. s.n. ( HVAT1669 ). São José dos Ausentes: Fazenda do Tabuleiro , 18 March 2002, Wasum, R. et al. 1409 ( HUCS). Vacaria: Fazenda da Ronda , June 1947, Rambo, B. s.n. ( PACA34905 ) ; Passo do Socorro , 26 December 1951, Rambo, B. s.n. ( PACA51431 ) .

Figures

FIGURE 17A–E: Chromolaena latisquamulosa. A. Fertile specimen. B. Capitulum. C. Involucral bracts. D. Floret. E. Palea. F–J: Chromolaena odorata. F. Fertile branch. G. Capitulum. H. Involucral bracts. I. Floret. J. Palea.

FIGURE 18A–C: Chromolaena latisquamulosa.A. Secondary capitulescence. B. Leaves. C. Xylopodium. D–E: Chromolaena odorata. D. Secondary capitulescence. E. Fertile branch. Credits:Anderson Christ (A–C) and Sérgio Bordignon (D–E).

FIGURE 19: Distribution of C. latisquamulosa (triangles) and C. odorata (circles) in Rio Grande do Sul.