Chromolaena diversifolia A.L.Christ, 2025

Christ, Anderson Luiz, Nakajima, Jimi Naoki & Ritter, Mara Rejane, 2025, Towards a better understanding of the Chromolaena congesta complex (Asteraceae, Eupatorieae): updated synopsis with taxonomic novelties, Phytotaxa 689 (2), pp. 163-184 : 170-172

4. Chromolaena diversifolia A.L.Christ , sp.nov.

Type:— BRAZIL. Paraná: Castro, PR-340, 24º45’55”S 50º09’31”W (WGS-84), 05 April 2019, A.L. Christ 687 (holotype: ICN 201696!, isotype: RB 1506296!).

( Fig. 3A–F )

Diagnosis: —Close to Chromolaena congesta , from which it differs by the sericeous indument of the stems and the adaxial surface of the leaves and the lanate indument of the abaxial surface of the leaves.

Description: — Subshrubs up to 50 cm tall, erect, xylopodium present, branched from base. Stems sericeous, mostly glandular, rarely eglandular, leafy until capitulescence, internodes 1.7–4.7 cm long. Leaves 1.3–2.8 × 0.9–2.2 cm, opposite, petiolate, 3-veined, veins emergent on abaxial surface, leaf blade deltate to ovate, rarely lanceolate or reniform, chartaceous to coriaceous, discolor, apex acute to obtuse, rarely rounded, base truncate to cuspidate, rarely obtuse or cuneate, margins crenate, adaxial surface sericeous, mostly glandular, very rarely eglandular, abaxial surface lanate, glandular, petioles 1–3.9 mm long, sericeous, glandular. Primary capitulescence usually corymbose, rarely glomerate. Secondary capitulescence corymbose, branches sericeous to tomentose, glandular, bracteate, bracts similar to ordinary leaves. Capitula subsessile to pedunculate, rarely sessile, peduncles up to 0.5 cm long, sericeous to tomentose, glandular, involucres cylindrical, 5.2–6.9 × 1.8–3 mm, involucral bracts 16–28, 4–5-seriate, outer oblong to ovate, rarely deltate, 1.5–2.1 × 0.6–1.03 mm, apex mostly apiculate, rarely acute or obtuse, vinaceous, ciliate, puberulous, glandular, erect, abaxial surface citrine, 3–5-veined, glabrous to puberulous, inner linear, 4.9–6.6 × 0.6– 1.2 mm, apex apiculate to acuminate, sometimes acute or rounded, vinaceous, ciliate, puberulous, glandular, erect, abaxial surface citrine to vinaceous, 1–3-veined, glabrous to puberulous, receptacles epaleate. Florets 9–11(–17), corollas 4–4.8 × 0.4–0.6 mm, lilac, lobes glabrous, glandular. Cypselae obconical, 1.8–3.2 × 0.4–0.8 mm, 5–8-ribbed, glabrescent to setulliferous, glandular, pappus setae ca. 32–45, stramineous, 4–5 mm long.

Distribution: —This species is restricted to Brazil, occurring in Paraná, Rio Grande do Sul, Santa Catarina and São Paulo states. There are historic collections of this species from the state of Minas Gerais, dating from the first half of the 19th century, but due to the lack of recent collections we could not determine if C. diversifolia still occurs in this state or if it is regionally extinct. This species inhabits highland grasslands of the Mata Atlântica domain.

Flowering period: —Flowers mostly from January to March.

Conservation status: —Near Threatened (NT). The projected AOO of C. diversifolia would normally yield it a status of Endangered, which could be supported by the observation that many populations are known only from historical records in Minas Gerais, São Paulo and Santa Catarina, and the continued degradation of grasslands habitats in southern Brazil ( Külkamp et al. 2018) suggests a decline in EOO and AOO. However, this species is protected in many conservation units across its range, and most known populations are numerous and extremely frequent throughout this species range. Nonetheless, the continued observed degradation of its habitat and the putative decline of both EOO and AOO indicates a future scenario in which C. diversifolia could be under extinction risk.

Comments: —Despite its status as a taxonomic novelty, C. diversifolia is fairly common in southern Brazil, especially in the Paraná and Santa Catarina states. This species is particularly interesting due to the unique lanate indument observed in the abaxial surface of the leaves ( Fig. 3F ), which is not present in any other Chromolaena species found in its distributional range. The name chosen for this taxon alludes to this distinct trait, as it comes from Latin words diversus (different) and folius (leaf).

Most specimens revised in herbaria were identified as C. congesta , with which this species exhibits a great morphological similarity. Nonetheless, C. diversifolia can be differentiated from C. congesta by the indument of stems and leaves ( Fig. 3D–I ). Other morphological traits useful to distinguish these species are the presence of glandular hairs on both surfaces of the leaves in C. diversifolia (vs. only on the abaxial surface in C. congesta ) and shape of inner phyllaries (usually apiculate in C. diversifolia and acuminate in C. congesta ). The distribution of C. diversifolia also seems to be more restricted by higher temperatures, with most populations restricted to highland grasslands associated with Araucaria Forests. Chromolaena diversifolia also becomes less frequent and abundant further south in the Rio Grande do Sul and Santa Catarina states, where C. congesta is more common. Still, both species are known to co-occur in a few localities, particularly in Santa Catarina state.

Paratypes: — BRAZIL. Paraná: Lapa, Colônia São Carlos , 22 February 2001, J. M. Silva 3290 ( HUFU) ; Piraí do Sul, 26 February 2007, E. Barbosa 2060 ( MBM) ; Ponta Grossa, Parque Estadual de Vila Velha, 07 March 2003, R. Gonçalves 94 ( UPCB). Rio Grande do Sul: São Francisco de Paula , Vila Seca, 08 March 1994, N. Silveira 11697 ( HAS). Santa Catarina: Chapecó, 21 February 1957, L. Smith 11568 ( RB) ; Três Barras, 25 February 1948, A. Mattos s.n. ( RB 63253 ). São Paulo: Itararé , 20 February 2011, V. C. Souza 34110 ( HUFU) ; São Paulo, 22 March 1956, M. Kuhlmann s.n. ( RB 119826 ) .

Additional selected specimens: — BRAZIL. Paraná: Arapoti, Rio das Cinzas, 10 November 1960, G. Hatschbach 6893 ( RB) ; Balsa Nova, São Luiz do Purunã, 25°28’05”S, 49°38’42”W, 02April 2019, A. L. Christ 633 ( ICN) ; Curitiba, 04 March 1958, R. B. Lange 1111 ( R) ; Jaguariaíva, 24°19’57”S, 49°47’26”W, 05 April 2019, A. L. Christ 674 ( ICN) ; Ponta Grossa, 14 February 1949, A. C. Brade 19547 ( RB) ; Tibagi, Parque Estadual do Guartelá, 30 January 2015, L. A. Souza 242 ( HUCS). Rio Grande do Sul: Arvorezinha, RS-332, 28°48’16.3”S, 52°15’46.7”W, 07 February 2019, A. L. Christ 546 ( ICN) ; Bom Jesus, Fazenda Caraúna , March 1936, J. Dutra 1270 ( ICN) ; Canela, Passo do Inferno , 11 April 2005, S. Bordignon 3096 ( ICN) ; Jaquirana, 03 March 2018, A. L. Christ 496 ( ICN) ; Passo Fundo , April 2009, M. Savaris 64 ( ICN) ; São José dos Ausentes, RS-020, 28°28’54.0”S, 49°53’33.7”W, 10 March 2019, A. L. Christ 620 ( ICN). Santa Catarina: Água Doce, Estância Bom Jesus da Roseira , 21 April 2013, S. Campestrini 486 ( ICN) ; Capão Alto, 28°03’43.1”S, 50°35’16.7”W, 07 March 2019, A. L. Christ 577 ( ICN) ; Curitibanos , 22 February 1962, R. Reitz 12213 ( RB) ; Painel, 28°04’45”S, 50°07’29”W, 28 February 2020, A. L. Christ 704 ( ICN). São Paulo: Botucatu , 14 March 1967, J. Mattos 14437 ( R) ; Itapetininga, 26 March 1945, J. I. de Lima s.n. ( RB 55746 ) .

Figures

FIGURE 3.A–F. Chromolaena diversifolia. A. Specimen growing in its natural habitat. B. Detail of the fertile part of the plant. C. Details of the stem and leaves. D. Sericeous indument of the stem. E. Sericeous indument of the adaxial surface of a leaf. F. Lanate indument of the adaxial surface of a leaf. G–I. Details of morphological traits of C. congesta, for comparison with C. diversifolia. G. Strigose indument of the stem. H. Strigose indument of the adaxial surface of a leaf. I. Strigose indument of the abaxial surface of a leaf. Scale bars of D and G = 2 mm; scale bars of E, F, H and I = 5 mm. Image credits: Claudenice Dalastra (A–C) and Anderson Christ (D–I).