Chromolaena rhinanthacea (Candolle) King & Robinson (1970: 205)

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 : 178

10. Chromolaena rhinanthacea (Candolle) King & Robinson (1970: 205) . Eupatorium rhinanthaceum Candolle (1836: 146) . Type:— BRAZIL. São Paulo, 1833, C. Gaudichaud 500 (holotype: P02411400!; isotype: G00494038!).

( Fig. 4J–L )

Distribution: —This species is restricted to Brazil, occurring in Paraná, Rio Grande do Sul, Santa Catarina and São Paulo states. Chromolaena rhinanthacea is typical of highland grasslands from the Mata Atlântica biome in southern Brazil. Cabrera et al. (1996) have reported the occurrence of this species in Paraguay. Our inspection of the examined specimen, however, has shown that it is in fact an atypical specimen of C. elliptica , thus confirming the endemism of this species in Brazil.

Flowering period: —Flowers mostly from December to early March.

Conservation status: —Endangered (EN), criteria B2ab(iii). This species was already evaluated as Endangered before ( Nakajima et al. 2013), but despite the discovery of new populations in recent years, we still estimate it to be under threat of habitat loss and fragmentation. Furthermore, despite its geographical range and EOO, Chromolaena rhinanthacea is currently confirmed to occur in only three locations in its entire distribution: in the Parque Nacional de Aparados da Serra, in Rio Grande do Sul state; and in the Bom Jardim da Serra and Lages municipalities, both in Santa Catarina state. Of these, only the first population is currently protected in a conversation unit. The population found in Lages is growing in an extremely degraded environment beside a highway, suggesting this population is at extreme risk of disappearing due to occasional construction work and highway maintenance in this location.

Comments: — Chromolaena rhinanthacea is characterized by elliptic or oblanceolate leaves with acute to attenuate bases ( Fig. 4J ); glabrous stems ( Fig. 4K ) and leaves; strigose branches; and by the absence of glandular hairs from the abaxial surface of the leaves and involucral bracts ( Fig. 4L ). Recent studies have shown this species has much greater variation in the length of the leaves, with some specimens having particularly smaller leaves (ca. 2.7–3 cm long) than previously reported (e.g. Christ & Rebouças 2020). This species is particularly close to C. gentianoides , from which it differs mostly based on the indument of the branches and a general appearance of the capitulum.

Selected specimens: — BRAZIL. Paraná: Curitiba, Capão da Imbuia, December 1975, L. T. Dombrowski 6297 ( MBM) ; Guarapuava, Fazenda Três Capões, 09 December 1969, G. Hatschbach 23186 ( MBM), Ponta Grossa, 13 April 1964, E. Pereira 8233 ( RB). Rio Grande do Sul: Cambará do Sul, Parque Nacional de Aparados da Serra, 29°09’37.9”S, 50°04’45.6”W, 06 December 2017, A. L. Christ 480 ( ICN). Santa Catarina: Bom Jardim da Serra, Desfiladeiro do Funil , 28°20’33.8”S, 49°32’31.4”W, February 1989, M. Sobral 6448 ( ICN) ; Curitibanos , December 1876, Fritz Müller 59 ( R) ; Lages, 27°40’45.7”S, 50°20’08.2”W, 08 March 2019, A. L. Christ 582b ( ICN). São Paulo: São Paulo, Jaraguá, 08 December 1912, A. C. Brade 5707 ( SP) .

Figures

FIGURE 4. A–C. Chromolaena gentianoides. A. Leaves. B. Branches and secondary capitulescence. C. Capitulum. D–F. Chromolaena hirsuta. D. Stem and leaves. E. Details of leaves. F. Capitulescence. G–I. Chromolaena latisquamulosa. G. Growing habit. H. Leaves. I. Capitulum. J–L. Chromolaena rhinanthacea. J. Leaves. K. Detail of stem. L. Capitulum. Scale bars of C, I and L = 2 mm; scale bar of K = 5 mm. Image credits:Anderson Christ (A–C, F–L), Rodrigo Dall’Agnol (D) and Sérgio Bordignon (E).