Baccharis sect. Illinitae G. Heiden, 2016

Heiden, Gustavo & Pirani, José Rubens, 2016, Novelties towards a phylogenetic infrageneric classification of Baccharis (Asteraceae, Astereae), Phytotaxa 289 (3), pp. 285-290 : 286-288

1.3. Baccharis sect. Illinitae G. Heiden , sect. nov. Type: — Baccharis illinita DC

Baccharis sect. Illinitae comprises geophytic subshrubs (with a thickened underground system) with subopposite, 3- nerved and toothed leaves, differing from B. sect. Tridentatae Giuliano (2005: 537) by the paniculate capitulescences (vs. capitulescences in corymbose or spike-like racemes).

The species included in B. sect. Illinita were previously assigned to B. sect. Tridentatae Giuliano (2005: 537) . Baccharis sect. Illinitae comprises two species of moist or flooded grasslands from southern and central Brazil and eastern Paraguay.

Species assigned (2):— B. illinita DC. and B. illinitoides Malag.

2. Baccharis subgen. Coridifoliae (Giuliano in Giuliano & Freire 2011: 339) G. Heiden, stat. nov. Baccharis sect. Coridifoliae Giuliano in Giuliano & Freire (2011: 339). Type:— Baccharis coridifolia DC

Baccharis subgen. Coridifoliae is recognized by the linear leaves, capitulescences paniculate or racemose, pistilodium of male florets with short ovate branches, broad corollas of female florets with five papillose teeth and a short style, and cypselae with twin trichomes.

Baccharis sect. Coridifoliae is not closely related to B. subgen. Tarchonanthoides Heering (1904: 26) fide Müller (2006). Consequently, the section was removed from B. subgen. Tarchonanthoides to keep it monophyletic ( Heiden & Pirani 2016). The lack of the tufted indumentum and a common occurrence of an indumentum of filiform trichomes is one of the main reasons why the species of Baccharis sect. Coridifoliae have been traditionally assigned to B. subgen. Tarchonanthoides. However, B. sect. Coridifoliae is not closely related to the clade containing the type species of B. subgen. Tarchonanthoides, being instead the sister-group of B. subgen. Baccharis (Heiden 2014) . Due to its morphological distinctiveness and since it represents a distinct lineage, the section is elevated here to the subgeneric rank.

Baccharis subgen. Coridifoliae comprises two sections and ten species assigned below, occurring in moist or dry grasslands and savannahs from Bolivia and central Brazil to central Argentina.

2.1. Baccharis sect. Coridifoliae Giuliano in Giuliano & Freire (2011: 339). Type:— Baccharis coridifolia DC Baccharis sect. Coridifoliae is characterized by the subshrubby habit with a common presence of a thickened underground system or rhizomes, and by the pluriseriate pappus of female florets strongly accrescent at maturity. It comprises eight species occurring in grasslands and savannahs from Bolivia and central Brazil to central Argentina.

Species assigned (8):— B. albilanosa A. S. Oliveira & Deble , B. artemisioides Hook.&Arn. , B. bicolor (Joch. Müll.) G. Heiden , B. coridifolia DC. , B. erigeroides DC. , B. napaea G. Heiden , B. ochracea Spreng. , and B. suberectifolia A. S. Oliveira & Deble.

2.2. Baccharis sect. Pluricephalae ( Deble 2012: 15) G. Heiden , comb. nov. Lanugothamnus sect. Pluricephalae Deble (2012: 15) . Type:— Lanugothamnus scabrifolius (G. Heiden) Deble [= Baccharis scabrifolia G. Heiden ] Baccharis sect. Pluricephalae is characterized by the shrubby habit and the uniseriate pappus of female florets not accrescent at maturity. It comprises two narrowly endemic species from southern Brazil, occurring in highland marshes and peat bogs.

Species assigned (2):— B. pluricapitulata (Deble) G. Heiden and B. scabrifolia G. Heiden.

3. Baccharis subgen. Heterothalamulopsis ( Deble et al. 2004: 1) G. Heiden , comb. et stat. nov. Heterothalamulopsis Deble et al. (2004: 1) . Type: — Heterothalamulopsis wagenitzii (F.H. Hellw.) Deble, A.S. Oliveira & Marchiori [= Baccharis wagenitzii (F.H. Hellw.) Joch. Müll. ]

Baccharis subgen. Heterothalamulopsis is characterized by the capitula arranged in terminal glomerules, pistilodium apex of male florets with short ovate branches, paleate female capitula and female florets bearing apically rayed corollas.

Hellwig (2003) described Heterothalamus wagenitzii Hellwig (2003: 135) as a dioecious species belonging to a gynodioecious group of Baccharidinae . Later, Deble et al. (2004) segregated Heterothalamulopsis as a monospecific genus distinct of Heterothalamus based on its dioecy. Müller (2006) synonimized Heterothalamus with Baccharis arguing that sexual expression does not justify the segregation of genera within Baccharidinae , and provided the new combination B. wagenitzii (F.H. Hellw.) Müller (2006: 306) including this species with the dioecious B. boliviensis (Weddel 1856: 179) Cabrera (1975: 256) , originally described in Heterothalamus , plus the gynodioecious species B. aliena ( Sprengel 1826: 446) Müller (2006: 305) and B. psiadioides ( Lessing 1831: 504) Müller (2006: 306) in the “ Heterothalamus group”. Giuliano & Freire (2011) provided the new combination and status Baccharis sect. Heterothalamus including the same species of Müller (2006) plus B. hyemalis Deble in Oliveira et al. (2006: 20) (= Heterothalamus rupestris Deble et al. 2003: 1 ). The three gynodioecious species described in Heterothalamus are closely related to each other and belong to B. subgen. Heterothalamus sect. Heterothalamus , while the other two dioecious species described in Heterothalamus are not closely related to this lineage. Baccharis boliviensis belongs to B. subgen. Molina sect. Pseudobaccharis ( Cabrera 1944: 246) Cuatrecasas (1982: 168) , while B. wagenitzii is an isolated lineage sister to the clade B. subgen. Coridifoliae + B. subgen. Baccharis (Heiden 2014) .

Due to its phylogenetic position, the new combinations and rank changes B. subgen. Heterothalamulopsis and B. sect. Heterothalamulopsis are provided to accommodate this species at subgeneric and sectional ranks. Thus, B. sect. Heterothalamulopsis is the only known section to belong to the subgenus and B. wagenitzii , a rupiculous shrub found in isolated basaltic cliffs in southern Brazil, is the only species known belonging to this intriguing lineage.

3.1. Baccharis sect. Heterothalamulopsis ( Deble et al. 2004: 1) G. Heiden , comb. et stat. nov. Heterothalamulopsis Deble et al. (2004: 1) . Type: — Heterothalamulopsis wagenitzii (F.H. Hellw.) Deble, A.S. Oliveira & Marchiori [ Baccharis wagenitzii (F.H. Hellw.) Joch. Müll. ]

Species assigned (1):— B. wagenitzii (F.H. Hellw.) Joch. Müll.

4. Baccharis subgen. Heterothalamus ( Lessing 1830: 145) G. Heiden , comb. et stat. nov. Heterothalamus Lessing (1830: 145) . Type: — Marshallia aliena Spreng. [= Baccharis aliena (Spreng.) Joch.Müll. ]

Baccharis subgen. Heterothalamus is characterized by the combination of glandular-punctate leaves crowded at the distal parts of branches, capitula arranged in corymbiform racemes or panicles, rarely isolate capitula, male florets with pistilodium style apex bearing short lanceolate lobes, paleate female capitula, apically irregularly denticulate short-rayed female corollas and cypselae 3–7-ribbed.

Baccharis subgen. Heterothalamus is recognized at subgeneric rank and the new combination is here provided. The subgenus comprises three sections and only seven species. The relationship of the sections here included in B. subgen. Heterothalamus was not formally recognized before. Albeit differing sharply in habitat and habit from the species of B. sect. Heterothalamus , B. acaulis (Weddel ex Fries 1905: 79) Cabrera (1975: 255) was originally described in the genus Heterothalamus , while the species assigned to the new B. sect. Bradeanae were coincidently named on herbarium labels as Heterothalamus , prior to the valid publication of its species in Baccharis . The three lineages are disjunct, occurring in Serra do Caparaó, Southeastern Brazil, along the Andes or in Pampean mountains and hilly ranges of Argentina, southern Brazil and Uruguay. The sections and species discussed below are assigned to Baccharis subgen. Heterothalamus .