A synopsis of Plagiocheilus (Compositae: Astereae)
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ISSN: 0075-5974 (print) ISSN: 1874-933X (electronic)
A synopsis of Plagiocheilus (Compositae: Astereae) D. J. Nicholas Hind1 Summary. A synopsis of Plagiocheilus (Compositae: Astereae) is provided, giving full synonymy, type citations and the location of known types, together with relevant notes and commentary, and the currently accepted distribution of each taxon; the distribution of taxa is also tabulated. Six species are recognised, one containing three subspecies. A key to species is presented. One author citation is corrected following an incorrect assumption by de Candolle when describing Plagiocheilus tanacetoides. The synonymy of Polygyne inconspicua, under Eclipta prostrata, is précised once again. An index to names associated with Plagiocheilus is given, and the nomen nudum of Plagiocheilus herzogii commented upon. Key Words. Anthemideae, Asteraceae, Eclipta prostrata, subtribe Grangeinae, subtribe Hinterhuberinae, Polygyne,
Polygyne inconspicua.
Introduction During the recent extraction of material of Bolivian endemic Compositae, as part of a wider TIPAs (Tropical Important Plant Areas) Project at the Royal Botanic Gardens, Kew, material of Plagiocheilus Arn. ex DC. (Compositae: Astereae) provided a few problems, not least the historical determination of Ecuadorian material as P. ciliaris Wedd. — which I consider a Bolivian endemic. Plagiocheilus is a genus of six species ranging from Colombia in the north (P. bogotensis (Kunth) Wedd.) south to northern Argentina, Paraguay and Southern Brazil (P. tanacetoides Hook. & Arn. ex DC.) (see Table 1); the majority of species are Andean. First recognised by Arnott, and described by de Candolle (1838: 142), the genus was placed in the tribe Anthemideae (although considered a subtribe by de Candolle) — the beginning of a tribal misplacement that has continued until relatively recently. Bentham (1873) maintained the tribal position, followed by Hoffmann (1892: 279), and in several Flora treatments, such as Baker (1884: 292 – 293 — Brazil), Cabrera (1974: 421 – 422 — Entre Rios, Argentina), Dillon (1981: 12 – 15 — Peru), and Ariza Espinar (1997: 24 — Argentina). However, Robinson & Brettell (1973) quite convincingly argued that the genus was misplaced and belonged in the Astereae, a treatment followed by several authors, e.g. Nesom & Robinson (2006), Hind (2011 — Bolivia) and Sancho (2014: 231 – 232 — Argentina). Its position in the Astereae was confirmed by KaramanCastro & Urbatsch (2009) and Brouillet et al. (2009), where the two species sampled (P. bogotensis (Kunth) Wedd. and P. soliviformis DC.) were placed next to species sampled in Archibaccharis Heering. This supports the
earlier proposals by Robinson & Brettell (1973), Grau (1977) and Bremer (1994). It is also clear from the molecular work that its position in the subtribe Grangeinae, as proposed by Nesom & Robinson (2006), is no longer tenable and that it is most probably best placed closer to, or in, the subtribe Hinterhuberinae s.str. The species are perennial herbs and, with the exception of the more
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