Plectocephalus illapelinus (Phil.) Penneck. & Gl. Rojas, 2020

Penneckamp, Diego, Chaura, Rodrigo, Rojas, Gloria & Stuessy, Tod, 2020, Taxonomic notes on Plectocephalus (Centaurea s. l., Centaureinae, Asteraceae) from Chile, including new combinations and synonyms, Phytotaxa 437 (4), pp. 227-236 : 232-233

Plectocephalus illapelinus (Phil.) Penneck. & Gl. Rojas , comb. nov. ( Figure 4 ).

Basionym:— Centaurea illapelina Philippi (1895: 43) . Type:— CHILE: Coquimbo Region, Elqui Province , El Peñon, R. A. Philippi s.n. (Holotype SGO 000005197 !; isotype SGO 000005196 !) .

Shrub ca. 0.6–0.8 m, perennial, branched, lignified at base, green-gray. Stems densely puberulent-tomentose, woollywhite at the base and glabrescent toward apex. Leaves narrowly pinnatifid to pectinate-pinnatifid, deeply divided, sessile, tomentose and glaucous, (1.5–)2.5–6.5(–12.5) × 1–2.5 cm, with 4–6 pairs of linear segment pairs opposite or slightly subopposite, (0.3–)0.5–1.6(–2) × 0.1–0.2(–0.3) cm, margin of segments entire or sometimes toothed, at apex acute, submucronate, or mucronate. Upper leaves of floral stem smaller and irregular, peduncle striated, glabrescent, with few leafy bracts, heads borne singly. Involucre hemispheric, subcampanulate, 2–3 cm diam. Phyllaries many in 5–6 series, lanceolate to narrowly lanceolate, acute, glabrescent on adaxial surface except at margin and sometimes basal phyllaries minutely pubescent. External phyllaries shorter and broad, 5–7 × 2–3 mm, inner phyllaries longer and narrower, 15–25 × 2–4 mm, with apex expanded into an erect spreading pectinate-fringed coriaceous appendage 1/4–1/3 of total phyllary length. Most inner phyllaries notably narrower and longer, linear-lanceolate. Ray flowers sterile, 3 × 0.3–0.4 cm, corolla 5-lobed, lobes lanceolate to narrowly lanceolate with acute apex, 1.2 × 0.3 cm, tube of (1–) 1.5–1.8 cm long. Disc florets tubular, smaller than ray florets, fertile and hermaphroditic, 1.6–2.1 × 0.2 cm, corolla 5-lobed, lobes acute, separated c. 1/3 of total corolla length. Corolla white to pale pink. Style with bifid stigma, 1–2 mm longer than anthers. Anthers ca. 8 mm long. Ovary ca. 3 mm long. Mature cypselae not seen.

Etymology:—From the type locality around Illapel, Coquimbo Region, northern Chile.

Distribution and ecology:—Plant from xerophytic shrubland communities, not along the coast.

Notes:—This species was synonymized by Reiche (1905) under Centaurea floccosa , but Plectocephalus illapelinus is different from P. floccosus by having a smaller capitulum and deeply pinnatifid leaves with narrow linear segments. This species is also similar to P. bridgesii , but the former is distinguished by its puberulo-tomentose stems and phyllaries without dark-colored appendages in contrast to glabrous stems and phyllaries with dark-colored appendages in the latter. As for the distribution, P. illapelinus does not grow along the coast, whereas P. floccosus and P. bridgesii are typical in the coastal vegetation.

Specimens examined: — CHILE. Atacama Region: Huasco Province: Embalse Santa Juana , nuevo mirador (28°40’ S, 70°38’ W), 670 m, 16 Oct 2010, A. Moreira 1312 ( SGO 160832 ) ; Embalse Santa Juana , mirador, km. 670 (28°40’27’’ S, 70°36’41’’ W), 800 m, 12 Nov 2004, Fundación Philippi 92 ( SGO 167510 ) ; Cuesta Pajonales , en cima, lado sur (29°9’ S, 70°58’ W), 1200 m, 27 Oct 1984, M. Muñoz 2015 ( SGO 108071 ) ; Vallenar, Cuesta de Pajonales (29°07’ S, 71°01’ W), 1200 m, 10 Oct 1987, S. Teillier 1027 ( SGO 141718 ) . Coquimbo Region: Elqui Province: Andacollo (30°15’ S, 71°4’ W), 800–1000 m, 24 Oct 1991, A. Brinck s.n. ( SGO 122806 ) ; Quebrada San Carlos, c. 5 km al Oeste de Vicuña, a los pies del Cerro Tololo , Valle del Río Elqui (30°4’ S, 70°49’ W), 600–800 m, 11 Nov 1974, C. Villagrán, R. Torres & R. Osorio s.n. ( SGO 126616 ) .

Figures

FIGURE 4. Plectocephalus illapelinus (SGO 108071).