Leucostele, Backeberg, 1953

Guerrero, Pablo C. & Walter, Helmut E., 2019, Nomenclatural novelties and a new species in Chilean Cactaceae, Phytotaxa 392 (1), pp. 89-92 : 89-90

Genus Leucostele

Schlumpberger & Renner (2012) showed that the genus Echinopsis is polyphyletic and split it into various genera, one of which is Leucostele . Schlumpberger (2012: 29) proposed the new combination Leucostele coquimbana ( Molina 1782: 170) Schlumpberger (2012: 29) . In the meantime, the old name Cactus coquimbanus Mol. had been rejected for being ambiguous ( Eggli & Walter 2012, Wilson 2016) and thus this taxon has to be renamed. The next available basionym for these shrubby columnar plants occurring along the coast of the Coquimbo and Atacama Regions is Cereus nigripilis Philippi (1860: 23) and, as a consequence of the rejection of the name Cactus coquimbanus , all combinations using this basionym have to be abandoned too—including Leucostele coquimbana .

Leucostele nigripilis (Phil.) P.C. Guerrero & Helmut Walter , comb. nov. ≡ Cereus nigripilis Philippi (1860: 23) ≡ Trichocereus chiloensis ( Colla 1826: 242) Britton & Rose (1920: 137) var. nigripilis (Phil.) Espinosa (1937: 242) ≡ Trichocereus nigripilis (Phil.) Backeberg (1959: 1145) ≡ Echinopsis nigripilis (Phil.) Friedrich & Rowley (1974: 96) .

Lectotype (designated by Muñoz in Muñoz 1960: 92):— CHILE. Coquimbo, November 1853, Philippi 35 (lectotype, SGO52682 !).

Epitype (here designated):— CHILE. Coquimbo, Punta Teatinos, c 10 km. N of La Serena and 2 km from Panamericana to the coast, Leuenberger & Eggli 2579 (CONC131947!).

Description: —Plants shrubby, 0.5–1.5 m high, branching basally or laterally from lying branches, first erect, later semi-procumbent with ascending ends; branches slender, 4–8 cm diam. Ribs few, 8–13, deeply crenate. Areoles convex, oval, 1.0– 1.5 cm, with orange-brown or beige wool, later grey, 0.5–1.5 cm apart. Central spines 2–4, stout, straight or somewhat curved, 2.5–12 cm; 10–20 radial spines, 1–3 cm, thinner. Flowers white, 8–12 cm, subapical to sometimes apical; hypanthium greenish, bract scales tipped brownish-reddish, axils with dark wool and contorted hairs; style and stigma whitish; stamens greenish. Fruits 4–5 cm, blackish-brownish, ovoid, somewhat tuberculate, covered as for the flower; perianth remnant mostly persistent. Seeds 1.2–1.7 mm; hilum position ±basal.Note: The above description of the plants matches Philippi’s original protologue very well.

Distribution: —From Coquimbo (30° S) to Tocopilla (22° 40 S), restricted to coastal plains and hills.

Notes on lectotype and epitypification: —The lectotype designated by Muñoz (in Muñoz 1960: 92) is ambiguous since it combines flowers of Leucostele and Eulychnia . The contorted flowers of Leucostele are the ones with the long and slender tube and a short globular pericarpel, while the stout flowers of Eulychnia have a short tube and a large conical pericarpel.