Senecio ephemerus J. Calvo & Saldivia, 2022

Calvo, Joel & Saldivia, Patricio, 2022, Taxonomic and nomenclatural notes on Chilean Senecio (Asteraceae, Senecioneae), including a new particular species, Phytotaxa 556 (1), pp. 76-86 : 83-85

5. Senecio ephemerus J. Calvo & Saldivia , sp. nov. ( Fig. 5 )

Type:— CHILE. Coquimbo Region: [Limarí Province], Llanos del Teniente , [31º02’S 71º36’’W], 12 Sep 1942, C. Muñoz & E. Pisano 3402 (holotype: SGO-118935) .

Species similar to Senecio infimus Cabrera (1954: 557) , from which it differs in having reduced uppermost peduncle bracteoles (vs. foliose), marginally straw-colored involucral bracts (vs. dark-purple), ca. 8 ray florets with limb 2.5 mm long widely elliptic to orbicular (vs. 12–15, with limb 5 mm long elliptic-lanceolate), and apparently glabrous achenes (vs. shortly papillose).

Herbs annual, 2.5–5 cm long, erect, mostly glabrous except for some scattered glandular short trichomes on stem, unbranched or barely branched at upper part. Leaves 6–10 × 1.8–2.5 mm, alternate, sessile, few, semi-succulent; laminae oblong-oblanceolate, apex acute to somewhat truncate, margin subentire, with 2–3 shallow teeth per side and one apical. Capitula 1–3, terminal, radiate. Involucres 3.5–4 × 4.5–5.5 mm, widely campanulate; involucral bracts ca. 12, 3–3.5 × 1–1.2 mm, linear-oblong, with broad hyaline margins, green, apex acute, blackish-tipped; supplementary bracts absent (sometimes uppermost peduncle bracteoles might resemble 1–2 supplementary bracts). Receptacles hemisphaerical, smooth. Ray florets ca. 8, 5–5.3 mm long, pistilate; corollas probably white, limb 2.5 × 2–2.5 mm, widely elliptic to orbicular, 4–5-veined, apex 0–3-toothed, tube 2 mm long; style branches 0.2 mm long, linear, apex obtuse to truncate. Disc florets 20–30, 2.8–3 mm long, perfect; corollas tubulose, probably yellow, 5-lobed, tube 1.8–2 mm long, lobes 0.5 mm long, apex papillose; filament collar 0.4 mm long, slightly balustriform, anthers 0.8 mm long, base shortly auriculate, appendages 0.2 mm long, deltoid, acute; style branches 0.8 mm long, linear, truncate with a crown of sweeping hairs. Achenes ca. 1 mm long, cylindrical, 4–5-ribbed, glabrous (only immature achenes examined); pappus 1.8–2 mm long, white, composed of numerous thin, finely barbellate bristles, easily falling. Fig. 6 .

Distribution and habitat. Species known only from the type material, which was collected in September in the coastal part of the Limarí Province in the Coquimbo Region. According to the label information, the species is very scarce and grows among plants of Puya , namely P. chilensis Molina (1782: 160 , 351). Field work focused on finding this species was carried out in early October 2018 although it was not fruitful in this regard.

Etymology. The epithet refers to the ephemeral condition of this species.

Notes. Among the native species of South America, Senecio ephemerus only resembles S. infimus from northwestern Argentina (Salta, Jujuy). However, they can be separated by the uppermost peduncle bracteole type, the involucral bract margin color, the ray floret number, the ray floret limb length and shape, and the achene indumentum (see diagnosis above). Moreover, these species appear to thrive in completely different habitats. Senecio infimus grows in meadows of the subhumid/dry puna at elevations of 3100–4600 m (Cabrera 1978; Novara 2012). In contrast, the type material of the new species was collected on the coast around 100–300 m, in a shrubby vegetation with marked seasonality.

Senecio ephemerus is an ephemeral species probably subjected to the annual rainfall pattern. This, besides its early development at the end of the austral winter, might explain the absence of additional material. Locating again a population is essential to improve the current knowledge of this species.

Figures

FIGURE 5. Holotype of Senecio ephemerus J. Calvo & Saldivia (SGO-118935).

FIGURE 6. Senecio ephemerus J. Calvo & Saldivia.A. Individual plant. B. Involucral bracts. C. Ray floret. D. Disc floret [Scale bars:A = 5 mm, B–D = 2 mm; pictures from the type material].