Senecio fernandinus H. Beltrán & J. Calvo, 2021

Beltrán, Hamilton & Calvo, Joel, 2021, Two new species of Senecio (Compositae, Senecioneae) from Peru, Phytotaxa 479 (2), pp. 198-204 : 201-203

2. Senecio fernandinus H. Beltrán & J. Calvo , sp. nov. ( Fig. 3 )

Type: — PERU. Ica: Nazca, Marcona, La Apreciada, 507544 8328369 [15º07’12’’S 74º55’47’’W], 500 m, 14 August 2017, P . Gonzáles & E. Becerra 4188 (holotype: USM 302265 ) .

Senecio fernandinus differs from other related species of the genus (see discussion below) in its narrowly lanceolate to oblong-lanceolate, glabrous, fleshy leaves, discoid, pedunculate capitula arranged in lax corymbiform cymes, and silky-pubescent achenes.

Perennial herb, up to 30 cm tall. Stems simple or barely branched, terete, somewhat furrowed. Leaves alternate, sessile; laminas 2–4 × 0.3–1 cm, narrowly lanceolate to oblong-lanceolate, rather acute at the apex, attenuate at the base, irregularly and distantly denticulate (3 to 4, ca. 0.5 mm long teeth per side), slightly revolute, pinnately veined with 3 to 4 barely conspicuous nerves per side, glabrous on both faces, fleshy. Synflorescences cymose-corymbose, lax. Capitula 2 to 6 (per cyme), discoid, erect, pedunculate; peduncles 0.5–2.5 cm long, with linear, 10–15 mm long bracteoles, glabrous. Involucres 5.5–6 × 4–5 mm, rather cylindrical; involucral bracts 11 to 13, 6–7.5 × 1–1.5 mm, linear to oblong-lanceolate, acute at the apex, with scarious margins, glabrous, green. Supplementary bracts (calyculus) 4 to 5, 2–3 × ca. 0.5 mm, linear-subulate, glabrous, green. Florets 16 to 28, 5– 6.5 mm long, hermaphroditic, tubulose, glabrous, yellow; tubes 3–4 mm long, somewhat swollen at the base; limbs 2–2.5 × 2–2.5 mm, cupuliform, 5-lobed, with triangular, somewhat incurved, 1–1.5 mm long lobes. Anthers 3–3.5 mm long, yellow; anther appendages 0.2–0.3 × ca. 0.1 mm, yellow; anther bases obtuse; filament collars 0.9–1 mm long, balusterform. Style branches ca. 1.2 × 0.15–0.2 mm, truncate with a crown of sweeping hairs. Achenes 3.5–4.5 mm long, cylindrical, 4 to 5-ribbed, covered by dense, whitish trichomes (when dried); pappus 3–5 mm long, barbellate, whitish.

Distribution and habitat: — Peru (Ica; also expected in Arequipa considering the proximity of the known populations to the Arequipa territory and the presence of similar environments across the border). Senecio fernandinus is known from a few localities around the Loma de San Fernando, in southern Ica, at elevations of 425–700 m ( Fig. 2 ). It is an element of the ephemeral desertic vegetation known in Spanish language as “vegetación de lomas” [lomas vegetation]. It grows on sandy soils along with species such as Ambrosia dentata (Compositae) , Cristaria multifida (Malvaceae) , Oenothera arequipensis (Onagraceae) , Palaua sandemanii (Malvaceae) , Solanum edmondstonii (Solanaceae) , Tillandsia latifolia , and T. landbeckii (Bromeliaceae) .

Phenology: —Flowering from August to November. One specimen was also collected in flower in April.

Etymology: —The epithet refers to the San Fernando Lomas [“lomas de San Fernando”], from where this species is known.

Additional specimens examined (paratypes):— PERU. Ica: Nazca, Marcona, Loma San Fernando , 35 km al NW del complejo minero Shougang , [15º07’28’’S 75º20’19’’W], 433 m, 1 April 2010, J . Roque , C . Arana & B . Britto 6290 ( USM); Loma San Fernando , 15º06’50’’S 74º55’54’’W, 445 m, 13 November 2018, N . Vega & R . Mallma 3534 ( USM); Lomas San Fernando , 15º06’55’’S 75º18’17’’W, 701 m, 30 October 2012, O . Whaley et al. KPP12 ( K n.v., USM) .

Discussion: — Senecio fernandinus shows morphological affinities with S. acarinus Cabrera (1955: 210) , a species described from the lomas of Pongo in northwestern Arequipa and distributed through the Peruvian departments of Ayacucho, Huancavelica, and Ica, up to elevations of 3000 m. It is indeed a common species of the vegetation thriving in the western slopes with oceanic influence of the mentioned region. Senecio acarinus mainly differs from the new species in its linear to linear-lanceolate, strongly revolute leaves with arachnoid indumentum beneath (rarely glabrous) and the denser synflorescences. It also has longer leaves (4–10 cm vs. 2–4 cm in S. fernandinus ), higher number of florets (ca. 35 vs. 16 to 28 in S. fernandinus ), and cylindrical limbs (vs. cupuliform in S. fernandinus ). Their distribution areas most probably overlap.

Because of the similar habit, leaf shape, and distribution area, S. fernandinus might also be confused with S. smithianus Cabrera (1950: 104) , however, this species has radiate capitula (vs. discoid in S. fernandinus ) and 20 to 21 involucral bracts (vs. 11 to 13 in S. fernandinus ). Senecio melanolepis var. discoideus Candolle (1838: 424) and S. vallestris Candolle (1838: 421) also resemble the new species. The former taxon differs in having higher number and larger supplementary bracts typically black-colored in the upper half; Senecio vallestris has stems, leaves, and involucres covered by glandular-hirtellous indumentum. Their distribution areas do not overlap.

The new species has been confused with S. calcicola Meyen & Walpers in Walpers (1843: 283); see Whaley et al. (2019). This species occurs in the lomas of southwestern Arequipa but can be readily distinguished from the new species by its densely arranged linear leaves and radiate capitula with 21 to 24 involucral bracts.

Figures

FIGURE 2. Distribution maps of Senecio phlomidifolius (red cross) and S. fernandinus (open circle).

FIGURE 3. Senecio fernandinus. A. Habitat and habit. B. Capitulum. C. Corolla. D. Involucral bract. E. Leaf shape variability. Pictures A by Luis Mirano, B by Berni Britto; details C–E from P. Gonzáles & E. Becerra 4188 (USM) by H. Beltrán.