Dorobaea linearifolia Montesinos & Pruski, 2025

Montesinos-Tubée, Daniel B. & Pruski, John F., 2025, Dorobaea linearifolia (Asteraceae, Senecioneae), a distinctive new species of the subtropical montane forests of central Peru, PhytoKeys 265, pp. 147-159 : 147-159

Dorobaea linearifolia Montesinos & Pruski sp. nov.

Type.

Peru • Dept. Huánuco, Prov. Pachitea, Dist. Chaglla, Locality: Path by the pass between Monopampa and Torre Jirca , 2302 m, 09°46'37"S, 75°44'17"W, 27 Apr 2019, D. Montesinos 7570 ( Holotype: HOXA-080342 !; isotype: MO-5452663 !). Figs 2 , 3 A, B , 4 A – D , 5 A – D .

Diagnosis.

Dorobaea linearifolia is distinguished by narrowly linear to narrowly oblanceolate leaves (3–4.5 × 0.1–0.4 cm) densely spiraled on the lower half of the caulescent stem, with entire to slightly serrulate margins and glabrous to sparsely hairy bases. It produces a solitary terminal capitulum with a 12–14 mm involucre and 11–14 narrow, orange ray florets with red edges. These features distinctly separate it from D. callacallensis , D. laciniata , and D. pimpinellifolia , which have broader, lobed or rosulate leaves and single-headed inflorescences.

Description.

Simple-stemmed caulescent-leaved perennial herbs, 20–70 cm tall, growing in small groups of up to 20 stems / plants, possibly from the same underground caudex system, individual stems leafy from base to mid-stem; stems erect or ascending, densely spiral-leaved in proximal half, herbage glabrous or nearly so. Rootstock rhizomatous, more or less fibrous, taproot nearly 2 mm diam., pale white with reddish surface in the upper section, rootlets white, fleshy, more or less equal in diam. ( 0.4–0.6 mm) and covered with thin hairs of about 0.1–0.35 mm long. Leaves sessile and slightly broadened at base, 30–75 per stem, not obviously clasping, moderately dense-clustered in proximal half of stem and much longer than the very short internodes; blade 3–4. 5 × 0.1–0.4 cm, linear to more frequently very narrowly oblanceolate, usually slightly broader at base and apex but extended middle portion of the blade with margins revolute, thus appearing narrower at midblade, with 1–2 pairs of remote leaves per side in apical ca. 0.6 cm of blade, midrib very narrow, impressed adaxially, broad, flat, and not at all prominent abaxially, secondary veins not seen and presumably basically obsolete, base slightly broadened (ca. 2 mm wide) and flat towards stem, margins revolute or at least drying so, entire except at the 1–2 - serrulate apex, serrulations to 0.5 mm deep, forward-directed, apex acute, surfaces pale greyish-green on the underside, dark green and shiny in the upperside, glabrous throughout except at the base of young leaves (basal and single trichomes 0.1–0.3 mm long). Cauline leaves, alternate, sessile; blade, linear-oblong, pale purple to purple, purple-coloured, surface glabrous, and apex aristulate, margins with scattered trichomes of about 0.1–0.3 mm long, mostly located at the base of the upperside of young bracteoles adhered to the involucre. Capitulescence of a single terminal capitulum per stem, peduncle erect or ascending, to about 20 cm long, green but sometimes tingled with purple. Peduncles glabrous except by the scattered presence of trichomes of about 0.1–0.3 mm long, surface varying in colour from light green to purple to yellowish red with age. Capitula radiate, 12–14 mm long, calyculate; involucre 10–12 mm diam., campanulate, the florets held about half again above involucre tips; phyllaries uniseriate, 11–13, 7.5–8.5 × ca. 1 mm, lanceolate, purplish, glabrous, apex acuminate; calycular bracts few, linear, 3–4 mm long, usually less than 1 / 2 the length of the involucre; Capitulum c. 8–10 mm in diam.; receptacle (clinanthium) epaleate, slightly convex, ca. 1 mm high, 3–4 mm in diam .. Ray florets 11–14, pistillate; corolla glabrous, tube ca. 5.5 mm long, yellow-green, limb orange, spreading laterally from involucre, 9–10 × 1.5–2 mm, narrowly oblanceolate, 4 - nerved, minutely 3 - denticulate; ray limb margins narrowly dark red coloured and scarcely covered with thin trichomes of less than 0.1 mm long. Disc florets ca. 60–80, bisexual; corolla 7–8 mm long, narrowly funnelform, limb (yellowish-) orange, tube yellow-green, glabrous throughout, tube and throat not very distinct from each other, lobes ca. 1–2 mm long, lanceolate, erect; anthers pale, ca. 1.8 mm long, endothecial tissue radial, collar balusterform; styles appendiculate, branches recurved, ca. 1 mm long, stigmatic surface 2 - banded and fertile to branch apex, dark orange, apical and apical-lateral papillae, 0.1–0.2 mm long, sterile. Pollen grains white, orbicular, 0.06–0.07 mm diam., surface is covered with spinules, typically with entire distal ends and acute apices. Cypselae 2–3.2 mm long, green to pale-brown, 10 - nerved, carpopodium 0.1–0.2 mm long; pappus consists of numerous white capillary bristles that vary in texture from smooth to scabridulous, typically measuring 6–8 mm in length, covered with fine, thin, and minute setulose (hair-like) outgrowths along their surface, in disc florets, the pappus bristles are relatively shorter, extending only to about the middle of the corolla throat

Figures

Figure 2. Dorobaea linearifolia (Montesinos 7570, Holotype HOXA- 080342).

Figure 3. Dorobaea linearifolia. A. Leaves, the two on left showing adaxial surface, the two on the right showing abaxial surface; B. Phyllaries, ray corolla, ray ovary, ray corolla, disk florets (from left to right). All from the isotype: Montesinos 7570 [MO- 5452663]).

Figure 4. Select microcharacters of Dorobaea linearifolia. A. Disk style branches showing convex apex with lateral and also the gradually elongated apical papillae; the distal abaxial surface of the branch is smooth; B. Two anthers (center of image; the dissected corolla is towards the lower right and lower left) showing long-triangular apical appendage and narrowly balusterform collars; C. Dissected disk floret showing parts of three corolla lobes, each with a medial resin duct; D. Staminode of a ray floret (adaxial view), curving from lower right to upper left; the staminode shows no development of a filament collar. Scale bars: 1 mm (A, C); 0.5 mm (B, D) (from an unmounted duplicate of Montesinos 7570).

Figure 5. A. Subtropical montane forest of Torre Jirca (2302 m) where the new species was found; B. Sprouts of leafy stems seen vertically; C. Stems densely covered by leaves; D. Capitulescence.