Centaurea rahiminejadii Negaresh (2016: 2)

Negaresh, Kazem & Rahiminejad, Mohammad Reza, 2018, A revision of Centaurea sect. Cynaroides (Asteraceae, Cardueae-Centaureinae), Phytotaxa 363 (1), pp. 448-450 : 448-450

26. Centaurea rahiminejadii Negaresh (2016: 2) . Type:— IRAN. Prov. Kermanshah: Ravansar toward Kamyaran , 1–3 km after Ravansar , 34° 71′ 53″ N, 46° 65′ 33″ E, 1375 m, 29 May 2014, Negaresh & Kamalnejad 28689 (holotype HUI!, isotypes FUMH!, herb. Negaresh!). ( Fig. 56 )

Biennial plants, up to 130 cm tall; collar of fibrous petiolar remains present at stem base. Stem erect, usually simple, ca. 15 mm in diam. at base, cylindrical, with thick brown striations, densely leafy in median part, lower part ± densely covered with hirsute-articulate hairs, up to 2 mm long, median part loosely covered with hirsute-articulate hairs mixed with scattered arachnoid hairs, upper part sparsely arachnoid, with sessile glandular hairs. Leaves thin, papyraceous (on drying), almost undivided, with prominent elevated veins on each side, loosely covered with short and deciduous hirsute-articulate hairs, denser along midrib and veins, sometimes scabrous. Basal leaves withered at anthesis. Lower cauline leaves simple, broadly ovate, 24–33 × 11–13 cm, with a 10–14 cm petiole, sometimes with basal auricles, loosely cartilaginous dentate or entire, obtuse to subacute at apex. Median cauline leaves sessile, simple, broadly oblanceolate, broadly oblong or oblong-elliptic, 16–24 × 6–11 cm, winged or broadly decurrent, up to 60 mm along stem, sparsely cartilaginous dentate or entire, acute at apex. Upper cauline leaves increasingly smaller towards stem apex, sessile, simple, oblong to narrowly oblong or narrowly lanceolate, 3–14 × 1–4 cm, loosely covered with arachnoid hairs mixed with sessile glands, entire or denticulate, broadly decurrent, up to 60 mm along stem, sometimes not decurrent, acute or subacuminate at apex. Capitula several, 8 to 10, arranged in a raceme, upper ones on peduncles 12–22 cm long, sometimes with bracts similar to phyllaries with small stramineous and chaffy appendages. Involucres ovoid to subglobose, 30–35 × 32–40 mm. Phyllaries multiseriate, green in vivo, imbricate, coriaceous, densely lanate-tomentose. Appendages very small, concealing a minor part of phyllaries, rigid, brown or pale brown, triangular or narrowly triangular, 2–5 mm long, 2–5 mm wide at base, weakly ciliate or pectinate, inner ones smaller and indistinct or linear; cilia short, 3–4 on each side, 0.5–1 mm long; spine 0.5–2 mm long, sometimes lacking. Outer phyllaries oblong, 3–7 × 3–6 mm; median phyllaries broadly lanceolate or oblong-lanceolate, 16–23 × 11–12 mm; inner phyllaries lanceolate or linear, 25–32 × 5–12 mm. Flowers purple; central florets hermaphroditic, 48–50 mm long, corolla 16–18 mm long, 5-lobed, lobes 8–10 mm long, with brownish nerves; peripheral florets sterile, equal to central ones, numerous (15–20 in each capitulum) and conspicuous, finely dissected, not radiant, 5-lobed, limb lobe filiform, ca. 7 mm long. Achenes oblong, ca. 8 mm long, 2.8–3 mm wide, smooth and shiny, whitish to yellowishwhite, rounded at apex, glabrescent; insertion areole lateral, ca. 1 mm long. Pappus persistent, multiseriate, scabrous, pale brown, ca. 13 mm long, bristles of inner rows very slightly shorter than others.

Taxonomic and distribution remarks: — Centaurea rahiminejadii is a very rare endemic to Kermanshah Province, W Iran ( Negaresh & Rahiminejad 2016) ( Fig. 55 ). It is an Irano-Turanian element, and grows on fallow fields and along roadsides, at elevations of 1300–1400 m ( Figs. 56C and 56D ). Centaurea rahiminejadii is only known from the type locality in Shahu Mountains (Ranvansar-Kamyaran road) ( Fig. 56C ). It is a distinct species which, with its diagnostic appendages that are smallest among the species of C. sect. Cynaroides , occurs exclusively in a very small area in the Kermanshah Province, in Iran ( Negaresh & Rahiminejad 2016). Centaurea rahiminejadii can be compared with several of the purple-flowering species of the section, but it seems to be related more closely to C. gigantea subsp. rechingeri in its small and brown appendages, purple flowers and the same length of pappus and achenes. However, it differs from C. gigantea subsp. rechingeri by its lower cauline leaves broadly ovate, 24–33 × 11–13 cm, loosely cartilaginous dentate or entire (vs. lanceolate, 22–24 × ca. 10 cm, entire), capitula 8 to 10, upper ones on peduncles 12– 22 cm long (vs. 3 to 7(–12), peduncles short or pedunculate in the upper part, gradually longer towards the base of the raceme, lowest ones sometimes with 2–4 heads), involucres ovoid to subglobose, 30–35 × 32–40 mm (vs. subglobose or obconical, ca. 45 × 45 mm), inner appendages smaller and indistinct or linear (vs. triangular, distinctly ciliate), cilia 3–4 on each side, 0.5–1 mm long (vs. 4–8 on each side, (2–) 3–5 mm long), spine 0.5–2 mm long, sometimes lacking (vs. 2–5 mm long), and also in the pappus: bristles of inner rows very slightly shorter than others (vs. double, bristle of inner rows much shorter than others).

Chromosome numbers: —Unknown.

Figures

FIGURE 55. Distribution of Centaurea phlomoides (circles), C. rahiminejadii (squares), and C. ravansarensis (triangles).

FIGURE 56. Centaurea rahiminejadii Negaresh (Negaresh & Kamalnejad 28689, HUI). A. close up of capitule with pollinator. B. indumentum of lower part of stem. C. habit and habitat. D. lower and median cauline leaves. Scale A = 1 cm, C = 15 cm, D = 10 cm.