Centaurea karajensis Negaresh
Creators: name: Negaresh, Kazem
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Asterales
Asteraceae
Centaurea
Centaurea karajensis

description: Centaurea karajensis Negaresh, s p. nov. (Fig. 1)
Type: — IRAN. Alborz Province: in ditione oppidi Karaj, in montibus cdc. Kuh-e Nemar, 1600–2000 m, 3 June 1937, Rechinger 638 (holotype W!, isotypes IRAN!, TARI!).
Diagnosis: — Centaurea karajensis is related to C. ammocyanus, from which it differs mainly in its plant never with capitula at base, main stem elongated, 50–60 cm long (vs. central capitulum nearly sessile, main stem very short, 1–3 cm long), stem with several branches divaricated and unequal in length (vs. with several prostrate or ascending branches arising below the terminal capitulum, often further branched), median cauline leaves narrowly linear (vs. lanceolate), upper cauline leaves narrowly linear to acicular, shorter than involucre (vs. linear-lanceolate, inserted directly below capitulum, usually longer than involucre), cilia 0.5–1 mm (vs. 1.5–2.5 mm) long, spine erect, 0.5–1 mm long (vs. patent, sometimes squarrose, 2–4 mm long), central florets 5–8 (vs. 15–20) in each capitulum.
Descriptions: —Annual plant, never with capitula at base, whole plant usually green, densely covered with arachnoid-tomentose hairs; main stem very long, 50–60 cm long, up to 4 mm in diameter at the base, with several branches divaricated and unequal in length, ribbed-sulcate. Leaves thin, loosely covered with arachnoid-tomentose hairs, denser along midrib. Basal and lower cauline leaves petiolate, 4–8 cm long, pinnatisect; segments in 4–6 pairs, 1.5–2 mm wide, linear, acute at apex, terminal segment longer. Median cauline leaves sessile, pinnatifid or sublyrate; segments in 1–3 pairs, 0.8–1.2 mm wide, narrowly linear, acuminate at apex, terminal segment longer. Upper cauline leaves sessile, simple, 0.3–0.5 mm wide, narrowly linear to acicular, shorter than involucre, acuminate or mucronate at apex, smooth at margins. Capitula numerous, persistent, solitary at tips of many branches, with short peduncles (0.5–1.5 cm long). Involucres ovoid, 10–12 × 5–6 mm. Phyllaries multiseriate, herbaceous, imbricate, yellowish-green, glabrous; median and inner ones with prominent longitudinal or elevated nerves. Appendages small, concealing part of phyllaries only, narrowly triangular, brown or dark brown, 0.6–0.8 mm wide at base (excluding cilia), not decurrent, ciliate; cilia several, scabrous, 4–5(–6) on each side, 0.5–1 mm long, brownish or whitish; spine erect, 0.5–1 mm long, equal the adjacent cilia. Flowers pale pink; central florets hermaphroditic, 5–8 in each capitulum, 7–8 mm long, corolla 3–3.5 mm long, 5-lobed; peripheral florets sterile, inconspicuous, finely dissected, not radiant, 5-lobed, limb lobe narrowly linear, ca. 3 mm long. Achenes oblong, glabrous, 2.5–3 mm long, 1.3–1.5 mm wide; insertion areole lateral, yellow, ca. 0.5 mm long. Pappus persistent, whitish, 2.8–3.5 mm long.
Etymology: —The specific epithet refers to Karaj city, where the new species was found.
Taxonomic and distribution remarks: — Centaurea karajensis is endemic to Alborz Province, N Iran. It is an Irano-Turanian element, and grows on sandy gravel and stony plains, at elevations of 1600–2000 m. Centaurea karajensis belongs to C. sect. Ammocyanus, which includes taxa with annual habit, lyrate or more often pinnatipartite lower cauline leaves, small-sized and ovoid to fusiform involucres, with triangular and ciliate appendages ending in a mucro or short spinule, and often pink-purple flowers (Wagenitz 1980). It is similar to C. ammocyanus in the indumentum of habit, shape of involucres, color of flowers and shape of achenes (Fig. 2), but differs in some important characters (see Table 1). Furthermore, C. karajensis occurs at elevations higher than 1600 m, whereas C. ammocyanus occurs at elevations lower than 1300 m.
Centaurea karajensis is also similar to C. patula, from Iran and Turkey, especially because of the indumentum of leaves, size of involucres, shape of appendages and length of achenes. However, it differs from C. patula in some characters like life form, ramification of stems, dissection of lower cauline leaves, shape of median cauline leaves, color of appendages, length of cilia and spine, number of central florets in each capitulum, and length of pappus (Table 1).
description: Published as part of Negaresh, Kazem, 2024, Taxonomic notes on Centaurea sect. Ammocyanus (Asteraceae, Cardueae- Centaureinae) from Iran, pp. 157-164 in Phytotaxa 663 (3) on page 158, DOI: 10.11646/phytotaxa.663.3.5, http://zenodo.org/record/14515672