Centaurea dezfulica Ranjbar & Mohamadi, 2021

Ranjbar, Massoud, Askari, Ali & Mohammadi, Somayeh, 2021, Two new species of Centaurea sect. Microlophus (Asteraceae, Cardueae) from Iran, Phytotaxa 480 (2), pp. 125-138 : 126

1. Centaurea dezfulica Ranjbar & Mohamadi , sp. nov. Figs. 1–5 .

Diagnosis:— Centaurea dezfulica is similar to C. pabotii but differs by its densely hispid indumentum (vs. sparsely hirsute-articulate or subglabrous), stems 45–50 cm high (vs. up to 60 cm), upper cauline leaves 3–7 × 0.3–0.7 cm (vs. 5–9 × 0.4–0.7 cm), upper cauline leaves decurrent for 2–3 mm (vs. sessile), median cauline leaves 14–16 × 2–4 cm (vs. 10–18 × 2–3 cm), lower cauline leaves lateral segment oblong-lanceolate (vs. lanceolate), incised (vs. dentate), 7–8 segments (vs. up to 10 segments), basal cauline leaves 23–26 × 6–10 cm (vs. 10–17 × 15–30 cm), 6–10 segments (vs. 10–12 segments), incised (vs. dentate or lobate), involucres 20–23 × 10–20 mm (vs. 12–18 × 17–22 mm), phyllaries obtuse (vs. acute), appendage 2–3 mm long (vs. 1–2 mm long), spinule 1–2 mm long (vs. 0.2–0.4 mm long), central florets up to 22 mm long (vs. up to 28 long), achene 2–3 mm long (vs. 5–6 mm long).

Typus:— IRAN. Khuzestan, Dezful, Dez Dam , 32° 38’ 27’’ N, 48° 27’ 13’’ E, 340 m, 29 July 2014, M . Ranjbar 36632 (holotype: BASU) .

Perennial plant, with thickened rootstock, up to 45–50 cm tall, green or pale green throughout. Stem upright, in lower part densely hispid. Stems many, erect to ascending, often branched in lower to upper parts striate striped, many branched, lateral branches 14–28 cm long bearing a few small leaves and ending in a capitulum, 1–2 mm in diam. at the base, cylindrical, sometimes ascending, often branched at the base, or branched in median part, thinly white striate, rigid, densely leafy throughout. Leaves and stem densely hispid-tomentose, venation actinodromous at basal and lower cauline leaves. Basal cauline leaves pinnatipartite-pinnatilobate or pinnatifid, 23–26 × 6–10 cm, terminal segments larger, lanceolate-linear, lateral segments 6–10 pairs, lanceolate-linear; segments sometimes lobed near the base, acute at apex, margin incised. Lower cauline leaves pinnatipartite-pinnatilobate or pinnatifid, 22–28 × 8–10 cm, terminal segments larger than lateral one, oblong-lanceolate, lateral segments 7–8 pairs, oblong-lanceolate; segments sometimes lobed near the base, acute at apex, margin incised. Median [lower] cauline leaves pinnatipartitepinnatilobate or pinnatifid, 14–16 × 2–4 cm, decurrent for 10–15 mm, margin incised, venation reticulate. Median [upper] cauline leaves sessile, simple oblong-lanceolate, 13–15 × 1–1.5 cm, acute to acuminate at apex, decurrent for 15–20 mm, perfoliate, margin dentate. Upper cauline leaves sessile, simple, oblong to oblong-lanceolate, 3–7 × 0.3–0.7 cm, shortly decurrent for 2–3 mm, acuminate at apex, venation parallel, margin entire. Capitula numerous, arranged in a corymb, usually somewhat removed from the base of capitula. Involucres subconical, contracted towards top, diamond, 20–23 × 10–20 mm. Phyllaries multiseriate, imbricate, coriaceous, yellowish or green, hairy. Outer phyllaries ovate, 4–10 mm long. Median phyllaries ovate to oblong 8–12 mm long. Inner phyllaries obtuse, 14–15 mm long. Appendages forming a minute deciduous tip, not decurrent, not concealing basal part of phyllaries, fringed in the upper part or with 1–2 pairs of cilia on each side, 1 mm long, spine triangular, 1–2 mm long, longer than the nearest cilia. Flowers yellowish pale green; central flowers hermaphrodite, up to 22 mm long; peripheral sterile, not radiant, limb lobes linear. Achene lanceolate-oblong, 2–3 mm long. Pappus multiseriate, scabrous, the outer 5–7 mm long, the inner much shorter.

Etymology: —The specific epithet refers to Dezful city, where the new taxon was found.

Phenology: —Flowering March to May.

IUCN Red List category:— Centaurea dezfulica is known from a few small populations, consisting of no more than five plants, observed in claystone and flat terrain around the Dez dam (M. Ranjbar, pers. obs.). According to the IUCN Red List criteria ( IUCN 2001), this species could be classified as Critically Endangered (CRD). This category includes taxa in which fewer than 50 mature individuals exist.

Distribution and habitat:—The new species is known only from the clay soils ( Fig. 6 ). It is distributed at lower altitudes (340 m) in Khuzestan province compared to the other related species ( Table 1). This taxon is restricted to south-western Iran and is endemic to the Irano Turanian floristic region. Centaurea dezfulica occurs with Anchusa strigosa , Convolvulus stachydifolius , Klasea khuzistanica , Onosma albo-roseum , Salvia syriaca , and Verbascum pseudodigitalis .

Figures

FIGURE 1. Centaurea dezfulica (M. Ranjbar 36632, BASU). A, habit. Scale = 5 cm.

FIGURE 2. Centaurea dezfulica (M. Ranjbar, 36632, BASU). A, taproot, B, and C, lower cauline leaves. Scale A–C= 5 cm.

FIGURE 3. Centaurea dezfulica (M. Ranjbar 36632, BASU). Scale = 5 cm.

FIGURE 4. Centaurea dezfulica (M. Ranjbar 36632, BASU). A1 and A2 close up of capitula, B1–B3, outer phyllaries, C1–C3, median phyllaries, D1–D3, inner phyllaries, E, leaf stomata, F, leaf indumentum. Scale A1 and A2 = 1 cm.

FIGURE 5. Measured morphological characters in Centaurea dezfulica (M. Ranjbar 36632, BASU). A, middle stem leaf, B, central floret, C, involucre, D, involucral bract. For character explanations see Table 1.

FIGURE 6. Distribution of Centaurea in Iran. A, C. dezfulica, B, C. pabotii, C, C. kuhdashtensis and D, C. koeieana.