Rhaponticoides nuriae Homrani-Bakali & Susanna

Bakali, A. Homrani & Susanna, A., 2024, Rhaponticoides nuriae (Asteraceae), a stunning new species from Morocco, Phytotaxa 659 (1), pp. 97-104 : 98-100

Rhaponticoides nuriae Homrani-Bakali & Susanna , sp. nov. ( Figs. 1–4 )

Diagnosis

Rhaponticoides nuriae is easily distinguished by its entire leaves, fully leafy glabrous stem, and distinct appendages with very wide scarious margins. It is quite different from the two species of the genus reported from Morocco ( Rhaponticoides africana (Lam.) M.V. Agab. & Greuter and Rhaponticoides eriosiphon (Emb. & Maire) M.V. Agab. & Greuter ) by its longer achenes and peculiar appendages that resemble Centaurea margaritacea aggr.

Description

Annual herbs with pivoting stump or narrowly napiform underground parts. Stems erect up to 30‒50 cm tall, wingless, simple or branched, section ± quadrangular, longitudinally striate, glabrous, very leafy especially at the base. Basal leave rosulate, the rest scattered and smaller towards the upper part with increasingly spaced internodes from the base to the top. Basal leaves oblanceolate to spathulate, limb (4‒) 6–20 (‒25) × 2–8 cm, cauline leaves elliptic to narrowly oblanceolate, distal leaves oblanceolate to linear oblanceolate. Leaves entire, narrowly serrate especially from the middle superior, green and glabrous on both faces, sometimes sparsely pubescent, ciliate in the margin, sessile, with conspicuous pinnate venation. Basal leaves wither earlier than cauline and distal leaves. Inflorescence branched or solitary. Capitula heterogamous, radiant, terminal on peduncles 3–8 cm long, subtended by the cauline leaves. Involucre globose to broadly ovoid, (2‒) 3–6 (‒7) × 2–5 (‒6) cm, slightly umbilicate at base, glabrous, clearly surpassed by the flowers of the periphery at anthesis. Involucral bracts adpressed, ± coriaceous, imbricated and apparently arranged in 7–8 rows, gradually increasing in length inwards, generally greenish and yellowish at the base, with (8‒) 9‒14 (‒16) marked nerves at maturity and scarious margin of 0.1–0.2 mm wide; distinct terminal appendages present, whitescarious, striate, concave, dentate, eroded in the inner bracts, not reflexed and never spinose, with a brown-black triangle in the middle part of the base of the appendage; outer bracts 1.5–2.5 cm with an appendage of 6–10 mm, generally larger than the bract, middle bracts 2.7–3.8 cm with an appendage of 7–11 mm, inner bracts 4.2–4.6 cm with an triangular or eroded appendage of 5–8 mm. Receptacle 1.5‒4 cm. Corolla 7–9 cm large, yellow with purple hermaphrodite florets, outer florets 3.6–4.5 cm, yellow funnel-shaped, ± actinomorphic, with 5 ± equal lobes, central florets 3.5–4.5 cm, tubular hermaphrodite, ± zygormorphic, with a clearly differentiated tube and blade, with five unequal lobes. Stamens with filaments free, papillose, inserted at the base of the corolla blade, with purple anthers. One style with two branches, with glabrous smooth receptive surface. Achenes homomorphic, 12–16 × 3–6 mm, prismatic, obovoid, with a ± quadrangular rhombic section, with four marked longitudinal ribs and a striate surface, glabrous, with a slightly concave apical plate and an entire edge, with a ± resalted cartilaginous ring 0.4–0.6 mm; nectary central; adaxial-basal carpic insertion areole 0.4–0.7 × 0.3‒0.5, pentagonal, with remarkable yellow elaiosome. Pappus double, persistent, with 3–7 linear or setaceous scales, uneven, larger inward, antrorse-scabride, erect-patent, white-brown, flattened at the apex, the inner one with a row of narrowly triangular and erect scales. Flowers from March to May.

Type:— MOROCCO. Rabat-Salé-Kénitra Region , Sidi Kacem Province , Zegota, Douar Lakerimate, elev. 370 m, coordinates (WGS84): 34.17558, –5.54481, April 2023, A. Homrani Bakali (holotype RAB-114357, Fig. 1 ; isotypes RAB-114358, RAB-114359) .

Eponymy: —The specific epithet honours Núria Garcia-Jacas (1961–2023), the wife of the second author (A.S.) and a monographer of tribe Cardueae who worked extensively on the Centaurea species in Morocco. She was the first botanist who demonstrated on molecular grounds that Rhaponticoides is a genus different from Centaurea .

Distribution and ecology:— Rhaponticoides nuriae has been found well-established around crops (especially cereals and fallow fields) in Sidi Kacem Province exclusively on clay soil, usually associated with Arisarum vulgare , Carduus tenuiflorus and many other species that grow on clay soils. This plant was found at very few points scattered around crop fields from Zegota to Jorf el Malha in Sidi Kacem Province. One GPS point was found on the borders of the province of Sidi Kacem next to the province of Taounate ( Fig. 3 ). This region is known for some endemic plants like Salvia mouretii Batt. & Pit. and Stachys durandiana Coss. We wonder how this plant, remarkable for its dazzling flowers, escaped the attention of botanists.

Conservation: —Populations of Rhaponticoides nuriae are strictly confined to the specific clay soil in Sidi Kacem province, which is a very much cultivated area with very little land that has been set aside. This population is very limited, the overall number of individuals counted at three points exceeds 200. The population is not protected; the parcel that housed the majority of individuals belonged to a farmer who did not practice breeding, the adjacent parcels were engaged in breeding and no individuals were found. The farmer said when we were collecting plants that “if I had cattle, you would not have found any individuals”. That is why conservation measures are necessary; around 800 seeds were collected and stored in the INRA gene bank in Settat, Morocco. Since populations are of very small sizes and occur scattered at small areas, we provisionally propose a conservation status of “critically endangered” until additional investigation efforts are completed to circumscribe the distribution of the species.

Figures

FIGURE 1. Holotype specimen of Rhaponticoides nuriae in RAB Herbarium.

FIGURE 2. Rhaponticoides nuriae: plants (A), root (B), stem (C), basal leaves (D), leaf margin (E), capitula (F), corolla (G), receptacle (H), involucral bracts (I), appendage of inner involucral bract (J), appendage of outer involucral bract (K), outer sterile flower (L), inner fertile flower (M), achenes (N), achene elaeosoma (O), achene cartilaginous ring (P).

FIGURE 3. Localities of Rhaponticoides nuriae (red rectangles) in Rabat-Salé-Kénitra Region, Morocco.

FIGURE 4. Phylogenetic position of the new species. Using Bayesian analysis of the pooled nuclear dataset, a 50% majority-rule consensus tree was produced, showing supported clades. Numbers occurring above branches are posterior probabilities (PP less than 0.6 are not shown). Likelihood bootstrap values figure below branches (BS lower than 60% are not shown). The countries of origin of species with multiple samples are indicated by capital letters after their names (see Table 1 in Bozkurt et al. 2022): AR Armenia, AZ Azerbaïdjan, BG Bulgaria, DZ Algeria, ES Spain, FR France, GR Greece, IN India, IR Iran, IT Italy, MA Morocco, PT Portugal, TJ Tajikistan, TR Turkey.