Centranthus amazonum Fridlender & Raynal (1998: 328)

Bacchetta, Gianluigi, Cambria, Salvatore, Castro, Olga De, Fenu, Giuseppe & Brullo, Salvatore, 2024, Centranthus pontecorvi (Valerianaceae) a new species from Sardinia, Phytotaxa 661 (3), pp. 253-266 : 261

3. Centranthus amazonum Fridlender & Raynal (1998: 328) ( Fig. 5 )

(=) Centranthus nervosus Moris (1827: 4) , nom. illeg. (art. 52)

(=) Centranthus trinervis sensu Corrias (1978a: 253) non Béguinot in Fiori & Paoletti (1903: 135).

Type. ITALY. Sardinia: Sardaigne, dans les fissures calcaires d’un cañon du Monte di Oliena (Su Thuthurreli), 27 June 1994, A. Fridlender 443 (holotype P!, isotypes G, K!).

Iconography. Tav. LXXVIII-2, Moris (1837) under the name Centranthus nervosus ; Fig. 3282, Fiori (1933) under the name Centranthus trinervis ; Fig. 1 , Corrias (1978) under the name Centranthus trinervis ; Fig. 1 (A–D), Fridlender & Raynal-Roques (1998).

Description. Plant in tufts 45–80(–90) cm tall when flowering, very branched with axillary twigs usually very long, 3–21 cm long. Stems fistulous, robust. Leaves glaucescent-opaque, lanceolate to linear-lanceolate, (4–)4.5–9(– 10) × (0.6–)0.7–1.8(–2.2) cm. Inflorescence in thyrse lax, (3–)8.5–11(–13) cm long at flowering, (11–)14–18(–20) cm long when mature. Bracts ovate-lanceolate 1.3–2 mm long. Ovary ovate, 1.2–1.7 × 0.5–0.7 mm, dorsally with a central rib, ventrally with 3 ribs and folded at the edges. Calyx with coronula 0.7–1.2 mm long, provided with 15–20 teeth, hairs of pappus 4–4.7 mm long, plumose with lax feathers 0.8–1.2 mm long. Corolla pinkish, 1.7–3 mm long, with tube 1–1.7(2) mm long, provided with a small lateral hump, and 5 lobes 0.6–1.2 × 1.1–1.2 mm. Staminal filament 1.1–1.2 mm long, provided with one anther 1–1.2 mm long. Style 3.7–4.5 mm long. Cypsela oblong-ovate, 2.5–3.5 × 1–1.2 mm.

Phenology. Flowering and fruiting June to July.

Chromosome number. 2 n = 4 x = 32, investigated by Corrias (1978b).

Ecology and distribution. Centranthus amazonum was previously recorded only from two localities ( Corrias 1978 a, Fridlender & Raynal-Roques 1998, Bacchetta et al. 2008), the first is Su Thuthurreli (Oliena) at 1200–1300 m of altitude with a population of less than 40 individuals and the second is Codula di Luna (Urzulei) at 140 m of altitude with 14–15 individuals ( Fig. 3 ). Recently, Fenu et al. (2024) found two new localities near the previous ones, represented by Su Nercone at 1035 m with 24 individuals and Baccu su Rascu at 165 m with two individuals. Furthermore, they noted that some individuals were recently introduced from seeds to Baccu Elistru and Baccu Torelogu. This species shows ecological requirements very different from the two previous ones, since it is a chasmophyte linked to isolated carbonate places, sheltered from the winds, like internal walls of chasms, or shaded canyons, with a cooler and more humid microclimate than the surrounding macroclimate. In this rupestrian habitat, the species grows with other Sardinian endemic species, such as Cephalaria mediterranea ( Viviani 1824b: 1) Szabó (1940: 149) , Ptychotis sardoa Pignatti & Metlesics (1976: 55) , Campanula forsythii ( Arcangeli 1886: 138) Podlech (1965: 81) , Armeria morisii Boissier (1848: 687) , Cerastium supramontanum Arrigoni (1984: 213) , and Sesleria insularis Sommier (1905: 126) subsp. barbaricina Arrigoni (1983: 270) .

Conservation status. Being a chasmophyte that grows on inaccessible cliffs or areas difficult to reach even by livestock, this species is not currently subject to specific risks or threats. However, it is important to note that natural threats such as landslides and collapses of rock walls pose a risk, as has already observed at one location. The collection of material for scientific investigations could also potentially harm to the population’s stability. Based on monitoring conducted in recent decades by various authors ( Bacchetta et al. 2008, Rossi et al. 2013, Orsenigo et al. 2018), Centranthus amazonum was treated as Critically Endagered [CR = B1ab(i,ii,iii,IV,V) + 2ab(i,ii,iii,IV,V) + D]. More recently, Fenu et al. (2024) suggest that it should be categorized as Near Threatened, given the discovery of two new populations and translocations to two additional locations, also hypothesizing that this species may be more widespread than current knowledge.

Specimens examined. ITALY. Sardinia: Sardinia, 1828, G. Moris s.n. (BOLO!) ; In rupestribus calcareiis Montium Oliena , May, G. Moris? ( PO4350810 !) ; Sardinia, s.d., G. Moris s.n. (K000762913!, K000726912!, FI!) ; In rupestribus Montium Oliena , June 1852, Moris s.n. (SASSA) ; Sardinia, 1887, R.J. Shuttworth s.n. ( BM001134444 !) ; Urzulei, Codula di Luna, rupi e rocce calcaree sulla destra del rio, sotto Sa Pala Umbrosa , 30 May 1968, P.V. Arrigoni & C. Ricceri (FI!) ; Monte di Oliena, salendo dalla sella verso M. Corrasi, Su Thuthurreli forra, 1200 m, 18 June 1974, B. Corrias s.n. (SS!) ; Monti di Oliena, Su Thuthurreli , 26 June 1974, S. Diana & B. Corrias, s.n. (SS!) ; Monti di Oliena , forra di Su Thuthurreli, 27 September 1974, S. Diana & B. Corrias, s.n. (SS!) ; Pendici di M.te Corrasi, Oliena (NU), 2 June 1993, G. Marras, s.n. (CAG!) ; Oliena (NU), pendici di M.te Corrasi, 2 June 1993, G. Marras, s.n. (CAG!) ; Sardaigne dans les fissures calcaires d’un cañon du Monte di Oliena ( Su Thuthurreli ), 27 June 1994, Fridlender 443 (holotype P01818135!; isotypes K000762908) ; Su Thuthurreli, Oliena (NU), substr. calcari dolomitici, N 355°, 1220 m slm, supramedit. inf./ subumido sup., 6 June 2001, G. Bacchetta, S. Brullo, M. Casti, Català & G. Giusso del Galdo , s.n. (CAG!) ; Codula di Luna, Baunei (NU). Sul greto, lato sinistro della Codula, alla base delle pareti calcaree, prima delle Ghiroe S’Ambizos , 80 m s.l.m., 10 June 2002, Arduino & R. Guarino s.n. (CAG!) ; Tuones, supramonte d’Oliena (NU), sfatticcio a matrice calcarea, 830 m s.l.m., 20° ONO, 7 June 2002, R. Guarino & Arduino, s.n. (CAG!) ; Su Thuttureli, Oliena (NU), substr. calcari mesozoici, 1200 m s.l.m., NO 5°, supramedit. inf. umido inf., 28 August 2004, G. Bacchetta, G. Fenu, G. Mandis, F. Mascia & E. Mattana s.n. (CAG!) ; Monte Corrasi, Oliena , 20 June 2016, A. Congiu & G. Fenu, s.n. (CAG!) ; Sardaigne, s.d., s.l. ( MPU1136131 !) .

Figures

FIGURE 1. Diagnostic features of Centranthus pontecorvoi. A. Habit. B. Inflorescence. C. Flowers. D. Flower bud. E. Stamen. F. Cypsela dorsal view. G. Cypsela ventral view. H. Cypsela cross section. I. Cypsela with pappus. J. Pappus. K. Pappus feathers. L. Stigma. Illustration by S. Brullo based on living and herbarium material coming from the type locality (CAT).

FIGURE 3. General distribution of the species belonging to the Centranthus sect. Nervosae (A). C. trinervis yellow dot, C. amazonum blu dots, C. pontecorvoi red dot. Local distribution of C. pontecorvoi (B) red area.

FIGURE 5. Diagnostic features of Centranthus amazonum. A. Habit. B. Inflorescence. C. Flowers. D. Cypsela ventral view. E. Cypsela dorsal view. F. Cypsela with pappus above view. G. Cypsela with pappus lateral view. H. Pappus feathers. I. Anther. J. Stigma. Illustration by S. Brullo based on living and herbarium material coming from the type locality (CAT).