Centaurea ambigua Guss.

Centaurea ambigua Guss., Pl. Rar.: 360 (– 362, pl. 61). 1826. [after 4 June 1826] subsp. ambigua ≡ Centaurea dissecta var. ambigua (Guss.) Fiori in Fiori & Bég., Fl. Italia 3 (2): 336. 1904. [April 1904] Protologue citation. “ In collibus aridis, et in cultis Aprutii; Caramanico, Roccamorice ”. Lectotype (designated here). [Italy, Abruzzo] tra Roccamorice e S. Spirito alla Majella nei siti calcarei, 20 August 1824, Gussone s. n. (NAP barcode NAP 0005395 [digital photo!], Suppl. material 1: fig. S 1). Nomenclatural note. Gussone (1826) described C. ambigua providing an extended diagnosis and a detailed description, both in Latin, and a precise locality. Furthermore, the author cited in the protologue the illustration “ Ic. nostra t. 61 ”. We performed a survey of the original material at NAP, where Gussone’s main collection is housed (Stafleu and Cowan 1976) and maintained as two separate collections, named “ Gussone Generale ” and “ Gussone Sicilia ” (La Valva 1993; Santangelo and Strumia 2014). We traced three specimens collected by Gussone before the description of the species in the collection “ Gussone Generale ”: 1) the herbarium specimen NAP 0005395 bears a label added by L. Grande “ Centaurea ambigua Guss! | tra Roccamorice e Santo Spirito | 20 agosto 1824 legit Gussone! ”; 2) the herbarium specimen NAP 0005395 bears two original labels manu Gussone not linked with the two individuals on the sheet (a whole individual on the left and a rosette of basal leaves on the right) “ Centaurea ambigua [Guss.! added by L. Grande] | 20 Agosto 1824 | tra Roccamorice e S. Spirito | alla Majella nei siti calcarei ” and “ (a) 20 Ago 1824 | tra Roccamorice e S. | Spirito nei luoghi | collinari ”; 3) the herbarium specimen NAP 0005396 bears a label manu Gussone “ (b) Centaurea | ambigua [Guss.! added by L. Grande] | 1824 Roccamorice | […] ”. The morphology of the three herbarium specimens is congruent with the protologue and with the current application of the name (Pignatti et al 2018; Bartolucci et al. 2024). Along with the illustration cited in the protologue, they can be safely considered as original material (Art. 9.4 of the ICN). We select here the herbarium specimen NAP 0005395 as the lectotype for the name C. ambigua. Taxonomic note. Based on a preliminary analysis of several herbarium specimens in APP collected within the putative native range (Apennines, from Emilia-Romagna to Campania), the typical C. ambigua (small capitula and pale involucral bracts), seems restricted to the low mountainous, calcareous sectors of the northern Maiella (Abruzzo, central Italy). Records from other areas in Abruzzo or other Italian administrative regions should be verified, and a more in-depth study is be needed to delineate the exact distribution range of C. ambigua subsp. ambigua.