[2.9.5] Viola sect. Melanium subsect. Pseudorupestres 

Viola subsect. Pseudorupestres (W. Becker) Marcussen & Danihelka, comb. et stat. nov.

—Basionym: Viola [sect. Melanium; unranked] “γ” Pseudorupestres W. Becker in Nat. Pflanzenfam., ed. 2 [Engler & Prantl], 21: 372. 1925 (“Pseudo-rupestres”).

Type: Viola nummulariifolia Vill.

Description.—Dwarf perennial. Stipules dentate, not foliaceous. Lamina of basal leaves entire. Calycine appendages 1.2–1.5 mm. Corolla violet with cream throat. Bottom petal (spur included) 9.5–11.5 mm. Spur 2.3–2.5 mm. Cleistogamous flowers not produced. Pollen apertures 3. Ploidy probably 4x. Chromosome number n = 7.

Diagnostic characters.—Dwarf perennial AND stipules dentate, not foliaceous AND corolla violet with cream throat.

Ploidy and accepted chromosome counts.—Probably 4x; 2n = 14.

Age.—Crown node age not applicable (monotypic subsection), stem node age c. 7.2 Ma (Figure 6).

Included species.—1. Viola nummulariifolia Vill.

Distribution.—Southern Europe: Maritime Alps and Corsica.

Discussion.—Section Melanium subsect. Pseudorupestres comprises a single species, Viola nummulariifolia Vill. (=V. argenteria Moraldo & Forneris). Chloroplast and ITS data place it in (or as sister to) the basal polytomy within sect. Melanium [94] (Figure 2), and in a PCO of genomic ISSR data the species ends up ‘close’ to the outgroup [217]. Furthermore, other attributes seem to suggest an isolated phylogenetic position. The low chromosome number of 2n = 14 and the 3-colporate pollen [157] indicate low ploidy level, presumably 4x, the ancestral condition in sect. Melanium [28]. Morphologically, V. nummulariifolia has a suite of character states that might be interpreted as plesiomorphic, e.g., perenniality, the flower having a cream throat (not bright yellow as in most other pansies) and simple, entire to dentate stipules, reminiscent of V. rupestris (sect. Viola), and not large and foliaceous as in many other pansies. Viola nummulariifolia has a relictual distribution at high elevations (1800–2900 m) on crystalline rocks in the Maritime Alps and in Corsica