Linaria pseudamethystea Blanca, R. Carmona, Cueto & J. Fuentes, 2023

Blanca, Gabriel, Carmona, Rafael, Cueto, Miguel & Fuentes, Julián, 2023, Linaria pseudamethystea (Antirrhineae, Plantaginaceae), a new species mimetic of and apparently sympatric with L. amethystea, Phytotaxa 585 (1), pp. 1-18 : 3

Linaria pseudamethystea Blanca, R. Carmona, Cueto & J. Fuentes , sp. nov. ( Figs. 1–3 )

Type:— SPAIN. Sevilla province : Aznalcóllar , entre Aznalcóllar y contraembalse del Agrio, pastizales terofíticos en zonas abiertas sobre sustratos silíceos, UTM 20 S 740658 /4156765 (Datum ETRS89 ), 100 m elevation, 8 April 2022, G. Blanca, M. Cueto, J.A. Figueras, J. Fuentes & J.J. Ranchal (holo-: GDA-Fanero 69422!).

Diagnosis:—This species differs from L. amethystea Hoffmanns. & Link , L. semialata D. López et al. and L. diffusa Hoffmanns. & Link in being completely glabrous, having unequal and glabrous calyx-lobes, abaxial lip of the corolla with reticulate ornamentation often including two thick spots, and having a densely papillose but not tuberculate disc surface of the seed (vs. pilose-glandulose at least on the inflorescence, subequal and pilose-glandulose calyxlobes, spotted abaxial lip of the corolla, and tuberculate and papillose disc surface of the seed). It also differs from L. amethystea in having a glabrous inflorescence axis, curved spur, glabrous capsule, and a not-thickened seed wing (vs. pilose-glandulose inflorescence axis, straight or slightly curved spur, pilose-glandulose at apex capsule, and thickened seed wing). It also differs from L. semialata in having a blue-violet corolla, glabrous capsule, and seed wing 0.3–0.5 mm wide (vs. white, pale-yellow or violet-pinkish corolla, pilose-glandulose capsule, and seed wing 0.12–0.25 mm wide). Finally, the new species is distinct from L. diffusa in having the inflorescence in flower up to 10 cm long and glabrous, pedicel in flower 0.6–3.2 mm long, and corolla 13–19 mm long (vs. inflorescence in flower up to 26 cm long and pilose-glandulose, pedicel in flower 1.5–9 mm long, and corolla 9–16 mm long).

Description:—Herbaceous annual plant, glabrous, glaucous. Stems decumbent to erect, thin, often simple or forked, sometimes more branched; fertile stems 2-numerous, 7–26 cm long; 1–5 sterile stems shorter, 1–7 cm long. Leaves in whorls of 3(–4), the upper alternate, linear to linear-oblong; leaves of fertile stems 5–24 × 0.5–2.8 mm; leaves of sterile stems 5–15 × 0.5–1.2 mm. Inflorescence up to 10 cm long, simple, racemiform, with 2–10(–15) flowers, laxly arranged, glabrous. Bracts 1.3–2.5 × 0.1–0.2 mm, linear. Pedicels 0.6–3.2 mm long in flower, suberect, 1.3–7 mm long in fruit, ascending. Calyx lobes unequal, oblong to narrowly lanceolate, fused at the base, acute, glabrous; adaxial lobe 3.2–3.8 × 0.4–0.8 mm in flower, and 4–4.2 × 0.7–1 mm in fruit; abaxial lobes 2–2.7 × 0.6–0.8 mm in flower and 2.5–3.3 × 0.8–1.1 mm in fruit. Corolla personate, spurred, 13–19 mm long, blue-violet, with conspicuous dark veins and yellow to orangish palate; tube 1.4–2.5 mm broad in dorsiventral section, erect; adaxial lip up to 8.5 mm long, bilobate, with a sinus of 2.5–4 mm; abaxial lip 3-lobate, with two prominent humps and ornamentation reticulate and often with two thick spots; spur (7–)8–9.5 × 1–1.6 mm (the width measured at the base), equalling the length of the rest of the corolla, curved, usually dark blue-violet. Capsule 3–4.2 × 3–4.2 mm, globose, apex bilobate, glabrous; style 2.7–3.5 mm, weakly bilobed at apex. Seeds 1–1.4 × 1.2–1.7 mm, suborbicular-reniform, discoid, slightly concaveconvex to flat ( Fig. 3 , D); disk reniform, black, densely papillose, not tuberculate ( Fig. 3 , E); wing 0.3–0.5 mm wide, subentire, not thickened, black or dark grey, with papillose inner margin ( Figure 3 , F).

Etymology:—The specific epithet refers to the surprising mimicry with Linaria amethystea , which has caused misidentification of its populations.

Distribution and ecology:— Linaria pseudamethystea should be considered an endemic species from the southwestern Iberian Peninsula ( Figure 4 ), from the east of the province of Seville ( Spain) to the Algarve and Alentejo ( Portugal), growing in ephemeral therophyte pastures of siliceous mountains. Here it grows on poorly developed and stony or sandy soils, in schists, slates and granites, between 50–300 m elevation, under a Mediterranean pluviseasonal oceanic bioclimate with a thermomediterranean to mesomediterranean thermotypes and dry ombrotype (Rivas Martínez et al. 2002).

Phenology:—The flowering period spans March to May, although depending on the annual climatic conditions it can start in mid-February or extend until the beginning of June. The fruiting time spans April to June.

Conservation status:—The distribution area of Linaria pseudamethystea extends over a relatively large area of the SW Iberian Peninsula. Its populations include many individuals, although, as an annual plant, its numbers may significantly fluctuate over the years, depending on weather conditions. There are also no significant threats to the populations, since sometimes they are part of grasslands typical of extensive areas of natural vegetation that are even part of protected areas. According to the IUCN categories (2012) and recommendations provided by IUCN (2017), we suggest labelling L. pseudamethystea as Least Concern (LC).

Figures

FIGURE 1. Linaria pseudamethystea (from holotype). A, Habit; B, leaves detail (fertile stems); C, inflorescence detail; D, flower front view; E, flower lateral view; F, capsule; G, seed front view.

FIGURE 2. A–F, Linaria pseudamethystea (A, Habit; B, inflorescence detail; C, flower detail; D, capsule; E, dehiscing capsule; F, seed). G, Linaria amethystea subsp. amethystea. H, Linaria amethystea subsp. albiflora. I, Linaria amethystea subsp. ignescens. J, Linaria semialata. [A–F, GDA-Fanero 69424!; G, GDA-Fanero 68074!; H, Alcaudete, Jaén, G. Blanca; I, GDA-Fanero 65958!; J, GDA-Fanero 69421!].

FIGURE 3. Scanning-electron micrographs of seeds of: A–C, Linaria amethystea subsp. amethystea (SEV 146590!); D–F, Linaria pseudamethystea (sub L. amethystea subsp. amethystea, SEV 146569!); G–I, Linaria semialata (GDA-Fanero 69080!); J–L, Linaria diffusa (sub L. amethystea, MA 550605!). [Scale bars:A, D, G, J, overview of the seeds 200 µm; B, E, H, K, disc detail 30 µm; C, F, I, L, wing detail 100 µm].

FIGURE 4. Distribution map of the studied localities of Iberian Linaria.