Alkanna semiromica Ranjbar & Khalvati, 2021

Khalvati, Sina & Ranjbar, Massoud, 2021, The comparative study of Alkanna and Huynhia (Boraginaceae, Lithospermeae), with description of a new species in Iran, Phytotaxa 524 (4), pp. 216-234 : 227-230

2. Alkanna semiromica Ranjbar & Khalvati , sp. nov. Fig. 10 .

Type: — IRAN. Isfahan: Semirom , 31°25’ 0.01”N, 51°34’0.01”E, 2950 m, 30 April 2012, Ranjbar 30880 (holotype BASU!). Fig. 11 .

Diagnosis: —The new species is similar to Huynhia pulchra , but differs by its smaller cauline leaves (1.2–2 cm versus 3–5 cm), pedicel in fruiting state (up to 8 mm versus up to 5 mm), blue to light violet corolla (versus sulphur yellow with purple spots), shorter corolla (12–14 mm versus 18–20 mm), calyx in flowering state (7–10 mm versus 8–14 mm), shorter style 5–7 mm (versus 9–10 mm) and stigma shallowly bilobed (versus deeply bilobed). The pollen grains are ovoid and 3-colporate, in contrast to prolate and stephanocolporate pollen in H. pulchra . Pollen characters fit Alkanna , in where the new species is similar to but differs from A. frigida . It differs by corolla dark blue (versus sulphur yellow), shorter basal leaves (8–15 × 0.5–1 mm versus 30–100 × 5–12 mm) and narrow corolla limbs (versus broad limbs).

Etymology: —The specific epithet refers to Semirom, a city in Isfahan province, where the new species was found.

Description: —Perennial green plant, with stout scaly stock. Stem multi-branched, branched from base, densely patent-pilose. Basal leaves, oblong to ovate, 8–15 × 0.5–1 cm, acute to subacute, tapering into the petiole, with entire, flat, or sometimes slightly undulate margins, white setose, sometimes with prominent base. Cauline leaves, oblong to lanceolate, 1.2–2 × 0.3–0.5 mm, acute or subacute, sessile, attenuate at base, with an evident midrib, veinless, densely white setose.

Inflorescence a compact terminal head; 2–3 × 1.5–3 cm, pedicels short, leafy, peduncle 1–2 cm long; bracts oblong to ovate, 12–15 × 3–5 mm. Calyx 7–10 mm long in flower, up to 15 mm long in the fruiting state, broad at nearly the base; lobes linear to lanceolate, acute, densely hispid-setose with yellowish, patent setae up to 2 mm long. Corolla blue to violet light, lobes 12–14 mm long, loosely pubescent outside, slightly pilose inside, slightly constricted below the anthers. Annulus absent. Stamens inserted irregularly at different levels; three higher at the throat and two lower down in the middle of the tube. Anthers 1.5–2 mm long. Style 5–7 mm long, reaching up to the middle of the corolla tube, shallowly bilobed; lobes 0.2 mm long. Nutlet not seen.

Palynology: —Pollen grains heteropolar, triangular concave, tricolporate, equatorial axis (E) 9.3 ± 1.9 μm, polar axis (P) 11.5 ± 3.85 μm, ornamentation psilate. Fig. 5 .

Distribution and ecology: — Alkanna semiromica was seen in the field by the first author and is known from a single specimen from the type locality that is deposited at the herbarium of Bu-Ali Sina University (BASU). The new species occurs in Isfahan province. It is endemic to southwestern Iran and known only from the type locality. It was collected from the rocky terrain along the roadside of the Black Mountains.

IUCN Red List category: —A low frequency of the new species in one field locality was observed and therefore decided to classify this species as VU (Vulnerable). This category includes taxa with small populations that could be at risk, according to IUCN criteria ( IUCN, 2001). We revisited the locality, where the new species was discovered and the neighboring areas in 2019. Our interpretation is based on a single known population.

Pollen morphology: —Members of the family Boraginaceae represent a great array of pollen types, and thus the family is interesting for investigating the evolution of pollen characters ( Noroozi et al 2021). Pollen characters can provide other elements with taxonomic significance can play important role in diversification of the group. According to previous studies, the pollen morphology of the Huynhia has been described as radial symmetric, isopolar with prolate shapes, polycolpate types, and with psilate ornamentations ( Tab. 1 ; Coppi et al. 2015, Khatamsaz 2001). The pollen grains of the new species were observed as triangular concave and 3-colporate, which fits the ancestral state of the Lithospermeae and is realized in the genus Alkanna ( Noroozi et al. 2021) . The average polar axis (P) was between 11.5–15.35 μm and the average equatorial axis (E) between 9.3–11.19 μm. From this palynological information we infer the taxonomic placement of the new species in the genus Alkanna .

Taxonomic discussion: —The specimens kept at BASU, M. Ranjbar 30880, were determined morphologically as H. pulchra (Willdenow ex Roemer & Schultes) Greuter & Burdet , which are confined to Isfahan province. Herbarium material of this species is very scarce. However, when the specimens were more thoroughly examined, several characters appeared to be dissimilar to that species and other closely related species. The new species is similar to H. pulchra , especially by its habit, indumentum, number of leaflets, and shape, size, and arrangement of pods, and also differs from H. pulchra , by pollen shape, stigma shallowly bilobed, shorter style, smaller corolla, and calyx in anthesis. General and detailed characters of the vegetative parts and flowers in Huynhia are already well known from various literature. Here, two characters are worthy of mention because of their taxonomic significance; one concerning the androecial arrangement and other the stigma structure. In Huynhia the epipetalous stamens are inserted through very short filaments at different heights within the corolla tube, e.g., three higher at the throat and two lower down in the tube, however, this character also occurs in Alkanna frigida ( Khatamsaz 2002) ( Fig. 12 ). Given the payonlogical evidence from above, the new Iranian blue to light violet-corolla species is fully described here as a new species and named as Alkanna semiromica .The differences in characters of the new species and its relatives are shown in Table 2 .

Figures

FIGURE 5. Pollen of Huynhia and Alkanna. A–B) H. pulchra (Ranjbar 22016); C–D) A. semiromica (Ranjbar 30880). Scale bars: A–B = 5 μm; C–D = 5 μm.

FIGURE 10. Alkanna semiromica (Ranjbar 30880). A) habit; B) stem & inflorescence; C) corolla; D) calyx; E) style. Drawn by: S. Khalvati.

FIGURE 11. Alkanna semiromica Ranjbar & Khalvati (Ranjbar 30880, BASU).

FIGURE 12. Open corolla, anther position, style and stigma in Alkanna, Huynhia and Arnebia. A) Alkanna semiromica (Ranjbar 30880); B) Alkanna frigida (Khatamsaz 2002); C) Huynhia pulchra (Ranjbar 22016) D) Arnebia linearifolia (Coppi et al. 2015). Scale bar: A–B, corollas = 5 mm, styles = 3 mm; C, corolla = 10 mm, style = 3 mm; D, corolla = 20 mm, style = 2 mm. Drawn by: S. Khalvati.