Swertia drassensis S. Banoo, A. A. Khuroo & A. H. Ganie, 2022

Banoo, Sakina, Khuroo, Anzar Ahmad & Ganie, Aijaz Hassan, 2022, Swertia drassensis, a new species from Drass, Ladakh Himalaya, Phytotaxa 571 (2), pp. 219-226 : 220-223

Swertia drassensis S. Banoo, A. A. Khuroo & A. H. Ganie , sp. nov. ( Figs. 1–3 )

Diagnosis

The new species differs from S. petiolata in several characters which include: basal leaves elliptic-spathulate, apices acute-acuminate in S. drassensis (vs. ovate-spathulate, apices sub-obtuse in S. petiolata ), sepal margins slightly membranous, apex acute-acuminate (vs. sepal margins markedly membranous, apex acuminate), petals greenishyellow, apices obtuse–retuse (vs. petals white or lurid grey, apices obtuse), shape of nectaries oval-oblong, 2, fused (vs. round, 2, distinctly separated), fimbriae absent (vs. fimbriae present), anthers ovate-obovate (vs. anthers ovateoblong), ovary smooth (vs. ovary grooved), capsule ovoid-ellipsoid (vs. narrowly ellipsoid), seeds sub-globose to ovoid or triangular, winged (vs. semi-spheroid to oblong, wingless).

Type:— INDIA, Ladakh , District Kargil, Tesboo Drass, 34°26ʹ16.90ʹʹ N, 75°45ʹ48.91ʹʹE, elev. 3178 m, 16 August 2021, Sakina Banoo, Anzar A. Khuroo & Aijaz H. Ganie, 4000A (holotype: KASHǃ, isotype 4000BCD; KASHǃ) .

Additional specimen examined (paratype):— INDIA, Ladakh , District Kargil, Tesboo Drass, 34°26ʹ16.90ʹʹ N, 75°45ʹ48.91ʹʹE, elev. 3178 m, 19 August 2021, Sakina Banoo, Anzar A. Khuroo & Aijaz H. Ganie 4001( KASH) .

Description

Perennial herbs, 15–100 cm tall. Root rhizomatous with secondary fibrous roots, 4.5–8 × 1.5–3 cm. Stem erect, simple, unbranched, hollow, glabrous. Basal leaves 4–6, petiolated, petiole at lower side purplish, 7–25 cm long, leaf lamina 7–20 × 2–6 cm, elliptic-spathulate, base cuneate, margin entire, apex acute-acuminate. Cauline leaves opposite, base usually free, rarely connate up to 2–4 mm, leaves gradually reduce in size upwards, lower ones 2–5 pairs petiolated, petiole 4–9 cm long, elliptic-spathulate, 7–15 × 2–5 cm, upper cauline leaves sessile, 5–8 pairs, base free, rarely connate, upto 2–4 mm, 0.5–8 × 0.2–3 cm, oblong-lanceolate, margin entire, apex acute-acuminate. Inflorescence paniculate cyme, 10–40 cm long. Flowers hermaphrodite, actinomorphic, pentamerous, rarely tetramerous,15–60 per individual, pedicellate, pedicel 0.9–7 cm. Sepals 5, rarely 4, polysepalous, basally fused, narrowly ovate-lanceolate, margin entire and slightly membranous, apex acute-acuminate, 3–4 × 1–2 mm. Petals 5, polypetalous, basally fused, up to 0.5 mm, rotate, greenish-yellow adaxially, creamish-blue abaxially, elliptic–oblong, margin entire, apex obtuse– retuse, 8–10 × 3–4 mm, venation divergent parallel; pair of fused nectaries adnate just 2 mm above the base of petal, smooth, oval–oblong, 1–1.5 mm, greenish-yellow, fimbriae characteristically absent. Stamens 5, filaments white to light greenish, 3–5 mm long, anti-sepalous, uniseriate, anthers yellowish-blue, obovate-ovate, 1.5–3.5 × 1.5–2.5 mm, dorsifixed to sub-basifixed, dithecal, dehiscence longitudinal, pollens yellow in colour. Carpels 2, syncarpous, ovary hypogynous, 3–5 × 2–3.5 mm, smooth, ellipsoid, style short, stigma bilobed, 1–1.5 mm. Fruit capsule, ovoid-ellipsoid, 8–12 × 3–6 mm. Seeds 35–55 per capsule, sub-globose to ovoid or triangular, dark brown, 3–3.2 × 2– 3.2 mm, winged, wings 0.2–2 mm wide, golden brown in colour.

Phenology:— Flowering and fruiting occurs from July to September.

Habit:— Mostly found in open fields along water channels and sloppy moist meadows. In its collected site, this species currently occurs in the form of abundant populations.

Etymology:— The specific epithet drassensis is after its collection area, i.e. Drass, Ladakh

Discussion

In genus Swertia , morphology and position of nectaries present on the corolla lobes are considered as important taxonomic character. The nectaries in the genus vary in terms of position, shape, number per corolla lobe, presence or absence of fimbriae ( Wang & Lu 1998). The newly described species, S. drassensis is unique in possessing a pair of fused nectaries lacking fimbriae. The species can be distinguished from commonly growing S. petiolata by having sepal margins slightly membranous, apex acute-acuminate, petals greenish-yellow, apices obtuse to retuse, nectaries oval-oblong, 2, fused, fimbriae absent, capsule ovoid-ellipsoid and winged seeds ( Table 1 ). In the study area, the former species occurs mostly in relatively lower elevations (3150–3400 m) as compared to the latter which grows at higher elevations (3700 –4100 m). Likewise, S. drassensis is morphologically similar to recently described species S. kashmirensis from neighbouring Kashmir Himalaya ( Wani et al. 2022) in leaf base, stem, inflorescence, nectaries fused together and winged seeds, but it differs by having oblong-lanceolate upper cauline leaves, absence of fimbriae, ellipsoid-ovoid capsules and sub-globose to ovoid or triangular seeds ( Table 1 ). The new species also shares the characteristic feature of absence of fimbriae on nectaries with S. cordata , but the latter possesses only a single nectary per corolla lobe and a cordate-ovate leaf. In addition, S. drassensis shares some features with S. thomsonii , such as fused nectaries and winged seeds, but it differs from the latter in having fimbriae on its nectaries ( Table 1 ).

In recent times of rapid climate warming and land-use changes experienced in the Himalaya ( Hamid et al. 2019; 2020), documentation of biodiversity assumes urgent priority to guide conservation and sustainable utilisation of biological resources ( Ganie et al. 2022). The scientific discovery of new taxa is the first and foremost step in achieving progress towards conservation and sustainable use of biodiversity ( Cheek et al. 2020; Rather et al. 2022). Therefore, the present study makes a contribution towards filling the Linnean shortfall in global biodiversity ( Hortal et al. 2015), by describing a new species from high-altitude Ladakh Himalaya—a remote region of the world.

Figures

FIGURE 1. A–—Map showing distribution of Swertia drassensis in Ladakh Himalaya.

FIGURE 2. A—Habitat of Swertia drassensis; B—Rhizome; C—Habit; D—Series of cauline leaves; E—Inflorescence; F—Flower (ventral side); G—Flower (dorsal side); H—Sepal (dorsal side); I—Petal with pair of nectary (ventral side); J—Petal (dorsal side); K— Pair of fused fimbriae-less nectary; L,M—Stamens with obovate-ovate and dorsifixed to sub-basifixed anthers; N—Carpel with bifid stigma; O—Unripe capsule; P—Ripened capsule; Q—Winged seeds.

FIGURE 3. Comparison of distinguishing characters between Swertia drassensis (A–G) and S. petiolata (H–N): A & H—Flower; B & I—Calyx; C & J—Pair of nectary on corolla lobe; D & K—Stamens; E & L—Carpel; F & M—Capsule; G & N—Seeds.