Lepidagathis dayanandanii A.F.J.King, Gnanasek. & Arisdason, 2023

A. F. J., King, R. R., Kolte, S. P., Nithya, W., Arisdason, Gnanasekaran, G. & Willd., Lepidagathis, 2023, Two new species of Lepidagathis (Acanthaceae: Barlerieae) from the low-elevation lateritic plateaus of Karnataka and Kerala, India, Rheedea 33 (4), pp. 332-344 : 333-337

Lepidagathis dayanandanii A.F.J.King, Gnanasek. & Arisdason , sp. nov. FiGS. 1–3 and 7a & e

Lepidagathis dayanandanii is morphologically similar to L. ushae but differs in having the following characters: (i) Vegetative leaves sub-sessile with petioles c. 1 mm long, elliptic, chartaceous, apex acute, purplish-green (vs. sessile, lance-ovate to oblong, rigid, apex acute with spinose process, green); (ii) Leaves of inflorescence bearing twig elliptic, thick and succulent (vs. lance-ovate to oblong, thin and rigid); (iii) Spikes both axillary and terminal, up to 3 cm long with maximum of 10 flowers (vs. only terminal, up to 7 cm long with maximum of 15 flowers); (iv) Flowers one or two per node (vs. always one flower per node); (v) Sterile bracts oblong (vs. lance-ovate to narrowly elliptic); (vi) Apex of leaves (inflorescence bearing twig), bracts, bracteoles and calyx lobes with a minute spinose process, less than 0.5 mm long (vs. with a long spinose process up to 1 mm long); (vii) Calyx posticous lobe lance-ovate to elliptic, length: width ratio is 2.7:1 (vs. lanceolate, length: width ratio is 3.4:1); and (viii) Corolla white, yellow at anthesis, 14.5– 16.5 mm long, middle lobe of lower lip prominently broader than the lateral lobes (vs. always pale pink, 10–13 mm long, middle lobe of lower lip slightly broader than the lateral lobes).

Type: INDIA, Karnataka, Udupi district, Byndoor taluk, Areshiroor , N 13°49’41.76”, E 74°44’53.29”, 87 m, 23.04.2023, A. F. J. King 13009 (holo CAL; iso MH, Madras Christian College Herbarium, Chennai) .

Prostrate perennial herb with woody rootstock; stems up to 1 m in diam., rooting at nodes, purplish-green when young, ash-coloured when old, well-branched, 4-angled, glabrous throughout, hirsute at nodes; internodal distance 3–20 mm. Leaves sub-sessile (petioles c. 1 mm long) opposite-decussate; vegetative leaves elliptic, 4–12 × 2–4 mm, base cuneate, margins entire, apex acute, purplish-green, glabrous, with 2–4 pairs of lateral veins; leaves of inflorescence bearing twig same as vegetative leaves except the apex acute with a minute (less than 0.5 mm long) spinose process, densely tomentose intermixed with glandular hairs throughout. Inflorescence a spike, axillary as well as terminal, 1–3 × 0.5–1 cm, green to purplish (bracts, bracteoles and calyx lobes). Flowers up to 10, arranged in 4 ranks as well as in 2 ranks, 1 or 2 flowers per node (half of the nodes bear 2 flowers). Bracts: sterile bract 1, (absent in half of the nodes), oblong, 8.2–10 × 2.3–2.5 mm, apex acute with a minute spinose process, tomentose intermixed with glandular hairs throughout, with 2 or 3 pairs of lateral veins; fertile bract 1, oblong to narrowly elliptic, 7.6–10.7 × 2–3.3 mm, otherwise as sterile bracts. Bracteoles 2, narrowly elliptic, 5–7 × 0.8–1.8 mm, apex acute with a minute spinose process, tomentose intermixed with glandular hairs throughout, 3-veined. Calyx 5-lobed; lobes heteromorphic, apices acute with a minute spinose process, tomentose intermixed with glandular hairs throughout; anticous lobes 2, equal, oblong to elliptic, 8–11 × 3.5–4.5 mm, 3–5-veined, connate at base (more than a quarter of its total length, i.e., 2.2–3.6 mm long), overlapping; posticous lobe lance-ovate to elliptic, 8.2–11 × 3–4 mm, 5–7-veined; lateral lobes 2, lanceolate to linear, 8–10.3 × 1–2 mm. Corolla 14.5–16.5 mm long, white (yellow at anthesis) with purplish-brown markings throughout the upper lip inside and orange patches on palate and purplish-brown horizontal striations only at membranous portion on either side of palate; tube 8–9.5 mm long, cylindrical below for 4–5 mm long, abruptly expanded above for 4–4.7 mm long, glabrous inside, retrorsely hirsute outside; upper lip arcuate, 3.2–3.7 × 5–6.5 mm, margins entire, apex minutely 2-lobed (0.4–0.8 mm long), each lobe 3-veined; lower lip 3-lobed, glabrous, 5–7 mm long including lobes; middle lobe prominently broader than lateral lobes, suborbicular, 2.7–4 × 3–4 mm, apex entire, 3-veined; lateral lobes oblong, 2.7–4 × 2.6–3 mm, 3-veined. Stamens 4, didynamous, filaments white with purple dots, adnate at base of expanded corolla tube, glabrous; anticous filaments 3.5–4.7 mm long; posticous filaments 2–2.7 mm long; anthers bithecous, thecae oblong-elliptic, divergent, 1.4–2 mm long, sparsely hairy at base of suture and at connectives, longitudinally dehiscing. Pollen grains prolate, 31.8–36.4 × 20.2–23.6 µm, tri-colporate; tectum reticulate, more open in area adjacent to apertures. Ovary sub-globose, 1.2–1.8 × 1.2–1.4 mm, glabrous, 2-loculed; ovules 2 in each locule; nectary disk cupulate; style 6.5–7.5 mm long, bristled-glandular-hairy up to half of its total length; stigma bi-lobed. Capsules ovoid in face view, 5.5– 6.6 × 3–3.7 mm, glabrous; seeds 2 (one fertile, one abortive), ovoid in face view, 3.4–4.2 × 2–2.6 mm, covered with short hygroscopic hairs.

Flowering & fruiting: Flowering from February to April; fruiting from April to May.

Habitat: Open low-elevation lateritic plateaus with sandy soils, at elevations ranging from 80 to 100 m.

Distribution: India, endemic to Karnataka.

Etymology: This species is named in honour of Dr. P. Dayanandan, former Head of the Department of Botany, Madras Christian College (Autonomous), Chennai, for his significant contributions in the field of Botany.

Specimens examined: INDIA, Karnataka, Udupi district, Byndoor taluk, Areshiroor , N 13°49’41.76”, E 74°44’53.29”, 87 m, 23.04.2023, A. F. J. King & R. R. Kolte 13010; Ibid., 29.07.2023, Abhishek Pujari 13022; Ibid., 11.12.2023, A. F. J. King 13031 (Madras Christian College Herbarium, Chennai) .

Conservation status: This species is known only from a single low-elevation lateritic plateau of 1 km 2 radius, i. e., Areshiroor in Udupi district of Karnataka, where it is commonly found. The quality of habitat is under threat owing to the developmental activities such as construction of buildings and roads. Although , this species would qualify as ‘ Critically Endangered’ [ CR B2 ab(iii)], it is required to carry out intensive field surveys around the type locality to determine the exact AOO and EOO. Therefore, it is provisionally assessed here as ‘Data Deficient’ [ DD] .

Notes: Lepidagathis dayanandanii can also be differentiated from L. keralensis by the following significant characters: (i) spikes 1–3 cm long and with up to 10 flowers (vs. up to 10 cm long and with up to 30 flowers), and (ii) corolla white, yellow at anthesis, 14.5–16.5 mm long (vs. pink, purplish at anthesis, 11.8–13.8 mm long).

Brahmadande and Nandikar (2023) synonymised L. ushae under L.prostrata Dalzell in a recently published synopsis of Indian Lepidagathis . However, we treat it as a distinct species here based on a thorough morphological studies of fresh and herbarium specimens. Lepidagathis ushae can be distinguished from the latter by the following characters: (i) Bracteoles lanceolate to narrowly elliptic, up to 8.5 mm long (vs. linear to oblong, up to 12 mm); (ii) Calyx anticous lobes oblong to narrowly elliptic, 8.5–9.5 × 1.5–2, connate for more than one-third of their total length i.e., 2.8–3.6 mm (vs. lanceolate, 9.8–13.7 × 4–4.8, connate for less than a quarter of their total lengths, i.e., 1.8–2.5 mm long); (iii) Corolla small, 10–13 mm long (vs. large, 17–20 mm long); (iv) Seeds 3–3.7 × 2–2.4 mm (vs. 4.2–5 × 2.7–3.2 mm).

Figures

FiG. 1. Lepidagathis dayanandanii A.F.J.King, Gnanasek.& Arisdason;a. Habit;b. Portion of stem;c. Leaf – upper surface;d. Leaf – lower surface;e. Inflorescence close-up;f. Dissected corolla with androecium (fromA.F.J.King 13009,Madras Christian College,Chennai;drawn by S. Madhura).

FiG. 2. Lepidagathis dayanandanii A.F.J.King, Gnanasek. & Arisdason: a. Habitat; b. Habit; c. Vegetative twig; d. Flowering twig; e. Reproductive leaves;f. Flower at anthesis;G. Outer (left) inner (right) surfaces of fertile bract;h. Outer (left) and inner (right) surface of bracteole;i. Capsule;j. Capsule split open;k, l. Seed with hygroscopic hairs (from A.F.J. King 13009 and Abhishek Pujari 13022, Madras Christian College Herbarium, Chennai; photos by A.F.J.King).

FiG. 3. Diagnostic characters of the new and allied species: a, b, f, h–j: Lepidagathis dayanandanii A.F.J.King, Gnanasek. & Arisdason; c,e,G,k–m:LepidagathisushaeBorude,Gosavi&Chandore:a, c.Inflorescenceclose-up;b,e.Outer (left)inner(right)surfacesof sterilebract; f, G. Outer surface of calyx lobes;h, k. Dissected corolla with androecium;i, l. Ovary;j, m. Pistil (fromA.F.J.King 13009 [L. dayanandanii] and A.F.J.King 12910 [L. ushae]; photos by A.F.J.King).

FiG. 7. Scanning electron micrographs of pollen grains (mesocolpial view) and seeds: a, e. Lepidagathis dayanandanii A.F.J.King, Gnanasek. & Arisdason; b, f. Lepidagathis keralensis Madhus. & N.P. Singh; c, G. Lepidagathis narasimhanii Gnanasek., A.F.J.King & Arisdason;d, h. Lepidagathis ushae Borude,Gosavi & Chandore (photos a–d by M. Boopathiayyanar; e–h by G. Gnanasekaran).