Strobilanthes brittoi B.Mani, Sinj.Thomas & A.K.Pradeep, 2023

Strobilanthes brittoi B.Mani, Sinj.Thomas & A.K.Pradeep View in CoL , sp. nov. FiGS. 1 View FiG , 2 View FiG & 3a–c View FiG

Strobilanthes brittoi shares morphological features with S. lupulina but distinguishes itself in several characteristics. Notably, it has an obtuse or rounded lamina base ( vs. attenuate-decurrent), pilose petioles ( vs. pubescent), elliptic bracts ( vs. obovate), unequal calyx lobes ( vs. equal), broadly elliptic corolla lobes ( vs. ovate), ellipsoid capsules ( vs. oblong-clavate), hairy seeds ( vs. glabrous), ellipsoid pollen grains ( vs. barrel shaped), and fusion of spiral and conical pollen ribs into two groups at the poles ( vs. fusion of straight rounded pollen ribs into one group at the poles). Simultaneously, this new species bears resemblance to S. heyneana . However, it can be easily differentiated by the obtuse or rounded lamina base ( vs. acute), pilose petioles ( vs. pubescent), unequal calyx lobes ( vs. equal), broadly elliptic corolla lobes ( vs. ovate), ellipsoid capsules and pollen grains ( vs. oblongoid and terete), as well as the fusion of spiral and conical pollen ribs into two groups at the poles ( vs. fusion of straight rounded pollen ribs into one group at the poles).

Type: INDIA, Kerala, Thiruvananthapuram district, Ponmudi , 950 m, 19.09.1968, K. M . Matthew 9162 (holo RHT [ RHT047864 About RHT !]) .

Plietesial shrubs, up to 1.5 m tall. Stems branched, rooting from lower nodes, quadrangular when young, then becoming terete when old, young stem channelled and pilose, old stem lenticellate. Leaves unequal; laminae elliptic-ovate, 6–20 × 4.2–9.5 cm, obtuse–rounded at base, crenate at margins, acuminate-caudate at apex, chartaceous, pilose on both surfaces; lateral nerves 5–11 pairs on each side of midrib, prominent on both surfaces; petioles 2.8–8.5 cm long, pilose. Inflorescences compound spikes, primary and secondary peduncles pubescent; bracts elliptic, 9.5–11.5 × 5.5–8 mm, obtuse at apex, longer than calyx, glabrous, green, veins prominent; bracteoles absent. Calyx tubular, 5–5.5 mm long, 5-lobed, creamy white; tube 1.5–2 mm long, glabrous; lobes unequal, narrowly linearlanceolate, 3–4 × 1–1.5 mm, apex acute, glabrous, purple. Corolla ventricose, 2–2.5 cm long, pale blue, 5-lobed; tube 4–5 mm long, glabrous out, hairy in; lobes equal, broadly elliptic, 4–4.5 × 4–5 mm, glabrous. Stamens 4, didynamous, included, staminal sheath hairy in throat region; filaments hairy, posterior filaments c. 5.5 mm long, straight, anterior c. 2 mm long, curved at apex; anthers oblong–elliptic, c. 2 × 1 mm, thecae two. Pollen grains prolate, ellipsoid, tricolporate, somewhat oblique at poles; exine divided into longitudinal ribs, slightly twisted, giving a spiral appearance; ribs coalesce into two groups at poles; tectum conical with microperforations at base. Pistils 1.8–2 cm long, attached to disc; ovary globose, c. 1 × 1 mm, glandular hairy at apex, 2-locular, ovules 2 per locule; style 15–17 mm long, slender, puberulent, included; stigma simple, straight, c. 2 mm long, glabrous. Capsules ellipsoid, c. 9 × 3–4 mm, glabrous, 4-seeded. Seeds ovate, c. 2.5 × c. 2 mm, hairy, areoles small.

Flowering & fruiting: The species is plietesial; flowers from September to November and fruits from January to March.

Habitat: The new species is found growing along the banks of small streams and on wet rocks along grassland margins at an elevation of 900–1000 m above sea level. The common associated species are Elaeocarpus weibelii (Zmarzty) Shareef, S.P.Mathew & Shaju ( Elaeocarpaceae ), Hedyotis ramarowii (Gamble) R.S.Rao & Hemadri ( Rubiaceae ), Jasminum cordifolium Wall. ex G.Don ( Oleaceae ), Osbeckia aspera (Meerb. ex Walp.) Blume ( Melastomataceae ), Syzygium gardneri Thwaites , S. myhendrae (Bedd. ex Brandis) Gamble (both Myrtaceae ), Tarenna alpestris (Wight) N.P.Balakr. ( Rubiaceae ), and others.

Distribution: Its habitat is localized to the Ponmudi hills, situated in the southernmost region of the Western Ghats in India. Currently, the new species is known only from its type locality.

Etymology: The specific epithet honours Late Rev.Dr. Susai John Britto SJ, whose significant contributions to the field of Indian plant systematics and other valuable services to society in general are notable.

Specimens examined: INDIA, Kerala, Thiruvanantha puram district, Ponmudi, 975 m, 16.11.1977, M . Mohanan 52517 ( MH); Ibid., 950 m, 12.10.2017, B . Mani 68826 ( RHT, MH); Ibid . , 12.12.2017, B . Mani 68827; Ibid., 1000 m, 26.01.2018, B . Mani & Pradeep 68828; Ibid., 975 m, 20.09.2018, B . Mani & Pradeep 68840 ( RHT) .

Notes: Strobilanthes brittoi is akin to S. lupulina and S. heyneana in the absence of bracteoles, as well as in having four didynamous stamens and fourseeded capsules.. However, it markedly differs in several morphological features ( Table 1; Figs. 4 View FiG & 5 View FiG ). Pollen morphology serves as a valuable tool for distinguishing species of Strobilanthes (Bremekamp, 1944; Terao, 1982; Carine & Scotland, 1998; Deng et al., 2006). The pollen grains of the new and the morphologically similar species studied here are ellipsoid, but in S. brittoi , they are oblique at the poles. A distinctive characteristic is the presence of conical ribs in S. brittoi , which are twisted and united into two groups at the poles, with none extending across the poles. In contrast, pollen of S. lupulina and S. heyneana exhibit straight ribs united in one group. This unique feature sets S. brittoi apart and is not observed in any known species of South Indian and Sri Lankan Strobilanthes ( Scotland, 1993; Wood, 1995; Carine & Scotland, 1998; Thomas et al., 2020). Consequently, pollen of S. brittoi represent an intermediate state between those of S. lupulina and S. heyneana (with straight ribs united in one group) and related Sri Lankan species, such as S. anceps Nees , S. punctata Nees , and S. zeylanica T.Anderson. In these the ribs are straight, with some encircling the poles while the rest join into two groups at the poles ( Scotland, 1993; Wood, 1995). Moreover, a recent study has shown that the pollen grains of S. lupulina from Sri Lanka are exactly the same as those in this study ( Nilanthi et al., 2022). A detailed comparison of pollen morphology between S. brittoi and its allied species is provided in Table 1.