Phyllanthus balakrishnanii Sunil, K.M.P. Kumar & Naveen Kum, 2016

Sunil, Chandrasseril Narayanan, Prabhukumar, Konickal Mambetta, Kumar, Vannaratta Veettil Naveen, Thomas, Valukattil Ponnachan, Bhavadas, Narayanan & Balachandran, Indira, 2016, Phyllanthus balakrishnanii sp. nov. (Phyllanthaceae), an interesting discovery from the southern Western Ghats, India, Phytotaxa 273 (1), pp. 65-71 : 65-68

Phyllanthus balakrishnanii Sunil, K.M.P. Kumar & Naveen Kum , sp. nov. ( Figs. 1 & 2 )

This new species is similar to P. chandrabosei Govaerts & Radcliffe-Smith (1995: 176) but differs in growing as shrubs and having densely verrucose branchlets, large, glabrous, glaucous, thickly-chartaceous leaves, shorter pedicelled male flowers, epunctate sepals with wavy margins, obovate and smooth disc, 4 stamens, shorter pedicelled female flowers and glabrous fruits prominently covered with six bands of reddish purple tubercels.

Type: — INDIA. Kerala: Ernakulam district, Shoolamudi , 10°13.316 ′ N, 76°56.512 ′ E, 1216 m, 26 September 2015, C. N. Sunil, K. M. Prabhukumar & V. V. Naveen Kumar 6899 (holotype CMPR!; isotypes CATH!, MH!, SNMH!) .

Erect branched shrub up to 2 m tall; branchlets resembling pinnate leaves, 4–15 cm long, green, glabrous, terete, densely verrucose. Leaves bifarious on branchlets, 1–5.5 × 0.8–2.4 cm, ovate to ovate-lanceolate, rounded to slightly cordate at base, margins entire, thick (cartilaginous) and recurved, acute to apiculate at apex, thickly chartaceous, glaucous beneath, dark green above; midvein verrucose on upper side towards base, lateral nerves 5–9 pairs, brochidodromous; petiole ca. 1 mm long; stipules 2–3.4 × 1–1.5 mm, subulate-lanceolate, subsagittate at base, long-acuminate at apex, deep-brown, persistent. Flowers unisexual, monoecious, male ones in axillary short, 1–5 mm long, bracteate racemes closely overlapping, female ones solitary, axillary; bracts 1.5–2 × 0.5–0.8 mm, lanceolate, acuminate at apex, deep brown, glabrous. Male flowers greenish-yellow, 5–6.3 mm across; pedicel 1.8–3 mm long, glabrous; sepals 4 (2 + 2), imbricate, 2–3 × 1.8–2.4 mm, subcoriaceous, obovate to orbicular-ovate, margins wavy, apex rounded, 1-nerved, glabrous, greenish-yellow, scarious at margins; disc glands 4, alternating with sepals, ca. 1 × 1.2 mm, obovate, retuse at apex, coriaceous, cream-coloured, smooth; stamens 4, filaments united in a column, column ca. 1 mm long, ca. 0.5 mm across, conical, anthers sessile, ca. 0.5 mm long, placed at the top of the column, horizontally dehiscent; pistillode absent. Female flowers greenish, 7–7.8 mm across, glabrous; pedicel 1–2.2 mm long, thickened towards apex; sepals 6 (3 + 3), imbricate, subequal, pale green, glabrous, broadly ovate, 3.2–3.8 × 2–2.2 mm, cordate at base, obtuse at apex, wavy along margins; disc 1.2–1.5 mm across, saucer-shaped, 6-lobed or undulate, verrucose towards outer half and smooth towards inner half; ovary on a ca. 1 mm long stalk, 1.3–1.5 × 1.4–1.6 mm, prominently covered with 6 bands of pinkish red tubercels, glabrous, 3-loculed; styles 3, 1.2–1.6 mm long, linear, divided up to 2/3 of their length; stigmas 6, punctiform. Capsules 4–5 × 6–7 mm, depressed globose, slightly trigonous, 3-valved, 6-seeded, prominently covered with 6 bands of purplish red tubercels, glabrous; fruiting sepals 3–4 × 2–3 mm, thick, coriaceous. Seeds 6, 3–3.5 × 2–2.5 mm, trigonous, reniform, rounded on back, brown, smooth when young and lineolate when mature.

Phenology:— Flowering and fruiting August–January.

Etymology:— The new species is named after Dr. N.P. Balakrishnan, formerly Joint Director, Botanical Survey of India, Southern Circle, Coimbatore for his excellent revision of the family Euphorbiaceae (including Phyllanthaceae ) in India and his contributions to the field of angiosperm taxonomy.

Distribution:— The new species was collected only in the open rocky mountains of Shoolamudi hills, Ernakulam district of Kerala at an elevation of about 1216 m, growing in association with Mussaenda tomentosa Wall. ex Don (1834: 491) , Strobilanthes dupenii Bedd. ex Clarke (1884: 453) , Strobilanthes lanatus Nees von Esenbeck (1847: 191) , etc.

Conservation status:— This species has so far only been collected from the type locality. The Shoolamudi hills are comparatively a undisturbed region in Ernamkulam district of Kerala. The type locality contains only few plants, 3–5 from a single population. Therefore , based on the present knowledge and available data, a provisional threat status of ‘ Critically Endangered’ ( CR B1 ab(i,ii,iv); 2ab(i,ii,iv); D) is suggested, using the IUCN Red List Categories and Criteria ( IUCN 2012). However, more complete studies are required to confirm the status .

Note:— The new species is best accommodated in subg. Eriococcus . The subgenus is characterized by species with phyllanthoid branching, staminate flowers with 4 sepals and 2–3 stamens, anthers dehiscing vertically to horizontally, pistillate flowers with 6 sepals, the ovary 3 − (8)-locular, sometimes hirsute, free or connate styles, bifid or entire, capsular fruits, and smooth or papillose seeds ( Croizat 1942). The present species comfortably fits with the characters in this subgenus.

Taxonomic affinity:— The new species shows similarities with P. beddomei ( Gamble 1925b: 331) Mohanan (1985: 480) , P. chandrabosei Govaerts & Radcliffe-Smith (1995: 176) , and P. cinereus Müller Argoviensis (1863: 48) ( Table 1).

Additional specimens examined (paratypes): — INDIA. Kerala: Ernakulam district, Shoolamudi, 10°13.316 ′ N, 76°56.512 ′ E, 1216 m, 26 September 2015, K.M. Prabhukumar 8627 (CMPR!), 05 January 2016, C.N. Sunil & V.V. Naveen Kumar 7126 (SNMH!).

Figures

FIGURE 1. Phyllanthus balakrishnanii A. Habit; B. Abaxial side of leaves; C, E, H. Female flowers; D. Capsule; F. Male flowers; G. Verrucose nature of stem; I. & J. Capsule showing red tubercels; K, L. Seed. (Photos: K.M. Prabhu).

FIGURE 2. Phyllanthus balakrishnanii A. Flowering twig; B. Fruiting twig; C. Female flower; D. Male flower; E. Seed. (Drawn from holotype by V.P. Thomas).