Biophytum agasthyamalayanum Jisha, E.S.S.Kumar, Decruse & Rajendraprasad, 2020

Daniel, Jisha, Kumar, Ettickal Sukumaran Santhosh, Decruse, Sabarimuthan William & Rajendraprasad, Madhavan, 2020, A new species of Biophytum (Oxalidaceae) from the Western Ghats (Kerala, India), Phytotaxa 438 (1), pp. 49-52 : 49-52

Biophytum agasthyamalayanum Jisha, E.S.S.Kumar, Decruse & Rajendraprasad , sp. nov. ( Fig. 1 ).

Type:— INDIA. Kerala. Thiruvananthapuram district, Agasthyamala Biosphere Reserve, Pongalappara , + 1442 m, 16 May 2018 (with flowers), M. Rajendraprasad & S. William Decruse 92501 (holotype TBGT!; isotype MH!)

Diagnosis:— Biophytum agasthyamalayanum is similar to B. intermedium Wight (1840: 162) but differs by the dwarf and slender stems with hard stipules (vs robust stems with soft stipules), the nodes swollen with long hairs (vs flattened nodes with short hairs), the smaller leaves, the sparsely strigose leaflets of which the terminal one is obliquely obovate (vs glabrous leaflets, the terminal one broadly obovate), the lanceolate bracts (vs narrowly ovate), and the strigose sepals (vs glandular hairy). The new species is also similar to B. nudum ( Arnott 1836: 326) Wight (1840: 161) , from which it differs on account of the shorter stem, the smaller leaves and leaflets, the obliquely obovate terminal leaflets, the presence of glandular trichomes on peduncles and pedicels, and the stamens 3–4 mm long; whereas B. nudum is characterized by fairly longer stems, larger leaves and leaflets, broadly ovate terminal leaflets, appressed pubescent trichomes on peduncles, glabrous pedicels, and also by shorter stamens (up to 2 mm). See Table 1 for further details.

Description:— Perennial herb, creeping and rooting from the lower nodes. Stem slender, dichotomously or trichotomously branched, 30–50 cm long, with nodes swollen and tomentose, with stiff hairs; stipules hard and deciduous. Leaves 15–20, jugate, 1.7–5 cm long, rachis winged, strigose; leaflets overlapping, 2–5.5 × 1–2.5 mm long, the terminal one obovate, oblique, with eccentric midrib; the others oblong, with truncate base, eccentric midrib, rounded and apiculate apex, glabrous above and sparsely strigosely beneath, with ciliate margins; lateral nerves in 8–14 pairs, oblique to midrib, inconspicuous. Inflorescence a terminal solitary umbel. Peduncle 3–8 cm long, strigose. Bracts lanceolate, 1–2 mm long, strigose, eglandular. Pedicels 3–4 mm long, glandular. Flowers 4–6 per inflorescence, short styled. Sepals lanceolate or narrowly lanceolate, 4–4.5 × 1–1.5 mm long, half as long as corolla, 5–7 nerved, strigose outside, glabrous within. Petals oblanceolate, 10–12 × 1.8–2 mm, retuse, yellow, 5–7 veined. Stamens 10, the shortest ones 2–3 mm long, glabrous; the others 3–4 mm long, puberulous. Ovary ovoid, 0.8–1 × 1 mm long, apically pubescent; style 0.2–0.3 mm long; stigma crenate-bifid. Fruits early caducous.

Etymology:— The new species is named after its type locality, i. e. Agasthyamala Biosphere Reserve in Kerala.

Distribution, habitat and phenology:— Biophytum agasthyamalayanum is known only from the type locality, at 1400–1450 m of elevation. It grows in open areas of the montane forests, particularly on rocky cliffs, with a very limited number of individuals. Each plant spreads over an area of nearly 1–2 m 2 and produces only one type of flowers (only the short styled form (SF) has been observed). Biophytum intermedium and B. nudum are also reported from the Agasthyamala Biosphere Reserve, but they are not sympatric with the new taxon. The most common associated species are Zenkeria sebastinei Henry & Chandrab (1976: 142) , Euphorbia santapaui Henry (1965: 329) , Ischaemum timorense Kunth (1835:369) , Osbeckia travancorica Bedd. ex Gamble (1919: 404) , etc. Flowering occurs from May to December. Fruits not seen.

Conservation status:— It is known only a single population, with about 20 mature individuals, occupying an area of less than 2 km 2. The seedlings are very few and prone to severe grazing and repeated fire. Following the IUCN Redlist criteria ( IUCN 2001), B. agasthyamalayanum is assessed as Critically Endangered (CR) in the category [B2a, b(v)].

Selected specimen examined:— Biophytum agasthyamalayanum : INDIA. Kerala. Thiruvananthapuram district, JNTBGRI Garden (introduced from Pongalappara), 26 June 2019 (with flowers), Jisha 92508 (Paratype, TBGT!).

Biophytum intermedium : INDIA. Kerala: Thiruvananthapuram district, Pandipathu , 24 November 1998, E. S. Santhoshkumar 39227 ( TBGT!) ; SRI LANKA.s.loc., s.d., G. H. Walker 259 (K-image!). B.intermedium var. pulneyense : INDIA. Kerala: Thiruvananthapuram district , TBGRI Garden, 100 m, 28 October 1994, E. S. Santhoshkumar 17395 ( TBGT!) ; INDIA. s.loc., September 1836, s.coll. 302 (K-image!). B. nudum : INDIA. Kerala: Thiruvananthapuram district, Agasthyamalai, 28 May 2010, Raju Antony 60980 ( TBGT!) ; Bonaccord , 04 February 2016, Usha & Deepthy 84583 ( TBGT!). SRI LANKA. s.loc., 1829, s.coll., s.n. (K-image!) ; ibid., 01 January 1838, G. H. Thwaites 06 (Pimage!) ; ibid., s.d., G. H. Walker s.n. (E-image!) .

Figures

FIGURE 1. Biophytum agasthyamalayanum Jisha, E.S.S.Kumar, Decruse & Rajendraprasad, sp. nov. (A & B) Habit; (B1) Node with retrorse hairs; (C) Leaflets-abaxial view; (D) Median leaflet; (E) Terminal leaflet; (F) Bract; (G) Flower; (H) Sepal; (I) Corolla; (J) Long stamen; (K) Short stamen; (L) Pistil; (M) Style and stigma. [Photographs by E. S. Santhosh Kumar & Jisha Daniel].