Miliusa agasthyamalana V.S.A. Kumar & Sindhu Arya, 2022

Arya, Sindhu & Kumar, Venugopalan Nair Saradamma Anil, 2022, Miliusa agasthyamalana (Annonaceae), a new species from southern Western Ghats, India, Phytotaxa 552 (4), pp. 252-258 : 253-257

Miliusa agasthyamalana V.S.A. Kumar & Sindhu Arya , sp. nov. (Figs. 1,2)

Type:— INDIA. Kerala: Thiruvananthapuram district, Athirumala , 8.970 N 77.30 E, 1200 m, 08 May 2020 (with flowers), Govind & VSA Kumar 590 (holotype UCBD; isotypes UCBD, KFRI) .

Diagnosis: — Miliusa agasthyamalana resembles M. wightiana Hooker & Thomson (1855: 285) with respect to solitary flowers, leaves with acuminate apex and ovate shape of the inner petal but is distinct with respect to the size of tree (small tree reaching a height of 9 m in M. agasthyamalana vs. medium sized tree reaching a height of 15 m in M. wightiana ), shape of leaves (ovate to ovate lanceolate vs. elliptic-lanceolate), hairiness on secondary veins (glabrous vs. pubescent), length of pedicel (3.0– 5.5 mm vs. 1.5 –2.5 mm), sepals (Ovate or obovate with hair along margin vs. oblong and pubescent throughout.)inner petals (1.5–2.2cm fleshy, yellow with pink stripes or spots vs. 10–15 × 6–8 mm non-fleshy, greenish), staminal connectives (included vs. apiculate), number of carpels per flower (17–22 vs. 10–15) and shape of monocarps (dumbbell-shaped with round apex vs. pisiform with acute apex).

The new species also shows resemblance to M. paithalmalayana Josekutty (2016: 287) reported from the Paithalamala range of Western Ghats with respect to the solitary flowers, included staminal connectives and linear carpels but is very distinct with respect to the inner petals (ovate, fleshy, yellow with pink stripes in M. agasthyamalana vs. elliptic to lanceolate, nonfleshy with purple color in M. paithalmalayana ), sepals (ovate or obovate with hairs along margin vs. lanceolate, glabrous) number of carpels per flower (18–22 vs. 10–15), shape of monocarp (dumbbell shaped with round apex, green with purple spots vs. oblong, crimson red)

Description: —Evergreen trees, 6–9 m high; bark brown, rough, branches terete, drooping, often spreading, young parts gloss, glabrous. Leaves chartaceous, 5.0–16.0 × 1.5–5.0 cm, ovate or ovate lanceolate, unequally rounded at base, wavy and slightly folded along margins, caudate-acuminate at apex, glabrous, subsessile or petiole to 1 mm long, terete, glabrous, black; lateral nerves 6–8 pairs, intramarginal nerves looping; tertiary nerves inconspicuous, nervules obscure, Flowers solitary, pseudo-terminal (slightly above and opposite the terminal leaf) yellowish-pink; pedicels 3.5–5.5 cm long, glabrous, glossy, yellowish to light green; bracts 2, ovate-triangular, acute, ca 0.5 mm long, hairy outside; sepals 3, ca 1.0 × 1.2 mm, ovate-lanceolate, apex acute, adaxial side glabrous in the middle, pubescent along margin; outer petals 3, ovate or obovate, apex acute, hairy along margins, slightly curved inwards, ca 3.0 × 3.5 mm; inner petals 3, ovate or obovate, 1–1.4 × 0.8–1.0 cm, thick ca 1mm long, fleshy, glabrous, thickly hooded on the lower half, cohering when young along margins, yellow with pink streaks inside and pink spots outside; torus ovoid, long with white hairs; stamens 15–20, anthers ca 0.5 mm long, connective included; carpels 17–22, linear in outline, slightly curved, ca 1 mm long, glabrous; stigma obovate-acute, about half the height of the ovary, ovules 1 or 2. Fruiting stalk terete, glabrous, dark brown, 7–9 cm long; monocarps usually 8–15, each 1–1.2 × 1–1.5 cm across, more or less dumbbell-shaped, green with purple stripes. Seeds 1–2.

Phenology:— Flowering and fruiting occur during April to July.

Etymology:— The specific epithet refers to the type locality, Agasthyamala Biosphere reserve in Thiruvananthapuram District of Kerala, south India.

Distribution and ecology:— Miliusa agasthyamalana is known only from the type locality, between 1000–1250 m elevations. It grows in the interior of the evergreen forest range of Athirumala, with a total of two individual only. Each individual is separated by a distance range of 1.5 km. The associated species include Garcinia imberti Bourdillion (1899: 349) (Clusiaceae) and Myristica beddomei King (1891: 327) (Myristicaceae) .The type locality Athirumala forms the base station of Agasthyamala biosphere reserve that is rich with moist deciduous forest, semi evergreen forest, grassland, evergreen forest and at the end, large rock formations. It has a unique biodiversity and is noted for the presence of many endemic medicinal herbs. The high conservation value of the area relies on its rich biodiversity, geography and hydrology and hence protected as a biosphere reserve.

Taxonomic notes:—The new species is similar to Miliusa campanulate Pierre (1881: 41) group ( Chaowasku & Kessler 2013), based on the tightly appressed nature of the inner petals ( Chaowasku & Kessler 2013) and Indian species to the Miliusa nilagirica group ( Van Heusden 1992) in having recurved inner petals. Miliusa agasthyamalana shows similarity to Miliusa tirunelvelica Murugan, Manickam, Sundaresan & Jothi (2004: 102) with respect to 6–8 pairs of secondary veins in leaf and included connectives but is distinct with respect to many characters summarized in Table 1 .

Conservation status:— There is only a single population, with about 2 mature individuals, occupying an area of less than 2 km 2. The estimated Extent of Occurrence (EOO) is 25 km 2 and the Area of Occupancy (AOO) is less than 2 km 2. The number of mature individuals is estimated to be two, when considering all the localities. Since these locations are inside a protected area, the likelihood of a decline due to anthropogenic activity is small. Nevertheless, we recommend that the species be categorized as Critically Endangered (CR) in the category [B2a, b(v)] ( IUCN 2020). The area is well protected but chances of forest fires pose a high threat to this area.

Selected specimen examined (paratypes):— INDIA. Kerala Thiruvananthapuram district, Athirumala 1110 m, 8.970 N 77.30 E, 25 May 2020 Govind 778 ( UCBD), 30 June 2020, S . Arya & V. S. A . Kumar 790 ( UCBD), 24 June 2021 S . Arya & V. S. A . Kumar 1226 ( UCBD) .