Miliusa gokhalaei Ratheesh, Sujanapal, Anil Kumar & Sivadasan

Ratheesh Narayanan, M. K., Anil Kumar, P. Sujanapal N., Sivadasan, M., Alfarhan, Ahmed H. & Thomas, Jacob, 2012, Miliusa gokhalaei, a new species of Annonaceae from India with notes on interrelationships, population structure and conservation status, Phytotaxa 42, pp. 26-34 : 27-32

Miliusa gokhalaei Ratheesh, Sujanapal, Anil Kumar & Sivadasan , sp. nov., Figs. 1 & 2

Miliusa indicae et M. eriocarpae similis foliis petiolatis nervis pubescentibus floribus axillaribus solitariis carpellis 1- vel 2-ovularibus infundibularibus, sed foliorum basi inaequaliter rotundata floribus sessilibus vel breviter pedicellatis petalis crasse carnosis carpellis glabris antherae connectivo incluso differt.

Type:— INDIA: Kerala: Wayanad district , Vythiri Ghat, 11 ° 30' 24.3' N , 76 ° 01' 49.1' E, 490 m, 26 September 2008 (with flowers) . Sujanapal & Narayanan MSSH 4312 (holotype MH, isotypes CAbC- MSSRF Herbarium, Wayanad CAL, CAL, KFRI) .

Evergreen trees, to ca. 5 m high; bark black, branches terete, drooping, young parts densely hairy. Leaves simple, alternate, 6.0–12. 0 × 2.5–4. 0 cm, oblong or obovate, glabrous, midrib pubescent below, slightly unequally rounded at base, apex caudate acuminate, subsessile or petiole to 3 mm long, membranous; lateral nerves 10–14 pairs, intramarginal nerves sub-marginal, looping; margins entire, slightly curved, thickened. Flowers solitary, pseudo-terminal (slightly above and opposite the terminal leaf) greenish-yellow; pedicel 2–4 mm long, glabrous; bracts two, small, ovate; bracteoles two at the base, unequal, ovate-triangular, acute, ca. 1.5 mm long, hairy outside; sepals 3, ca. 1.5 × 2.0 mm, broadly ovate, acute, glabrous; outer petals 3, broadly ovate, acute, hairy on margins, slightly hooded, ca. 2.0 × 1.5 mm; inner petals 3, ovate-lanceolate, 2.0–2.4 × 0.8–1.3 cm, thick, fleshy, glabrous, thickly hooded on the lower half, cohering when young along margins, greenish-yellow with brown streaks inside; torus ovoid, long hairy; stamens many, 40–50, anthers in pairs, ca. 1 mm, connective included; staminodes absent; anthers extrorse; carpels 10–15, linear-oblong in outline, slightly curved, ca. 2 mm long, glabrous; stigma ovoid-acute, about half the height of the ovary, with viscous exudate; ovules 1 or 2. Fruiting stalk terete, 8–11 mm long; monocarps usually 8–12, each 10–12 mm across, obovoid, mammose, apex projecting, more or less obturbinate, glabrous, deep pink; stipe ca. 5 mm long. Seeds 1-2.

Phenology:— Flowering and fruiting occur during September to February.

Eponymy:— The specific epithet honors Padmashree Mr. A.M. Gokhalae (IAS, Retd.), former Director of the M.S. Swaminathan Research Foundation, Chennai, India, for being a great lover of plants and plant taxonomy; he prepared a detailed electronic database for more than 7000 species of Indian angiosperms, which is one of the pioneering comprehensive efforts in digitization and digital identification of the group in India.

Distribution and habitat:— Windward side of Wayanad-Silent Valley-Kodagu sub-cluster in the Nilgiri phytogeographical region of the Western Ghats. The range starts in Nadukani forests of Nilambur (Malappuram district) and extends to the Kakkayam and Thusharagiri forests of Kozhikode district through the evergreen forests in the western side of Wayanad Ghats.

Evergreen forests, at elevations of ca. 400–750 m a.s.l. are the ideal habitat of the new species. It is seen mostly along the slopes as a lower stratum tree or shrub with scandent branches. Arenga wightii Griffith (1845: 475) is a common associate in most of its habitats. Rare, endemic and endangered species of Annonaceae such as Desmos lawii Safford (1912: 506) , Goniothalamus wynaadensis Beddome (1868 - 1874:13), Meiogyne ramarowii ( Dunn1914: 183) Gandhi (1976: 38) , Orophea malabarica Sasidharan & Sivarajan (1990: 269) , Polyalthia suberosa ( Roxburgh 1795: 31.t.34) Thwaites (1864: 398), Sageraea laurina Dalzell (1851: 207) , etc. are also found in its northern distributional ranges. Endangered and economically important trees such as Cynometra beddomei Prain (1897: 478) , C. travancorica Beddome (1873: 316) , Kingiodendron pinnatum Harms (1897: 194) , Myristica beddomei King (1891: 291) , etc. are common in its habitats. Artabotrys zeylanicus Hooker & Thomson (1855: 128) , Desmos lawii , Smythea bombaiensis (Dalzell 1851: 36) Banerjee & Mukherjee (1970: 214) , etc. are the woody climbers common in the habitats. In Nadukani forests a critically endangered tree species, Atuna indica ( Beddome 1864: 45) Kostermans (1969: 422) , is seen along with this new species.

Interrelationships:— Miliusa gokhalaei is similar to M. indica and M. eriocarpa in having subsessile or shortly petiolate, hairy-nerved leaves, and axillary solitary flowers, flask-shaped carpel with 1–2 ovules. However, it differs in its unequal rounded leaf bases, sessile or shortly pedicellate flowers, thick fleshy petals, glabrous carpel and included connective of anther. The other related species is Miliusa montana , and the diagnostic morphological characters of the new species and the related species are given in table 1.

Van Heusden (1992) studied morphology and evolution of flowers in Annonaceae and assigned key features for Miliusa group. Based on her characterization and structure of inner petals, the southern Indian-Sri Lankan and Andamanese species of Miliusa can be broadly classified into three groups - Miliusa nilagirica group, Miliusa indica group and Miliusa velutina group. Miliusa nilagirica group is peculiar among these because of the presence of recurved petals. However, van Heusden never noticed recurved petals in Miliusa group. This group is distinct from all others of the region in having fewer stamens. The peculiarity of Miliusa velutina group is the presence of flat inner petals. Miliusa mukerjeeana is the only other member of this group. All other species belong to Miliusa indica group in having saccate, sub-saccate or pouched petals. The new species also belongs to the Miliusa indica group in having saccate petals and numerous stamens.

Additional specimens examined: — INDIA: Kerala: Wayanad District, Vythiri Ghats, 11 ° 30ʹ 24.3ʹ N, 76 ° 01ʹ 49.1ʹ E, 490 m, 30 September 2008 (with flowers), Sujanapal & Narayanan MSSH 4320 ; Ibid., 27 August 2009, Sujanapal & Narayanan MSSH 4388 (with flowers); Malappuram District , Nadukani Forests (Nilambur), 11 ° 29ʹ22.6ʹ N, 76 ° 15ʹ 19.4ʹ E, ± 510 m, 01 January 2009, Sujana MSSH 4382 (with fruits); Kozhikode District , Kakkayam Forests 11 ° 32ʹ 12.2ʹ N, 75 ° 55ʹ 12.2ʹ E, ± 525 m, 22 October 2008 (with flowers), Sujanapal & Narayanan MSSH 4378 (with flowers); Thusharagiri Forests, 11 ° 28ʹ 12.7ʹ N, 76 ° 08ʹ 11.2ʹ E, ± 450 m, 12 October 2008, Sujanapal & Narayanan MSSH 4372 (Herbarium of CAbC-MSSRF, Wayanad) .

Population structure and conservation status:— Populations of the new species are fragmented and seen in the lower storey, mainly along the western slopes of the Western Ghats between 400 m and 750 m a.s.l. in evergreen forests; they are represented by a few scattered mature individuals. There is no continuity in distribution from the southern to the northern populations. The southern-most population is located in the evergreen forests of Nadukani (Nilambur, Malappuram District). The major central population is in the Vythiri Ghats of Wayanad district and Thamarassery Ghats up to Kakkayam and Thusharagiri Range of Kozhikkode district at the northern tip.

In all locations, populations of this new species are small. Our observations showed that there were only nine mature individuals in a 1 km 2 area of Nilambur. Compared to Nilambur, the population is comparatively large in Wayanad and Kozhikkode forests with more or less continuous distribution from Thamarassery up to Peruvannamuzhi. Altogether the distribution of this new species is restricted to 50 km 2. None of the localities is protected. The population at Nilambur is adjacent to human habitation, and waste disposal, pollution and degradation of habitat due to the nearby Sate Highway-28 are the main threats to this population. Increased anthropogenic interference in the form of firewood collection deepens the crisis. In Thamarassery Ghats the population is near to the National Highway-212, and the area is highly subject to various kinds of disturbances. The habitats in Kakkayam and Peruvannamuzhi ranges are highly disturbed due to construction activities related to two reservoirs and the forthcoming hydroelectric project. These construction activities promote calamities like landslides, soil erosion, etc. since it is lying along the sharp western slopes. By following IUCN criteria ( IUCN, 2001) for assessing the status of Rare and Threatened plants, M. gokhalaei is assessed as belonging to Critically Endangered (CR) category. Its range (extent of occurrence) is less than 100 km 2, the population is severely fragmented and the quality of habitat is declining continuously.

Figures

FIGURE 1. Miliusa gokhalaei A. Flowering branch. B. Flower bud. C. Mature flower. D. Flower with petals removed. E. Sepal. F. Outer petal. G. Inner petal, ventral view. H. Inner petal, dorsal view. I. Stamen, lateral view. J. Stamen, ventral view. K. Pistil. L. Infructescence with fruits. Drawings by K. M. Manudev from living specimens.

FIGURE 2. Miliusa gokhalaei A. Small twig with young flower. B. Branch with mature flower. C. Young fruit with cream-coloured monocarps. D. Mature fruit with pinkish monocarps.