Eugenia sphaerocarpa Vadhyar, Sujana, J. H. F. Benj. & Murthy, 2020

Vadhyar, Rakesh G., Sujana, K. A., Franklin Benjamin, J. H. & Murthy, G. V. S., 2020, Eugenia sphaerocarpa (Myrtaceae), a new species from Western Ghats of Kerala, India, Phytotaxa 442 (2), pp. 121-127 : 122-125

Eugenia sphaerocarpa Vadhyar, Sujana, J. H. F. Benj. & Murthy , sp. nov. Figures 1–3 .

Type: — INDIA, Kerala, Kozhikode district, Malabar Wildlife Sanctuary, Kakkayam, Ambalapara, 11° 32.741’ N, 075° 56.076’ E, 768 m, 01 March 2019, Rakesh G. Vadhyar & K.A. Sujana 144714 (Holotype CAL!, Isotype MH!).

Diagnosis:— Eugenia sphaerocarpa shows resemblance with E. codyensis but differs in having elliptic-ovate leaves with prominent secondary, intersecondary and tertiary veins on lower side (versus venation not prominent in E. codyensis ), flowers with obconic hypanthium (vs. hypanthium globose), staminal disk round (vs. quadrangular) and fruits 2.5–3 cm diameter, glossy lemon-yellow coloured with 3–6 seeds (vs. 1–2 cm in diameter, white, with 1–2 seeds) (see Table 1).

Trees, 6–12 m tall; bark fissured, greyish-brown; inner bark pale pinkish orange; branchlets woody, terete, glabrous, stout, brown. Young innovations sericeous or ferrugineous pubescent. Leaves simple, opposite, elliptic-ovate, 7.5–11.5 × 5.3–7.2 cm, subcoriaceous, cuneate at base, acuminate at apex, acumen 0.5–1.8 cm long, margin entire, slightly revolute, greenish above, pale green beneath, glabrous; venation pinnate, secondary veins 18–24 pairs, camptodromous-brochidodromous, originating from the midrib at angles about 40°, uniformly spaced at intervals ca. 2 mm, intersecondary veins 10–18 pairs, running parallel to secondary veins, prominent only on lower surface, tertiary veins present in between secondary veins, prominent only on lower surface, intramarginal nerves ca. 1 mm away from margin, midrib impressed or sunken above, raised beneath; petioles subterete, 0.6–1.3 cm long, canaliculated, drying black. Flowers sessile, 2–2.3 cm across, in fascicles of 1 or 2 pairs, usually on tubercles from the axils of fallen leaves or rarely terminal, white; bracts 2, ovate, ca. 1.8 × 1.2 mm, concave, acute at apex, adpressed-strigose externally towards apex, persistent; bracteoles 2, ovate-deltoid, ca. 9 mm long, adpressed-strigose externally towards apex, persistent. Sepals 4, in two unequal pairs, broadly ovate, ca. 4 × 6 mm, rounded at apex, pilose along margin, white, gland-dotted; glands convex, scattered externally, brown. Petals 4, ovate-elliptic, ca. 12 × 9 mm, acute at apex, adpressed-strigose externally, glabrous internally, caducous after anthesis, reflexed, white; glands convex, brown, scattered externally. Stamens 100–120, unequal, 8–10 mm long, glabrous, white; filaments slender, terete, 7.5–9.5 mm long; anther 2-celled, dorsifixed, lobes oblong, 0.5–0.6 mm long, dehiscing longitudinally, light pink when young; disc flat, round, ca. 0.8 cm in diameter, brown, sparsely glandular-hairy. Hypanthium broadly obconic, ca. 8 × 7 mm, pilose, greenish white, bilocular, ovules 6–10 per locule, 6-seriate, placentation axillary; style slender, 8–12 mm long, glabrous, white; stigma simple, brown. Fruit globose, 2.4–3 cm in diameter, crowned with persistent calyx, young fruits green-flushed with pale purple, lemon yellow on ripening, glossy. Seeds 3–6, angular ovoid, 3–4 angled, 1.5–1.8 × 1–1.2 cm, smooth, pale white.

Flowering and fruiting: —December–May.

Habitat: —The species is growing in tropical evergreen forests at an altitude of 700– 900 m. The associated species recorded are Baccaurea courtallensis ( Wight 1852: 1912) Mueller Argoviensis (1866: 459) , Dimocarpus longan Loureiro (1790: 233) , Erythropalum scandens Blume (1826: 922) , Goniothalamus cardiopetalus Hooker filius & Thomson (1855: 107) and Leptonychia caudata (Wallich ex G. Don 1831: 547) Burret (1926: 729) .

Distribution:—So far known only from Malabar Wildlife Sanctuary of Kozhikode, Kerala, India and likely to considered as endemic to southern Western Ghats.

Etymology:—The specific epithet denotes to the large, showy spherical fruits.

Conservation status:—The area of occupancy of the taxa is estimated to be less than 10 km 2 and known to exist only in three populations in Malabar Wildlife Sanctuary, Kozhikode district, Kerala. In the absence of detailed data on populations, the species is categorized as ‘Data Deficient’ (DD) ( IUCN 2012).

Paratypes:— INDIA. Kerala, Kozhikode district, Malabar Wildlife Sanctuary, Kakkayam, Sankaranpuzha, 11° 31.980’ N, 075° 55.453’ E, 890 m, 28 February 2019, Rakesh G. Vadhyar & Sujana K. A. 133494 (MH!).

Palynological Studies:—Pollen grains from the collection (Vadhyar & Sujana 133494) shows 3-zonocolporate pollen with scabrate exine surface while from the second collection (Vadhyar & Sujana 144714) most of the pollen grains are globular, larger and atreme ( Figure 3 ). Authors observed profuse flowering in population of the former collection growing at Sankaranpuzha and no fruit set and recruitment of seedlings in the vicinity of that population, while fruits were observed in the later population growing at Ambalapara. Although both populations are morphologically similar, the palynological evidence suggests that the species is functionally androdioecious. Recently many researchers have reported cryptic dioecy in Eugenia from Africa ( Van der Merwe et al. 2005) and Comoros archipelago ( Byng et al. 2016). All African members of the genus either have male flowers with greatly reduced pistils or structurally hermaphroditic (functionally female) flowers whose anthers do not produce viable pollen (Van Wyk & Lowrey 1988). Our findings ( Figure 3 ) substantiate those of Van Wyk & Dedekind (1985) and Byng et al. (2016) and suggest that E. sphaerocarpa present male and female forms. Nevertheless, available evidence is presently too scanty and further field level studies including reproductive biology, pollinators and host relationship, phenology and biochemical analysis are essential to confirm the cryptic androdioecy in this species.

Figures

FIGURE 1. Eugenia sphaerocarpa (A) Flowering twig; (B) Single flower; (C) Bract; (D) Bracteole; (E) Petal, adaxial view; (F) Petal, abaxial view; (G) Calyx with pistil; (H) Stamens; (I) Hypanthium (longitudinal section); (J) Fruits. Drawn by A.T. Durgadas.

FIGURE 2. Eugenia sphaerocarpa (A) Habit; (B) Bark-close view; (C) Bark-slashed view; (D) Flowering twig; (E) Young innovation; (F) Leaf, abaxial view; (G) Branches with full bloom; (H) Flower buds; (I) Single flower; (J) Young fruit; (K) Mature fruit; (L–M) Seeds.

FIGURE 3. Pollen of Eugenia sphaerocarpa (A) Pollen from male flowers (Vadhyar & Sujana 133494); (B) Pollen from functionally female flowers (Vadhyar & Sujana 144714).