Myristica pushpangadaniana Govind

Govind, Murugan Govindakurup & Dan, Mathew, 2022, Status of the subspecies of Myristica beddomei (Myristicaceae), endemic to the Western Ghats, India, Phytotaxa 541 (3), pp. 261-269 : 262-263

Myristica pushpangadaniana Govind & M.Dan, nom. nov. ( Figs 2 , 3 )

Type:— INDIA. Tamil Nadu: Thirunelveli, 1976, Kostermans 26276 (holotype: L, online image!; isotype: K!)

Replaced name: M. beddomei subsp. spherocarpa W.J.deWilde, non Myristica sphaerocarpa Wallich (1830: 79)

Evergreen, dioecious trees, 20–35 m tall, branching usually whorled, main trunk 90–120 cm in diameter; bark rough, brown; exudate orange-red, viscous. Leaves alternate, petiolate; petiole 3.5–4.2 cm long, round to shallowly grooved, glabrous; lamina 8–10 × 4–6 cm, broadly lanceolate, apex acute to acuminate, margin undulate, base rounded, adaxially dark green, gland-dotted, abaxially glaucous, glabrous; midvein prominent, lateral veins not prominent, 8- 13 paired. Male inflorescence 2–3-flowered, axillary umbel; peduncle erect, 2 cm long, cylindrical, scurfy tomentose. Flowers caducous, urceolate, longer than broad, 4.1-4.3 × 2.3–3.0 mm, brownish yellow, pedicellate; pedicel 7–10 mm long, pubescent; bracteole 2.1–3.0 × 2.2–3.1 mm, ovate, acute at apex, appressed to the base of male flower, dorsally convex, brownish yellow, densely pubescent outside, persistent. Perianth trilobed, equal, acute, curved outward, brownish yellow, densely pubescent outside; staminal column 3–5 mm long, cylindrical, pilose up to anthers from base; anthers 12–13. Female inflorescence 2-flowered, axillary umbel; peduncle erect, 3 mm long, cylindrical, puberulous; flowers urceolate, 4.2–6.1 × 4.0–5.0 mm, yellow, persistent, pedicellate; pedicel up to 5 mm long, pubescent; perianth trilobed, equal, acute, curved outward, scabrid outside; stigma bilobed; ovary ovate, 2–3 mm, densely tomentose. Fruits usually solitary, rarely in pairs, dehiscent, 2.5–4.0 × 3.5–5.0 cm, subglobose to globose, brown, apex obtuse, base round, longitudinal suture on both sides, scurfy pubescent; rind 7–10 mm thick, brown; seed 2.0–3.6 × 2.5–4.0 cm, oblong, black, arillate; aril partially covering seed, yellow turning orange-red, lacerate.

Distribution:— Endemic to the southern Western Ghats at 900-1100 m.

Phenology:— Flowering August–November, fruiting March–June.

Etymology:— Named in honour of Padma Shri Dr. P. Pushpangadan, former Director of JNTBGRI, Palode and CSIR-NBRI, Lucknow, India, a renowned Indian ethnobotanist.

Notes:— Based on detailed morphological evaluation and comparison with M. beddomei , this subspecies differs in key characters, smaller leaves (7–10 × 3–5.5 cm), fewer lateral veins (8–13 pairs), more anthers (13), globose fruits and seeds partially covered by aril ( Figs 2 , 3 , 4 ; Table 1 ).

The chemical profile of essential oils isolated from rind, aril, seed and leaf of M. beddomei subsp. beddomei and M. beddomei subsp. ustulata was found to be similar, whereas that of M. beddomei subsp. spherocarpa was different. In M. beddomei subsp. spherocarpa , monoterpenes, phenyl propanoids and aliphatic hydrocarbons were absent in the leaf and seed essential oil, whereas these compounds were present in M. beddomei subsp. beddomei and M. beddomei subsp. ustulata . In the rind essential oil of M. beddomei subsp. beddomei and M. beddomei subsp. ustulata , E-caryophyellene and α-terpineol were the major compounds, whereas in M. beddomei subsp. spherocarpa , E-nerolidol and linalool were the major compounds. Likewise, in the arils of M beddomei subsp. beddomei and M. beddomei subsp. ustulata , α-humulene was the major compound followed by trans-α-bergamotene, to the contrary, E-caryophyellene and αhumulene were the major compounds in M. beddomei subsp. spherocarpa giving it a distinct chemical profile. The dissimilarities of chemical profile in M. beddomei subsp. spherocarpa combined with the morphological differences are supporting evidence for its elevation to species level.

Petiole cross sections of M. beddomei subsp. beddomei and M. beddomei subsp. ustulata were grooved and glabrous. That of M. beddomei subsp. spherocarpa was round to shallowly grooved and had epidermal trichomes. Five vascular bundles were observed in M. beddomei subsp. beddomei and M. beddomei subsp. ustulata , two at adaxial side, one at abaxial side and one each on each side. A lunar type of arrangement of phloem patches occurs in the pith region. The anatomical features of the petiole of M. beddomei subsp. spherocarpa were found different from the other two subspecies. The petiole was almost circular in outline with shallow groove. Three vascular bundles are enclosed in separate sclerenchyma patches, one large in the pith region and a small vascular bundle on each side. The anatomical characters in the petiole of M. beddomei ssp. spherocarpa are distinct from that of M. beddomei ssp. beddomei and ssp. ustulata ( Fig. 5 ).

Other specimens examined:— INDIA. Near Agasthyarkoodam, Thirunelveli district , May 2019, Govind 91047 (TBGT). Kerala: Chemunji hills, Bonaccadu, Thiruvananthapuram, Apr 2019, Govind 91046 (TBGT) .

Figures

FIGURE 2. Myristica pushpangadaniana A. Twig with leaves and fruit. B. Dehisced fruit. C. Male flower. D. Androecium exposed. E. Female flower. F. Gynoecium exposed.

FIGURE 3. Myristica pushpangadaniana: A. Twig with leaves. B. Male inflorescence. C. Female inflorescence. D. Male flower. E. Androecium exposed. F. Female flower. G. Gynoecium exposed. H. Fruit. I. Arillate seed. J. Bark exudate.

FIGURE 4. Subspecies of Myristica beddomei (Prior). A1–5. M. beddomei subsp. beddomei. B1–5. M. beddomei subsp. spherocarpa. C1–5: M. beddomei subsp. ustulata. 1. Twig with leaf. 2. Male flower. 3. Female flower. 4. Fruit. 5. Seed with aril

FIGURE 5. Diagrammatic representation of vasculature in petiole (CS) of M. beddomei and its subspecies.