Mitrephora langsuanensis Leerat., Chalermglin & R.M.K.Saunders, 2023

Leeratiwong, Charan, Chalermglin, Piya & Saunders, Richard M. K., 2023, Three new species of Mitrephora (Annonaceae) from Thailand, PhytoKeys 218, pp. 93-107 : 93

Mitrephora langsuanensis Leerat., Chalermglin & R.M.K.Saunders sp. nov.

Figs 1 , 2

Diagnosis.

Mitrephora langsuanensis is similar to M. macclurei Weerasooriya & R.M.K.Saunders, but differs in having: leaves with more secondary veins (7-14 pairs), sometimes with domatia abaxially; yellow outer petals with pink stripes, densely hairy abaxially, and with a margin that becomes undulate with age; more carpels per flower (10-12); and longer fruiting pedicels (20-25 mm).

Types.

Thailand: TISTR Annonaceae collection plot, Khlong Luang District, Pathum Thani Province, Central Thailand, ca. 5 m alt., 3 May 2021, P. Chalermglin 640503 (originally from Phu Muang temple, Lang Suan District, Chumphon Province, Peninsular Thailand, ca. 100 m alt.) (holotype PSU; isotypes BKF, KKU, QBG).

Description

(from cultivated material). Small trees, to 4 m (in cultivation). Young branches densely pubescent. Leaf laminas coriaceous, (elliptic-)lanceolate, (5.5-)8-22 by 3-5 cm, base obtuse or rounded, apex acute to acuminate, glossy, glabrous adaxially, sparsely to moderately pubescent (sometimes pilose) abaxially, secondary veins 7-14 pairs per leaf, sometimes with domatia at axils of secondary veins abaxially; petioles 6-12 mm long, moderately pubescent. Inflorescence rachides simple, with rachis internodes remaining short, 2-4 mm long, 2-3-flowered, densely pubescent; pedicels 23-30 mm long. Sepals free, broadly ovate, not imbricate, 4-6 by 5.5-6.5 mm, densely pubescent abaxially, glabrous to sparsely pubescent, denser at margin adaxially. Outer petals creamy white, turning yellow with pink stripes, ovate, 20-27 by 15-17 mm, not clawed, margin undulate with age, acute, densely pubescent ab- and adaxially. Inner petals with greenish-yellow claw, purple towards apex with a yellow stripe, 13-15 by 9-11 mm, claw incurved, densely pubescent ab- and adaxially. Stamens 1.2-1.3 mm long, connective truncate, glabrous. Carpels 10-12 per flower, 2-2.7 mm long; ovary oblong, 1.3-1.6 mm long, moderately pubescent; stigma subglobose, 0.4-0.6 mm long, hairy; ovules 4-8 per carpel. Fruits with up to 12 monocarps, borne on a pedicel 20-25 mm long, 3-5 mm wide, densely pubescent. Monocarps yellow when ripe, ellipsoid, ovoid to oblong-ellipsoid, 20-40 by 17-20 mm, smooth, with longitudinal ridge, sparsely pubescent; stipes 16-20 mm long, moderately pubescent. Seeds 2-6 per monocarp, semi-lenticular (lowermost and uppermost within monocarp) or discoid (others), 10-13 by 5-8 mm, glabrous, pitted.

Phenology

(in cultivation). Flowering between May and June; fruiting in May.

Distribution and habitat.

Endemic to Chumphon Province, Peninsular Thailand (Fig. 3 ). Growing on limestone hill in tropical rain forest; ca. 100 m alt.

Etymology.

From the name Lang Suan district, Chumphon Province.

Local name.

Phrom lang suan (พรหมหลังสวน) (Chumphon).

Additional specimens examined

(paratypes). Thailand: Pathum Thani Province, Khlong Luang District, TISTR Annonaceae collection plot, ca. 5 m alt., 23 June 2022, P. Chalermglin 650623/1 (originally from Phu Muang temple, Lang Suan District , Chumphon Province, Peninsular Thailand, ca. 100 m alt.) (PSU).

Discussion.

Mitrephora langsuanensis resembles M. macclurei Weerasooriya & R.M.K.Saunders, but differs in having leaves with or without domatia on abaxial leaf surface (absent in M. macclurei ), and a densely hairy indument abaxially (vs sparsely hairy). The flowers of Mitrephora langsuanensis have yellow outer petals with pink stripes (vs yellow petals without pink stripes in M. macclurei ), margins that undulate with age (not undulate in M. macclurei ), densely hairy indument abaxially (vs sparsely hairy), more carpels (10-12 vs 7-8) and longer fruiting pedicels (20-25 mm vs ca. 13 mm).

Mitrephora langsuanensis also resembles M. wangii Hu from China ( Weerasooriya and Saunders 2010), but differs in its leaf laminas that are densely pubescent (sparsely hairy in M. wangii ), sometimes with domatia at axils of secondary veins abaxially (absent in M. wangii ), outer petals with pink stripes (absent in M. wangii ), longer fruiting pedicels (10-16 mm in M. wangii ) and longer monocarp stipes (9-13 mm in M. wangii ).

Figures

Figure 1. Mitrephora langsuanensis sp. nov. A flower buds B flower C flowering branch D, E fruits (slightly immature). Photos by P. Chalermglin.

Figure 2. Mitrephora langsuanensis sp. nov. A, B flowering branches C flower D, E Sepals (ab- and adaxial) F, G outer petals (ab- and adaxial) H, I inner petals (ab- and adaxial) J, K stamens (ab- and adaxial) L carpel M fruit, composed of separate monocarps N seeds (longitudinal and transverse sections). Drawn by A. Somphrom, from P. Chalermglin 640503 (PSU).

Figure 3. Distributions of Mitrephora langsuanensis, M. sirindhorniae and M. sukhothaiensis.