Alphonsea longicarpa Leerat. & Chalermglin, 2020

Leeratiwong, Charan, Chalermglin, Piya & Johnson, David M., 2020, Two new species of Alphonsea (Annonaceae) from Thailand, Phytotaxa 429 (3), pp. 225-232 : 225-226

Alphonsea longicarpa Leerat. & Chalermglin , sp. nov. ( Figs. 1 , 2 , 4 )

Type:— THAILAND. Loei, Phu Kradueng, Phanok Khao , 750 m elev., 20 February 2019, Leeratiwong & Chalermglin 19-1421 (holotype: PSU; isotypes BKF, PSU, QBG) .

The new species is similar to Alphonsea siamensis Kessler (1995: 100) in its vegetative features but differs in having sepals 3.0–4.0 mm long, petals 13–20 mm long, 25–35 stamens per flower and only sparsely to moderately pubescent monocarps usually 4.5–10.0 cm long. In contrast, A. siamensis has sepals 1.2–2.0 mm long, petals 10–15 mm long, 15–22 stamens per flower and densely pubescent monocarps 1.5–4.0 cm long.

Trees 6–10 m tall, bark grey to greyish brown, twigs sparsely lenticellate, glabrous or sparsely covered with reddish brown appressed hairs when young, later glabrous. Leaves with petioles 3–6 mm long, sparsely brown-pubescent, transversely densely striate, blade elliptic, lanceolate, lanceolate-elliptic or ovate-elliptic, 7–13 × 3–5 cm, apex acute to acuminate, the acumen 3–10 mm long, base cuneate or slightly cordate, margins revolute, lamina shiny, glabrous on adaxial surface, glabrous except for sparse, long, brown appressed pubescence on midrib and abaxial margins, primary veins slightly raised above and below, secondary veins 7–12 per side, tertiary veins reticulate, distinct on both surfaces. Inflorescences 1–3-flowered, extra-axillary or leaf-opposed, peduncle 1.5–3.0 mm long, pedicels 5–8 mm long, each bearing an ovate bract near to the base, 2.5–3.0 × 2.5–3.0 mm, pubescent outside and glabrous inside, buds broadly conical. Sepals 3, brownish green, connate basally, broadly ovate, 3.0–4.0 × 2.5–3.5 mm, apex obtuse, reflexed, hairy outside, glabrous inside. Petals 6 in two whorls, outer petals greenish yellow or yellow in vivo, black in sicco, triangular-ovate or ovate, 13–17 × 6–10 mm, apex obtuse, hairy on both sides except glabrous at base inside, inner petals greenish yellow to pale whitish yellow in vivo, black in sicco, ovate-triangular or triangular-elliptic, 14.0–20.0 × 6.0– 9.5 mm, apex obtuse to acute, hairy outside, glabrous to sparsely hairy at apex inside. Stamens 25–35, ovate to elliptic, 0.8–1.5 mm long, extrorse, connective apex apiculate. Carpels 3–5, ovary ellipsoid-oblongoid or oblongoid, 3–4 mm long, pubescent; stigma U-shaped, 0.5–0.8 mm long. Torus conical. Fruits of 3–4 monocarps, green in vivo when young, colour at maturity unknown, black in sicco cylindrical to ellipsoid, 4.5–10.0 × 2.0– 3.5 cm, apex rounded, smooth, sparsely to moderately brown pubescent, with a longitudinal groove abaxially, sometimes constricted between seeds, pedicel 1–4 cm long, stipe 3–8 mm long. Seeds 5–16 per monocarp, attached laterally in two rows, ellipsoidreniform, 1.5–2.0 × 0.5–1.0 cm, brown, smooth with plate-like endosperm ruminations.

Distribution and ecology:— Endemic to Thailand in the northern, northeastern, eastern and central regions, occurring in dry evergreen forest on foothills to higher areas on limestone and in dry dipterocarp forest on granite, 40–750 m elevation.

Phenology:— Flowering from December–August, fruiting from February–October.

Local Names:— Luk khu, tam yao phon yao khao hin poon (Thai).

Etymology:— In reference to the long monocarps of the fruit.

IUCN Conservation Status:— Provisional status considered to be least concern (LC) according to IUCN (2012). This species is not under immediate threat because of its wide distribution and existence in well-protected habitats.

Additional specimens examined:— THAILAND. Chiang Mai: Chiang Dao, ca. 500 m elev., 7 June 1973, Geesink et al. 5768 ( BKF, L). Loei: Phu Kradueng, Pha Nok Khao , 700 m elev., 20 Feb. 2019, Leeratiwong & Chalermglin 19-1934 ( PSU) ; Phu Kradueng, Pha Nok Khao , 750 m elev., 20 February 2019, Leeratiwong & Chalermglin 19-1421 ( BKF, PSU, QBG), Leeratiwong & Chalermglin 19-1435 ( PSU), Leeratiwong & Chalermglin 19-1436 ( PSU) ; Wang Sa Phung, ca. 300 m elev., 17 March 1924, Kerr 8769 ( AAU, BK, L, K) ; Wang Sa Phung, 370 m elev., 21 February 2019, Leeratiwong & Chalermglin 19-1437 ( PSU). Khon Kaen: Phu Pha Man National Park , 310 m elev., 17 Nov. 1979, Shimizu et al. T-23229 ( BKF) ; Phu Pha Man National Park , 18 February 2008, Norsaengsri & Lakoet 3456 ( QBG) ; Phu Pha Man National Park , 20 February 2008, Norsaengsri & Lakoet 3456 ( QBG) ; Phu Pha Man National Park, Pha Nok Khao , 508.2 m, 12 January 2010, Norsaengsri et al. 0013 ( QBG) ; Phu Pha Man National Park, Pha Nok Khao , 298.8 m, 11 May 2010, Norsaengsri & Thongsorn 6644 ( QBG) ; Phu Pha Man National Park, Pha Nok Khao , 682 m, 15 August 2012, Norsaengsri et al. 9932 ( QBG) ; Phu Pha Man National Park , Pha Phuang cave, 292.5 m, 18 February 2008, Norsaengsri & Lakoet 3424 ( QBG, SING) ; Phu Pha Man National Park, Pha Phuang cave, 270 m, 13 May 2009, Norsaengsri 5462 ( QBG), Norsaengsri 5463 ( QBG). Nakhon Ratchasima: Pak Thong Chai, 15 February 1976, Sutheesorn 3675 ( BK). Lop Buri: Chaibadan, 50 m, 15 December 1923, Kerr 7983 ( K). Saraburi: Maenam Sakca. 40 m, 3 June 1923, Kerr 7046 ( BK) .

Notes:— Alphonsea longicarpa is characterized by mostly long cylindrical to ellipsoid monocarps (the longest monocarp in Thailand, to 10 cm long). This species may be confused with A. siamensis but can be separated by several characters ( Table 1).

Figures

FIGURE 1. Distribution of Alphonsea longicarpa and A. phuwuaensis in Thailand.

FIGURE 2. Alphonsea longicarpa. A. Flowering branch. B. Side view of flowers. C. Apical view of flowers. D. Young monocarps. E. Dry mature monocarps, longitudinal section showing the seeds. Photos by C. Leeratiwong.

FIGURE 4. Alphonsea longicarpa. A. Flowering branch. B. Flower, side view. C. Flower, side view, showing inner petal, torus and arrangement of stamens and carpels. D. Sepal, abaxial view. E. Sepal, adaxial view. F. Outer petal, abaxial view. G. Outer petal, adaxial view. H. Inner petal, abaxial view. I. Inner petal, adaxial view. J. Inner petal, side view. K. Stamen, abaxial view. L. Stamen, adaxial view. M. Carpel. N. Young fruit. O. Single dry mature monocarp. Drawn by W. Thammarong.