Dasymaschalon halabalanum Jongsook & Chaowasku, 2020

Jongsook, Hathaichanok, Samerpitak, Kittipan, Damthongdee, Anissara & Chaowasku, Tanawat, 2020, The non-monophyly of Dasymaschalon dasymaschalum (Annonaceae) revealed by a plastid DNA phylogeny, with D. halabalanum sp. nov. from Thailand and D. argenteum comb. nov., Phytotaxa 449 (3), pp. 265-278 : 269-270

Dasymaschalon halabalanum Jongsook & Chaowasku , sp. nov. ( Figs. 2A , 3–5 )

Type:— THAILAND. Narathiwat Prov.: Cultivated in Her Majesty The Queen’s 60 th Birthday Anniversary Botanical Garden [originally collected as a sapling from Hala-Bala Wildlife Sanctuary, Waeng Distr., Narathiwat Prov.], 24 April 2018, Chaowasku 180 (holotype: CMUB! [ Fig. 4 ], isotypes: BKF!, G!, P!), in flower.

Diagnosis:— Closely related to Dasymaschalon dasymaschalum , differs primarily by having longer pedicels, larger petals with different color, and a higher number of stamens per flower (see Table 1).

Description:— Shrubs 2–2.5 m tall. Young twigs glabrous. Petioles 5–7 mm long, slightly grooved on upper surface, glabrous on both surfaces; leaf blade elliptic to obovate, 15.3–24.2 × 6–9.2 cm, both surfaces glabrous, apex caudate-acuminate, sometimes less acuminate and more acute, base cordate; midrib raised and glabrous on lower surface, sunken and glabrous on upper surface; secondary veins 10–13 per side, angle with midrib 50°–60° (at middle part of leaf blade). Inflorescences of 1-flowered, axillary (but sometimes appearing as terminal-like); pedicels 5–10.3 cm long, almost glabrous, with ca. 2 bracts at base. Sepals free, broadly triangular, 3.1–3.2 × 4.5–5 mm, outside and margin puberulous with appressed hairs, inside glabrous. Petals free, ± elliptic, 6.3–9.9 × 3.7–6 cm, glabrous on both sides and margin, apex acute. Torus depressed-hemispherical, ca. 2 × 4 mm, apex villous with erect hairs. Stamens 152–175 per flower, ca. 3.1 × 1.1 mm, connective apex acute-obtuse, with an arrow-head appearance, covering thecae. Carpels 16–25 per flower, ca. 3.2 × 1.1 mm; stigmas ± elongated club-shaped, almost glabrous except apex which is puberulous with erect hairs, with a slight lateral groove; ovaries villous, mostly with appressed hairs; ovules 5–8 per ovary, lateral, uniseriate. Fruits consisting of ca. 13 moniliform monocarps borne on a pedicel not less than 6.4 cm long; monocarps 2.3–7 × 0.5–0.6 cm, surface smooth and pilose with appressed hairs, apex apiculate, base contracted into a stipe 7–11 mm long, pilose-villous with appressed hairs. Seeds 2–8 per monocarp, ellipsoid, ca. 8 × 6 mm, smooth and glabrous, raphe slightly raised.

Etymology:— The epithet is derived from “Hala-Bala”, which is the name of a wildlife sanctuary where this species occurs.

Habitat and phenology:— At original location, occurs in evergreen forests. Flowering specimen collected in April; fruiting specimen collected in November.

Additional specimen studied (paratype):— THAILAND. The same place where the type specimens were collected, 4 November 2018, Chaowasku 181 (CMUB), in fruit.

Notes:— Besides Dasymaschalon grandiflorum (see Wang et al.2009), D.halabalanum also possesses considerably large petals ( Fig. 5A, B ). Both species occurs in the same province and probably the same protected areas; however, they can be readily distinguished by their habit: climbers in D. grandiflorum vs. shrubs in D. halabalanum . The population structure of the new species in Hala-Bala Wildlife Sanctuary and probably adjacent areas (both southern Thailand and northern Peninsular Malaysia) is currently unknown; therefore, the conservation status category “DD: Data Deficient” ( IUCN 2012) is herein applied.

Figures

FIGURE 2. Floral morphology of Dasymaschalon spp. A. Dasymaschalon sp. TH (= Dasymaschalon halabalanum). B. Dasymaschalon dasymaschalum 1 (= true Dasymaschalon dasymaschalum). C. Dasymaschalon dasymaschalum 2 (= Dasymaschalon argenteum). Photographs by K. Aongyong (C), P. Dammit (A), and T. Chaowasku (B).

FIGURE 3. Distribution of Dasymaschalon halabalanum (square), locality of Dasymaschalon dasymaschalum 2 (= Dasymaschalon argenteum; inverse triangle), and locality of the lectotype of Unona dasymaschala (= Dasymaschalon dasymaschalum; triangle).

FIGURE 4. Holotype of Dasymaschalon halabalanum at CMUB.

FIGURE 5. Dasymaschalon halabalanum. A. Flower. B. Petal, adaxial side. C. Flower with petals removed. D. Flower, top view, showing sepals (abaxial side) enlarged. E. Stamen, adaxial (left) and abaxial (right) sides. F. Carpel.All from the holotype.