Dasymaschalon bachmaensis N.S. Lý, T.H. Lê, T.B.

Ð ỗ, Ng ọc-Ðài, Lý, Ng ọc-Sâm, Lê, Th ị-Hương & Vương, Trương Bá, 2018, Dasymaschalon bachmaensis (Annonaceae), a new species from B ch Mã National Park, North Central Coast region, Vietnam, Phytotaxa 379 (1), pp. 49-56 : 50-54

Dasymaschalon bachmaensis N.S. Lý, T.H. Lê, T.B. VƯƠng & N.Đ. Đỗ sp. nov. ( Figs.1 & 2 )

Type:― VIETNAM. Thừa Thiên Huế Province: Nam Ðông District , HƯƠng Phú Commune, MƠ Waterfall, Bạch Mã NP, 16°12′47″N, 107°43′33″E, 116 m a.s.l., May 2013, Ðài ĐN-255 (holotype VNM; isotypes HN, P) .

Most similar to D. glaucum Merr. & Chun (1934: 227) but differs in its leaf blades that are sparsely hairy abaxially with an obtuse leaf base (vs. glabrous, cordate), pedicels that are 30–48 mm long (vs. 17–19 mm), triangular-ovate sepals that are larger (6.5–7.2 × 1.8–3 mm vs. 2.5–3 × 2.5–3 mm) and hairy on both surfaces (vs. triangular with sparsely hairy abaxially), a shorter floral chamber (4.8–7.2 mm long vs. ca. 24 mm), the petals are pale greenish-yellow and much longer, 55.2–71.5 × 7–10 mm (vs. purplish-red and shorter, 26–42 × 8–10 mm), fewer stamens per flower (58–65 vs. ca.120), fruits that lack constrictions between seeds, 12–14.4 × 6–7.2 mm (vs. constricted, 16–55 × 5–7.5 mm) and the subglobose seeds, 5–6 × 3.5–5.4 mm (vs. ellipsoid, 6.5–13 × 4.8–7).

Small trees, up to 5–7 m tall, 16–25 cm d.b.h. Young branches (twigs) 1.5–2 mm in diam., greenish with rustybrown hairs, with longitudinal wrinkled or somewhat ridged, dark brown and glabrous when older. Laminas 7.8(9.4)– 15.5(18.6) × 3(3.6)–5(6) cm, length/width ratio 2.6–3.1, elliptic to somewhat obovate, green adaxially, glaucous abaxially, drying dull brownish-yellow to olive-yellow, sparsely hairs when young then glabrous with age except sparse hairs abaxially, coriaceous, apex acuminate, with a short mucro ca. 2 mm long, base obtuse and symmetric; midrib slightly sunken above, prominent below; secondary veins (8–)9–10(–11) per side, arching and looping indistinctly near margin, somewhat flush adaxially, prominent below, insertion on midrib perpendicular, tertiary venation percurrent; petioles stout, shallowly canaliculated adaxially, 2.6(3.1)–6(7.2) × 1.2–1.5 mm, dull greenish, drying dark brown, dense hairs when young then very scattered hairs with age, irregular and finely wrinkled. Flowers on young growth, pendent, axillary or terminal, usually solitary, sometimes 2-flowered fascicle on the short peduncle, 4–5 × 0.5–0.7 mm; pedicels 30–42 × 0.5–1 mm, green, sparsely hairy. Bracts narrowly lanceolate, 1.2–1.5 mm long, 0.3–0.5 mm at widest point, greenish, dense hairs. Sepals 6.5–7.2 mm long, 1.8–3 mm wide, length/width ratio 2.4–3.6, narrowly triangular-ovate, light green, sparsely hairy adaxially, densely hairy abaxially, apex attenuate. Petals 3, connivent to base at maturity, 55.2–71.5 mm long, 7–10 mm wide, length/width ratio 7.2–7.8, narrowly-ovate, spirally twisted, ca. 0.5 mm thick, coriaceous, glabrous adaxially, sparsely hairy abaxially, pale greenish-yellow; floral chamber 4.8–7.2 mm long (7.8%–9.3% of petal length). Stamen 58–65 per flower, 2–2.4 mm long; connectives somewhat truncate, ovate, 0.4–0.5 mm long, 0.6–0.8 mm wide, glabrous, concealing the extrorse anther cells; filaments ca. 0.1 mm long. Carpels 19–23 per flower; ovaries cylindrical, 1.4–1.8 mm long, 0.5–0.6 mm, wide, very densely hairy; stigma capitate, 0.4–0.6 mm long, ca. 0.2 mm wide, glabrous. Fruiting pedicels 3–4.2 × 1–1.5 mm wide, glabrous to scattered hairy. Monocarps 9–13(–20); fruit obloid-ovoid, 12–14.4 × 6–7.2 mm, lacking constrictions between seeds, smooth, glabrous excepted scattered hairy at apical part; apicule ca. 0.2 mm long; stipes 2–2.5 × 1–1.5 mm, glabrous. Seeds 2 per monocarp, 5–6 × 3.5–5.4 mm, length/width ratio 1.1–1.4, subglobose, apical strongly concave, drying brown, with a longitudinal circle groove, with ruminations in cross-section, endosperm lamelliform, soft.

Distribution: Vietnam, Thừa Thiên Huế and Ðà Nẵng City.

Habitat and Ecology: —Grows along stream bank or hill slopes in secondary evergreen broad-leaved forest.

Phenology: —Flowering in May-June and fruiting in July-September.

Preliminary conservation assessment: —Endangered (EN B2 a,b(ii,iii), C2a(i), D). Four subpopulations comprising fewer than 10 scattered mature individuals were observed at Bạch Mã NP. In addition to the type locality,

this new species collected c. 40 km north at Tourane (the former name of Ðà Nẵng City) by Clemens in 1927, which is closed to Bạch Mã NP. The extent of occurrence (EOO) is estimated at less than 1000 km 2. The habitat is fragmented and still faces some at risk due to loss of the habitat within its range (in particular the clearing of forest land for Acacia and rubber plantations). Some surveys have been conducted in neighbouring areas around Bạch mã NP by the first author but no population of this species was found. Based on currently available data we therefore provisionally assess this species as Endangered (EN B2 a,b (ii,iii), C2a(i), D) according to the IUCN Red list criteria (IUCN, 2012).

Etymology: —The specific epithet refers to the type locality, Bạch Mã NP, where the new species was discovered and collected.

Additional specimens examined: — INDO-CHINE. Annam: Enroute to Asclp. Falls , Hoi Mt, 40 km north Tourane, 10 August 1927, J. Clemens & M.S. Clemens No. 4217 (P: P00451192!). VIETNAM. Th ừa Thiên-Huế Province: Nam Ðông District, HƯƠng Lộc Commune, Village 3, Bạch Mã NP, 16°12′47″N, 107°43′33″E, 147 m a.s.l., May 2013, Ðài ÐN-274 (VNM) ; The same locality, July 2012, Ðài ÐN-157 (VNM), Ðài ÐN-720 (HN, VNMN) and Ðài- ÐN 722 (VNM, VNMN) ; The same locality, HƯƠng Phú Commune, Bạch Mã NP, MƠ Waterfall, around 116°12′47″N, 107°43′33″E, 116 m a.s.l., May 2013, Ðài ÐN 257 (VNM) ; The same locality, ThƯợng Lộ Commune, Rội Village, Bạch Mã NP, around 16°08′25″N, 107°43′36″E, 203 m a.s.l., May 2013, Ðài ÐN-543 (VNMN) ; The same locality, Dớn Ravine, Bạch Mã NP, 16°08′21″N, 107°48′06″E, 18 m a.s.l., July 2011, Ðài ÐN 267 (HN) .

Notes: —in Vietnam, the new species is similar to D. glaucum , D. sootepense Craib (1912: 144) and D. wallichii (Hook. f. & Thomson (1855: 135)) J. Wang & R.M.K. Saunders (2009: 263) in having glaucous leaves, petals that are somewhat ovate and spirally twisted, and stamens that are truncate with a glabrous connective, and glabrous ovaries and stigmas. The major differences between the new species and D. glaucum are outlined above in the diagnosis. Dasymaschalon sootepense and D. wallichii can be distinguished from D. bachmaensis by their leaf shape, the triangular sepals that are smaller and sparsely hairy abaxially, the pale greenish-yellow petals, the numerous stamens, the larger ovaries, the larger fruits that are constricted between seeds, and the larger seeds that are somewhat ellipsoid ( Table 1).

Dasymaschalon bachmaensis firstly discovered over 90 years ago by Clemens and Clemens in Vietnam and their collection kept in the Muséum National d’Histoire Naturelle in Paris (P: P00451192!), remained unnamed until now. The specimen was collected at Hoi Mt, 40 km North of Tourane (the former name of Ðà Nẵng City), Annam. Although the Clemenses’ specimen was not flowering, its leaves are elliptic to obovate, dull brownish-yellow to olive-yellow, with 8–10 pairs of secondary veins, fruiting pedicels that are 3.1–4 cm long, and obloid and brown monocarps are clearly match our new collections from Bạch Mã NP. Hence we conclude that the Clemenses’ specimen and all specimens from Bạch Mã NP are conspecific.

Seven species inducing one new species and two new varieties of Dasymaschalon , D. teuanum Bân (2000: 178) , D. rostratum var. glacum (Merr. & Chun (1935: 227)) Bân (2000: 184) and D. rostratum var. logniusculum (Merr. & Chun) Bân (2000: 183) , have been recognized by Bân (2000) in his revision of Annonaceae in Vietnam, where D. sootepense Craib (1912: 144) was reported for the flora of Vietnam based on the herbarium specimen was collected by E. Poilane at Mt. Mam Ray, province de Kon Tum, 2 December 1930, 1200 m alt., Poilane No. 18191 (P: P00451254!). However, Wang et al. (2009) have been treated the Poilane’s specimen as D. acuminatum Jing Wang & R.M.K. Saunders (2009: 254) and also considered D. rostratum var glaucum as a synonym of D. glaucum Merr. & Chun (1935: 227) . In the present study, we adopted the Wang et al. work (2009) and further studies to clarify taxonomic status of D. sootepense in Vietnam are required. The main distinguishing characters among the 10 taxa of Dasymaschalon in Vietnam are presented in a key to species. A distribution map of all species is also given ( Fig. 3 ).

Key to species of Dasymaschalon in Vietnam

1. Petals not twisted, <30 mm long.......................................................................................................................................................2

– Petals twisted, ≥ 30 mm long............................................................................................................................................................6

2. Leaf laminas glabrous, 6–10 cm long.................................................................................................................................................3

– Leaf laminas somewhat hairy abaxially,> 10 cm long......................................................................................................................4

3. Leaf laminas oblong-elliptic, 6–7.5 × 1.5–3 cm long, base rounded, apex obtuse; petiole 4–5 mm long; sepals ca. 3 × 2 mm, glabrous; petals ca. 11 × 5 mm, glabrous; connectives rounded; monocarps ovate..................................... Dasymaschalon ervardii

– Leaf lamina oblong-elliptic, 6–7.5 × 1.5–3 cm long, obtuse at both ends, sometimes base cordate; petiole 2–4 mm long; sepals ca. 5 × 2 mm, hairy abaxially; petals 20–25 × 7–8 mm, hairy abaxially; connectives acuminate; monocarps globose ............................ ................................................................................................................................................................... Dasymaschalon robinsonii

4. leaf laminas elliptic to oblong or obovate, hairy abaxially, apex acute; flowering pedicel 2–25 mm long; sepals triangular, hairy abaxially; connectives truncate to apiculate.......................................................................................................................................5

– Leaf laminas ± ovate, glabrous, except midrib sparsely hairy, apex obtuse or short acuminate; flowering pedicel ca. 5 mm long; sepals ± ovate, hairy on both surfaces; connectives rounded.............................................................. Dasymaschalon lomentaceum

5. Young branches glabrous; leaf laminas elliptic, apex acuminate, base slightly attenuate cordate or rounded, sparsely hairy abaxially; leaf petioles 4–8 mm long; flowering pedicel ca. 15 mm long; sepals 1.5–2 × 1.5–2.5 mm; petals 27–31× 7–9 mm; connectives truncate; monocarps and seed ellipsoid................................................................................................. Dasymaschalon acuminatum

– Young branches rusty brown hairs; leaf laminas oblong or obovate, (7)10–14(16) × 3–5(6) mm, leaf base rounded or cordate, apex acute, rusty brown hairy abaxially; leaf petioles 2–3 mm long; flowering pedicel 2–25 mm long; sepals 6–15 × 4–7 mm; petals 15–25 × 6–10 mm; connectives apiculate; monocarp and seed globose................................................. Dasymaschalon macrocalyx

6. Petals glabrous or hairy on both surfaces; sepals broadly ovate........................................................................................................7

– Petals hairy abaxially; sepals triangular.............................................................................................................................................8

7. Leaf laminas elliptic to obovate, leaf base obtuse, apex acuminate; sepals 6.5–7.2 × 1.8–3 mm, hairy on both surfaces; petals 55.2–71.5 × 7–10 mm; monocarps obloid-ovoid 12–14.4 × 6–7.2 mm; seed sub-globose, 5–6 × 3.5–5.4 mm .................................. .............................................................................................................................................................. Dasymaschalon machmaensis

– Leaf laminas ± obovate-oblong, leaf base rounded, apex short acute; sepals 2.5–3 × 2.5–3 mm, hairy abaxially; petals 44–50 × 10 mm; monocarps ellipsoid, 6–55 × 5–7.5 mm; seeds ellipsoid, 6.5–13 × 4.8–7 mm ................................... Dasymaschalon glaucum

8. Leaf laminas elliptic-oblong, (6)8–13(15) × (2.5)3–4.5(5) cm, hairy abaxially, leaf petiole 4–5 mm long; petals narrowly-ovate, 35–55 × 7–8 mm, glabrous; flowering pedicel 3–5 mm long ..................................................................... Dasymaschalon tueanum

– Leaf laminas oblong or obovate obong, 15–22 × 4–7 cm, glabrous except veins abaxially, leaf petiole ca. 10 mm long; petals oblong-ovate, 40–88 × 10–25 mm, slightly hairy on both surfaces; flowering pedicel 15–40 mm long ............................................. ................................................................................................................................................................... Dasymaschalon rostratum

8A. Flowers on young branches, single; petal oblong-ovate oblong, 4–8 × 1–2.5 cm; monocarps oblong ............................................... ................................................................................................................................................................... Dasymaschalon rostratum

8B. Flowers usually on old branches, two; petal oblong, 15–20 × ca. 1 cm; monocarps ovate or globose................................................ ...................................................................................................................................... Dasymaschalon rostratum var. longiusculum

Figures

FIGURE 1. Dasymaschalon bachmaensis. A. Flowering branch; B. Detail of leaf; C. Flower; D. sepal; E. Tepal; F. Torus showing sepals, stamens and carpels; G. Torus showing sepals and carpels; H. Carpels; I. Stamens; J. Infructescence; K. Fruits; L seeds. Drawn from the type material, Ðài ĐN-255.

FIGURE 2. Dasymaschalon bachmaensis. A. Flowers with a mature flower showing the petals opened at base (a red arrow); B. Infructescence with mature monocarps.

FIGURE 3. Distribution of Dasymaschalon species in Vietnam. A. D. acuminatum, D. bachmaensis, D. glaucum, D. ervardii and D. lomentaceum. B. D. macrocalyx, D. robinsonii, D. rostratum, D. rostratum var. longusculum and D. teuanum.