Musa ruiliensis W.N. Chen, Häkkinen & X.J. Ge, 2014

Chen, Wenna, Häkkinen, Markku & Ge, Xue-Jun, 2014, Musa ruiliensis (Musaceae, Section Musa), a new species from Yunnan, China, Phytotaxa 172 (2), pp. 109-116 : 110-113

Musa ruiliensis W.N. Chen, Häkkinen & X.J. Ge , sp. nov. ( Figs. 1–2 )

The new species is similar to M. chunii Häkkinen (2009: 87) and M. rubinea Häkkinen & C.H.Teo (2008: 24) in habit, but differs from them in its higher plant and erect leaves. In addition, it also can be distinguished from M. chunii by its buds pink-red abaxially and pale-yellow adaxially, fruit slightly ridged, 30 seeds per fruit, and from M. rubinea in its 2–3 fruits per hands of fruit on average, individual fruit to 10 cm long, 3–3.5 cm in diameter, slightly ridged, apex rounded, seeds black, tuberculate, irregularly angulated, depressed, ca. 6 mm in diameter, ca. 30 per fruit. In addition, M. ruiliensis can be distinguished from M. zaifui Häkkinen & H.Wang (2008: 43) by much higher plant and its fruit bunch compact with 7–8 hands ( Figs. 1 A–D ).

Type: — CHINA. Yunnan Province: Dehong Dai and Jingpo Autonomous Prefecture, Ruili , Daoba village (24°4’ N, 97°49’ E), 10 January 2013, 1055- 1460 m, X. J. Ge 2013 M01 (holotype: IBSC!, isotype: IBSC!). Figs. 2 A–B .

Plant slender, suckering freely, close to parent plant 20–60 cm, 8–10 suckers, position vertical. Mature pseudostem 1.8–2.5 m high, 6–9 cm diameter at the base, underlying colour light green, devoid of wax with small purple blotches and covered with old brown leaf sheaths, sap watery. Leaf habit erect, lamina 100–120 × 25–35 cm, intermediate with corrugated lamina, truncate at apex, adaxially dark green, dull, abaxially light green, appearance shiny, leaf bases asymmetric, both sides rounded, midrib adaxially medium green, abaxially light-pink. Petioles 60–90 cm long, petiole margins curved inwards, petiole bases winged and clasping the pseudostem. Inflorescence at first erect, then pendulous, peduncle 12–20 cm long and ca. 3 cm at diameter, pink, densely puberulent with short hairs. Sterile bract one, persistent at the opening of the first female flowers, pink-red abaxially and adaxially pale yellow. Female bud lanceolate, convolute. Female bracts 15–18 × 5–8 cm, pink-red abaxially and pale-yellow adaxially, shiny, apex pointed, lifting several bracts at a time, revolute and partly persistent. Basal 6–7 hands, flowers hermaphrodite. Flowers on average to 4 per bract in a single row, ovary to 5 cm long, light green, arrangements of ovules in two rows per locule. Compound tepal ca. 5 × 1.5–1.8 cm, orange-yellow, lobes orange, ribbed at dorsal angles, lobes 5. Free tepal ca. 3.5 cm long, translucent white, oval shaped, corrugated at apex with a short acumen, re-curved. Stamens 5, to 4.5 cm long, dark brown, light green style with orange stigma, style straight, inserted, creamy yellow. Male bud lanceolate, up to 14 × 4 cm, convolute, pendulous, bracts pink-red abaxially and adaxially pale yellow, lifting several bracts at a time, revolute and persistent, male bud commonly aborting after producing few bracts of male flowers. Male flowers on average 3–4 per bract in one row, 4.8–5.4 cm long. Compound tepal to 7 × 1.2 cm, cream, ribbed at dorsal angles, and with 5-toothed orange-yellow lobes. Free tepal to 5 cm long, translucent white, oval, with a short orange acumen, stamens 5, yellow-brown, light green style with orange stigma. Stamens 5, ca. 7.5 cm long, exserted, filament white. Ovary straight, 1.1–1.2 cm long, creamy white. Fruit bunch compact with 7–8 hands and on average 4 fruits per hand, in a single row, fingers curved towards the peduncle, individual fruit to 10 cm long, 3–3.5 cm diam., pedicel ca. 1 cm long, glabrous, fruits curved, slightly ridged, apex rounded with floral relicts, immature fruit peel light green becoming at maturity yellow. Seeds black, tuberculate, irregularly angulated, depressed, 4–6 mm across, 2–3 mm high, ca. 6 mm in diameter, ca. 30 per fruit.

Distribution and habitat: — Musa ruiliensis occurs in Yunnan, southwestern China. We found many fruiting plants along valley and stream around Daoba village, Ruili, Dehong Dai and Jingpo Autonomous Prefecture. This location is around 10 km to the border between China and Myanmar.

Etymology: —In reference to the location, Ruili city, where this species was collected.

Chromosome cytology: —For chromosome observation, root tips from seedlings of M. ruiliensis were pretreated using 0.1% colchicine and 0.002M 8-hydroxyquinoline with a ratio of 1:1 for 2 h before being fixed in Carnoy I (glacial acetic acid: absolute ethanol = 1:3), then macerated in a 1:1 mixture of 45% acetic acid and 1 M HCl at 60°C for 3 min, stained and squashed in Carbolfuchsin. The metaphase chromosomes were clearly counted as 2n = 2 x = 22 ( Fig. 3 ). The chromosome number of Musa sect. Musa (former Rhodochlamys ) species is 2n = 2 x = 22 ( Cheesman & Larter 1935, Simmonds 1962, Shepherd 1999, Häkkinen 2005, 2007, 2013).

Figures

FIGURE 1. The morphological comparisons of Musa ruiliensis and its close sister species.A. Inflorescence with flowers and fruit of M. ruiliensis. B. Inflorescence and fruit of M. chunii. C. Petiole basis and inflorescence with male bud and fruit of M. rubinea. D. Female flower and inflorescence with male bud of M. zaifui. Photos by X.J. Ge: A, and M. Häkkinen: B–D.

FIGURE 2. Holotype of Musa ruiliensis (Ge 2013M01, IBSC).A: inflorescence and fruits. B: leaf base and leaf apex. Note the fruits are from the same plant’s different stem.

FIGURE 3. Metaphase chromosomes (2n = 2x = 22) of Musa ruiliensis.