Musa haekkinenii N.S.Lý & Haev., 2012

Lý, Ng ọc-Sâm, Lê, Công-Ki ệt, Tri ệu, Tién-Dùng, Haevermans, Agathe, Lowry Ii, Porter P. & Haevermans, Thomas, 2012, A distinctive new species of wild banana (Musa, Musaceae) from northern Vietnam, Phytotaxa 75 (1), pp. 33-42 : 35-37

Musa haekkinenii N.S.Lý & Haev. , sp. nov. ( Fig. 1 )

Similar to M. coccinea , but differs by its leaf shape and size (lamina oblong-elliptic, c. 112 × 40 cm, one side pointed and the other rounded at base, the apex truncate vs. oblong, c. 100 × 25 cm, rounded on both base and apex), persistent non-withering male bracts on the inflorescence axis that are denser and longer (up to 40 bracts, each 7.5–9.2 × 2–3 cm vs. c. 20 bracts c. 7 × 3 cm), and differences in the shape, color and habit of male bracts (ovate, bright orangered, recurving downward to touch the erect axis vs. ovoid, deep scarlet, ascending).

Type:— VIETNAM. Phú Th ọ Province : Phú Th ọ District, Phú H ộ Commune , 21°27’11”N, 105°15’16”E, 54 m, 19 November 2008, T . Haevermans et al. 508 (Holotype P! (incl. spirit material), isotypes VNM!, H!) .

Clump-forming, slender, herbaceous plant, suckering freely, with 2 to 6 suckers borne close to the base of the parent plant, up to 75–90 cm, oriented vertically; sucker leaves mostly auriculate at base, without blotches on leaves of water suckers. Mature pseudostem slender, up to 1.0– 1.5 m, 3–7 cm in diameter at base, medium green, shiny, predominantly light green with small brownish pigmentations, without wax, sap watery. Leaf habit semi-erect; petiole c. 33–35 cm, green, with sparse black-purple blotches at base, petiole canal straight with erect margins, petiole margins narrow, 5–7 mm wide, quickly scarious, winged and clasping pseudo-stem at the base. Lamina oblong-elliptic, 112–150 × 40–45 cm, narrowing gradually toward both ends, abaxial surface green and dull, adaxial surface dark green and shiny, no visible sign of wax on either surface, lamina moderately corrugated; midrib green on abaxial surface, green-cream on adaxial surface; insertion point of leaf base asymmetric and both sides attenuate on young stems/suckers, one side attenuate and the other rounded on mature stems; leaf apex aristate on young leaves (young stems/suckers), truncate with age. Inflorescence erect; peduncle 8–10 cm, 2.0– 2.4 cm in diameter, green, sometime tinted with red, glabrous; fertile leaf bracts 2, bright orange-red with a green leaf-like tip, persistent, non-withering. Female bud lanceolate, up to 19–20 × ca. 4.5 cm; female bract lanceolate, ca. 19 × 4 cm, inner bracts smaller, bracts lifting one at a time, recurved downward to axis with age, moderately grooved, lacking wax, not imbricate, bract base forming a small shoulder, margin not revolute, apex rounded, tinted yellow-green, not revolute; outer surface bright orange-red, inner surface paler. Basal flowers female, borne in 3 to 6 female hands, female flowers 2 or 3(or 4) per bract, arranged in a row, 6.4–7.1 cm, cylindrical, glabrous; the compound tepal 2.9–3.6 cm, orange tinted reddish, apex 5-lobed, without an appendage, green, lateral lobes 2.0– 2.5 mm, the 3 central lobes shorter, ca. 1.5 mm; free tepal oblong-ovate, as long as the compound tepal, 2.9–3.6 × 5–7 cm, dorsally thickened, opaque orange, closely appressed to the stigma, margin entire, apex rounded; stamens 5, infertile, lanceolate, short, 1.0– 1.5 cm, pale yellow, inserted at the base of the style; style straight, as long as the perianth, pale yellow; stigma terete, 6–8 × 4–6 mm at broadest part, orange; ovary straight, 2.6–3.5 × 0.6–1 cm at broadest part, yellow, with no other pigmentation, smooth, waxy, 3-locular, each locule with the ovules borne in two rows; pedicel almost indistinguishable from ovary. Male peduncle in older flowers erect, 18–20 cm, green to yellow-green, with a dense covering of 40 persistent bracts; male bud ovate, up to 8–10 × 4 cm, bracts imbricate at the tip; male bract oblong-ovate, strongly grooved, 7.5–9.2 × 2–3 cm, lifting one bract at a time to 45°, recurving downward to axis with age, lacking wax, persistent and non-withering, base with a small shoulder, margin not revolute, apex rounded, not revolute, tinted yellow-green, external surface bright orange-red, internal surface paler, color fading towards the base to yellow-orange. Male flowers (1 or)2 or 3 per bract (when 3, arranged in a row), 4.1–4.5 cm; compound tepals 3.7–4.5 cm long, orange with reddish pigmentation, lobes 5-toothed at apex, green, lateral lobes ca. 2 mm, the 3 central lobes shorter, ca. 1 mm; free tepal as long as the compound tepal or slightly exserted, narrowly oblong, 3.7–4.6 × 0.5–0.7 cm, opaque orange, thickened, smooth, apex rounded; stamens 5, 3.4–4.1 cm long, not exserted; filaments and anthers yellow, pollen cream or white-cream; style straight, held and at the same level as the stamens and compound tepal, yellow, with no other pigmentation; stigma orange, 4–6 cm long, 2.5–4.0 mm wide at broadest point, terete; ovary straight, very short, ca. 3.5 mm long, ca. 4.5 mm in diameter, orange, with other no pigmentation, bearing some wax, glabrous. Fruit bunch lax, with 3 to 6 hands, 2 or 3 fruits per hand, borne in a row, fingers orientated obliquely respective to the axis, forming a 45° angle upward; mature un-fertilized fruit narrowly ovoid, slightly triangular, 3.2–3.7 cm long, ca. 1.2 cm in diameter, orange-yellow, waxy, straight, slightly ridged, apex blunt, bearing the persistent perianth; pedicel very short, ca. 4 mm long, ca. 6 mm wide, fruits nearly sessile, glabrous. Mature fruits, seeds and chromosome number unknown.

Distribution and habitat: — Musa haekkinenii is known only from cultivated material, which bore flowers and infructescences with unfertilized fruits when it was observed and collected in December 2008 and December 2010. The prevailing climate in areas where the cultivated plants were growing is monsoon tropical, with an annual average rainfall ranging from 1560 mm (Sσn La) to 1850 mm (Phú Thọ) and an annual average temperature from 18.5°C in Sσn La to 23.1°C in Phú Thọ ( Nguyễn et al. 2000).

Conservation status: —This species is so far known only as cultivated plants in Phú Thọ and Sσn La province. Because no data are available on its distribution in the wild, Musa haekkinenii is provisionally considered as Data Deficient (DD) according to the IUCN (2001) Red List criteria and categories.

Etymology: —Our new species is named in honor of Markku Häkkinen, a world expert on banana taxonomy and associate researcher at the Botany Unit, Finnish Museum of Natural History, University of Helsinki, Finland. He has made remarkable contributions during more than 30 years of study on Musaceae and has conducted many collecting trips to Southeast Asia. The diacritic sign on the letter “ä” in his family name has been transliterated into Latin as “ae”, as recommended in Article 60.4 of the International Code of Botanical Nomenclature (McNeill et al. 2006), in spite of this being a latinisation of that letter from Germanic, not Fenno-Ugric languages.

Additional specimens examined (paratypes): — VIETNAM. L ạng Sσn Province : Uyên Châu District, Tú Nang Commune, 20°57’28.09”N, 104°26’05.82”E, 299 m, 21 December 2010, Lý 516 [P! (incl. spirit material), VNM!].

Notes: —Five previously published species of Musa indigenous to Vietnam are currently placed in sect. Callimusa , including M. coccinea (Andrews 1794: 47) and M. splendida ( Chevalier 1934: 517) , and three that were recently described: M. exotica ( Valmayor 2001) , M. viridis and M. lutea ( Valmayor et al. 2004) . The latter two are invalidly published, because the types mentioned are living specimens and no associated herbarium specimens were made according to the curator of the Phú Thọ fruit center (pers. comm.). Neotypes will be prepared as soon as the original live plants bloom again.

Musa haekkinenii resembles these species in several ways, such as the presence of erect inflorescences, the persistence of a perianth on the fruit and overall plant stature (leaf habit semi-erect, slender pseudostem of small diameter at base). While we have not seen mature fruit of our new species, it shares many features with M. coccinea , including plant height, petiole length, several inflorescence bract characters (color, persistence and non-withering habit) and the oblique fruit shape, all of which point strongly toward its placement in section Callimusa . However, M. haekkinenii differs markedly from M. coccinea by several other characters (Table 1), in particular its oblong-elliptic leaf shape, denser male inflorescence bracts that are more persistent, male bud shape and male bract color and habit. Moreover, the male flowers of M. haekkinenii are predominantly orange with spots of reddish pigmentation and the 5 green lobes lack appendages, whereas the flowers of M. coccinea are mostly bright orange without spots and the 2 lateral lobes each bear a spike-like appendage c. 1 mm long at the tip ( Cheesman 1950).

Several features shared by M. haekkinenii and M. coccinea , such as inflorescence structure, bract color and fruit position, distinguish them from other small wild banana species, including M. exotica , which has male bracts that persist but turn brown and ultimately fall off, imbricate bracts that are orange-red with a yellow apex and fruits that are attached perpendicular to the erect stalk. Musa haekkinenii can also be distinguished from the four other native Musa species known from northern Vietnam and adjacent southwestern China (viz. M. lutea , M. splendida , M. viridis and M. paracoccinea ) by plant height, male bract habit and color, fruit position and the color of immature fruit on the fruit bunches, as summarized in Table 1.

According to the owners of the gardens where we observed and collected Musa haekkinenii , the presumed origin of the cultivated material must have been from areas of native forest in northern Vietnam. During our field expeditions in 2008 and 2010 we traveled throughout the region, surveying ten National Parks and Nature Reserves, as well as other sites with remaining intact and partially degraded forest, but we failed to locate any wild populations of M. haekkinenii , although we did find wild populations of other members of sect. Callimusa , including M. exotica , M. lutea , M. splendida and M. viridis . As all these taxa were found in extremely limited and sparse populations growing on steep hills, open areas and along stream banks in secondary forest, it seems reasonable to anticipate that wild populations of our new species persist and that additional field trips to unexplored areas in the region planned for the near future may lead to their discovery.

As currently circumscribed, Musa sect. Callimusa comprises some 22 species, with representatives in three regions recognized as centers of diversity for wild members of the group: Borneo (14 species), Indochina (6 species) and the Sumatra-Malaysian Peninsula area (3 species), see Hakkinen (2009), Organization for Economic Co-operation and Development (OECD) (2009) and Li et al. (2010). In Indochina, one of the six species in the group, M. coccinea , is known throughout the provinces along the border between China and northern Vietnam, while the three others, M. exotica , M. lutea and M. viridis , occur somewhat further south and are restricted to northern Vietnam. Regarding the two remaining species, M. paracoccinea is also indigenous in Yunnan Province of southern China, while M. splendida is restricted to Lao Cai Province in northern Vietnam, which is separated from Yunnan by the Red River ( Valmayor et al. 2004). According to Liu et al. (2002), M. paracoccinea is closely related to M. coccinea , but Valmayor et al. (2004) consider it instead closer to M. splendida . In a recent comprehensive account of this section by Häkkinen (2009), however, M. splendida was not included, while OECD (2009) and Li et al. (2010) treated it as a member of this group. Similarly, M. viridis was recognized as a member of sect. Callimusa by OECD (2009), but was not mentioned by Li et al. (2010). The lack of consistency among authors currently studying wild bananas in the Indo- Chinese region points to the fragmentary nature of our taxonomic understanding of the group, a situation that reflects a paucity of field observations and adequate herbarium material. Additionally it is compounded by a large number of misidentifications and complex nomenclatural problems. Overcoming these challenges will require additional focused field work, coupled with molecular and phylogenetic analyses. An ongoing molecular phylogeny focused on the Callimusa section will be published soon (Lý et al., in prep.)

Vernacular name: —This species is locally referred to as Chu ṍ i r ù ng hoa d, “Chuỗi rừng” meaning wild banana and “hoa đỏ” meaning red inflorescence.

Figures

FIGURE 1. Musa haekkinenii. A—habit; B—cross-section of petiole; C—old leaf base; D—old leaf apex; E—young leaf base; F—young leaf apex; G—young female inflorescence; H—male inflorescence with many persistent bracts; I—inner surface of male bract; J—outer surface of male bract; K—male flower, ventral view; L—male flower, dorsal view; M—compound tepal; N—free tepal; O—female flower: ovary, compound tepal, free tepal, filaments, style and stigma; P—lateral view of male flower; Q—close-up of filaments, anthers, style, and stigma of male flower; R—un-fertilized fruit with persistent perianth. Scale bars: A = 50 cm; B = 1 cm; C–F = 20 cm; G = 10 cm; H = 5 cm; I–S = 2 cm. Based on dried materials, spirit materials (P) and photos of TH–508 and Lý–518.