Amorphophallus bubenensis J.T.Yin & Hett., 2016

Yin, Jian-Tao, Yong, Luo, Li, Jian-Wu, Liu, Qiang, Huang, Zi-Yun & Hetterscheid, Wilbert, 2016, Amorphophallus bubenensis (Araceae), a new species from Yunnan, China, Phytotaxa 270 (2), pp. 155-157 : 155

Amorphophallus bubenensis J.T.Yin & Hett. , sp. nov. ( Fig.1 )

Differs from A. tonkinensis Engl. & Gehrm. in Engler (1911: 87) (SE China & N. Vietnam), the latter being at least twice as large, the stigmas having a circular or triangular outline and often being two- or three-lobed, a broadly ovate-conical appendix and a smooth tuber. Amorphophallus croatii Hett. & A.Galloway in Hetterscheid (2006: 53) ( Laos) differs in half as long a style and a much more heavily verrucate stigma.

Type:— CHINA. Yunnan province: Buben, Mengla County, elevation 600 m., in dense rainforest, 17 July 2012, Yin Jian-Tao2186 (holotype, HITBC! infl.).

Herb tuberous, semi-evergreen. Tuber subglobose, surface with many raised areas, brown outside, white inside, 2.5 cm high, 3.8 cm in diameter. Leaf appearing without inflorescence; petiole terete, 50 cm long, 1 cm in diameter, green with pale green, white-margined, irregular spots, developing a bulbil at the top; lamina ca. 70 cm in diameter, decompound, divided into 3 main segments; anterior segment shorter than posterior ones and consisting of only one elongate elliptical leaflet of ca. 27 cm long and 6 cm wide, acuminate; posterior segments with three leaflets each; rachises only winged distally. Inflorescence solitary, long pedunculate; peduncle 13.5 cm long, 6 mm in diameter., colour and spotting as petiole but generally darker. Spathe broadly cymbiform, 10 cm long, 9.5 cm wide, mid green outside with several paler, white margined spots near the base, pale green inside, top broad acute, margin of upper half recurved. Spadix shorter than spathe, ca. 7.5 cm, producing a light soap-like fragrance during female anthesis, sessile; female zone cylindrical, 1.5 cm long, 1 cm in diam., contiguous with male zone, pistils slightly congested; ovary subhemisperical, pale green, 2 mm in diameterer, 2 mm high, 2-locular, one basal ovule per locule; style cylindric, 1 mm long, ca. 0.8 mm in diameter., purple; stigma disciform, penta- to hexagonal with slightly concave sides and broadly obtuse angles (lobe apices), surface verruculose with a shallow central depression, dirty yellow; male zone cylindrical, 1.8 cm long, 1.2 cm in diam., flowers congested; number of stamens per flower indeterminable, stamens 2 mm in diameter., 1.2 mm long, thecae obovoid, dehiscing apically by a pore, pollen yellow; appendix contiguous with male zone, elongate conical, 4 cm long, 1.1 cm in diameter., obtuse, slightly laterally compressed, off-white, smooth to shallowly corrugated.

Distribution and ecology:— China, Yunnan province, Mengla County. The species grows in humid dense tropical forest at an elevation of 500–800 m and flowers in July.

Eponymy:— Buben (Bubeng) is a small town in Mengla county in China.

Notes:— Amorphophallus bubenensis is thought to belong to a small group of semi-evergreen species found in humid forests in S & SE China, Laos and northern Vietnam. This group belongs to a larger subclade of species with short spadices, conical smooth appendices and often foliar bulbils. This subclade is part of a larger clade (molecular phylogenetic results by Claudel & al., unpublished data) uniquely characterized in the genus by blue fruits. This latter character has been confirmed for A. tonkinensis and A. croatii but not yet in A. bubensis (no fruits as yet observed). Direct comparison with the two morphologically most similar species are given in de diagnosis (see above).

Additional material examined (paratypes):— CHINA. Yunnan province: Buben , Mengla County, elevation 600 m., in dense rainforest, 10 August 2012, Yin Jian-Tao 2187 ( HITBC!, leaf) ; Mengxing, Menglun, Mengla , elevation 600 m., in wet valley, 25 July 2008, Yin Jian-Tao 1060 ( HITBC!, infl.) .

Figures

FIGURE 1. Amorphophallus bubenensis, A: Flowering plant; B: inflorescence, spadix exposed; C: lower part of spadix with pistils and stamens (spathe base cut open); D: dried leaf showing small triangular bulbil at the top of the petiole.