NOVON 9(4): 526-529. 1999.
Supee Saksuwan Larsen
Department of Systematic Botany, Institute of Biology, Aarhus University, DK-8240 Risskov, Denmark
Bauhinia wuzhengyii, a new species from Yunnan, China, is described and illustrated. Its relationship within the section Loxocalyx is discussed. The section Loxocalyx Bentham, containing the new species, is reinstated based on re-assessment of the obliquely campanulate hypanthium and free gynophore.
During a visit to the Chinese Kunming Institute of Botany in May 1997, the author, who has been invited to act as co-author of Bauhinia for Flora of China, went through the herbarium of the genus. Here a specimen of an undescribed species was discovered. This sheet had been annotated (in 1959) by the eminent Chinese botanist Wu Zheng-yi as Bauhinia cinnamomifolia sp. nov. This name, however, has been ascribed to section Cinnamomifolia under Phanera, a group to which this species clearly does not belong. From discussions with Prof. Wu it was evident that he had no plans to describe this species. It is therefore a great pleasure to dedicate this new species to him.
Bauhinia wuzhengyii S. S. Larsen sp. nov. TYPE: China. Yunnan: Malipo County, Tian Bas, in thin forest on mountain slope, 480 m, 27 July 1958, Hu Yue Ying & Wen Shao Kong 580812 (holotype, KUN). Figure 1.
Bauhinia wuzhengyii species nova sectionis Loxocalycis, Bauhiniae wallichii MacBride affinis a qua differt foliis integris, stigmate subsessile.
Liana, tendrils not seen. Flowering branches terete, glabrous. Leaf lamina entire, elliptic, 9.0--10.3 × 4.8--5.3 cm, glabrous both sides, base attenuate, apex abruptly acuminate; nerves 3; stipules not seen; petiole 2.3--3 cm long, thickened at both ends. Inflorescence terminal, an elongated raceme, with 2 racemes evident on type, one with a reduced leaf at base. Inflorescence axis up to 19 cm long, finely grayish pubescent; bracts 4--5 mm long, setaceous, finely pubescent outside; bracteoles similar but minute, 0.5 mm long, subopposite, inserted below the middle of the pedicel; pedicel 2.5--3 cm long, finely grayish pubescent. Flower buds ellipsoid, 9--10 × 5--6 mm, finely grayish pubescent; hypanthium obliquely campanulate, enlarged adaxially, ca. 4 mm, twice the length of abaxial portion (Fig. 2A, B), apically pubescent except middle part of adaxial margin ( Fig. 2F). Calyx 3--4 mm long, campanulate (occasionally slightly bilabiate, Fig. 2B), open in bud, split in upper half to 5 lobes, each with acute apex, finely grayish pubescent outside, inside glabrous to sparsely pubescent. Corolla with 5 subequal petals, 4 lateral ones spathulate, 7--10 mm long including a 2--3-mm claw, densely brownish pubescent on both sides, becoming glabrous toward claw; posterior petal ± obovate-oblong, carinate, basally fleshy, ca. 2 mm, with claw indistinct, upper portion, ca. 5 mm, finally reflexed, inside glabrous, outside pubescent in upper portion, marginally and basally glabrous. Fertile stamens 3; filaments ca. 10 mm long, glabrous; anthers 1.5--2 mm long, glabrous, dehiscing longitudinally; staminodes 5--7, 3 posterior forming a 3-dentate connate structure, 1.5 mm long (Fig. 2F); middle connate staminode slightly larger, inflated at base to a low rim, the 2 lateral teeth inserted behind the rim; 1--2 minute staminodes at both sides of the teeth and 1--2 minute staminodes between the fertile stamens. Pistil with thick stipe, free, 2--3 mm long, brownish woolly pubescent, inserted at lower abaxial side of hypanthium (Fig. 2F); ovary ca. 9 mm long, brownish woolly pubescent throughout, stigma subsessile, ± punctate, style glabrous, very short, ca. 1 mm. Ovules ca. 8. Pods not seen.
Distribution and habitat. Only known from the type locality.
Bauhinia wuzhengii is here described based on a single collection in KUN, as the author was unable to locate any iso- or paratypes (see Note 1). After my experience of revising the genus Bauhinia for Flora Malesiana and the Indochinese floras, this new species is, however, so striking in both flower and leaf morphology that I am not in doubt that it deserves specific status.
Bauhinia wuzhengyii belongs to the section Loxocalyx Bentham (Syn.: series Loxocalyx (Bentham) Wunderlin, Larsen & Larsen, 1987) together with B. wallichii MacBride and B. japonica Maximowicz. These three species have a free gynophore (stipe) inserted at the lower or upper abaxial side of the hypanthium. The new species is easily distinguished from these two other species by having entire leaves with 3 nerves, a subsessile stigma, and a 3-dentate, staminodial structure. Bauhinia japonica has bilobed leaves (1/3--2/3 of the length), while B. wallichii has leaves emarginate to bilobed (1/3 of the length); both species have 9--13-nerved leaves, distinct style, and a 5-digitate staminodial structure. Bauhinia japonica is a coastal species distributed from Japan to Hainan, extending to a single locality along the coast of Kwangtung (Larsen & Larsen, 1982). Bauhinia wallichii is distributed from India (Silhet, Assam) to Myanmar and northern Vietnam (Larsen et al., 1980). Bauhinia wallichii was recently reported from southeastern Yunnan by Zhang and Chen (1996) and from northern Thailand (S. S. Larsen, in press).
The tri-nerved leaves with entire margins of Bauhinia wuzhengyii are similar to those in section Tubicalyx Wunderlin, Larsen & Larsen (1987). Despite superficial similarities between floral structures, the Tubicalyx group is distinguished by hypanthia not being oblique, gynophores adnate to the hypanthium wall, and all the staminodes being free and not connate as a compound structure.
The pollen grains of Bauhinia wuzhengyii are 3-colporate (Fig. 3A) with rugulose tectum (Fig. 3B, C). Pollen of this new species belongs to the curtisii pollen type, grouping together with B. japonica (S. S. Larsen, 1975) and B. wallichii (S. S. Larsen, in press).
In conclusion, the morphology and palynology point to this species being related to Bauhinia wallichii and B. japonica. It must, however, be emphasized that very little pollen has been available for SEM studies. Further studies, including sectioning of pollen, are highly needed for a comparison with other members of the curtisii pollen type.
Note 1.Zhang (1993) reported a Bauhinia strychnoidea Craib from Yunnan, probably referring to B. strychnifolia Craib, as B. strychnoidea Prain is a Malaysian species. This record is based on the same collecting number as the type of B. wuzhengyii. Dr. Zhang (pers. comm.) has seen material either in Kunming (KUN) or in Xishuangbanna (HITCB), but his determination does not appear on the holotype specimen.
Note 2.Since the work by Wunderlin et al. (1987), knowledge on the variation and structure of floral characters in Bauhinia has considerably increased. Consequently, the section Loxocalyx Bentham (1865) is reinstated under Bauhinia subg. Phanera. This was earlier referred to as series Loxocalyx Wunderlin, Larsen & Larsen (1987); Zhang (1996) raised series Loxocalyx to a subsection, transferring it to section Lasiobema, but in this we cannot follow him for the diagnostic reasons listed below.
Bauhinia [subg. Phanera] section Loxocalyx Bentham (1865), emended description:
Differs from other sections of subgenus Phanera by the campanulate, 5-dentate calyx open in bud; the hypanthium being obliquely campanulate, with the adaxial side twice as long as the abaxial and with the posterior staminode forming a dentate or digitate, fleshy structure; the gynophore (stipe) free, inserted on the lower or upper abaxial side of the hypanthium, and the stigma ± punctiform.
The author is indebted to Hu Chi Ming for translating the Chinese texts on the label, to Benjamin Øllgaard for latinizing the diagnosis, to Anni Sloth for technical work on pollen and photography, and to Oratai Kirdkaew for preparing the line drawing from sketches made by the author. The stay in Yunnan was sponsored by the Academia Sinica; a grant from the Carlsberg Foundation covered the travel expenses to China. Warm thanks are also extended to the staff of the botanical institutes in Kunming and Xishuangbanna.
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