Thursday, January 3, 2019

[Botany • 2018] Tacca khanhhoaensis (Taccaceae) • A New Species from southern Vietnam

Tacca khanhhoaensis V.S. Dang & Vuong

in Dang, Truong, Nguyen & Hoang, 2018.

Tacca khanhhoaensis V.S. Dang & Vuong (Taccaceae) is described as a new species from Hon Ba Nature Reserve in southern Vietnam. This species is morphologically similar to T. chantrieri and T. ampliplacenta but differs from its allies by several salient characters: size of leaves and petioles, inflorescent much shorter leaves, number of flowers, stigma lobes, buds colour. A description, conservation assessment, together with photographs and a key to the species of Tacca in Vietnam are presented.

Keywords: Hon Ba Nature Reserve, Khanh Hoa, Taccaceae, Taxonomy, Vietnam


Tacca khanhhoaensis V.S. Dang & Vuong

Figure 2. A Habit B Inflorescent much shorter leaves C Habitat. 
Figure 3. A Inflorescence B Fruits C Flowers, top view showing perianth lobes, stamens and stigma D Outer perianth lobes E Inner perianth lobes F Inner surface of perianth tube G Anther and connective H Longitudinal section of Anther with a pair of theca I Outer involucral bracts J Inner involucral bracts K Stigmas L Finely pubescent hairs at apex of stigma lobes M Black hairs on style N Longitudinal section of flower O Transverse section of fruit P Transverse section of ovary Q Seeds.

Tacca khanhhoaensis V.S. Dang & Vuong, sp. nov.

Diagnosis: Tacca khanhhoaensis is similar to Tacca chantrieri André in leaf shape and bracts, but differs from it in having shorter leaves (up to 45 cm vs. 60 cm long) and petioles (up to 22 cm vs. 43 cm long), inflorescences with fewer flowers (5 to 10 vs. 15 to 25), 2-lobed stigma vs. 3-lobed stigma and dark red buds vs. green buds. The new species is also somewhat similar to T. ampliplacenta L. Zhang & Q.-J. Li of China, but differs from it by having smaller leaves (30–45 × 10–14 cm vs. 55 cm long) and fruits (3–4 × 1.5–2 cm vs. 4–6 × 2–2.5 cm) and very short petioles (22 cm vs. 50 cm long), inflorescent much shorter leaves (vs. longer), number of flowers (5 to 10 vs. 25) and dark red buds vs. black-purple.

Distribution and habitat: Tacca khanhhoaensis is only known from Hon Ba Nature Reserve, Khanh Hoa Province, southern Vietnam. It was growing under the shade of the canopy on dry soil or close to the stream, where Aporosa tetragona Tagane & V.S. Dang, Bambusa sp., Barringtonia macrostachya (Jack) Kurz, Calamus sp., Croton sp., Desmos sp., Goniothalamus flagellistylus Tagane & V.S. Dang, Ixora sp., Microcos tomentosa Sm., Phyllanthus reticulatus Poir. and Streblus indicus (Bureau) Corner are dominant.

Etymology: The name of this species is derived from the name of the province Khanh Hoa, where the species was discovered.

Van Son Dang, Ba Vuong Truong, Thi Phuong Thao Nguyen and Nghia Son Hoang. 2018. Tacca khanhhoaensis V.S. Dang & Vuong (Taccaceae), A New Species from southern Vietnam. PhytoKeys.  114: 115-122.  DOI: 10.3897/phytokeys.114.29367