Monday, July 11, 2022

[Botany • 2022] Isotrema haimingii (Aristolochiaceae) • A New Species from Dayaoshan Mountain of Guangxi, China

 

Isotrema haimingii Y.S. Huang & Yan Liu,

in Huang, Qin, ... et Liu, 2022. 
海明關木通  ||  taiwania.NTU.edu.tw

Abstract
Isotrema haimingii Y.S. Huang & Yan Liu, a new species from Dayaoshan Mountain of Guangxi, China, is described and illustrated. It is morphologically most similar to I. championii and I. yachangense in the shape of leaf blade, lanceolate-ovate bracteoles, oblong anthers, 3-lobed gynostemium and ellipsoid capsules, but can be easily distinguished from them by length of the basal perianth tube, colour of calyx limb and the outside of perianth tube, surface texture of calyx limb and throat. Photos of this new species, as well as a table to distinguish it from other morphologically similar Isotrema species, are provided. The threatened status of the new species is also assessed.

Keyword: Aristolochia, Dayaoshan Mountain, Flora of Guangxi, Isotrema championii, I. yachangense, new species, taxonomy

Isotrema haimingii Y.S. Huang & Yan Liu, sp. nov.
A: Habit. B: Leaf blades (adaxially and abaxially view). C: Portion of adaxially leaf blade (magnified view). D: Portion of abaxially leaf blade (magnified view). E: Cymes (showing unopened and blooming flowers). F: Flower (lateral view). G: Flower (front view, showing the calyx limb). H: Flower (dorsal view). I: Longitudinally dissected flower (showing the inside characters). J: Gynostemium and anthers. K: Capsule.
 (Drawn by Yun-Xi Zhu)

Isotrema haimingii Y.S. Huang & Yan Liu, sp. nov.
A: Habitat. B: Flowering branch. C: Leaf blades (adaxially and abaxially view). D-E: Flowers (front view, showing the calyx limb) F: Flower (lateral view). G: Flower (dorsal view). H: Ovary. I: Longitudinally dissected flower (showing the inside character). J: Gynostemium (vertical view). K: Anthers and gynostemium (lateral view). L: Bracteole. M: Capsule.


    

  

Isotrema haimingii Y.S. Huang & Yan Liu, sp. nov. 
海明關木通 

Diagnosis: Isotrema haimingii Y.S. Huang & Yan Liu is morphologically similar to I. championii (Merr. & Chun) X.X. Zhu, S. Liao & J.S. Ma and I. yachangense (B.G. Huang, Yan Liu & Y.S. Huang) Luu, Q.B. Nguyen & H.C. Nguyen in the shape of leaf blade, lanceolateovate bracteoles, oblong anthers, 3-lobed gynostemium and ellipsoid capsules, but can be distinguished from the former by cyme on old woody stems or in the axils of leafy shoots (vs. on old woody stems only); bracteoles ca. 5 × 2 mm (vs. ca. 10 × 5 mm); perianth tube yellowish-green outside (vs. mauve), basal portion of tube 4–5 cm long (vs. 5–7 cm long); calyx limb yellowish-green, with dark purple mural-like stripes on the upper portion and mauve stripes on the lower portion (vs. purple reticulate stripes, papillate), and from the latter by cyme on old woody stems or in the axils of leafy shoots (vs. on old woody stems only); pedicel 2.5–4 cm long (vs. 1–2 cm long); perianth tube yellowish-green outside (vs. mauve); basal portion of tube 4–5 cm long, longer than the upper (vs. 2–2.5 cm long, shorter than the upper); calyx limb yellowish-green, with dark purple mural-like stripes on the upper portion and mauve stripes on the lower portion (vs. yellow, with dark purple mural-like stripes), capsules villous (vs. glabrous). The detailed morphological comparisons amongst the three species are summarized in Table 1.

Etymology: The specific epithet is derived from Hai-Ming Tan, who has made important contributions to plant diversity conservation of Dayaoshan mountain in Guangxi, 
The Chinese name is given as “海明關木通” (pinyin: hǎi mǐng guān mū tōng).

Isotrema haimingii Y.S. Huang & Yan Liu, sp. nov. (A–C). A: Leaves. B: Flower (lateral view). C: Flower (front view).
I. championii (Merr. & Chun) X.X. Zhu, S. Liao & J.S. Ma (D-E). D: Leaves. E: Flower.
I. yachangense (B.G. Huang, Yan Liu & Y.S. Huang) Luu, Q.B. Nguyen & H.C. Nguyen (F-G). F: Leaves. G: Flowers.
(All by Yu-Song Huang, except D and E by Jin-Gang Liu)


Yu-Song Huang, Kun Qin, Chun-Yu Zou, Zhi-Ping Huang and Yan Liu. 2022. Isotrema haimingii, A New Species of Aristolochiaceae from Dayaoshan Mountain of Guangxi, China. Taiwania. 67(3); 380-385. DOI: 10.6165/tai.2022.67.380