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| Isotrema putalengense Luu, Q.B.Nguyen & H.C.Nguyen, in Nguyen, Nguyen, ... & Luu. 2022. |
Abstract
Isotrema putalengense Luu, Q.B.Nguyen & H.C.Nguyen is described as a new species from northern Vietnam. It looks most morphologically like I. wardianum but is distinguishable by a combination of different leafy and floral characters. Morphological comparison between the new plant and closest species is provided. In addition, combinations of two recently described Aristolochia species are made, namely Isotrema vuquangense (T.V.Do) Luu, Q.B.Nguyen & H.C.Nguyen and Isotrema yachangense (B.G.Huang, Yan Liu & Y.S.Huang) Luu, Q.B.Nguyen & H.C.Nguyen.
Keywords: Aristolochia, Isotrema vuquangense, Isotrema yachangense, Pu Ta Leng Mountain, Siphisia
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Isotrema putalengense Luu, Q.B.Nguyen & H.C.Nguyen A habit B leaf C leaf lamina, adaxial surface D leaf lamina, abaxial surface E flower, side view F flower, front view G bracteole H perianth, longitudinal dissection I utricle, inside J ovary, cross section K gynostemium, side view L stigma, view from above M stem, cross section. Photographs by Hieu Cuong Nguyen from SH992 at the type locality. |
Isotrema putalengense Luu, Q.B.Nguyen & H.C.Nguyen, sp. nov.
Diagnosis: The new species is most morphologically similar to I. wardianum in the shape of leaves and flowers but differs in having densely brown villous (vs. abaxially light brown villous) bracteoles, flowers on old woody stems (vs. in axils of leafy shoots), basally truncate perianth limb that is ovoid in front view and with purple apex (vs. basally obtuse, oblong in front view and with yellow apex), indistinct (vs. distinct) utricle from lower tube, U-shaped (vs. V-shaped) tube notch and internally black purple (vs. purple) tube.
Etymology: The specific epithet refers to the type locality, Pu Ta Leng Mountain which is part of the Hoang Lien Son Mountain Range and located about 30 km northwest of Vietnam’s highest Mt. Fan Si Pan.
Common and vernacular names: Putaleng’s pipevine
(Vietnamese name: Phòng kỷ Pu Ta Leng).
New combinations for some species of Isotrema
As a result of their study, Zhu et al. (2019a) has already transferred almost all species of Aristolochia subgenus Siphisia to Isotrema. Another four combinations were made for later described species (Wang et al. 2020a). Following this generic concept, here we propose new combinations for the other taxa of the subgenus that were described recently.
Isotrema vuquangense (T.V.Do) Luu, Q.B.Nguyen & H.C.Nguyen, comb. nov.
≡ Aristolochia vuquangensis T.V.Do. Phytotaxa 500 (1): 41. 2021.
Isotrema yachangense (B.G.Huang, Yan Liu & Y.S.Huang) Luu, Q.B.Nguyen & H.C.Nguyen, comb. nov.
≡ Aristolochia yachangensis B.G.Huang, Yan Liu & Y.S.Huang. PhytoKeys 153: 51. 2020.
Quoc Binh Nguyen, Hieu Cuong Nguyen, Duc Binh Tran, Phuong Hanh Nguyen and Hong Truong Luu. 2022. Isotrema putalengense, A New Species of Aristolochiaceae from northern Vietnam and Two New Combinations in Isotrema. PhytoKeys. 197: 71-79. DOI: 10.3897/phytokeys.197.73596
