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| representative Elatostema species in Vietnam: (A) E. crassiusculum; (C) E. hookerianum; (G), E. obtusum; (H) E. ramosum; (J) E. fengshanense; (K) E. austrosinense.
in Fu, Monro, Do, et al., 2019.
DOI: 10.7717/peerj.6188
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Abstract
Elatostema (Urticaceae) comprises several hundred herbaceous species distributed in tropical and subtropical Africa, Asia, Australia and Oceania. The greatest species richness occurs on limestone karst in Southeast Asia. Taxonomic revisions of Elatostema are largely out of date and contradict each other with respect to the delimitation of Elatostema and Pellionia. Most herbaria in SE Asia and worldwide contain significant amounts of unidentified material. As part of a broader revision of Elatostema in SE Asia, we present an updated checklist for Vietnam based on field visits, a review of specimens in herbaria worldwide, a review of type material and nomenclature. We recognize 77 taxa (75 species and two infraspecific taxa) of Elatostema in Vietnam, 23 of which were previously ascribed to Pellionia. Nineteen of these are new records for the country, i.e., E. attenuatoides, E. austrosinense, E. backeri, E. brunneinerve, E. crassiusculum, E. crenatum, E. fengshanense, E. glochidioides, E. malacotrichum, E. nanchuanense, E. oblongifolium, E. obtusum, E. oppositum, E. pergameneum, E. prunifolium, E. pseudolongipes, E. pycnodontum, E. salvinioides and E. xichouense. We place E. baviensis in synonymy of E. platyphyllum, E. colaniae in synonymy of E. myrtillus, P. macroceras in synonymy of E. hookerianum, and P. tetramera in synonymy of E. dissectum for the first time. Fourteen taxa (18% of all the recognized taxa) are endemic to Vietnam, which makes Elatostema one of the richest genera for endemic species in this country; this level of endemism is comparable to levels observed in Orchidaceae. Our checklist suggests that the highest diversity and endemism of Elatostema occurs in northern Vietnam, and that there is the greatest floristic similarity of northern Vietnam to SW China. The relationship among floristic regions is also investigated. We could find no records of Elatostema for 33 out of 63 provincial units of Vietnam, including all the southernmost provinces. We propose that further studies on the diversity of Elatostema in central and southern Vietnam are severely needed.
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| Figure 3: Plate I of representative Elatostema species in Vietnam: (A) E. crassiusculum; (B) E. glochidioides; (C) E. hookerianum; (D) E. prunifolium; (E), E. arcuatobracteatum; (F), E. retrohirtum; (G), E. obtusum; (H) E. ramosum; (I) E. integrifolium; (J) E. fengshanense; (K) E. austrosinense; (L) E. malacotrichum. |
Conclusions:
This study combines taxonomic and field expertise from China, Russia, the United Kingdom and Vietnam. It has strongly benefited from the availability of type images online which has accelerated the process of identification and the evaluation of taxon names. Ongoing research to document the floras of Cambodia, Laos, Thailand and Vietnam provides a huge opportunity for the taxonomy of Elatostema. Once combined with the completed Flora of China and Flora Malesiana accounts our updated checklist for Vietnam will fill a significant knowledge gap for this species-rich genus and lay the foundations for a global checklist. This fourth checklist for Vietnam not only doubles estimates of the diversity of the genus, it also identifies major knowledge gaps for the country, i.e., central Vietnam and, most notably, southern Vietnam. We propose that greater sampling effort of the flora of central Vietnam and southern Vietnam will result in a number of new additions to the flora of the country.
Long-Fei Fu, Alex Monro, Truong Van Do, Maxim S. Nuraliev, Leonid V. Averyanov, Fang Wen, Zi-Bing Xin, Tatiana V. Maisak, Andrey N. Kuznetsov, Svetlana P. Kuznetsova, Khang Sinh Nguyen and Yi-Gang Wei. 2019. Checklist to the Elatostema (Urticaceae) of Vietnam including 19 New Records, Ten New Combinations, Two New Names and Four New Synonyms. PeerJ. 7:e6188. DOI: 10.7717/peerj.6188
