Abstract
Argostemma tortilobum, a new species endemic to Vietnam, is described and illustrated. The species is morphologically most similar to A. sarmentosum, but differs in having erect stem without runners, densely pilose peduncle and twisted corolla lobes with ciliate margins.
References
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Beentje, H. (2016) <em>The Kew Plant Glossary: an illustrated dictionary of plant terms, 2nd Edition</em>. Royal Botanical Gardens, Kew, Richmand, 184 pp.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Bremer, B. (1989) The genus <em>Argostemma</em> (Rubiaceae-Argostemmateae) in Borneo. <em>Missouri Botanic Garden</em> 76: 7–49. [https://www.jstor.org/stable/2399341]</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Chen, T., Zhu, H., Chen, J., Taylor, C.M., Ehrendorfer, F., Funston, A.M. & Puff, C. (2011) Rubiaceae. <em>In:</em> Wu, Z.Y., Raven, P.H. & Hong, D.Y. (eds.) <em>Flora of China</em>, Vol. 19. Science Press, Beijing and Missouri Botanical Garden, St. Louis, pp. 57–368.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Das, S.C. & Ranman, M.A. (2010) Notes on the Rubiaceae. 3. Five new records for Bangladesh. <em>Bangladesh Journal of Botany</em> 39 (2): 215–222.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">IUCN Standards and Petitions Committee. (2022) Guidelines for Using the IUCN Red List Categories and Criteria. Version 15. Prepared by the Standards and Petitions Committee, 116 pp. [https://www.iucnredlist.org/documents/RedListGuidelines.pdf]</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Kress, W.J., Defilipps, R.A., Farr, E. & Kyi, D.Y.Y. (2003) A checklist of trees, shrubs, herbs, and climbers of Myanmar. <em>Systematic Botany</em> 29 (2): 462–463. https://doi.org/10.1600/036364404774195674</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lanorsavanh, S. & Souvannakhoummane, K. (2020) Six new species of <em>Argostemma</em> Wall. (Rubiaceae) from Laos. <em>Nordic Journal of Botany</em> 2020: e02714. https://doi.org/10.1111/njb.02714</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Pitard, J. (1922-1924) RUBIACEES. <em>In:</em> Lecomte, H., Humbert, H. & Gagnepain, F. (eds.) <em>Flore Génerale de l’Indo-Chine</em>, Vol. 3, fasc 1–4. Masson, Paris, pp. 20–442.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Ridley, H.N. (1923) LXXIV. RUBIACEAE. <em>In:</em> Ridley, H.N. (ed.) <em>The Flora of the Malay Peninsula</em>, Vol. 2. Baptist Mission Press, London, pp. 3–177.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Roxburgh, W. (1824) <em>Flora Indica: or description of Indian plants</em>, Vol. 2. Mission Press, Serampore, 588 pp.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Sridith, K. (1999) A synopsis of the genus <em>Argostemma</em> Wall. (Rubiaceae) in Thailand. <em>Thai Forest Bulletin</em> 27: 86–138.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Sridith, K. (2007) Notes on the genus <em>Argostemma </em>(Rubiaceae) of the Malay Peninsula and Peninsula Thailand. <em>Blumea </em>52: 367–377.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Sridith, K. & Puff, C. (2000) Distribution of <em>Argostemma</em> Wall. (Rubiaceae), with special reference to Thailand and surrounding areas. <em>Thai Forest Bulletin</em> 28: 123–137.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Thiers, B. (2022) Index Herbariorum: A global directory of public herbaria and associated staff. New York Botanical Garden’s Virtual Herbarium. Available from: http://sweetgum.nybg.org/science/ih/ (accessed 29 September 2022)</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Vu, H.T., Nguyen, T.T., Nguyen, H.Q., Le, K.D. & Do, T.V. (2020) Notes on taxonomy of the genus <em>Argostemma </em>(Rubiaceae) from Vietnam. <em>Thai Forest Bulletin</em> 48: 234–238. https://doi.org/10.20531/tfb.2020.48.2.16</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Bremer, B. (1989) The genus <em>Argostemma</em> (Rubiaceae-Argostemmateae) in Borneo. <em>Missouri Botanic Garden</em> 76: 7–49. [https://www.jstor.org/stable/2399341]</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Chen, T., Zhu, H., Chen, J., Taylor, C.M., Ehrendorfer, F., Funston, A.M. & Puff, C. (2011) Rubiaceae. <em>In:</em> Wu, Z.Y., Raven, P.H. & Hong, D.Y. (eds.) <em>Flora of China</em>, Vol. 19. Science Press, Beijing and Missouri Botanical Garden, St. Louis, pp. 57–368.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Das, S.C. & Ranman, M.A. (2010) Notes on the Rubiaceae. 3. Five new records for Bangladesh. <em>Bangladesh Journal of Botany</em> 39 (2): 215–222.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">IUCN Standards and Petitions Committee. (2022) Guidelines for Using the IUCN Red List Categories and Criteria. Version 15. Prepared by the Standards and Petitions Committee, 116 pp. [https://www.iucnredlist.org/documents/RedListGuidelines.pdf]</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Kress, W.J., Defilipps, R.A., Farr, E. & Kyi, D.Y.Y. (2003) A checklist of trees, shrubs, herbs, and climbers of Myanmar. <em>Systematic Botany</em> 29 (2): 462–463. https://doi.org/10.1600/036364404774195674</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Lanorsavanh, S. & Souvannakhoummane, K. (2020) Six new species of <em>Argostemma</em> Wall. (Rubiaceae) from Laos. <em>Nordic Journal of Botany</em> 2020: e02714. https://doi.org/10.1111/njb.02714</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Pitard, J. (1922-1924) RUBIACEES. <em>In:</em> Lecomte, H., Humbert, H. & Gagnepain, F. (eds.) <em>Flore Génerale de l’Indo-Chine</em>, Vol. 3, fasc 1–4. Masson, Paris, pp. 20–442.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Ridley, H.N. (1923) LXXIV. RUBIACEAE. <em>In:</em> Ridley, H.N. (ed.) <em>The Flora of the Malay Peninsula</em>, Vol. 2. Baptist Mission Press, London, pp. 3–177.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Roxburgh, W. (1824) <em>Flora Indica: or description of Indian plants</em>, Vol. 2. Mission Press, Serampore, 588 pp.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Sridith, K. (1999) A synopsis of the genus <em>Argostemma</em> Wall. (Rubiaceae) in Thailand. <em>Thai Forest Bulletin</em> 27: 86–138.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Sridith, K. (2007) Notes on the genus <em>Argostemma </em>(Rubiaceae) of the Malay Peninsula and Peninsula Thailand. <em>Blumea </em>52: 367–377.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Sridith, K. & Puff, C. (2000) Distribution of <em>Argostemma</em> Wall. (Rubiaceae), with special reference to Thailand and surrounding areas. <em>Thai Forest Bulletin</em> 28: 123–137.</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Thiers, B. (2022) Index Herbariorum: A global directory of public herbaria and associated staff. New York Botanical Garden’s Virtual Herbarium. Available from: http://sweetgum.nybg.org/science/ih/ (accessed 29 September 2022)</span></span></span></p>
<p align="justify"><span style="color: #000000;"><span style="font-family: Times New Roman, serif;"><span style="font-size: small;">Vu, H.T., Nguyen, T.T., Nguyen, H.Q., Le, K.D. & Do, T.V. (2020) Notes on taxonomy of the genus <em>Argostemma </em>(Rubiaceae) from Vietnam. <em>Thai Forest Bulletin</em> 48: 234–238. https://doi.org/10.20531/tfb.2020.48.2.16</span></span></span></p>