Abstract. Amaranthus pakai Faccenda & N. Bayón (Amaranthaceae), a new Hawaiian endemic species from the main islands, is described. It is most probably closely related to A. brownii Cristoph. & Caum, an extinct species from Nihoa Island. It also morphologically resembles A. interruptus R. Br. and A. viridis L. Amaranthus pakai differs from these species in its leaves with elliptical lamina, and pistillate flowers with three widely spathulate sepals, which are longer than the fruits. The first collections date back to the 19th century and suggest that this species was formerly rather widespread across the main Hawaiian Islands, but the population probably crashed during the 1800s. However, these early specimens were misidentified until recently. Amaranthus pakai was last seen in the wild in 2014 and, following its assessment against the IUCN criteria, is considered Critically Endangered, as only 30 to 40 plants were seen at that time.

A specimen collected from Nepal in 1821 by Wallich (2707.B in the Wallich Catalogue), stored at the Herbarium of the Royal Botanic Gardens Kew (K), is designated here as the lectotype of Aristolochia saccata Wall. In addition, the nomenclature for A. saccata var. dilatata Hook. f., A. dilatata N. E. Br., and Isotrema dilatatum (N. E. Br.) X. X. Zhu, S. Liao & J. S. Ma is considered. Since the name A. dilatata is based on A. saccata var. dilatata Hook. f., it is regarded that I. dilatatum was validly published as a new combination based on A. saccata var. dilatata Hook. f., and the correct author citation is “(Hook. f.) X. X. Zhu, S. Liao & J. S. Ma.”

Una nueva especie del estado de Guerrero, Hoffmannia tlapaneca Lozada-Pérez (Rubiaceae), es descrita e ilustrada. Esta nueva especie se relaciona morfológicamente con H. cuneatissima B. L. Rob. y H. nicotianifolia (M. Martens & Galeotti) L. O. Williams, pero difiere en el tipo de indumento, caracteres florales y de fruto.

A new species from the state of Guerrero, Hoffmannia tlapaneca Lozada-Pérez (Rubiaceae), is herein described and illustrated. This new species is morphologically similar to H. cuneatissima B. L. Rob. and H. nicotianifolia (M. Martens & Galeotti) L. O. Williams, but differs in the type of indumentum and floral and fruit features.