A new generic circumscription of Hydrochorea (Leguminosae, Caesalpinioideae, mimosoid clade) with an amphi-Atlantic distribution Author Vinicius Batista Soares, Marcos https://orcid.org/0000-0003-2660-1771 Universidade Federal do Rio Grande do Sul, Programa de Pos-Graduacao em Botanica, Av. Bento Goncalves 9500, Bloco IV, Predio 43433, 91501 - 970, Porto Alegre, Rio Grande do Sul, Brazil Author Mathieu Koenen, Erik Jozef https://orcid.org/0000-0002-4825-4339 Rua dos Bandeirantes 1020, Caranazal, 68040 - 329, Santarem, Para, Brazil erikk_botany@gmx.com Author Ricardo Vieira Iganci, Joao https://orcid.org/0000-0002-5740-3666 Universidade Federal do Rio Grande do Sul, Programa de Pos-Graduacao em Botanica, Av. Bento Goncalves 9500, Bloco IV, Predio 43433, 91501 - 970, Porto Alegre, Rio Grande do Sul, Brazil & Evolutionary Biology & Ecology, Universite Libre de Bruxelles, Faculte des Sciences, Campus du Solbosch - CP 160 / 12, Avenue F. D. Roosevelt 50, 1050 Bruxelles, Belgium Author Morim, Marli Pires Instituto de Biologia, Universidade Federal de Pelotas, Campus Universitario Capao do Leao, Travessa Andre Dreyfus s / n, 96010 - 900, Capao do Leao, Rio Grande do Sul, Brazil text PhytoKeys 2022 2022-08-22 205 401 437 http://dx.doi.org/10.3897/phytokeys.205.82775 journal article http://dx.doi.org/10.3897/phytokeys.205.82775 1314-2003-205-401 71D1ED9CE6165A94A2A330D2DA4D6DD9 1. Hydrochorea corymbosa (Rich.) Barneby & J.W. Grimes, New York Bot. Gard. 74(1): 27. 1996. Fig. 2A, C , 3A-C , 4 Pithecellobium subcorymbosum Hoehne [as Pithecolobium ], Comiss. Linhas Telegr. Estrateg ., Mato Grosso-Amazonas, Bot. 8: 18, Ic. 133. 1919. Type: Brazil, Mato Grosso, Sao Luiz de Caceres , nas margens do rio Paraguai, perto da Campina, Hoehne 4582 (lectotype, designated here from amongst the syntypes: R! [R000003169]; isolectotype: SP). Basionym. Mimosa corymbosa Rich., Actes Soc. d'Hist . Nat. Paris 1: 113. 1792. Figure 3. The genus Hydrochorea Barneby & J.W. Grimes (continued). Species from the Americas A flowering branch of Hydrochorea corymbosa (Rich.) Barneby & J.W. Grimes B close-up of inflorescence of H. corymbosa C discolorous leaves of H. corymbosa D close-up of inflorescence of Hydrochorea panurensis (Spruce ex Benth.) M.V.B. Soares, M.P. Morim & Iganci E unripe lomentiform pod of H. panurensis F close-up of inflorescence of Hydrochorea pedicellaris (DC.) M.V.B. Soares, Iganci & M.P. Morim, with a few peripheral flowers removed to expose sessile terminal flowers G unripe pods of H. pedicellaris H dehisced follicular pods of H. pedicellaris showing papery septate endocarp I detail of primary rachis of H. pedicellaris showing interpinnal extra-floral nectaries J inflorescence of Hydrochorea uaupensis M.P. Morim, Iganci & E.J.M. Koenen showing large sessile central flower and pedicellate peripheral flowers K unripe crypto-lomentiform pod and seed enveloped by septate endocarp of H. uaupensis ; African species L inflorescence of Hydrochorea obliquifoliolata (De Wild.) E.J.M. Koenen M pinnae of Hydrochorea rhombifolia (Benth.) E.J.M. Koenen showing rhombic leaflets. A-E, J, K Erik Koenen F-I Colin Hughes L Jan Wieringa M William Hawthorne. Vouchers A-C J.R.V. Iganci 862 D, E M.P. Morim 563 F-I L.P. Queiroz 15529 J, K M.P. Morim 577 L J.J. Wieringa 6519 M unvouchered. Figure 4. Hydrochorea corymbosa (Rich.) Barneby & J.W. Grimes A branch with inflorescences B-D extra-floral nectaries E peripheral flower bud F peripheral flower G terminal flower bud H terminal flower I fruit J seed. A, E-H from M.V.B. Soares 75 B-D from M.V.B. Soares 180 I-J from M.V.B. Soares 174 . Illustration by Alex Pinheiro. Type material. French Guiana , frequens in sylvis ripariis fluvii Kourou, Louis Claude Richard s.n. (lectotype, designated by Barneby and Grimes 1996 , p. 27, as holotype, here corrected: P [P02142909] digital image!). Distribution and habitat. Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Venezuela. Hydrochorea corymbosa occurs in periodically or permanently inundated riparian forest, gallery forest, and open vegetation, up to 480 m elevation ( Barneby and Grimes 1996 ). Notes. Hydrochorea corymbosa is morphologically similar to H. gonggrijpii by its leaves with (2-)3-6 pairs of pinnae (3-5 pairs of pinnae in H. gonggrijpii ), but differs by presenting (4-)5-11(-14) leaflet pairs per pinnae (vs. (12-)14-35 in H. gonggrijpii ). Hydrochorea corymbosa has a wide distribution in the Brazilian Amazon, and displays wide morphological plasticity. Barneby and Grimes (1996) recognised the specimen Louis Claude Richard s.n. (P02142909) as holotype, although the species protologue did not present a type specimen. The specimen does represent original material that the author associated with the taxon, being a specimen collected by the author and annotated as Mimosa corymbosa . Thus, Louis Claude Richard s.n. (P02142909) is here corrected to lectotype (Art. 9.3, 9.4, 9.8 and 9.10; Turland et al. 2018 ). Selected specimens examined. Brazil , Amazonas : Sao Gabriel da Cachoeira , entre Assuncao do Icana e Camarao , mato de Igapo , margem do rio, 10 July 2012 , J.R.V. Iganci 862 (RB) . Bolivia , Pando : Federico Roman , bordo del Rio Abuna , 18 November 2006 , S. Altamirano & H. Ramos 4293 (K) . Colombia , Vaupes : Mitu and Vicinity , lower rio Kubiyu , 26 September 1976 , Zarucchi 2147 (INPA) . Ecuador , Francisco de Orellana : Estacion Cientifica Yasuni , Rio Tiputini , este de la Carretera Repsol-YPF, km 7 desvio hacia el pozo Tivacuno , Laguna Herradura , 20 April 1999 , G. Villa 177 (K) . Guyana : Potaro-Siparuni , riparian zone lower Kuribrong , April 2010 , Zartman et al. 8002 (INPA) . Peru , Loreto : Jenaro Herrena , Cano Supay , flooded forest along cano, 23 May 2002 , T.D. Pennington et al. 17430 (K) . Venezuela , Amazonas : Departamento Rio Negro , middle part of the Rio Baria , 21 July 1984 , G. Davidse 27570 (K) .