Eighteen new species of Neotropical Costaceae (Zingiberales) Author Maas, Paul J. M. Naturalis Biodiversity Centre, Botany, P. O. Box 9517, 2300 RA Leiden, Netherlands Author Maas-van de Kamer, Hiltje Naturalis Biodiversity Centre, Botany, P. O. Box 9517, 2300 RA Leiden, Netherlands Author Andre, Thiago https://orcid.org/0000-0003-4148-3662 Universidade de Brasilia, Departamento de Botanica, Campus Universitario Darcy Ribeiro, Asa Norte, Brasilia (DF), Brazil Author Skinner, David https://orcid.org/0000-0003-4585-925X Le Jardin Ombrage, Tallahassee, (Private botanical garden, Botanic Gardens Conservation International - BGCI - registration ID 50148), Florida, USA Author Valderrama, Eugenio Cornell University, Section of Plant Biology and the L. H. Bailey Hortorium, School of Integrative Plant Science, Ithaca, NY, USA Author Specht, Chelsea D. https://orcid.org/0000-0001-7746-512X Cornell University, Section of Plant Biology and the L. H. Bailey Hortorium, School of Integrative Plant Science, Ithaca, NY, USA cdspecht@cornell.edu text PhytoKeys 2023 2023-03-22 222 75 127 http://dx.doi.org/10.3897/phytokeys.222.87779 journal article http://dx.doi.org/10.3897/phytokeys.222.87779 1314-2003-222-75 348E6053A6D55787993694B23682FDE9 Chamaecostus manausensis Maas & H.Maas sp. nov. Diagnosis. Chamaecostus manausensis sp. nov. (Fig. 1 ) looks quite similar to C. congestiflorus and has been regularly confused with that species but can be distinguished by a narrowly cylindric (instead of broadly obovoid) inflorescence and a non-fimbriate labellum. Figure 1. Chamaecostus manausensis Maas & H.Maas A plant in habitat Floresta Nacional do Tapajos , Brazil B flower showing the non-fimbriate margin of the labellum C, E inflorescence narrowly cylindric instead of broadly obovoid D sheath and ligules. Photos A-E by Thiago Andre . Type . Brazil . Amazonas : Maua Road , 22 Mar 1971 , Prance , Coelho , Kubitzki & Maas 11529 ( holotype : U 2 sheets: U1219716 & U1219717; isotypes: BR, COL128233, CR, DAV, E, F175333, F1842269, GH, INPA, K, MO, NY, P, S, US , VEN, W). Description. Herb 0.4-1 m tall. Leaves sheaths 2-15 mm diam; ligule 1-2 mm long; petiole 0-5 mm long; sheaths, ligule and petiole densely puberulous; lamina 13-25 x 3-6 cm, narrowly elliptic, adaxially sparsely puberulous to glabrous, abaxially sometimes reddish-purple, sparsely to densely puberulous, particularly the primary vein, base obtuse, apex acuminate, acumen 5-15 mm long. Inflorescence 4-10 x 1.5-3 cm, up to ca. 13 x 4 cm in fruit, narrowly cylindric, terminating a leafy shoot; bracts, bracteoles, calyx, ovary, and capsule rather densely to densely puberulous; bracts 2.5-3.5 x 0.3-0.5 cm, narrowly triangular, green, chartaceous, apex often mucronate, callus 3-6 mm long; bracteole 15-20 mm long, tubular, often deeply split on the abaxial side, 2-lobed, lobes 3-7 mm long, deltate. Flowers calyx 20-33 mm long, green, tube often deeply split during anthesis, lobes 5-10 mm long, subulate; corolla 50-65 mm long, cream, densely puberulous, lobes 30-40 mm long narrowly, obovate; labellum ca. 35 x 40 mm, cream, distal edge horizontally spreading, broadly angular-obovate, margin crenulate; stamen 25-30 x 10 mm, cream, apex reflexed, irregularly dentate, anther 5-6 mm long. Capsules 11-13 mm long, ellipsoid. Distribution. Brazil (Amazonas, Para ) (Fig. 21A ). Habitat and ecology. In terra-firme rainforests or campinarana vegetation, on sandy or clayey soils, at elevations of about sea level. Flowering and fruiting: October to March, July. Etymology. This species is named "manausensis" after the city of Manaus, State of Amazonas, Brazil, where this species is most commonly distributed. Paratypes. Brazil. Amazonas : Reserva Florestal Ducke, km 26 of Manaus-Itacoatiara road, 1 Dec 1994, Assuncao 107 (INPA, U), 5 Jan 1995, Costa et al. 73 (INPA, U), 12 Dec 1996, 568 (INPA, U), 10 Oct. 1995, Miralha & Maas 296 (INPA, U), 26 Jan 1995, Nascimento & Silva 726 (INPA, U); Cachoeira Alta do Taruma , Manaus, 7 Feb 1930, Ducke RB 25622 (U); Rio Maues-Acu , across from Maues , Mun. Maues , 21 Jul 1983, Hill et al. 13138 (INPA, MG, NY, RB, US). Para Floresta Nacional do Tapajos , comunidade Jamaraqua , Mortati 92 (HSTM). Notes. For additional field data, see Costa et al. (2011) , where this species has been treated under the name Costus congestiflorus .