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 Costus alticolus Maas & H.Maas sp. nov. Diagnosis. Costus alticolus sp. nov. (Fig. 4 ) can be recognised by its leafless flowering shoots up to ca. 1 m long, combined with large, red and unappendaged bracts, tubular and yellow flowers, and stamen far exceeding the labellum like in C. pulverulentus C.Presl. Figure 4. Costus alticolus Maas & H.Maas A inflorescence with flower, showing stamen (st) extending far beyond labellum, fully exposing the thecae B, C plant in habitat D flower and bract details E flowering shoot. Photos in habitat in Chinantla region near Santa Cruz Tepetotutla, Oaxaca, Mexico by Dave Skinner. Type . Mexico . Oaxaca : Sierra Mazateca , Mun. Santa Maria Chilchotla , Cuauhtemoc , ca. 4 km NE of Santa Maria Chilchotla , near Clemencia and Santa Rosa , 1200 m , 16 Jan 1984 , Solheim & Reisfeld 1367 ( holotype WIS) . Description. Herb 2-3.5 m tall. Leaves sheaths 10-30 mm diam; ligule truncate, 4-12 mm long; petiole 5-20 mm long; sheaths, ligule and petiole densely to sparsely puberulous; lamina narrowly elliptic, 25-47 x 6-14 cm, adaxially glabrous, abaxially densely (particularly along the primary vein) sericeous to almost glabrous, base acute, apex acuminate (acumen 5-10 mm long). Inflorescence cylindric, 11-18 x 5-9 cm, terminating a leafless shoot 20-95 cm long, sheaths obliquely truncate, 4-7 cm long, rather densely puberulous to glabrous; bracts, bracteole, calyx, ovary, and capsule glabrous to densely puberulous. Flowers abaxially oriented; bracts red to bright crimson, coriaceous, ovate-oblong, 4-6 x 3-4 cm, apex obtuse, callus ca. 10 mm long; bracteole boat-shaped, 30-35 mm long; calyx red, 13-21 mm long, lobes deltate to shallowly triangular, 3-6 mm long; corolla yellow to orange, 50-60 mm long, glabrous, lobes narrowly elliptic, ca. 40 mm long; labellum yellow, lateral lobes rolled inwards and forming a slightly curved tube 18-20 mm diam, obovate when spread out, ca. 60 by 35 mm, irregularly lobulate, lobules recurved, ca. 4 mm long; stamen yellow, ca. 65 x 11 mm, far exceeding the labellum, apex acute, anther ca. 8 mm long. Capsule ellipsoid, 17-18 mm long. Distribution. Mexico (Oaxaca) (Fig. 21D ). Habitat and ecology. In primary, wet montane to premontane cloud forests, with some mosses on trunks, drier on ridge crests, with Hedyosmum mexicanum Cordem. Ex Baill., Liquidambar macrophylla Oerst., Siparuna andina A.DC., Posoqueria latifolia (Rudge) Roem. & Schult., Heliconia sp., Deppea sp, Chamaedorea sp., Solenophora sp., and Salvia divinorum Epling & Jativa , at elevations of 1040-1900 m. Flowering year-round. Etymology. Costus alticolus sp. nov. occurs at quite high elevations up to 1900 m, hence the specific epithet alticolus ( 'altus' means 'high' in Latin; 'colere' means 'to live' in Latin). Paratypes. Mexico. Oaxaca : Distr. and Mun. Ixtlan , near abandoned community of Tarabundi, S side of Rio Soyolapan , access via La Luz, primary forest toward Rio Langaro, 1230-1260 m, 16 Nov 1993, Boyle & Massart 2556 (MO, U); Mun. San Felipe Usila, cuenca del Rio Perfume, 4.4 km SE of Santa Cruz Tepetotutla, 1400 m, 29 Mar 1995, Rincon Guttierrez et al. 592 (MO); Distr. Mixe, Mun. Totontepec, Totontepec, 1900 m, 9 Aug 1990, Rivera Reyes & Martin 1610 (CAS), Hwy 175, km 169, near La Esperanza, 1075 m, 12 Aug 2017, Skinner R3400 (BH). Notes. We are greatly indebted to Manuel Gutierrez , who assisted Dave Skinner in obtaining permission from the indigenous people of Santa Cruz Tepetotutla, Oaxaca, Mexico, to study this new species common in the Chinantla region of Oaxaca.