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A new species of Elleanthus (Orchidaceae) from Central America Fredy Archila Morales1,2 & Guy R. Chiron3 ________________________________ 1Estación Experimental de orquídeas de la familia Archila 2Herbario BIGU, Universidad de San Carlos de Guatemala 3Herbiers, Université de Lyon 1, F-69622 Villeurbanne Cedex (France) ________________________________ Abstract During botanical tours in Alta Verapaz (Guatemala), a plant of the genus Elleanthus drew the attention of the senior author by the color of its leaves, intense purple on their abaxial side. After having thoroughly examined it we came to the conclusion that it was something different from any known species. It is described here as a new species and compared to its closest relative, Elleanthus hymenophorus, by means of morphological descriptions, botanical drawings and photos. Résumé Au cours de sorties botaniques réalisées en Alta Verapaz (Guatemala), une plante du genre Elleanthus a attiré l'attention du premier auteur par la couleur de ses feuilles, d'un violet intense en partie abaxiale. Une étude approfondie a montré qu'il s'agissait d'un taxon ne correspondant à aucune espèce connue. Elle est décrite ici comme espèce nouvelle, comparée à l'espèce la plus proche, Elleanthus hymenophorus. Sa description est accompagnée de dessins botaniques et de photographies. C'est une espèce qui est menacée par la destruction des habitats et une collecte d'autant plus excessive qu'elle possède des caractéristiques faisant d'elle une plante ornementale. Manuscrit reçu le 20/10/2018 Article mis en ligne le 25/10/2018 – pp. 166-171 Resumen En recorridos realizados en Alta Verapaz, llamo la atención una planta del género Elleanthus, por el color de sus hojas un morado intenso en la parte abaxial, al estudiarla detenidamente se pudo establecer que se trataba de una especie que no encajaba con ninguna de las especies ya descritas, por lo que después de elaborar los iconos botánicos, el descriptor, su diagnosis, se presenta como nueva especie y se compara con su pariente más próxima, Elleanthus hymenophorus. Posee características potenciales para convertirse en cultivo ornamental. Keywords: Elleanthus, Guatemala, Neotropics, taxonomy. Mots clés : Elleanthus, Guatemala, néotropiques, taxinomie. Palabras clave: Elleanthus, Guatemala, Neotrópico, taxonomia. Introduction For most authors the genus Elleanthus C. Presl (1827: 97) belongs to the subtribe Sobraliinae which has been placed in various tribes among which the tribe Sobralieae, described by Pfitzer in 1887, and usually considered as a natural group, at least in parte (Neubig et al., 2011). We must note that Szlachetko (1991) placed the genus in its own subtribe, Elleanthinae. The main centre of diversification of Elleanthus is the Andine region; however the genus is present up to the Neotropical Mesoamerican zone. It is comprised of ca. 100 species, distributed in tropical America and the eastern West Indies. In Guatemala Ames & Correll (1952-1953) reported three species, however two are now placed within Adeneleuterophora Barbosa Rodrigues (1882: 171): A. linifolia (C. Presl, 1827: 97) Dudek & Szlachetko (2010: 5) and A. poiformis (Schlechter, 1923: 164) Dudek & Szlachetko (2010: 5). Only one is still treated as a true Elleanthus, E. capitatus, though cited with a wrong authority: the basionym of the species cited by Ames & Correll is Bletia capitata R. Brown (1813: 206) = Elleanthus cephalotus Garay & H.R. Sweet (1972: 390), a species endemics to West Indies. Finally we do not know which species represents the plant listed in their book. Among the seven species listed by Dix & Dix (2000), apart from the same “E. capitatus”, only two are true Elleanthus: E. caricoides Nash (1907: 119) and E. hymenophorus (Reichenbach f., 1852: 710) Reichenbach f. (1862: 480). Recently Archila & Chiron (2017) proposed two Guatemalan new species, Elleantus asturiasii Archila & Chiron (2017: 149) 167 and Elleanthus gelatinosus Archila & Chiron (2017: 152), both with lilas- colored capitate flowers, who are now considered as members of the genus Evelyna Rafinesque (1838: 164). Finally, only two Elleanthus species have hitherto been found in Guatemala (Archila et al., in press). During one of his botanical tours in Alta Verapaz, the senior author noticed an Elleanthus plant leaves of which were intense purple on their abaxial face. It is described below as a new species. In Orchidaceae the rewards to pollinators are very diverse (Van der Cingel, 2001) and include nectar, resins, wax and other types of food, fragrances ... and pseudocopulation, as in Lepanthes (Archila, 2001). However, the most common reward is nectar, which is present in flowers of various morphologies, adapted to various pollinators, insects such as Diptera (flies), Hymenoptera (bees and wasps), Lepidoptera (butterflies), and birds such asTrochilidae (colibris) in the New World (Neubig et al., 2015). It can be observed that Elleanthus flowers are visited by colibris which pollinate 95-98% of their flowers; however it is suspected that the colibri, when collecting the nectar, pushes with its beak the pollinia towards the stigma, instead of transporting the pollinia from a flower to another one. It could explain the high pollination rate. Besides, these observations can indicate that the bird is attracted by the color of the flowers (orange), little variable in the species of the genus, more than by the shape of the flowers. That is why the morphology is very stable within a particular species. So the morphological differences within the genus are considered as a strong taxonomic basis to differentiate species. Taxonomic treatment Elleanthus C. Presl, Reliquiae Haenkeanae 1(2): 97. 1827. TYPE: Elleanthus lancifolius C. Presl. Epiphytic, terrestrial or lithophytic plants with no storage organs. Leaves linear, lanceolate to elliptic-lanceolate, plicate, glabrous or pubescent. Inflorescence terminal, usually densely few- to many-flowered, arranged spirally or distichiously. Floral bracts prominent, imbricating, often brightly coloured, yellow, orange to purple. Flowers small to medium, erect, tubular, white, lemon-yellow, orange to deep purple. Tepals dissimilar or subsimilar. Lateral sepals free or partially connate at the base. Lip saccate and tubular at the base, more or less enclosing the gynostemium, unlobed or obscurely 3-lobed, with fimbriate or dentate A new Elleanthus from Guatemala – Archila & Chiron margins, with a pair of large globose or subglobose calli. Gynostemium slender. Anther terminal, erect. Pollinia 8, clavate to obovoid, laterally compressed. Caudiculae sticky. Apical clinandrium obscure or rather prominent. Stigma obtriangular to elliptic, deeply concave. Rostellum shelf-like to ligulate, erect to subincumbent, truncate to rounded. Viscidium single of various sizes, sometimes relatively large. Rostellum remnant foveolate. (Archila et al., in press). Elleanthus archilae Chiron & Tribouillier, sp. nov. Type: Guatemala, Alta Verapaz, Cobán, collected by Fredy Archila en Chamá Grande, 1000 m. s.n.m., XI/2009, FA-sn (holotype & isotype BIGU). Etymology: dedicated to Fredy Archila Morales, who collected the type specimen. Haec herba Elleanthus hymenophorus (Reichenbach f.) Reichenbach f. similis est sed foliis violaceis, bracteis acuminatis, sepalo intermedio triangulare-ovato acuto, sepalis lateralibus oblongis, petalis lineare-ellipticis acutis, labello leviter incurvato subquadrato, columna oblongo-ovata, ovario glabro, differt. Plant medium-sized, thin; leaves elliptic, with a very strong apical constriction, 10-18.7 cm long, 5-7 cm wide, purple on their abaxial face, sheathing petiole corinthe glabrous; inflorescence with a basal bract elliptic and wide; floral bracts short and acute, 0.5-1 cm long, 0.2-0.3 cm wide; dorsal sepal triangular-ovate, apically acute, 0.55 cm long, 0.35 cm wide; lateral sepals oblong, shortly mucronate, 0.55 cm long, 0.4 cm wide; petals linear-elliptic, apically acute, 0.4 cm long, 0.1 cm wide; lip 0.75 cm long, 0.5 cm wide, divided into two parts, apical lamina subquadrate, basal part saccate, with lateral projections obliquely orbicular and with two obliquely oblong appendages inside; gynostemium 0.3 cm long, oblong-ovate; anther totally covering the apical part of the gynostemium; ovary 0.4 cm long, glabrous. Fig. 1. Taxonomic notes. The closest relative of this new species is Elleanthus hymenophorus (Fig. 2). However a number of differences allow to easily distinguish them. In the latter the plants are large and robust, the leaves are green, orbicular-eliptic, inconspicuously constricted, with a green pubescent (scattered scaly pubescence) petiole, the inflorescence bract is linear-oblong, the floral bracts long and acuminate, the dorsal sepal and the petals oblong obtuse, the lateral sepals elliptic long-mucronate, the apical 169 lamina of the lip orbicular, the lateral projections of the lip basal part are not oblique, the gynostemium is oblong, the anther covers only 80% of the gynostemium apex and the ovary is adorned with a scattered scaly pubescence. See Fig. 3 & 4. Fig. 1. Elleanthus archilae Fig. 2. Elleanthus hymenophorus [drawings F. Archila] Fig. 3. Elleanthus archilae Fig. 4. Elleanthus hymenophorus [ph. F. Archila] Conservation status. The species is threatened by the destruction of the forests and by illegal collections. Especially as its characteristics can make it a decorative plant. 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