Orchidaceae, Cymbideae, Oncidiinae) from Amazonian Venezuela
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A New Species of Cohniella (Orchidaceae, Cymbideae, Oncidiinae) from Amazonian Venezuela William Cetzal Ix El Colegio de la Frontera Sur, Unidad Chetumal, Av. del Centenario, Km 5.5, Chetumal 77000, Quintana Roo, Mexico. [email protected] German Carnevali Ferna´ndez-Concha Herbario CICY, Centro de Investigacio´n Cientı´fica de Yucata´n, A.C., Apartado Postal 87, Cordemex, Me´rida 97310, Yucata´n, Mexico. [email protected] ABSTRACT. A new species was detected while The genus Cohniella Pfitzer consists of 17 conducting a monographic study of Cohniella Pfitzer described species that are distributed from northern (Orchidaceae, Cymbideae, Oncidiinae). Cohniella Mexico into southern Brazil and northern Argentina. croizatii Cetzal & Carnevali is newly described from The members of this orchid genus can be easily material collected in the vicinity of Puerto Ayacucho distinguished from other members of the Oncidiinae and from the upper Orinoco, Amazonas State, by their succulent, terete leaves and Oncidium-like Venezuela. The new species is illustrated and its flowers (Carnevali et al., 2010). Characters used to affinities are discussed. The novelty is similar to C. distinguish species are mainly floral, such as the cebolleta (Jacq.) Christenson from northern Venezue- shape and position of the basal lobes of the lip, the la and Colombia, but differs in the callus that consists shape and number of teeth of the callus of the lip, and of three large, apical teeth of more or less similar size the column shape and position of the column wings. that emerge directly from the labellum disk, with the Additionally, we have used diagnostic elements for two lateral teeth marginally serrate to dentate on the species-level taxa that consider the size and proximal half. In contrast, the callus in C. cebolleta is orientation of the plants (e.g., pendent or erect), leaf more complex, consisting of five teeth that emerge thickness, the relative sizes of pseudobulbs, ecolog- from a conspicuous central platform, and the central ical preferences, and geographic distribution (Cetzal tooth is proportionately larger. & Carnevali, 2010). Since its resurrection by Christenson (1999), the RESUMEN. Una especie nueva fue encontrada du- generic status of Cohniella as distinct from Oncidium, rante nuestro trabajo monogra´fico en el ge´nero as well as from a broadly circumscribed Trichocen- Cohniella Pfitzer (Orchidaceae, Cymbideae, Oncidii- trum Poepp. & Endl., has been controversial. As nae). Cohniella croizatii Cetzal & Carnevali se opposed to other authors (Sandoval-Zapotitla & propone como nueva de Puerto Ayacucho y del Alto Terrazas, 2001; Sosa et al., 2001; Williams et al., Orinoco del Estado Amazonas, Venezuela. Esta 2001a, 2001b; Chase, 2009) who have treated especie nueva es ilustrada y sus afinidades son members of Cohniella, Lophiaris Raf., Lophiarella discutidas. La novedad esta´ relacionada con C. Szlach., Mytnik & Romowicz, and Trichocentrum s. cebolleta (Jacq.) Christenson del norte de Venezuela str. as belonging to a single genus (Trichocentrum y Colombia, pero difiere por el callo que consiste de s.l.), we describe this new taxon in the genus tres dientes apicales ma´s o menos del mismo tamano˜ Cohniella. Below, we offer a key to the genera of que emergen directamente del disco del labelo, los the Trichocentrum clade, based upon both vegetative dos dientes laterales son marginalmente serrados a and floral traits. The rationale behind this narrower dentados en la mitad proximal. Por el contrario, generic circumscription is discussed in depth mientras que el callo en C. cebolleta es ma´s complejo, elsewhere (Pupulin & Carnevali, 2005; Cetzal et consistiendo de cinco quillas que emergen de una al., 2008; Carnevali et al., 2009, 2010). Our plataforma central conspicua, y el diente central es treatment recognizes more, easily diagnosable, mono- proporcionalmente muy grande. phyletic entities rather than larger, polymorphic Key words: Amazonas, Cohniella, IUCN Red generic units that may be unwieldy or difficult to List, Oncidiinae, Orchidaceae, Venezuela. define. NOVON 21: 178–181. PUBLISHED ON 27 JUNE 2011. doi: 10.3417/2009063 Volume 21, Number 2 Cetzal Ix & Carnevali 179 2011 Cohniella (Orchidaceae) from Venezuela KEY TO THE GENERA OF THE TRICHOCENTRUM CLADE channel and are marginally serrate to dentate on their proximal half (Fig. 1B, H). 1a. Leaves terete, fleshy-coriaceous; pseudobulbs relatively small and inconspicuous ....... Cohniella 1b. Leaves conduplicate, either rigidly fleshy or Cohniella croizatii Cetzal & Carnevali, sp. nov. coriaceous; pseudobulbs ranging from small and TYPE: Venezuela. Amazonas: Mpio. Alto Or- inconspicuous to relatively large and conspicu- inoco, 1951, L. Croizat 984 (holotype, NY; ous. isotype, CICY [fragm.]). Figure 1. 2a. Plants small (leaves rarely exceeding 10 cm long); inflorescences shorter than the sub- tending leaves, mature plants bearing few (1 Species haec Cohniellae cebolletae (Jacq.) Christenson to 3[to 5]), successive flowers; labellum similis, sed ab ea callo minore tridentato e dentibus basally produced into a spur . Trichocentrum lateralibus margine proximaliter pauce serrato-dentatis et 2b. Plants usually larger (leaves usually exceed- apicali lateraliter compresso dentes laterales subaequante ing 12 cm long; however, they may be constante differt. smaller in Lophiaris pumila (Lindl.) Braem and relatives, but these flowers lack a spur); Epiphytic erect herbs; rhizome short, thin, brittle; inflorescences usually longer than subtend- roots ca. 2 mm thick, white; pseudobulbs ca. 8 3 9 mm, ing leaves (shorter in L. pumila and subspherical to broadly ovoid. Apically 1-leaved, relatives), mature plants bearing many ([5 green, totally enclosed by 3 imbricate sheaths, 30–70 to]10 to 50[to 150]), 6 simultaneous, rarely successive (e.g., L. lindenii (Brongn.) Braem) 3 5–10 mm, eventually deciduous; leaves terete, flowers; labellum lacking a spur. thickly fleshy-coriaceous, 23–37.2 cm 3 4–6 mm, 3a. Leaves rigidly and thickly fleshy-coria- dark green; inflorescences solitary from the base of the ceous; pseudobulbs large and conspicu- pseudobulbs, 63–123 cm, a 10- to 15-flowered raceme ous, at least 2 cm long, but up to 4 cm long; inflorescences stiffly erect, peduncle and or panicle with 3 to 4 long branches, each of these 3.6– rachis glaucous, with a thin film of wax; 10 cm, the branches 3- to 4-flowered; peduncle and plantsusuallylithophytic ....... Lophiarella rachis dark green with brownish spots; peduncle 6 3b. Leaves coriaceous or fleshy-coriaceous, erect, 2–4 mm thick, terete, with 8 to 13 remotely rarely rigid; pseudobulbs small, rarely exceeding 1.5 cm long; inflorescences bracted internodes, the basal and apical bracts equally more commonly ascendent or arching to long, oblanceolate, acuminate, tubular; floral bracts 2– nutant, never stiffly erect; peduncle and 3 mm, narrowly elliptic, acuminate. Flowers resupinate, rachis not glaucous; plants usually with perianth segments widely opening, the petals and epiphytic, rarely lithophytic . Lophiaris sepals somewhat reflexed; ovary with pedicel 15–20 During the course of preparing a monographic study mm, of which ca. 4–7 mm correspond to the ovary, this of Cohniella (Cetzal et al., in prep.), a hitherto structure 0.4–0.8 mm thick; sepals basally clawed for unknown taxon was detected. The new species is about 1/3 their total length, flat or somewhat reflexed, closely related to, yet geographically disjunct from C. dorsal sepal 6.5–7 3 4–5 mm, in general outline cebolleta (Jacq.) Christenson. Cohniella cebolleta is obovate, apically obtuse and minutely apiculate, known from northern Venezuela and Colombia and concave in the upper half, the claw ca. 2 3 1 mm; grows in drier environments, typically tropical dry lateral sepals partially fused at the very base, then free, forest or thorn forests. The novelty proposed here, C. similar to dorsal sepal, 8–9 3 4–5 mm; petals 7–8 3 3– croizatii Cetzal & Carnevali, is known from two 4 mm, oblong, somewhat oblique, the apex subacute, Venezuelan populations, one from Puerto Ayacucho somewhat reflexed in natural position; labellum deeply in northern Amazonas State, where the plants grow in 3-lobed, 9–13 mm from the base to the apex of the tropical rainforests, and the second collection from the central lobe, 12–15 mm wide across the apices of the upper Orinoco in the southern portion of the Amazonas lateral lobes, the lateral lobes in the same plane as the State. At this second locality, the plants grew in central lobe and 6 perpendicular to it; central lobe (6–) Amazonian rainforests on white sand substrates. 9–12 3 (11–)17–21 mm, transversely elliptic or The most distinctive feature of the new species is subreniform in outline, apically rounded, deeply the callus. In most Cohniella species, the callus is an emarginate, (2–)3–4 mm, basally produced into a short extremely complex structure. It is conventionally isthmus, ca. 2.5 3 3 mm; lateral lobes 5–6 3 3–5 mm, composed of a variously shaped basal platform from 6 oblong to orbicular, obliquely obtuse; disc short, ca. which two or four lateral teeth emerge, and the 4 3 4 mm; callus with 3 large apical teeth, similarly platform terminates in a much larger apical tooth or sized, emerging directly from the labellum disk, the 2 keel (Fig. 1A). In contrast, in the new species, the lateral teeth separated by a narrow channel and callus is composed of three large apical teeth of about marginally serrate to dentate on the proximal half, ca. the same size that emerge directly from the labellum 2.8 3 0.6 mm, the central tooth is laterally compressed, disk. The two lateral teeth are separated by a narrow 6 equally sized to the lateral teeth, ca. 2 3 0.6 mm; 180 Novon Figure 1. —A. A complex callus of Cohniella cebolleta (Jacq.) Christenson, based on G. Carnevali 7222 (CICY). B–H. Cohniella croizatii Cetzal & Carnevali. —B. A simpler callus. —C. Habit with inflorescence. —D. Intact flower. —E. Sepals (above) and petals (below).