Elleanthus albiflorus (Orchidaceae) a new, white-flowered species from Peru Author Dudek, Magdalena Author Baranow, Przemysław Author Kolanowska, Marta Department of Biodiversity Research, Global Change Research Institute AS CR, Bělidla 4 a. 603 00 Brno, Czech Republic Author Rykaczewski, Max text Phytotaxa 2017 2017-07-07 312 2 256 262 http://dx.doi.org/10.11646/phytotaxa.312.2.8 journal article 10.11646/phytotaxa.312.2.8 1179-3163 13700130 Elleanthus albiflorus Dudek, Baranow, Kolan. & Rykaczewski , sp. nov. ( Figs 1–3 ) Type :— PERU . Oxapampa, Ex cult. Peruflora sub Kolanowska, Rykaczewski & Baranow P2016-4 ( holotype UGDA !–plant fragment preserved in alcohol; drawings, photos) . Diagnosis :—Species resembling Elleanthus flavescens ( Lindley 1846: 60 ) Reichenbach (1862: 479) distinguished by the lip flabellate in outline (vs. deltoid), subquadrate and deeply concave lip basal half (vs. lip base suborbicular, slightly depressed), presence of two large, well separated calli with narrowly triangular outgrowths that reach ca. 2/3 of the lip cavity (vs calli small, approximate, without any outgrowths), white flowers (vs. yellowish or orange) and oblanceolate, falcate petals (vs linear to oblong-ligulate). Description :—Plant caespitose. Stem with numerous short branches, leafy above. Leaves narrowly lanceolate, acuminate, sessile, plicate, very rigid, 3–7.5 × 0.8–1.1 cm , trifurcate. Inflorescence terminal, short, sublaxly several-flowered, up to 3 cm long; bract supporting the inflorescence 21 mm long, ovate, deeply cucullate, attenuate towards the apex, sparsely furfuraceous on the outer surface, obtuse. Flowers small, white. Floral bracts lanceolate, acute, somewhat longer or subequal in length to the flowers, sparsely furfuraceous, 15–18 × 3–4 mm . Ovary 5 mm long, densely furfuraceous. Sepals sparsely furfuraceous along the mid-vein. Dorsal sepal 6.0 × 3.5 mm , ovate-elliptic, acute, 3-veined, lateral veins branching, margins entire. Lateral sepals 6.8 × 3.5 mm , somewhat oblique, ellipticovate, acuminate, 5–6-veined, margins entire. Petals 6.0 × 1.2 mm , falcate, oblanceolate, acute, 3-veined. Lip 6.5 × 6.0 mm, basal half subquadrate, deeply concave, margins entire, apical half flabellate, margins irregular, erose; a thin, inconspicuous, transverse thickening present on the border between basal, concave part and the apical part of lip; basal calli large, separated, reaching ca. 2/3 of the cavity, ovoid with, narrowly triangular outgrowths running from the basal, exterior corner towards the cavity bottom. Column 4 mm tall, slightly falcate, lunate in the cross section. FIGURE 1 . Elleanthus albiflorus . A. Flower with floral bract. B. Dorsal sepal. C. Lateral sepal. D. Petal. E. Lip. F–G. Column–various views. Drawn from the holotype. FIGURE 2 . Elleanthus albiflorus . A. Fragment of inflorescence. B. Flower, side view. C. Lip, side view. D. Column, front view. E. Column and ovary. F. Lip. FIGURE 3 . Elleanthus albiflorus in situ. Etymology:— In reference to the flower colour. Distribution:— Known so far exclusively from locus classicus ( Fig. 4 ). Habitat and ecology:— Terrestrial among shrubs on the roadbank in the area covered with humid premontane forest ( Fig 4 ). It was found growing at the altitude of about 2000 m . Flowering in February. Taxonomic notes:— The new species of Elleanthus belongs to the group of taxa with more or less branching stems, leafy above. E . albiflorus morphologically resembles E . flavescens . Both these species share a similar form of inflorescence, which is terminal, short and mostly sublaxly flowered (in E . flavescens it is dense above and sublax below), with small flowers. However, new species may be easily distinguished based on flower colour (white vs yellowish or orange). While both species are characterized by thin, transverse thickening between basal and the apical part of the lip, they differ in lip and calli form. The calli of new species are large (reaching ca. 2/3 of the cavity), well separated and characterized by presence of narrowly triangular outgrowths while those of E. flavescens are small, approximate without appendices. The lip of E. flavescens is ovate to deltoid in outline, while in the new species it is more or less flabellate and the lip base is suborbicular, slightly depressed in the former species while in E. albiflorus it is subquadrate and deeply concave. Moreover, petals of E. flavescens are linear to oblong-ligulate, subacute while petals of new species are oblanceolate, falcate and acute. There is a single other species of Elleanthus with white flowers reported from Peru – E. wallnoeferi Szlachetko (1996: 23) . However, this taxon differs from E. albiflorus in both vegetative (non-branching stems) and floral (obliquely obovate petals, lip form, ovoid calli) characters.