Pleurothallis pugio (Orchidaceae), a new Pleurothallidinae from Costa Rica Author Karremans, Adam P. 0000-0001-5987-7710 Jardín Botánico Lankester, Universidad de Costa Rica. Apdo. 302 - 7050 Cartago, Costa Rica. & Naturalis Biodiversity Center, Endless Forms Group, Sylviusweg 72, Leiden 2333 BE, The Netherlands. & adam. karremans @ ucr. ac. cr; https: // orcid. org / 0000 - 0001 - 5987 - 7710 adam.karremans@ucr.ac.cr Author Jiménez, José Esteban 0000-0002-8154-2156 University of Florida Herbarium, Florida Museum of Natural History, 379 Dickinson Hall, 1659 Museum Rd., and Department of Biology, University of Florida, Gainesville, Florida 32611, USA. & Research Associate, Herbario Luis A. Fournier Origgi (USJ), Centro de Investigación en Biodiversidad y Ecología Tropical, Universidad de Costa Rica, Apartado 11501 - 2060, San José, Costa Rica. & gaiadendron. jej @ gmail. com; https: // orcid. org / 0000 - 0002 - 8154 - 2156 gaiadendron.jej@gmail.com text Phytotaxa 2023 2023-06-07 599 3 150 154 http://dx.doi.org/10.11646/phytotaxa.599.3.2 journal article 10.11646/phytotaxa.599.3.2 33fc78fe-fc70-479c-a7df-45ed80b97885 1179-3163 8012497 Pleurothallis pugio Karremans & J.E. Jiménez , sp. nov. ( Figures 1–2a ). Type :— COSTA RICA . Alajuela : San Carlos , Ciudad Quesada , Buena Vista , bosque aledaño a Laguna González , bosque primario Intervenido , 10°17’11.63’’ N , 84°27’54.19’’ W , 767 m , florecido y preparado el 07 febrero 2023 , J.E. Jiménez & P. Morales 6614 ( holotype : JBL-spirit) . Similar to P. imitor in the two-flowered inflorescence branches bearing yellow flowers, but distinguished by significantly smaller flowers with the dorsal sepal ovate-lanceolate, with the apical margin undulate ( vs. elliptic, margin entire), strongly decurved, conspicuously dentate petals ( vs. slightly decurved, margin entire), lip ovate ( vs. triangular-sagittate). The overall appearance of the flower is similar to P. rowleei ( Figure 2b ), but the new species is distinguished in the two-flowered branches bearing tiny yellow flowers ( vs. inflorescence branches bearing many purple flowers), the sepals marginally undulate ( vs. margin entire), the petals oblong-lanceolate ( vs. sigmoid) and the lip ovate ( vs. triangular-sagittate, with a narrow midlobe). Description:— Plant epiphytic, herbaceous, erect, caespitose, up to 17 cm tall. Roots flexuous, thin, 0.5–1 mm diameter, densely sub-fasciculate. Ramicauls erect, terete, thin, up to 5.0–9.0 cm long, covered by tubular, papyraceous sheaths close to the base, tightly adpressed, up to 2.4–3.2 cm long. Leaves sub-horizontal to arching, coriaceous, sessile, narrowly ovate, acute, slightly emarginate at the apex, 5.8–7.5 × 1.5–1.8 cm . Inflorescence with an extremely reduced peduncle, producing multiple 2-flowered branches in slow succession, subtended by a spathaceous bract 0.5–0.8 cm long, papyraceous when mature; pedicels terete, pale green. Ovary somewhat clavate, 2.6–2.8 mm long, green. Flowers slightly spreading, solid yellow; dorsal sepal ovate-lanceolate, slightly concave, membranous, acute, 3-veined, 6.2–6.4 × 2.5–2.7 mm , with the apical margin undulate; lateral sepals connate into an ovate, slightly concave synsepal, membranous, obtuse, 4-veined, 6.2–6.4 × 3.2–3.5 mm , minutely bifid at the apex, apical margin undulate; petals strongly decurved, oblong-lanceolate, oblique, conspicuously dentate, acute, 3.3–3.5 × 0.8–1.1 mm ; lip ovate, thick, papillose, decurved, 1.3–1.5 × 1.2–1.4 mm , apex acute, the base deflexed into a claw, hinged to a short columnfoot, 0.9–1.1 mm long; glenion inconspicuous transversally oblong. Column short, straight, transversely elliptic, 0.8– 0.9 mm long. The anther and the stigma apical; anther cap ovate, cucullate, obtuse at the base, bilobed at the apex, 2-celled, ca. 4 × 4 mm ; pollinia 2, narrowly ovate-pyriform, 4 mm long, joint by an elliptic viscidium. Fruits and seeds unknown. Distribution and ecology :—Only known from the type locality in Ciudad Quesada, Costa Rica . The species is only known from Buena Vista de Ciudad Quesada, Central Volcanic Mountain Range. It is found in a transitional forest from lowland tropical rainforest to premontane forest, at an elevation between 700– 800 m . Plants were seen to flower in July in the field, and February in cultivation. Like many Pleurothallis species it is likely able to continue blooming successively indiscriminately. Etymology :—From the Latin pugio , a Roman dagger in reference to the petal morphology. Taxonomic Discussion :— Pleurothallis pugio is known from a single collection the surrounding of Ciudad Quesada. The new species can be easily distinguished by the two-flowered inflorescence branches, bearing tiny yellow flowers with an ovate-lanceolate, undulate dorsal sepal, decurved, oblong-lanceolate, dagger-like petals and an ovate lip. Pleurothallis pugio belongs to Pleurothallis series Acroniae having a close floral affinity with P. dentipetala Rolfe ex Ames (1923: 7–8) and P. rowleei ( Figure 2 ), which also occur in Costa Rica . Pleurothallis dentipetala differs in its congested, many-flowered raceme ( vs. two-flowered branches), flowers light rose or brownish rose ( vs. yellow), suborbicular dorsal sepal ( vs. ovate-lanceolate), elliptic-ovate petals ( vs. oblong-lanceolate), and a sub-trilobed lip ( vs. entire). Pleurothallis rowleei can be distinguished from P. pugio by its longer inflorescences with many purple flowers (up to 14 cm long vs. up to 1.5 cm , with yellow flowers), sigmoid petals ( vs. oblong-lanceolate), and a lip with a rounded glenion ( vs. lip with a transversally oblong glenion). The plant morphology and two-flowered branches bearing yellow flowers are reminiscent of P. imitor a species with longer sepals ( 11–12 mm long vs. 6.2–6.4 mm long), entire, oblong-subfalcate petals ( vs. dentate, oblong-lanceolate), and a triangular-sagittate lip ( vs. ovate). In Costa Rica , Pleurothallis pugio is found growing at lower elevation in the mountains of the Central Volcanic Range, between 700–800 m , whereas P. imitor is found in the continental divide in Monteverde Reserve, Tilarán Range, at 1500 m .