Pleurothallis pugio Karremans & J.E. Jiménez, 2023

Karremans, Adam P. & Jiménez, José Esteban, 2023, Pleurothallis pugio (Orchidaceae), a new Pleurothallidinae from Costa Rica, Phytotaxa 599 (3), pp. 150-154 : 152-153

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.

Figures

FIGURE 1. LCDP of Pleurothallis pugio Karremans & J.E. Jiménez. A. Habit. B. Inflorescence, showing the branching succession. C. Two-flowered inflorescence branch. D. Flower. E. Dissected perianth. F. Column and lip, lateral view. G. Column and ovary, lateral view. H. Anther cap and pollinarium. Plate by APK based on type specimen Jiménez & Morales 6614 (JBL-spirit).

FIGURE 2. Floral comparison. A. Pleurothallis pugio Karremans & J.E. Jiménez, Jiménez & Morales 6614 (JBL-spirit). B. Pleurothallis rowleei Ames, JBL-033598 (JBL-spirit). C. Pleurothallis dentipetala Rolfe ex Ames, Karremans 7287 (JBL-spirit). Photographs by APK and Lizbeth Oses.