Psilochilus panamensis Kolan., 2015

Psilochilus panamensis Kolan. View in CoL sp. nov. —TYPE: PANAMA. Veraguas: 6.4 km outside of Santa Fé on the road that passes the agriculture school. Headed toward the cordillera, 5 May 1977, Folsom 2954 (holotype: MO-3608752!; isotypes: MO-2608327!).

The new species is similar to Psilochilus physurifolius (Rchb.f.) Løjtnant from which it differs in the shorter lip claw and larger, ovate to elliptic lip middle lobe.

Terrestrial herbs up to 35–45 cm tall. Leaves 4–5, distributed in the upper half of the stem, blade 5.5–7 cm + 2.5–4 cm, ovate to elliptic, obtuse to subacute, occasionally with silver stripes; petiole 0.8–1.5 cm long. Inflorescence up to 4.5 cm long in total, peduncle abbreviated, up to 8 mm long, 4– 7-flowered. Flower with green sepals and pale green petals, lip purple, gynostemium white. Floral bracts 9–14 mm long, ovate, subacute. Ovary 12–20 mm long. Dorsal sepal 21–23 + 2.8–3.0 mm, oblong-lanceolate, subacute to acute, 5-veined. Lateral sepals 18 –20 mm long, 2.5 –4, obliquely linear-oblanceolate acute, 3- or 5-veined. Petals 17.5–18 + 3–3.5 mm, elliptic-lanceolate to oblong-elliptic, obtuse, 3- or 5-veined. Lip 15.5– 16 + 5– 6 mm, clawed, 3-lobed, disc ornamented with 3 or 5 thickened veins; claw 4.2– 4.6 mm long, with two thickenings at the base; middle lobe 6–6.5 + 3–4.5 mm, ovate to elliptic, subacute; lateral lobes up to 8 + 2.3–2.8 mm, obliquely ovate, rounded at the apices, extending to about the middle part of middle lobe. Gynostemium 16–17 mm long, slender, slightly arcuate in the upper part. Figures 2 View FIG , 3 View FIG .

Etymology— The name refers to the country where the type specimen was collected.

Distribution and Ecology— Localities of this species are distributed along Cordillera Central ( Fig. 4 View FIG ). It grows terrestrially in premontane forest at altitudes of 900–1,700 m. Flowering have been recorded in May, June, and October.

Observations— The new species resembles Psilochilus physurifolius (Rchb.f.) Løjtnant , but it is easily distinguished from it by the lip form. In P. physurifolius the lip claw is usually 8–10 mm long (vs less than 5 mm in P. panamensis ), its middle lobe is short, about 4–5 mm long, suborbicular (vs middle lobe up to 6.5 mm long, ovate to elliptic). The other Panamanian representative of P. physurifolius -complex, P. dressleri Kolan. ( Fig. 5 View FIG ), is characterized by the subsessile leaves, suborbicular, rounded lip middle lobe and large, obliquely ovate-falcate lip lateral lobes that extend up to two-third of the middle lobe. The lip disc of P. dressleri is ornamented with 3 thickened veins.

Other species with petiolate leaves, namely Psilochilus dusenianus , P. maderoi , P. modestus and P. mollis , may be distinguished from P. panamensis by the lip size (20–25 mm long in P. mollis ), length of the lip claw (very short in P. modestus ), lip isthmus (prominent in P. dusenianus ) and shape of the lip middle lobe (suborbicular in P. maderoi ). The comparative morphology of those species is presented in Table 1.

Conservation status— Based on the small geographic range and just three known locations of populations of the new species ( B2 a) compiled with lack of data on population size, the estimated Red List Category is vulnerable ( VU; IUCN 2010 ). Populations of Psilochilus usually count less than 10 specimens hereby any negative changes in their habitat may cause serious damages for the whole population .

Representative Specimens Examined— PANAMA. Coclé: Hills N of El Valle, E slope and ridges leading to Cerro Gaital, 900 – 1,000 m, 8 40 0 N, 80 07 0 W, 27 Jun 1982, Knapp 5778 (MO!). Chiriqui / Bocas del Toro: Cerro Colorado. Along intersection of Bocas Road with main ridge road. 11.8 km from Chami along path headed into Bocas del Toro, 1,400 – 1,700 m, 24 Oct 1977, Folsom 6115 (MO!).