Vanilla dressleri Soto Arenas 2010

2. Vanilla dressleri Soto Arenas (2010: 303) (Figure 5 G, H)

Type:— PANAMA. Colón: end of Pipeline Road on Río Agua Salud, 20–50 m, 15 April 1982, S . Knapp & J. Mallet 4621 (holotype: MO3032052!).

Distribution:— Panama, Costa Rica, Colombia, Venezuela, French Guiana (Figure 4).

Taxonomic Discussion:—This species is part of a group that includes Vanilla cribbiana Soto Arenas (2010: 300), Vanilla hostmanni Rolfe (1896: 462), and V. corinnae. These species feature long inflorescences with a densely papillose rachis and sepals, and yellowish to orange flowers. What sets V. dressleri species apart is the sub-rhombic lip, which is unlobed and has flat, minutely papillose veins. While initially thought to be restricted to Costa Rica, Panama and Colombia, the distribution is here expanded to include Venezuela and French Guiana.

The French Guiana specimen cited here (Cremers et al. 13016) was identified as Vanilla porteresiana Veyret & Szlach. (1995: 219) by Szlachetko (2016). However, we concur with Soto Arenas & Dressler’s (2010) assessment that V. porteresiana is based on an immature flower of V. hostmanni. The wide dorsal keel on the petals depicted for V. porteresiana (Figure 1 in Szlachetko & Veyret 1995) is characteristic of the immature petals of V. hostmanni, whereas in mature flowers the keel becomes slimmer. We have compared immature flowers (3 cm long) of V. hostmanni from Peruvian material with the drawings provided for V. porteresiana and found no significant differences. Additionally, we were unable to distinguish V. barrereana Veyret & Szlach. (1995: 2020) which appears to be based on mature flowers as evidenced by its narrow dorsal petal keel and larger size, from any Peruvian, Ecuadorian, or Brazilian specimens of V. hostmannii that we examined. Even though V. hostmannii and V. dressleri share features, such as the papillose external sepals and thickened veins in the lip, they can be easily differentiated by their lip morphology. V. hostmannii has a clearly trilobed lip, while V. dressleri has a sub-rhombic lip shape.

Specimens examined:— VENEZUELA. Amazonas: Along river just below mouth of Rio Cunucunuma, 20 June 1959, J. J . Wurdack & L. S. Adderley 43074 [flower] (US 00319616, NY 04170449). FRENCH GUIANA. Saint-Laurentdu-Maroni: Layon Eaux Claires-Region de Saul, 53 12’, 3 37’, 250 m, 16 February 1993, Cremers G ., Granville J. & Mori S. A. 13016 [flower] (NY04170422).