First record of Vanilla labellopapillata (Orchidaceae: Vanilloideae) in the state of Amazonas, Brazil

The first record of Vanilla labellopapillata is presented for the state of Amazonas, Brazil, in the region of Manaus, now the western limit of the species, which was previously known only from the type locality in the state of Pará. A brief description is provided and taxonomic and ecological aspects of the species are discussed in the light of this new finding.

Vanilla Plumier ex Miller is a pantropical genus (Cameron 2011;Soto-Arenas and Cribb 2010) and it is composed of just over 100 species (Cameron 2003;Soto-Arenas and Cribb 2010). Its species develop preferentially in tropical forests and a few species are adapted to drier climatic and environmental conditions (Rodolphe et al. 2011). Moreover, the genus has the greatest economic importance among orchids, because Vanilla planifolia Andrews is the natural source of vanilla (Rain 2004).
Species in this genus can be terrestrial, rarely epiphytic and most often hemiepiphytic, some of them being up to 25 m long (Cameron 2003;Soto-Arenas 2003;Soto-Arenas and Cribb 2010;Soto-Arenas and Dressler 2010). Curiously, their flowers last less than 12 hours, which very often makes their observation in the wild somewhat difficult (Soto-Arenas 2003;Soto-Arenas and Cribb 2010;Soto-Arenas and Dressler 2010). The species are characterized by a hemiepiphytic habit, a flexible and lianescent stem, the lack of pseudobulb, alternate leaves with variable sizes and shapes, a lip adnate to the column, a versatile and saddle-shaped anther and entire seeds (Hoehne 1945;Dressler 1993;Soto Arenas and Cribb 2010).
According to Flora do Brasil 2020 in construction (2020), a part of the updated inventory of the Brazilian Flora (BFG 2015), 37 Vanilla species grow in Brazil, 20 being endemic, whereas Soto-Arenas and Dessler (2010) recognized only 26 species in their synopsis of the genus. This discrepancy is due to both new synonyms and the new species described (e.g. Pansarin et al. 2012;Koch et al. 2013;Pansarin and Miranda 2016;Fraga et al. 2017). Again according to BFG 2020 in construction (2020), 17 species have been recorded for the Brazilian Amazon, among which 13 occur in the Amazonas state.
Material Vanilla labellopapillata has been recently described by Koch et al. (2013) from the Pará state. In the present study it was found in two places in a dense ombrophilous forest near the city of Manaus, namely the Reserva Florestal Adolpho Ducke (RFAD), near the area of the botanical garden of the Museu da Amazônia (MUSA) (Museum of Amazonia) and Sítio Angelim, located on the Ramal Castanheira road, Km 901 of the BR 174 highway, that connects Manaus (Amazonas state) to Boa Vista (Roraima state).
According to Koch et al. (2013), V. labellopapillata is a close relative of V. insignis Ames. In V. insignis, the bracts and the flower parts are larger, the leaf is oblong-elliptic with an abruptly acuminated apex (vs. linear-lanceolate with an reflexed apex) and the penicillate callus is composed of ca. 13 rows of imbricated and congested scales (vs. 3 rows of imbricated and denticular scales) (see more details in Koch et al. 2013). Vanilla insignis was recorded from the Caribbean basin in Central America, in Honduras, Belize, Guatemala and Mexico, at an altitude of ca. 900 m. (Soto-Arenas and Cribb (2010), whereas V. labellopapillata is only found in the Brazilian Amazon, growing in floodplain forest (várzea) (Koch et al. 2013) and terra firme forest (our own observations) at an altitude of about 100 m. This last type of vegetation is therefore a novelty for V. labellopapillata, since it had been registered only for várzea forest.
Vanilla labellopapillata can also be confused with V. odorata C.Presl [=V. uncinata Huber ex Hoehne according to Garay (1978), Hamer (1984), Dodson and Dodson (1980), Soto-Arenas and Cribb (2010) and Koch et al. (2013)]. However it differs from V. labellopapillata in the longer internodes (approximately over 10 cm long vs. less than 10 cm), shorter floral bracts (less than 6 mm vs. more than 8 mm) and a distinctly trilobed lip without branched and thickened veins and with fimbriate margins (vs. obscurely trilobed lip with branched and slightly thickened veins in the distal third and long-lacerate/fimbriate to laciniate margins).