Drosera amazonica Rivadavia, Fleischmann & Vicentini

Gonella, Paulo Minatel, Sano, Paulo Takeo, Rivadavia, Fernando & Fleischmann, Andreas, 2022, A synopsis of the genus Drosera (Droseraceae) in Brazil, Phytotaxa 553 (1), pp. 1-76 : 19-20

1. Drosera amazonica Rivadavia, Fleischmann & Vicentini in Rivadavia et al. (2009: 13). Figures 8a, 9a, b.

Type: — BRAZIL. Amazonas: Rio Cueiras , igarapé de Cachoeira, 15 November 1964, Rodrigues 6042 (holotype INPA-15093!) .

Perennial, column forming, stem usually short, reaching up to 10 cm long in submerged plants. Leaves semi-erect, with geniculate-involute vernation, distinctly petiolate, spatulate; lamina spatulate to obovate, adaxial petiole surface glabrous, abaxial leaf surface glabrescent, eglandular only; stipule rectangular in outline, divided into laciniate segments from the base. Flowers solitary, sub-sessile, sweetly perfumed; pedicel erect in flower and reflexed in fruit; sepals eglandular pilose only, horizontally patent in the ripe fruit; petals white; gynoecium 3-carpelate, styles bifurcated at the base. Seeds ovoid to subglobose, testa foveate (based on Rivadavia et al. 2009).

Illustrations: — Rivadavia et al. (2009: 14, fig. 1—habit and details).

Distribution: — Brazil (North: AM, RR) and Venezuela (according to a single, old herbarium specimen with vague locality, no state or region given). A new population of the species was also recorded from the Brazilian state of Amazonas (near the Paraná do Jacaré, left margin of Rio Negro, 2°00’17.9”S 61°06’39.6”W; photographic record by Arthur Monteiro Gomes, Fig. 8a). Therefore, in Brazil, D. amazonica is known from two localities in Amazonas and one in Roraima, in the northern Amazon Basin (Fig. 8a). It is here first recorded for Venezuela.

Habitat: —Lowland open habitats in seasonally flooded white quartz sand savannas (campinas), around 50 m a.s.l.

Phenology:— Collected with flowers in April, June, November and December, suggesting it may be found in flower year-round.

Conservation status: —Data Deficient (DD). Native to remote areas in the northern Amazon Basin, D. amazonica is under-collected and is likely to be more widespread and common than currently reported (AOO= 12 km 2, EOO= 2,405 km 2). Given the low sampling density and the large availability of favorable habitats between the known localities, there is currently insufficient information about the geographic distribution and population sizes of this species to properly evaluate its conservation status. Drosera amazonica is known to occur inside the Viruá National Park (RR) and Parque Estadual do Rio Negro Setor Sul (AM).

Notes: — Drosera amazonica is promptly distinguished from all other Brazilian Drosera by the sub-sessile solitary flowers (Fig. 9b) and the reflexed pedicel in fruit. Rivadavia et al. (2009) assumed this species to be related to D. felix based on reproductive characters, but morphologically most similar to D. roraimae based on its vegetative characters. However, with the recent re-discovery of D. biflora Willdenow in Roemer & Schultes (1820: 763) and careful examination of live and herbarium material (including the type, see under that species entry), it became evident that D. biflora is morphologically, ecologically, and very likely also phylogenetically closer to D. amazonica , with both species sharing the unique, foveate seeds, sepals reflexed in fruit, and a similar overall habit and habitat.

Representative specimens examined: — BRAZIL. Amazonas: Manaus, Rio Cuieiras , Igarapé Cachoeira , 16 December 2006, Rivadavia & Azevedo 2458 ( INPA, SPF) , Rivadavia & Azevedo 2460 (M, SPF) , Rivadavia & Azevedo 2461 ( INPA, M, SPF); Rio Negro, Rio Cuieiras, Igarapé da Cachoeira , 22 June 1992, Mori & Gracie 22444 ( INPA, NY). Roraima: Caracaraí, Parque Nacional do Viruá , 05 December 2006, Carvalho & Nascimento 1129 ( INPA) ; ibid., 27 March 2011, Barbosa & Costa 1433 ( INPA) .

Material outside Brazil examined: — VENEZUELA. Without further locality data, 07 April 1921, Grisol s.n. (P-4962855) .