9. Tanaecium duckei A.Samp., Ann. Acad. Brasil. Sci. 7: 125. 1935. Fig. 1C

Spathicalyx duckei (A.Samp.) A.H.Gentry, Phytologia 35(3): 194. 1977. Type: Brazil. Pará: Óbidos, 21 July 1918, A. Ducke s.n. (holotype, MG!; isotypes, MO [MO-077163]!, R!, RB [RB00536923]!, US [US00125782]!).

Habitat and distribution.

Tanaecium duckei grows in Amazonian forests with sandy soils and canga vegetation. It occurs in Brazil (Acre, Amazonas, Pará, Mato Grosso), Colombia (Amazonas), and Peru (Loreto, Pasco).

Phenology.

Flowering: July and September to October; fruiting: September.

Notes.

This species differs from other species of Tanaecium by the spathaceous calyces, reflexed anthers, and vegetative structures covered by stipitate glandular trichomes. It is morphologically most similar to T. kuhlmannii, with which it shares trifid tendrils and spathaceous calyces (Tab. 1). It is possible to separate T. duckei from T. kuhlmannii by the lack of patelliform glandular trichomes along the tertiary veins (vs. present in T. kuhlmannii), green fruits with sparse stipitate glandular trichomes (vs. yellow fruits covered by stipitate glandular trichomes in T. kuhlmannii), smaller anthers with 4.17-4.34 mm long (vs. larger anthers with 7.0-10.0 mm long in T. kuhlmannii), and stamens inserted at the same height (vs. stamens inserted at two different heights in T. kuhlmannii) (Tab. 1).