Guatteria alba Maas & Westra, 2015

Maas, P. J. M., Westra, L. Y. T., Guerrero, S. Arias, Lobão, A. Q., Scharf, U., Zamora, N. A. & Erkens, R. H. J., 2015, Confronting a morphological nightmare: revision of the Neotropical genus Guatteria (Annonaceae), Blumea 60 (1), pp. 1-219 : 26-28

5. Guatteria alba Maas & Westra , sp. nov. — Fig. 10 ; Map 3

Arbor parva, petalis albis pro genere minimis et petiolis tenellis facile recognoscenda. — Typus: Rimachi Y. 2714 (holo MO), Peru, Loreto, Maynas, Distr. Iquitos, Carretera de Peña Negra at 25 km from Iquitos , 30 Nov.1976 .

Tree c. 3 m tall, diam not recorded; young twigs turning whitish, rather densely covered with appressed hairs, soon glabrous. Leaves: petiole 3–6 mm long, c. 0.5 mm diam; lamina narrowly elliptic to narrowly ovate, 6–9 by 2–3.5 cm (leaf index 2.4–4), chartaceous, not verruculose, dull, dark blackish brown above, brown below, glabrous above or primary vein sparsely covered with appressed hairs, sparsely covered with appressed hairs below, base acute to obtuse, apex acuminate (acumen 5–15 mm long), primary vein flat above, secondary veins distinct, 10–12 on either side of primary vein, raised above, smallest distance between loops and margin 2–3 mm, tertiary veins raised above, reticulate. Flowers mostly solitary or sometimes in 2-flowered inflorescences in axils of leaves or often on leafless branchlets; pedicels 13–30 mm long, ≤ 1 mm diam, rather densely covered with appressed hairs, articulated at 0.2–0.4 from the base, bracts 5–7, soon falling, few basal ones seen, broadly ovate, c. 1 mm long, occasionally a foliaceous bract observed (below the articulation), shape as in normal leaves, c. 30–40 by 10–11 mm; flower buds depressed ovoid; sepals free, broadly ovate-triangular, 3–4 by 3–4 mm, margins and apex reflexed, outer side densely covered with appressed,brown hairs; petals white in vivo, ovate, 6–8 by 2.5–4 mm, outer side densely covered with appressed, brown hairs; stamens c. 1 mm long, connective shield papillate. Monocarps and seed not seen, but fruit mentioned on label as green (Rimachi Y. 2714).

Distribution — Amazonian Peru (Loreto).

Habitat & Ecology — In non-inundated forest, on sandy soil. At an elevation of c. 120 m. Flowering: November, December; fruiting: unknown.

Vernacular names — Peru: Anona (Rimachi Y. 2714), Espintana (Rimachi Y. 9860).

Other specimens examined. PERU, Loreto, Maynas, Distr. Iquitos, Car- retera de Zungaro Cocha, margen del terreno de la ‘FAP’, 120 m, 19 Dec. 1990, Rimachi Y . 9860 ( MO, US) .

Notes — Guatteria alba is unique in the genus by its very small petals 6–8 mm long that are reported to be white. Other features are the very narrow petioles, and sepals with recurved apex and margins. Two collections are known so far, both from the surroundings of Iquitos and growing on sand. It is somewhat surprising that, given the area of Iquitos having been wellcollected, only two gatherings of this species exist.

The white colour of the petals of G. alba is unusual in the genus where flowers during their (long) development mostly are green and turn into yellow only in the very short stage of anthesis. Small white flowers are rather reminiscent of, e.g., Unonopsis and Bocageopsis , and therefore field observations should be interesting.

Guatteria alba differs from another small-flowered species, the Venezuelan G. stenopetala , by much smaller pedicels (13–25 vs 30–40 mm long).

Figures

Fig. 10 Guatteria alba Maas & Westra. Flowering branch (Rimachi Y. 2714; holotype MO).