Trichilia minima T.D.Penn., 2016

Pennington, Terence D., 2016, Systematic Treatment Of American Trichilia (Meliaceae), Phytotaxa 259 (1), pp. 18-162 : 140-142

78. Trichilia minima T.D.Penn. , spec. nov. (sect. Moschoxylum ). Type:— BRAZIL. Acre, Tarauacá, Bacía do Alto- Jurua, Rio Tarauacá, fl., November 1995, Silveira, Daly , Costa, Ehringhaus, Oliveira, Lima & Figueiredo 1018 (holotype, NY). Plate 17 , Map 87

Trichiliae reynelii affinis sed indumento hispido, foliis minoribus, corolla breviter tubulosa glabriuscula et tubo stamineo glabro differt.

Young shoots hispid (hairs up to 0.75 mm long, straight, stiff, erect, basifixed), 3–4 mm diam., smooth, brown. Bud scales absent. Leaves pinnate, either with a terminal leaflet or with one of the ultimate pair orientated to simulate a terminal leaflet, petiole + rhachis 11–13 cm long, petiole semiterete, rhachis terete, hispid; petiolule 4–5 mm long. Leaflets opposite to alternate, dimorphic, normal leaflets 5–7, plus 2 pairs of greatly reduced leaflets at the base of the petiole; normal leaflets 9–13.5 cm long, 3.6–4 cm broad, (terminal leaflets 15–16 cm long, 4.7–5.7 cm broad), oblanceolate, apex acuminate, base acute, chartaceous to thinly coriaceous, upper surface with hispid midrib, lower surface hispid on midrib and veins and with scattered hairs on the lamina, sparsely glandular-punctate and -striate; basal reduced leaflets 1.5–2.3 cm long, broadly ovate to orbicular, persistent; venation eucamptodromous, midrib slightly sunken on the upper surface; secondaries 15–18 pairs, ascending, parallel, straight or arcuate; intersecondaries absent; tertiaries oblique, obscure. Inflorescence axillary, 25–28 cm long, a slender, laxly-flowered panicle, the branches spreading widely and the lower ones up to 5 cm long, hispid; pedicel 1–1.5 mm long. Calyx ca. 0.3 mm long and ca. 1 mm broad, patelliform, obscurely 4-lobed, with scattered hispid hairs outside, glabrous inside. Corolla shortly tubular. Petals 3–4, 1.75–2 mm long, ca. 0.5 mm wide, fused for about 1/3 their length, valvate, lanceolate, acute, remaining erect, with scattered minute appressed hairs outside, glabrous inside. Staminal tube shortly cylindrical, filaments completely fused, ca. 1 mm long, margin with 8 slender attenuate lobes alternating with the anthers and about half their length, glabrous; anthers 8, ca. 0.5 mm long, oblong, rounded, glabrous. Nectary absent. Ovary ca. 0.75 mm long conical, 3-locular, locules with a single ovule, densely strigose; style ca. 0.25 mm long, glabrous, style-head capitate, scarcely expanded. Fruit unknown.

Field Characters. Small tree to 8 m high, with white flowers. Flowering in November.

Distribution & Ecology. In lowland evergreen forest below 500 m elevation, on periodically flooded land, in Acre, Brazil.

Collections Examined. BRAZIL. Acre: Tarauacá, Bacía do Alto Jurua, Tarauacá (SW0871), Silveira et al. 1018 (NY).

Relationships. Trichilia minima is morphologically closest to T. reynelii , but differs from it in a number of small but consistent characters. The stiff hispid indumentum differs from the weaker +/- villose or tomentose indumentum of T. reynelii . Other differences are the smaller leaflets, subglabrous petals, glabrous staminal tube and 3-locular ovary with 1-ovulate locules.

MAP 87. Distribution of Trichilia minima T.D.Penn. Total distribution to 2010.

The flower size and structure of this species are also similar to T. minutiflora (Mexico-Honduras) , but the latter differs in lacking the much reduced basal leaflets on the petiole, and its flowers have 4–6 stamens, and a 2-locular ovary with 2-ovulate locules. Trichilia minima is also similar to some dimorphic-leaved species such as T. pseudostipularis (coastal Brazil), but this has a very short inflorescence and much larger flowers. It is also close to T. amapaensis , but the latter has a congested inflorescence and larger flowers.

Figures

PLATE 17. Trichilia minima T.D.Penn.A, habit with inflorescence; B, detail of leaf upper surface; C, detail of leaf lower surface; E, whole flower; F, half flower; G, cross-section of ovary. (A–G, Silveira et al. 1018).