Trichilia amapaensis T.D.Penn., 2016

Pennington, Terence D., 2016, Systematic Treatment Of American Trichilia (Meliaceae), Phytotaxa 259 (1), pp. 18-162 : 106-108

52. Trichilia amapaensis T.D.Penn. spec. nov. (sect. Moschoxylum ). Type:— BRAZIL. Amapá, Rio Araguari, fl., September 1961, Pires, Rodríguez & Irvine 50677 (holotype, NY; isotype, NY). Plate 11 , Map 58

Trichiliae schomburgkii et T. pleeanae affinis sed ramulorum, inflorescentiae et calycum indumento dense hispido differt.

Young branches densely hispid (hairs simple, ca. 1 mm long, stiff, straight, erect and spreading), ca. 4–5 mm diam, eventually becoming glabrous, dark brown, scaling and suberous, with pale lenticels. Bud scales absent. Leaves pinnate, with one leaflet of the ultimate pair orientated to simulate a terminal leaflet, petiole & rhachis 7–11 cm long, petiole semiterete, rhachis terete, densely hispid; petiolule 2–3 mm long. Leaflets alternate, dimorphic, normal leaflets 3, plus 1–2 pairs of greatly reduced leaflets at the base of the petiole, normal leaflets 17.5–19 cm long, 7–9 cm broad, broadly oblanceolate, apex shortly acuminate, base acute, sometimes finally rounded, chartaceous, upper surface with hispid midrib, lower surface hispid on midrib and veins with sparser indumentum on the lamina, not glandular-punctate or -striate; basal reduced leaflets 1–2 cm long, suborbicular, caducous; venation eucamptodromous in the lower half, brochidodromous in the upper half, midrib and secondaries slightly sunken on the upper surface; secondaries 12–13 pairs, ascending, slightly arcuate and convergent; intersecondaries short to long, tertiaries few, oblique to reticulate. Inflorescence axillary, 5–12 cm long, a laxly branched panicle, with rather dense terminal thyrsoid clusters of flowers, densely hispid; pedicel ca. 1 mm long. Calyx 1.25–1.5 mm long, shallowly cyathiform, with 4 shallow, obtuse lobes, densely hispid outside, glabrous within. Petals 4, ca. 4 mm long, fused for one third to half their length, valvate, lanceolate, naviculate, apex acute, remaining erect, densely appressed pubescent outside, glabrous inside. Staminal tube shortly cylindrical, filaments completely fused into a tube ca. 2.5 mm long, ca. 1.5 mm broad, margin with 8 attenuate lobes alternating with the anthers and about1/2 their length, glabrous; anthers 8, ca. 0.75 mm long, ellipsoid, glabrous. Nectary absent. Ovary ca. 1 mm long, ovoid, 3-locular, loculi with 2 collateral ovules, densely strigose; style ca. 1 mm long, stout, glabrous, style-head simple, scarcely expanded, below the level of the anthers. Fruit unknown.

MAP 58. Distribution of Trichilia amapaensis T.D.Penn. Total distribution to 2010.

Field Characters. A small treelet with yellowish-green flowers. Flowering in September.

Distribution & Ecology. In lowland evergreen rain forest on upland non-flooded sites. At present known only from the type collection in Amapá, Brazil.

Collections Examined. BRAZIL. Amapá: Rio Araguari (NW0258), Pires et al. 50677 (NY).

Relationships. On morphological grounds Trichilia amapaensis belongs in the group of species with dimorphic leaflets, corolla of free or partially united valvate petals and 3-locular ovary, in which T. pleeana and T. schomburgkii are the most widespread. The latter two species and most other species of this group differ from T. amapaensis in having closely appresed minute indumentum and fewer leaflets. Only T. inaequalatera and T. pseudostipularis have coarser spreading (but not hispid) indumentum and flowers of comparable size. Trichilia pseudostipularis (coastal Brazil) differs in its short fasciculate inflorescence up to 2 cm long, glabrous or subglabrous corolla and reflexing corolla lobes. Trichilia inaequilatera differs in the coarsely pubescent indumentum, more numerous leaflets, generally smaller flowers and free petals.

In the ITS analysis this species is sister to a small group of Central American species ( T. moschata , T. minutiflora and T. breviflora ), all of which lack the dimorphic leaflets. This is another example of the incompatability of ITS data with the morphological characters that are most useful for species delimitation in sect. Moschoxylum .

Figures

PLATE 11. Trichilia amapaensis T.D.Penn. A, habit with inflorescence; B, detail of leaf undersurface; C, detail of peduncle; D, whole flower; E, half flower; F, detail of staminal tube. (A–F, Pires et al. 50677).