Trichilia vestigialis T.D.Penn., 2016

Pennington, Terence D., 2016, Systematic Treatment Of American Trichilia (Meliaceae), Phytotaxa 259 (1), pp. 18-162 : 142-144

79. Trichilia vestigialis T.D.Penn. spec. nov. (sect. Moschoxylum ). Type:— BRAZIL. Acre, R. Jurua, Jurua Mirím, fr., Oct. 1901, Ule 5808 (holotype, K). Plate 18 , Map 88

Trichiliae areolatae affinis sed ramulorum et inflorescentiae dense pilosi, foliolis chartaceis, nervis tertiariis obscuris et floribus minoribus, staminibus 5 differt.

Young branches densely pilose with long spreading weak straw-coloured hairs, 2–3 mm diam., eventually becoming glabrous, smooth, pale brown, without lenticels. Bud scales absent. Leaves 1–6-foliolate, petiole and rhachis of pinnate leaves 5–7 cm long, of 1–3-foliolate leaves 1–3 cm long, petiole semi-terete, rhachis terete, pilose; petiolule 1–2 mm long. Leaflets alternate to subopposite, dimorphic, normal leaflets 1–6, plus 1 pair of greatly reduced subulate leaflets at the base of the petiole, normal lateral leaflets 4.5–6 cm long, 2.3–3.2 cm broad, elliptic, apex acuminate, base acute, solitary and terminal leaflets 9–10 cm long, 4–4.2 cm broad, oblanceolate, apex acute, base acute; lowermost lateral leaflets sometimes reduced to ca. 2 cm long; chartaceous, upper surface subglabrous, lower surface with midrib and veins sparsely pilose and scattered hairs on the lamina; glandular-punctate and -striate; basal reduced leaflets 3–4 mm long, subulate, densely pilose; venation eucamptodromous, midrib slightly sunken on the upper surface; secondaries 11–12 pairs on the lateral leaflets, up to 15 pairs on the terminal leaflets, ascending, slightly arcuate and convergent, intersecondaries short; tertiaries few, oblique. Inflorescence axillary, up to 1.5 cm long, a few-flowered panicle or flowers solitary, sparsely pilose; pedicel ca. 1 mm long. Calyx ca. 0.75 mm long, patelliform, lobed to about halfway, lobes 5, acute, pilose outside, glabrous inside. Petals 5, ca. 2 mm long, ca. 0.5 mm wide, fused for ca. ½ their length, valvate, lanceolate, boat-shaped, apex acute, remaining erect, with scattered appressed hairs on the outside of the lobes, glabrous inside. Staminal tube shortly cylindrical, filaments completely fused, ca. 1 mm long, ca. 0.75 mm broad, margin with 5 short acute lobes, alternating with the anthers and ca. 1/3 of their length and glabrous; anthers 5, ca. 0.5 mm long, narrowly ellipsoid, glabrous. Nectary absent. Ovary ca. 0.5 mm long, conical, 3-locular, densely strigose; style ca. 0.5 mm long, glabrous, style-head a small scarcely expanded disk, below the level of the anthers. Capsule ca. 2 x 0.6 cm, 3-valved, oblong, apex and base rounded, smooth, densely pilose with golden hairs, pericarp ca. 0.3 mm thick. Seed solitary, ca. 1.3 x 0.3 cm, completely surrounded by a thin fleshy arillode which also develops around the aborted ovules, or occasionally a small area near the base of the seed exposed; arillode slightly extended at apex and base, free except for attachment from micropyle to raphe; seed coat thin and membraneous. Embryo with plano-convex, collateral cotyledons, radicle apical, included. Endosperm absent.

Field Characters. A small treelet to 8 m high with greenish-cream flowers, flowering August to September, capsule maturing in October.

Distribution & Ecology. In lowland evergreen rain forest, below 400 m elevation, mostly on fertile non-flooded soil. Known only from western Amazonian Brazil and adjacent Peru.

Collections Examined. BRAZIL. Acre: Tarauacá, Bacía do R. Juruá, Rio Murua, Seringal Lancha (SW0870), Silveira et al. 907 (K); Juruá Mirím (SW0872), Ule 5808 (K).

MAP 88. Distribution of Trichilia vestigialis T.D.Penn. Total distribution to 2010.

PERU. Ucayali: Alexander on Humboldt Reserve (SW0875), Froehner 305 (MO), Maas et al. 4514 (K). Loreto: between Yurimaguas and Balsapuerto (SW0576), Killip & Smith 28700 (NY).

Three further collections are included with some reservations, Huashikat 104 (MO), Leveau 15 (K, MO), Pena 109 (K), all from the R. Santiago in northern Peru. They have slightly longer and denser indumentum, and the reduced basal leaflets are caducous.

Relationships. This species is closest in its morphology to T. areolata (central Amazonian Brazil to the Guianas), which shares a generally similar flower, fruit and glandular leaves, and the greatly reduced subulate basal leaflets. The differences are in the detail. The leaves are chartaceous and with inconspicuous lax venation (coriaceous with very conspicuous fine reticulate venation on both surfaces in T. areolata ), the midrib is sunken on the upper surface (raised in T. areolata ), petals 2 mm long and fused for about half their length (3–3.5 mm long and free in T. areolata ), the stamen number is 5 (9–10 in T. areolata ).

Figures

PLATE 18. Trichilia vestigialis T.D.Penn.A, habit with immature infructescence; B, detail of leaf undersurface; C, detail of basal reduced leaflets; D, whole flower; E, half flower; F, cross-sectiion of ovary; G, habit with fruit; H, seed with arillode (A–C, Maas et al. 4514; D–F, Silveira et al. 907; G–H, Ule 5808).