Trichilia trimera T.D.Penn., 2016

Pennington, Terence D., 2016, Systematic Treatment Of American Trichilia (Meliaceae), Phytotaxa 259 (1), pp. 18-162 : 59-61

14. Trichilia trimera T.D.Penn. spec. nov. (sect. Trichilia ). Type:— PERU. Huánuco, Prov. Pachitea, region of Pucallpa, ca. 26 km S of Puerto Inca, Biological Station Panguana, fl., August 1988, Gottsberger & Döring G19-4888 (holotype, K, isotype, K). Plate 4 , Map 20

Ab speciebus aliis sectionis Trichiliae inflorescentia congesta minima , floribus subsessilibus cum sepalis 3, petalis 3, antheris 6 et tubo stamineo distinguenda.

Young shoots minutely appressed puberulous with dibrachiate hairs, soon becoming glabrous, 4–5 mm diam., becoming dark brown and scaling; lenticels few or absent. Bud scales absent. Leaves imparipinnate, petiole 5.5–13 cm long, rhachis 9.5–17 cm long, petiole semiterete and narrowly winged towards the base, rhachis semiterete, glabrous, petiolule of lateral leaflets 0.8–1.5 cm long, of terminal leaflet 1.5–3 cm long, all petiolules pulvinate at base. Leaflets opposite, 7, lateral leaflets 11.2–22.5 cm long, 4.9–7 cm broad, terminal leaflet 17–22 cm long, 6.3–7 cm broad, elliptic or slightly oblanceolate, apex shortly acuminate, base narrowly attenuate, chartaceous, glabrous, coarsely glandular-punctate; venation eucamptodromous, midrib slightly raised on the upper surface, secondaries 8–10 pairs, ascending, arcuate and convergent; intersecondaries weak or absent; tertiaries forming a lax reticulum. Inflorescence cauliflorous, ramiflorous and axillary, a minute congested panicle less than 1 cm long, minutely appressed puberulous; pedicel 0.75–1 mm long. Calyx ca. 1 mm long, cyathiform, deeply 3-lobed almost to base, lobes broadly ovate, apex obtuse, appressed puberulous outside, glabrous inside, margin ciliate. Petals 3, 4.5–5 mm long, free, imbricate, ovate or broadly elliptic, apex rounded, appressed puberulous outside, minutely papillose inside. Staminal tube ca. 3.5 mm long, ca. 1.5 mm broad, cylindrical, filaments completely fused, margin with 6 narrowly attenuate lobes alternating with the anthers and about1/2–3/4 their length, glabrous; anthers 6, 0.75–1 mm long, tapering to an acute apex, glabrous. Nectary absent. Ovary ca. 2 mm long, ovoid, 2-locular, locules with 2 collateral ovules, appressed pubescent, style ca. 0.5 mm long, glabrous, style-head capitate, below the level of the anthers. Capsule 1.8–2.5 cm long, 1.5–2.5 cm broad, 2-valved, globose, apex and base rounded, smooth or slightly warty, finely appressed puberulous, becoming glabrous with age; pericarp ca. 1 mm thick. Seeds 4, 1.3–1.5 cm long, 0.6–0.7 cm broad, oblong, rounded at apex and base, surrounded by a thin free arillode except for a small area at the base. Seed coat thin and membraneous. Embryo with thick, free, plano-convex, collateral cotyledons, radicle apical, included. Endosperm absent.

Field Characters. Small tree up to 10 m high and 7 cm diam., with yellowish-white flowers. Flowering recorded August to November, mature fruit in October. The mature fruit is yellow and the seed surrounded by the fleshy red arillode, slightly 4-lobed.

Distribution & Ecology. Western Amazonian Brazil and Peru, where it is an understorey treelet in non-flooded lowland rain forest below 300 m elevation.

Collections Examined. BRAZIl. Acre: Municipio Sena Madureira, basin of R. Purus, R. Iaco, Novo Olinda (SW1069), Daly et al. 7896 (K, NY); Municipio Santa Rosa , Rio Purus, Seringal Terra Nova (SW0969), Daly et al. 11154 (K); Tarauacá, Rio Jurua, Rio Tarauacá, Seringal Macuripe (SW0871), Silveira et al. 827 (K); Tarauacá, Rio Jurua basin, R. Tarauacá, Seringal Maceio (SW0870), Silveira et al. 897 (K).

PERU. Huánuco: Prov. Pachitea, region of Pucallpa, western part of Sira mountains, ca. 26 km S of Puerto Inca (SW0974), Gottsberger & Döring G19-4888 (K). Loreto: Maynas Prov., Distrito Amazonas, Explorama Napo Camp (Rio Sucusari) (SW0372), Vásquez & Grandez 17606 (MO).

MAP 20. Distribution of Trichilia trimera T.D.Penn. Total distribution to 2010.

Relationships. A very distinct species within sect. Trichilia . It has the opposite leaflets and corolla of free, imbricate petals that characterize species of this section but is otherwise unlike any other species. The axillary inflorescence is greatly contracted to less than 1 cm long, and bears only one open flower at any one time, and the floral formula of 3 sepals, 3 petals, with 6 stamens is not known elsewhere in the section. Its isolated position within the section is confirmed by its placement on the ITS tree at the end of a long branch, next to T. euneura .

Figures

PLATE 4. Trichilia trimera T.D.Penn. A, habit; B, detail of leaf undersurface; C, detail of petiolules; D, inflorescence; E, whole flower; F, half flower; G, cross-section of ovary; H, infructescence; I, seed. (A–C, Vásquez & Grandez 17606; D–G, Gottsberger & Döring G19- 4888; H–I, Daly et al. 7896).