Trichilia obovata W.A. Palacios, Novon

Pennington, Terence D., 2016, Systematic Treatment Of American Trichilia (Meliaceae), Phytotaxa 259 (1), pp. 18-162 : 78-80

30. Trichilia obovata W.A. Palacios, Novon 4(2): 157 (1994); Fl. Ecuador 82: 72 (2007). Type:— ECUADOR. Pastaza, Pozo Petrolero Danta 2, 50 km SW of Curaray , fl., Rubio & Coba 855 (holotype, QCNE; isotype, MO). Plate 7 , Map 35

Young branches slender (2–4 mm diam.), finely appressed puberulous at first, soon glabrous, smooth, greyish-brown, with scattered pale lenticels. Bud scales absent. Leaves imparipinnate, petiole 3–5.5 cm long, semiterete, finely appressed puberulous at first, soon glabrous, rhachis 3–4.5 cm long, terete, with scattered appressed hairs at first, soon glabrous; petiolule of lateral leaflets 0.5–1 cm long, petiolule of terminal leaflet 1–2.2 cm long. Leaflets opposite (1–)2 pairs, lateral leaflets 8 × 3–16.5 × 6.6 cm, lower pair usually smaller than upper pair, elliptic to oblanceolate, apex acuminate, base narrowly attenuate, terminal leaflet 11.5 × 5.2–19 × 9 cm, broadly oblanceolate to obovate, apex acuminate, base narrowly attenuate, chartaceous, glabrous, not glandular-punctate or -striate; venation eucamptodromous or sometimes brochidodromous in the upper half, secondaries 8–11 pairs, ascending, straight or slightly arcuate, parallel; intersecondaries absent; tertiaries oblique. Inflorescence axillary, 8–18 cm long, peduncle 2–6 cm long, lateral branches up to 6 cm long, a rather lax-flowered panicle, with sparse minute appressed hairs or glabrous; pedicel 2–3 mm long; bracts minute. Flowers unisexual (plant dioecious). Calyx 0.5–0.75 mm long, patelliform, sepals 5, fused to about halfway, narrowly triangular, acute, aestivation open, subglabrous. Petals (4–)5, 2–3 mm long, 0.75–1 mm broad, free, valvate to slightly imbricate, oblong or lanceolate, apex acute, subglabrous. Staminal tube 2–2.5 mm long, 1–1.5 mm broad, shortly cylindrical, with alternate filaments slightly shorter, filaments fused for about half their length, apex truncate, barbate in the throat, otherwise subglabrous; anthers 10, 0.5–0.6 mm long, broadly ovoid, glabrous; antherodes in female similar, but shrunken and without pollen. Nectary a small annulus around the base of the ovary, pubescent, scarcely visible in female. Ovary ca. 0.5 mm long, ovoid, 3-locular, locules with 2 collateral ovules, pubescent, style ca. 0.5 mm long, style-head capitate; pistillode in male flattened, with reduced locules and ovules minute or absent. Capsule 1.3–1.5 cm. long, 1.5–1.8 cm broad, 3-valved, ovoid or globose, often trigonous at base and slightly broader than long, apex obtuse to rounded, base obtuse to truncate, smooth, minutely granular papillose and with scattered short appressed hairs; pericarp ca. 0.3 mm thick. Seeds 3–6, 1–2 collateral in each valve, ca. 1 cm long, shaped like the segment of an orange and rounded at apex and base, with a fleshy, free, arillode covering most of the seed except for the lower half of the abaxial surface. Embryo with thick plano-convex, collateral cotyledons, radicle apical, extending to the surface, endosperm absent.

MAP 35. Distribution of Trichilia obovata W.A.Palacios. Total distribution to 2010.

Field Characters. Treelet or small tree to 15 m high and 25 cm diam. Flowers pale greenish-cream and fruit green or greenish-yellow and surrounded by an oily red arillode. Flowering has been recorded in October and February, fruiting from February to August.

Distribution & Ecology. In lowland rain forest over non-flooded red or alluvial soils, usually below 600 m elevation (1 record at 1000 m). Known only from Amazonian Ecuador and Peru.

Collections Examined. ECUADOR. Napo: Cantón Archidona, Hollin-Loreto km 50 (SW0077), Cerón & Hurtado 6674 (K); Sinagre, Cayambe-Coca Ecological Reserve (NW0077), Jaramillo & Coello 3090 (QCA); 30 km NNW of Coca, R. Huashito (SW0077), Pennington 10625 (K, QCA); 3.5 km W of R. Huataraco (SW0077), Vargas & Grefa 740 (K). Orellana: Yasuní Forest Reserve, E of Scientific Station (SW0076), Acevedo-Rodríguez & Cedeño 7409 (K, NY, US); Sumaco National Park, Amoco Block 18, R. Payamino (SW0077), Dik 1724 (K); La Joya de los Sachas, Maxus road km 18–33 (SW0076), Grijalva 657 (NY); Yasuní National Park, Maxus road km 1 (SW0076), Grijalva 734 (MO); Cantón Pompeya, La Joya de los Sachas (SW0076), Gudiño et al. 1828 (K); INIAP Experimental Station Payamino, El Chuncho Forest Reserve (SW0077), Jaramillo 8373 (NY), Palacios et al. 1229 (MO, NY); Yasuní National Park, Añangu (SW0076), Luteyn et al. 8507 (NY, QCA); Cañon de los Monos, 15 km N of Coca (SW0077), Neill et al. 6310 (K), Zaruma et al. 96 (K, MO); Sumaco National Park, Rio Pujuno, sector Juan Pio Montufar (SW0077), Tirado & Grefa 2092 (K); Sumaco Napo-Galeras National Park, Comuna Limucha (SW0077), Vargas & Alvarado 1020 (K); Yasuní Scientific Station, Rio Tiputini, 50 hectare plot (SW0076), Villa & Alvia 537 (F), 1087 (F). Pastaza: Rio Lliquino, 1 km N of Pozo Villano 2 (SW0177), Alvarez et al. 2247 (K); Villano, between Rio Villano & Rio Lliquino (SW0177), Neill et al. 10842 (K); Villano, Pozo 3-Pista Villano (SW0177), Palacios 12154 (K), 12161 (K, MO, NY); Via Auca, 115 km S of Coca, near R. Tiguino (SW0176), Rubio 101 (MO); Cantón Pastaza, Pozo petrolero “Danta 2” 50 km SE of Curaray (SW0176), Rubio & Coba 855 (MO, QCNE). Sucumbios: Cantón Lago Agrio, Parroquia Tarapoa (SW0076), Cerón & Ayala 9712 (MO).

PERU. Amazonas: Rio Santiago, 2 km from Caterpiza (SW0377), Huashikat 1362 (K); Huambisa, 65 km N of Pinglo, Quebrada Caterpiza (SW0377), Huashikat 2345 (K).

Relationships. On morphological grounds T. obovata is closely related to T. martiana , a widespread species distributed from Mexico to eastern Brazil and present along the Pacific coast of Ecuador. It differs from it in having fewer leaflets (2 pairs versus nearly always 3–4 in T. martiana ), fewer secondary veins (8–11 pairs versus 12–18 pairs in T. martiana ), +/- valvate petals (imbricate in T. martiana ) and in fruit size (1.3–1.5 cm long versus 0.9–1.3 cm long in T. martiana ). Additional differences are the frequently cuneiform and usually pubescent leaflets of T. martiana . The +/- valvate petals are anomalous in section Trichilia . Petals with valvate aestivation are present in all species of section Moschoxylum . However, other vegetative, floral and fruit characters such as opposite leaflets, partially united staminal filaments, fruit and seed structure place it clearly in section Trichilia .

Figures

PLATE 7. Trichilia obovata W.A.Palacios.A, habit with inflorescence; B, whole flower; C, half flower; D, habit with fruit; E, seed (A–C, Pennington 10625; D, Acevedo-Rodriguez & Cedeño 7409).