Trichilia pachypoda (Rusby) C.DC. ex Harms

Pennington, Terence D., 2016, Systematic Treatment Of American Trichilia (Meliaceae), Phytotaxa 259 (1), pp. 18-162 : 84-86

33. Trichilia pachypoda (Rusby) C.DC. ex Harms in Engl. & Prantl., Nat. Pflanzenfam., ed. 2, 19b1: 114, 177 (1940); T.D.Penn., Fl. Neotrop. 28: 160 (1981). Plate 8 , Map 39

Moschoxylum pachypodum Rusby, Mem. Torrey Bot. Club 6: 17 (1896). Type:— BOLIVIA. between Guaina and Tipuani, fl., Bang 1454 (holotype, NY; isotypes, B, BM, C, E, F, G, GH, K, MO, PH, US).

MAP 39. Distribution of Trichilia pachypoda (Rusby) C.DC. ex Harms. Solid dots, distribution pre-1981, open dots new records 1981–2010.

Young shoots 3–5 mm diam., softly tomentose with erect, spreading and crisped yellowish- brown basifixed hairs, indumentum persistent. Bud scales absent. Leaves imparipinnate or pinnate with one leaflet of ultimate pair orientated to simulate a terminal leaflet, petiole 4.5–7 cm long, semiterete or slightly winged at the base, softly tomentose; rhachis 10–20 cm long, semiterete or somewhat flattened at each node, softly tomentose; petiolule 2–4(–5) mm long. Leaflets opposite to alternate, 9–11, usually with a pair of caducous linear to subulate vestigial leaflets 1–2 mm long and 1–3 cm above the base of the petiole; normal leaflets 7.5 × 2.8–18 × 6.5(–22 × 6.5) cm, elliptic or oblong elliptic, apex acuminate, base usually obtuse or rounded; the basal pair of leaflets may be much smaller; chartaceous; upper surface glabrous except for residual pubescence along midrib, lower surface pubescent on midrib and veins, sometimes with scattered pubescence on the lamina; not glandular-punctate or -striate; venation eucamptodromous, midrib flat or slightly sunken on the upper surface; secondaries 14–16 pairs, shallowly ascending, straight or slightly arcuate, parallel or slightly convergent; intersecondaries short or absent; tertiaries obscure. Inflorescence axillary and sometimes clustered around the shoot apex on short leafless axillary shoots, 10–18 cm long, a many-flowered pyramidal panicle, softly pubescent; pedicel 1–1.5 mm long. Calyx 0.5–1 mm long, 2.5–3 mm broad, patelliform, shallowly 4–5-lobed, lobes acute to obtuse, pubescent outside, glabrous inside. Petals 4–5, 3.5–4 mm long, 1.5–2 mm broad, lanceolate, apex acute, free, valvate, reflexing with age, sparsely appressed pubescent outside, glabrous inside. Staminal tube ca 2.5 mm long and broad, cup-shaped, filaments completely fused, margin entire or with 8–10 very short subulate lobes alternating with the anthers, glabrous outside, sparsely hairy inside; anthers 8–10, 0.7–0.8 mm long, lanceolate, glabrous. Nectary absent. Ovary ca. 1.5 mm long, conical, 3-locular, locules with 2 collateral ovules, densely puberulous; style ca. 1.5 mm long, glabrous, style-head capitate. Capsule ca. 1.8 x 0.9 cm (slightly immature), 3-valved, oblanceolate, apex rounded, base acute, smooth, densely pubescent with golden-brown hairs; pericarp ca. 0.5 mm thick. Seeds 1–3, ca. 1 cm long (immature), plano-convex, rounded at the apex, completely surrounded by a thin fleshy arillode, seed coat membraneous. Embryo with plano-convex collateral cotyledons, radicle apical, included; endosperm absent.

Field Characters. Tree to 18 m high and 33 cm diam., bark scaling in small plates, greyish-green, slash whitish-cream and astringent. The flowers are cream-coloured and the fruit pale green. Flowering is recorded in July and August, fruit maturing in October.

Distribution & Ecology. Known only from Amazonian Peru and Bolivia, where it is a component of lowland and lower montane rain forest up to 700 m elevation.

Additional Collections Examined. PERU. Junín: Rio Tambo, Oserato (SW1074), Weiss 156 (F).

BOLIVIA. Beni: Province Ballivian, 4 km S of Triunfo, Meneces et al. 148 (K, QCNE). La Paz: Province Sud Yungas, Sapecho, Seidel et al. 5752 (K). Pando: Province Manuripi, near Puerto America (SW1167), Jardim 2336 (K). Santa Cruz: Province Ichilo, Amboro National Park (SW1763), Nee 38854 (COL, NY); Ichilo Province, Rio Ibabo, Chore Forest Reserve (SW1664), Neill et al. 9242 (K, MO, NY); Velasco Province, Noel Kempff Mercado National Park (SW1461), Guillen 1151 (K).

Relationships. In Flora Neotropica (1981: 160) this was treated as a doubtfully distinct species very close to T. quadrijuga . Since that time a few new collections have come in which confirm that it is indeed closest to T. quadrijuga , but consistently different from it in its spreading yellowish-brown indumentum on the young parts, leaves and inflorescence. The spreading hairs are basifixed while those of T. quadrijuga are dibrachiate or medifixed and closely appressed. In flower and fruit structure they are the same. Its position next to T. quadrijuga is confirmed by the ITS data.

Trichilia pachypoda is distributed from Amazonian Bolivia to central Amazonian Peru. I have seen no material of it from Ecuador. Specimens referred to T. pachypoda in the Flora of Ecuador ( Palacios, 2007), such as Balslev et al. 97289 belong in T. inaequilatera . The latter lacks the soft tomentose indumentum of T. pachypoda , and has reticulate tertiary venation which is conspicuous on the lower leaflet surface, whereas that of T. pachypoda is not reticulate but obscure. The reduced basal leaflets of these species are also significantly different. Those of T. pachypoda are minute and vestigial, 1–2 mm long, whereas those of T. inaequilatera are foliose, 0.7–2(–3) cm long, ovate to elliptic.

Figures

PLATE 8. Trichilia pachypoda (Rusby) C.DC. A, habit with inflorescence; B, detail of reduced basal leaflets; C, detail of leaf upper surface; E, shoot apex; F, whole flower; G, half flower; H, cross-section of ovary. (A–H, Meneces et al. 148).