Bolivia. La Paz: Larecaja near Sorata, Cochipata, 3300 m, 9 Oct 1818, Mandon 674 (lectotype designated by Simpson 1979, pg. 42: G!; isolectotypes: BM!, F! GH!, GOET!, K!, NY!, P!, S!, US!).

Trees 1–10 m tall. Leaves slightly congested at the branch tips, imparipinnate with 1(–2) pair of leaflets, obtrullate in outline, (3.7–)4.4–4.9 × 3.2–4.1 cm; rachises densely lanate, points of leaflet attachment with a tuft of long hairs; stipular sheaths apically truncate, densely lanate on the outer surfaces; leaflets narrowly elliptic in outline, second pair from the terminal leaflet the largest, one of this pair (2.0–)2.6–3.3 × 0.7–1.1 cm; margin crenate with 8–12 teeth, apically acute to obtuse or slightly emarginate, basally cuneate; upper leaflet surfaces glabrous; lower leaflet surfaces densely tomentose with whitish hairs 0.4–0.8 mm long mixed with pannose hairs, second pair of leaflet, if present, very small. Inflorescences pendant, (4.9–)5.5–7.0(–9.5) cm long, bearing 11–13 flowers; floral bracts 5.9–7.6 mm long, narrowly triangular, densely villous on the outer surface; rachises villous. Flowers 5.8–8.2(–10.1) mm diam.; sepals 4, ovate, green, densely villous outside; stamens 21–23, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 3.3–3.8 mm long. Fruits turbinate, with 2–4 irregular flattened ridges with a series of spines, densely villous; 4.9–5.7 × 3.4–5.7 mm including spines. Tetraploid.

Polylepistriacontandra has been found in southern Puno (Peru), where it has been collected at just one locality in Sandia Province, across the Cordillera Apolobamba to the northern Cordillera Real in La Paz (Bolivia) (Fig. 92). It grows on the upper limit of the humid Yungas forests at 2360–4310 m elevation. It has been often planted around communities near Titicaca Lake and in the City of La Paz (Kessler 1995b). Many populations are remnants growing in areas with abrupt topography, such as inaccessible headwaters, micro-basins and rocky slopes (Navarro et al. 2010).

The EOO for Polylepistriacontandra is estimated as 27,030 km², the AOO is assessed at 60 km² and it is known from 12 locations. Polylepistriacontandra was categorized as VU (B1+2c, D2) in the World List of Threatened Trees (Oldfield et al. 1998). Later, it was classified as VU (B1b(i,ii,iii)) in the Red List of Threatened Flora of Bolivia (Arrázola et al. 2012). It is protected within the Apolobamba Integrated Management Natural Area. Although the species is under some protection, its populations are also heavily fragmented. We assess P.triacontandra as Endangered (A1, B1a+B2a, C1).

Polylepistriacontandra resembles P.subtusalbida in having 1(–2) lateral leaflet pairs and tomentose hairs. However, it has narrowly elliptic leaflets with crenate margin, inflorescences 4.9–9.5 cm long with 11–13 flowers and styles 3.3–3.8 mm long, whereas P.subtusalbida has obovate leaflets with serrate margin, inflorescences 1.8–3.7 cm long with 3–4 flowers and styles 2.8–3.4 mm long. Polylepistriacontandra is also morphologically similar to P.pallidistigma with which shares the number of lateral leaflets and margin type. It differs by its leaflets (2.0–)2.6–3.3 × 0.7–1.1 cm long with tomentose hairs on the lower leaflet surfaces, and inflorescences 4.9–9.5 cm long with 11–13 flowers, compared to the smaller leaflets (1.2–.2.0 × 0.5–0.8 cm) with pannose hairs on the lower leaflet surfaces and shorter inflorescences (2.7–6.0 cm) with 5–6 flowers of P.pallidistigma. For additional morphological similarities, see under P.lanata.

Bolivia. La Paz: Bautista Saavedra, Chajaya, a few kilometers from Charazani, 15°13'S, 069°01'W, 3500 m, 30 March 1985, Solomon 13346 (MO!). Camacho, Puerto Acosta, 3860 m, 05 April 1982, Beck 7662 (GOET!). Franz Tamayo, Madidi, Apolobamba, Agua Blanca, Area Natural de Manejo Integrado Apolobamba, Agua Blanca y carretera hacia Antaquilla, 14°49'11"S, 069°07'00"W, 4031 m, 07 June 2008, Fuentes 12780 (BOLV, LPB, MO!, QCA!, USZ); Area Natural de Manejo Integrado Apolobamba, Keara Bajo, 14°42'43"S, 069°05'03"W, 3500 m, 18 June 2005, Fuentes 8390 (LPB, MO!, QCA!); Area Natural de Manejo Integrado Apolobamba, Pelechuco camino hacia Agua Blanca, 14°49'19"S, 069°07'01"W, 3593 m, 07 June 2008, Huaylla 2566 (BOLV, LPB, MO!, QCA!, USZ); 2 km S Pelechuco on road to Ulla Ulla, 3700 m, 28 August 1991, Kessler 3051; 3052 (AAU!, GOET!); 3402 (AAU!); 3420 (GOET!, LPB, MO!); 3421 (GOET!); 3422 (AAU!, GOET!, LPB, MO!); 3423 (GOET!); 3424 (AAU!, GOET!); 3425 (GOET!, LPB, MO!); 3558; 3559; 3560; 3561; 3562; 3563; 3564; 3565; 3566; 3567; 3568; 3569; 3570; 3571; 3572; 3573; 3574; 3575; 3576; 3578; 3579; 3580; 3581; 3582; 3583; 3584; 3585; 3586; 3587 (GOET!); Apolobamba, Puina, 14°35'43"S, 069°07'05"W, 3747 m, 24 April 2008, Quisbert 929 (LPB, MA, MO!, QCA!); Area Natural de Manejo Integrado Apolobamba, Pelechuco, 3647 m, 24 May 2009, Reguerin 116 (QCA!); 116 (LPB, MO!, QCA!, USZ); Área Natural de Manejo Integrado Apolobamba, Pelechuco, 14°49'15"S, 069°04'07"W, 3614 m, 24 May 2009, Reguerín 118 (BOLV, LPB, MO!, QCA!, USZ); 119 (LPB, MA, MO!, USZ); Área Natural de Manejo Integrado Apolobamba, Pelechuco, 14°49'17"S, 069°04'10"W, 3649 m, 25 May 2009, Reguerín 121 (LPB, MA, MO!, USZ); Madidi, Apolobamba, Pelechuco-río abajo, Santa Ana, 14°46'14"S, 068°58'21"W, 2184 m, 16 May 2009, Torrez 550 (LPB, MA, MO!, QCA!); 550 (QCA!); 553 (LPB, MO!, QCA!); 553 (QCA!); Madidi, Apolobamba, Pelechuco-río abajo, Santa Ana, 17°49'15"S, 069°04'01"W, 3547 m, 25 May 2009, Torrez 586 (LPB, MA, MO!, NY, QCA!); 58.5 km N of Sorata on road to Quiabaya, 15°36'S, 068°41'W, 3600 m, 16 December 1981, Solomon 6640 (MO!); Sorata, 15°40'03"S, 068°39'18"W, 3660 m, 31 July 2010, Steudel 426; 427; 428; 431; 433 (Z!). Murillo, Calacoto (La Paz), ornamental plants, 16°31'S, 068°08'W, 3300 m, 15 August 1986, Solomon 15492 (MO!).