Ecuador. Loja: Laguna Chinchilla, 03°36'20"S, 079°23'08"W, 3610 m, 21 Dec 2019, T.E. Boza E. & C. Medina 3185 (holotype: QCA!; isotypes: Z!, CUZ!).

Trees 4–10 m tall. Leaves strongly congested at the branch tips, imparipinnate with 3–4(–5) pairs of the lateral leaflets, obtrullate in outline, 2.6–3.6 × 2.1–3.2 cm; rachises densely sericeous, points of leaflet attachment with a tuft of long, straight whitish hairs; stipular sheaths apically truncate, densely sericeous in the upper surface; leaflets narrowly to broadly obovate in outline, second pair from the terminal leaflet the largest, one of this pair 1.2–1.6 × 0.5–0.8 cm; margin serrate at apex with 3–4 teeth, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous with few hairs on mid-depression; lower leaflet surfaces densely sericeous with whitish silky hairs 0.2–0.6 mm long. Inflorescences pendant, (3.5–)4.3–10.5(–12.2) cm long, bearing 9–27 flowers; floral bracts 5.5–6.3 mm long, narrowly triangular, densely sericeous on the outer surface; rachises densely sericeous. Flowers 4.4–5.2 mm diam.; sepals 4, ovate, green, densely sericeous outside; stamens 7–9, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.7–2.0 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 1.7–3.0 × 1.4–1.5 mm including spines. Diploid.

Polylepisloxensis is restricted to south-western Ecuador (Fig. 41). It has been collected in southern Azuay Province (Nabon) and at Laguna Chinchilla and Fierro Urco in northwest Loja Province bordering with El Oro Province. The páramos in this region are part of the physiographic unit called ‘Páramos del Sur’ of the Western Cordillera or Ecuador. The species occurs in the humid páramo at 2650–3700 m elevation, where it grows in mixed forest with Gynoxiscuicochensis, Brachyotumledifolium and Weinmanniaglabra (Lassermann 2009). In this region, a new, endemic species of hummingbird has recently been discovered (Sornoza-Molina et al. 2018), which together with this new Polylepis species suggests that this mountain region may be a center of endemism.

Polylepisloxensis is known from six locations with an EOO of 728 km² and an estimated AOO of 32 km². No conservation actions have been taken to date. The area is heavily grazed by cattle and horses, pine plantations occupy large extensions and a large proportion of the area is under gold mining concessions (Sornoza-Molina et al. 2018). Based on its restricted distribution, fragmented and degraded habitat with low populations size and lack of habitat protection, we assess P.loxensis as Critically Endangered (A2a, B1a+B2a, C2a).

Polylepisloxensis is most similar to P.ochreata, with which it shares the emarginate leaflet apices and subcordate leaflet bases and similar dense, short, white silky hair on the lower leaflet surfaces. Indeed, they were treated as conspecific by Boza Espinoza et al. (2019), but later, Boza Espinoza et al. (2020a) recognized their morphological and ecological distinctness. The two species differ in number of leaflet pairs, with P.loxensis having 3–4(–5) and P.ochreata 4–7. Polylepisloxensis further has shorter inflorescences (3.5–12.2 cm) bearing 9–27 flowers, fewer stamens (7–9) and shorter styles (1.7–2.0 mm), whereas P.ochreata has longer inflorescences (8.1–17.4 cm) bearing 21–49 flowers, more stamens (9–15) and longer styles (2.1–2.6 mm).

Ecuador. Azuay: Nabón, 3°28'20"S, 79°02'24"W, 2800–3300 m, 15 November 2008, Salgado 1419 (LOJA!); Loja: Loja, Fierro Urco, 03°36'20"S, 079°23'08"W, 3610 m, 19 December 2019, Boza & Medina 3184 (QCA!, Z!, CUZ!); Fierro Urco, Saraguro-Loja, km 12.4 turnoff towards Fierro Urco, km 23.8, 03°43'10"S, 079°19'18"W, 3840 m, 6 December 1994, Jørgensen et al. 1240 (AAU!, LOJA!, MO!); road San Lucas–Saraguro, km 9, turn off to Fierro Urco, 11 km to the pass, 03°43'03"S, 079°19'25"W, 3630 m, 4 November 2000, Jørgensen et al. 2228 (QCA!); ca. 10 km along road to Fierro Urco, 03°41'S, 079°01'W, 2850 m, 8 September 1998, Laegaard 19109 (AAU!, LOJA!, QCA!); Fierro Urco, grass Páramo 12 km to the left (northbound) from the Panamericana highway, 03°43'S, 079°19'W, 3600–3650 m, 9 June 1999, Sklenár & Laegaard 7096 (AAU!, GOET!); ca. km 12 along Páramo road to Fierro Urco, 03°41'S, 079°01'W, 3650 m elev., 9 June 1999, Laegaard & Sklenár 20279 (AAU!, LOJA!, QCA!); Páramo of Fierro Urco SW of Saraguro, 03°43'S, 079°19'W, 3500 m elev., 21 November 1996, Lewis et al. 2121 (AAU!); road Loja-Cuenca, km 50, track to Fierro Urco, km 5–7, 03°41'S, 079°17'W, 3150–3350 m elev., 25 October 1996, Lewis & Lozano2724 (AAU!,LOJA!, MO!, QCA!); road Loja-Saraguro, km 52, track to Fierro Urco, km 10, 03°42'S, 079°18'W, 3350–3450 m elev., 17 January 1997, Lewis et al. 2932 (AAU!, LOJA!, MO!); road Loja–Saraguro, 8.5 km N of San Lucas, track to Fierro Urco, km 11, 03°43'10"S, 079°19'18"W, 3550 m elev., 15 January 1998, Lewis & Hughes 3804 (AAU!, LOJA!, MO!, QCA!); Fierro Urco, 03°41'S, 079°22'W, 3700 m elev., 11 January 1995, P. Lozano 172 (LOJA!); Saraguro, Laguna Chinchilla, 03°36'20"S, 079°23'08"W, 3610 m elev., 21 December 2019, Boza & Medina 3186 (QCA!, Z!, CUZ!), cerro Chinchilla, parroquía Celén, 03°35'44"S, 079°20'17"W, 3000 m elev., 19 September 1984, Jaramillo 7332 (QCA!), 7335 (GB, QCA!); Laguna Chinchilla, 03°36'17"S, 079°23'49"W, 11 November 2008, Salgado et al. 1392; 1394 (LOJA!).