Polylepis longipilosa T.Boza, K.Romoleroux & M.Kessler, Phytoxa 454(2): 116. 2020

Boza Espinoza, Tatiana Erika & Kessler, Michael, 2022, A monograph of the genus Polylepis (Rosaceae), PhytoKeys 203, pp. 1-274 : 1

3. Polylepis longipilosa T.Boza, K.Romoleroux & M.Kessler, Phytoxa 454(2): 116. 2020

Figs 18 , 19

Type.

Ecuador. Carchi: Cantón Montúfar, Loma El Corazón ( Bretaña), al sureste de Huaca, al este de la Colonia Huaqueña, Rio Minas , 00°35'N, 077°42'W, 3200-3500 m, 9 Apr 1989, Tipaz 35 (holotype: QCA!; isotypes: AAU!, MO!) .

Description.

Trees 5-10 m tall. Leaves strongly congested at the branch tips, imparipinnate with (4-)5-6 pairs of the lateral leaflets, obtrullate in outline, (3.8-)4.3-7.3 × 2.4-4.5 cm; rachises densely sericeous, points of leaflet attachment with a tuft of long, straight whitish to yellowish hairs; stipular sheaths apically truncate, densely sericeous in the upper surface; leaflets narrowly to ovate in outline, second pair from the terminal leaflet the largest, one of this pair 1.4-2.2 × 0.4-0.5 cm; margins entire to slightly crenate with 6-7 teeth, apically slightly emarginate seemingly acute by the prolongation of hairs, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely lanate with whitish silky hairs 1.1-1.6 mm long. Inflorescences pendant, (6.8-)11.1-16.6 cm long, bearing 19-29 flowers; floral bracts 6.1-9.4 mm long, narrowly triangular, glabrous on the outer surface; rachises densely sericeous. Flowers 4.8-5.5 mm diam.; sepals 4, ovate, green, glabrous outside; stamens 8-10, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.6-2.0 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 3.9-6.7 × 4.3-7.5 mm including spines. Diploid.

Distribution, habitat and ecology.

Polylepis longipilosa is restricted to north-western Ecuador (Carchi) (Fig. 24 ). It is highly likely that the species also occurs in adjacent Colombia. It grows in humid páramo habitats at 3200-3900 m elevation where it often co-occurs with P. ochreata , with which it hybridizes ( Romoleroux 1996). It grows in mixed forest with Espeletia pycnophylla , Weinmannia sp. and Oreopanax sp. ( Boada et al. 2008).

Conservation status.

The EOO for Polylepis longipilosa is estimated as 17,689 km2, the AOO is assessed at 60 km2 and it is known from eight locations. It occurs in Reserva Ecológica El Angel. However, the Andean Forest and páramos at Carchi have, in recent years, come under increasing threat from timber cutting and forest burning and advancement of the agricultural frontier, which has contributed to the fragmentation and destruction of high Andean ecosystems ( Boada et al. 2008). Based on its degraded and fragmented distribution, we assess P. longipilosa as Critically Endangered (A2a, B1a+B2a, C1+C2a).

Notes.

The populations of Polylepis from Carchi on the southern slopes of Volcán Chiles and on the road between Maldonado and Tulcán have previously been identified either as P. ochreata ( Simpson 1979; Romoleroux 1996, as P. sericea ) or P. pauta ( Romoleroux 1996). Here, we treat it as a distinct species which is morphologically closest to P. ochreata and P. pauta . The most obvious differences between P. longipilosa and these species are its longer (1.1-1.6 mm), densely lanate hairs compared to the shorter (0.3-0.5 mm), densely sericeous hairs of P. ochreata and relatively short (0.4-0.9 mm), sparsely sericeous hairs of P. pauta ; the hairs of P. longipilosa are concentrated on the leaflet veins (as is also the case in P. pauta ), whereas in P. ochreata , the hairs are generally evenly distributed. Polylepis longipilosa also differs from the other two species by the leaflet apex, with P. longipilosa having acute or rarely emarginate leaflet apices, whereas P. ochreata and P. pauta have always emarginate leaflet apices. Additionally, P. longipilosa has shorter styles (1.6-2.0 mm), whereas P. ochreata and P. pauta have styles 2.1-2.6 mm and 2.2-3.0 mm long, respectively. Romoleroux (1996) reported hybrids between P. longipilosa and P. ochreata (as P. sericea ).

There are three distinctive collections of the P. pauta / Polylepis sericea complexes that Boza Espinoza et al. (2020a) were unable to assign to species: Loja, Cerro Chinchilla, J. Jaramillo 7312B, AAU!, QCA!; Pichincha, Laguna Mojanda, Brandbyge 42200, AAU!, MO!, NY, QCA! and Molau 2294, AAU!, GB, QCA!. These collections resemble P. longipilosa , but have different leaflet shape (obovate vs. ovate) with serrate margins (vs. entire to slightly crenate), longer lower leaflet surface hairs (1.5-1.8 mm vs. 1.1-1.6 mm) and longer styles (2.7-3.0 mm vs. 1.6-2.0 mm). Despite targeted fieldwork at both collecting localities, we have been unable to study this form in the field. The specimens at Mojanda were collected in a well-known hybrid zone and although they are not simply intermediate between the potential parent species ( P. incana , P. ochreata , P. pauta ) so that they cannot simply be interpreted as hybrids, it is possible that some unique gene combinations in hybrids might lead to morphotypes that fall outside of the morphological range of the parent taxa. In Loja, the situation is somewhat different, because the only species present there is P. loxensis , so that a hybrid origin is less likely, although in a wind-pollinated genus, such as Polylepis , pollen dispersal might conceivably take place over long distances. Should these collections represent one or even two separate species, then, on present knowledge, they would be very rare or even on the verge of extinction.

Specimens examined.

Ecuador. Carchi: Tulcán, carretera Túlcan-Tufiño-Maldonado-Chical col. en km 12 de Tufiño, cerca de las lagunas, 00°48'N, 077°55'W, 3900 m, 23 April 1993, Freire & Andersen 2547 (AAU!); road Tulcán-Maldonado, near Volcán Chiles, 00°48'N, 077°56'W, 3850-4000 m, 16 August 1985, Laegaard 54965 (AAU!, MO!, QCA!), 54967A, 54967B, 54967C (AAU!), 54967D, 54967E, 54967F (AAU!, QCA!); along the road from Tulcán to Volcán Chiles, 3900 m, 6 October1995, Sklenár & Kosteckova 1412A (QCA!); camino Tufiño, sitio Agua Hediondas, en la base del Volcán Chiles, límite con Colombia, 00°48'N, 077°54'W, 3500 m, 8 November 1993, Palacios 11847 (AAU!, MO!, QCNE); carretera entre Tulcán y Maldonado, faldas del Volcán Chiles, punto más alto del cruce de carretera, 00°45'N, 077°59'W, 3800 m, 19 May 1991, Palacios & Rubio 7349 (AAU!, MO!); southern slopes of Volcan Chiles, 00°49'N, 077°57'W, 3600 m, Ramsay 911 (QCA!, QCNE); route de Tufiño a Maldonado , 10 km après Tufiño, zone très humide, 3850 m, 06 July 1988, Huttel 1390 (QCA!); carretera San Gabriel-Shután alto, 3500 m, 25 March 1989, Jaramillo-Asanza 10862 (QCA!); comuna La Esperanza, páramo de El Artezón, sector Monte Redondo, 3789 m, 18 September 2007, Salgado 220B, 239A (QCA!) .

Figures

Figure 18. Polylepis longipilosa T. Boza, K. Romoleroux & M. Kessler. Isotype: Tipaz 35 (AAU).

Figure 19. Polylepis longipilosa T. Boza, K. Romoleroux & M. Kessler A Flowering branch B young leaves C stipular sheaths D upper leaf surface E lower leaf surface (A Ramsay 911 B Hutel 1390 C Laegaard 54965 D, E Salgado 239 a). Scale bars: 6 cm (A); 3 cm (B, D, E). Photographs by E. G. Urquiaga F.

Figure 24. Geographical distribution of the species of the subsections Lanuginosae, Pauta and Pepea.