Polylepis besseri Hieron., Bot. Jahrb. Syst. 21(3): 312. 1896.

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

35. Polylepis besseri Hieron., Bot. Jahrb. Syst. 21(3): 312. 1896.

Figs 93 , 94

Polylepis besseri var. longipedicellata Bitter, Bot. Jahrb. Syst. 45: 629. 1911. Type. Bolivia. Cochabamba: Puna of Mizque, d’Orbigny 495 (holotype: G!; isotypes: F! NY, US, photos at US!, GH!).

Type.

Bolivia. Capi : Mar 1890, Bang 769 (lectotype: G!; isolectotypes: BR!, E!, F!, GH, MO!, NY (2)!, US!, W).

Description.

Trees 2-6 m tall. Leaves slightly congested at the branch tips, imparipinnate with 1-2(-3) pairs of leaflets, obtrullate in outline, 3.6-4.0 × 2.5-3.0 cm; rachises densely tomentose, points of leaflet attachment with a tuft of long hairs; stipular sheaths apically truncate or slightly spurred, densely tomentose on the outer surfaces; leaflets obovate in outline, second pair from the terminal leaflet the largest, one of this pair 1.4-1.6 × 0.6-1.1 cm; margin crenate with 5-8 teeth, apically obtuse or emarginate, basally unequally attenuate or cordate; upper leaflet surfaces smooth to slightly rugose, glabrous; lower leaflet surfaces densely tomentose hairs 0.6-0.8 mm long, with a dense layer of very short, white pannose hairs. Inflorescences pendant, (3.6-)4.9-8.9 cm long, bearing 7-9 flowers; floral bracts 4.7-4.9 mm long, narrowly triangular, sparsely tomentose on the outer surface; rachises sparsely to densely tomentose. Flowers 8.3-8.6 mm diam.; sepals 4, ovate, green, densely tomentose outside; stamens 13-23, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.5-3.1 mm long. Fruits turbinate, with 2-5 flattened ridges with a series of spines, densely tomentose; 6.1-9.7 × 4.0-5.8 mm including spines. Tetraploid.

Distribution, habitat and ecology.

Polylepis besseri is restricted to the Departments of Cochabamba. Chuquisaca and Potosí in Bolivia (Fig. 103 ). It occurs in relatively dry regions at 2200-4250 m elevation. Frequently, it forms pure stands, but it can also locally co-occur with P. subtusalbida , P. tomentella and P. lanata ( Kessler 1995b). It usually grows with Escallonia myrtilloides in northern Chuquisaca ( Navarro et al. 2010). At Sacha Loma (Cochabamba), low annual growth rates (<1 mm/y) have been reported ( Gareca et al. 2010). There as well, it was found that> 90% of viable seeds germinate under appropriate laboratory conditions ( Gareca et al. 2012). In the same region, there is a loss of genetic diversity and increasing differentiation in offspring related to adults, which suggest that P. besseri is experiencing genetic erosion and genetic drift ( Gareca et al. 2013). Forests of P. besseri support specialist bird species, such as Conirostrum binghami (= Oreomanes fraseri ), Leptasthenura yanacensis and Carduelis crassirostris , as well as other species that show marked affinity for this habitat, such as Asthenes dorbignyi , Phacellodomus straticeps , Polioxolmis rufipennis , Ochthoeca oenanthoides and Pseudosaltator (= Saltator ) rufiventris ( Herzog et al. 2002; Herzog et al. 2003). Larger forests with larger trees have higher arthropod density, allowing for higher bird densities ( Cahill et al. 2021). Carduelis crassirostris is one of the few bird species that specifically feed on the seeds of Polylepis trees, but the effects of this remain unexplored.

Conservation status.

The EOO for Polylepis besseri is estimated as 58,954 km2, the AOO is assessed at 76 km2 and it is known from 18 locations. Polylepis besseri was categorized as VU (A1abc, B1+2c) in the World List of Tthreatened Trees ( Oldfield et al. 1998). Later, it was classified as EN B2ab(ii,iii) in the Red List of Threatened Flora of Bolivia ( Arrázola and Coronado 2012). It is not protected within any conservation area. Polylepis besseri forests are under increasing threat from human activities and disturbance. We assess the species as Vulnerable (A1, B1a+B2a, C1).

Notes.

Polylepis besseri is morphologically closest to P. pacensis with which it shares similar obovate leaflet shape with crenate margins. It differs from this in its longer (0.6-0.8 mm), densely tomentose hairs mixed with a dense layer of very short, white pannose hairs compared to the shorter (0.4-0.9 mm), densely villous hairs without pannose hairs of P. pacensis . Additionally, P. besseri can be distinguished from P. rugulosa by the number of lateral leaflet pairs (1-2(-3) versus 1) and lower leaflet hairs length (0.6-0.8 mm versus 0.8-1.0 mm) which, in P. besseri , is mixed with a very dense layer of very short pannose hairs that is absent in P. rugulosa . In Potosí, hybrids have been found with P. neglecta ( Schmidt-Lebuhn et al. 2006a).

Specimens examined.

Bolivia. Chuquisaca: Belisario Boeto, Municipio Villa Serrano, Comunidad Nuevo Mundo, Piso Superior Tucumáno Boliviano, 18°59'20"S, 064°18'17"W, 2369 m, 17 August 2005, Villalobos 56 (MO!). Oropeza, ca. 40 km W Sucre on road to Macha, 18°53'S, 065°26'W, 3300 m, 26 September 1991, Kessler 3263 (GOET!, LPB); 3264 (AAU!, GOET!); 3265 (GOET!); 3266 (AAU!, GOET!); 3267 (AAU!, GOET!, LPB); Cerca de Río Ravelo, 3800 m, 15 June 1918, Murguía 145 (GOET!, LPB); Localidad Chataquilla, 3400 m, 06 December 1989, Murguía 377 (GOET!). Zudañez, 25 km S Icla on Tarabuco-Azurduy road, 19°27'S, 064°49'W, 3500 m, 24 September 1991, Kessler 3208 (GOET!); 3209 (AAU!); 3210; 3212 (AAU!, GOET!); 40 Km S Icla on Tarabuco Azurduy road, 19°33'S, 064°39'W, 3700 m, 24 September 1991, Kessler 3223 (AAU!, GOET!). Cochabamba: Arque, proximidades a la comunidad de Kutimarca, Sumuruni, camino hacia Arque, 3850 m, 11 April 1999, Mercado 2149 (MO!). Campero, Pallamiani Khasa, camino Aiquile-Rakaypampa, hacia Pallamiani Khasa-Lenkho, 3200 m, 09 May 1987, Estenssoro 692 (GOET!, LPB). Carrasco, Entrando uno 23 km de la carretera (cerca Epizana) a la ciudadela incaica Inkallajta, 17°36'15"S, 065°24'57"W, 3400 m, 09 May 2014, Beck 34452 (LPB); 6.6 km by road, NW Lopez Mendoza, at Km 98 from Cochabamba, 3250 m. Quebrado Majón, 17°33'20"S, 065°21'31"W, 3250 m, 15 May 1984, Schmitt 108 (MO!); 5 km al este del puente sobre el Río López Mendoza por el camino entre Cochabamba y Santa Cruz (19 km al oeste de Epizana), 17°32'S, 065°22'W, 2900 m, 11 February 1987, Solomon 16038 (LPB, MO!, NY). Cercado, Estancia Sipirita entre Apote y Tiquipaya, 2650 m, 18 January 1996, De la Barra 656 (BOLV); Parque Nacional Tunari, N and above the center of Cochabamba, at about km. 11.5 above the entrance, about 1 km by switchback road above and NE of the recreation area at "km 10.", 17°19'45"S, 066°08'15"W, 3500 m, 02 May 2005, Nee 52934 (MO!, NY, USZ!). Chapare, Parque Tunari; the road to Laguna Wara Wara, 3600 m, 28 May 1994, Ritter 1060 (GH!, MO!). Mizque, Cañada Pucara Mayu, a 37 km de Rodeo Mizque, entre Khewiña Khasa y Pucara Khasa, 17°49'S, 065°26'W, 3200 m, 08 May 1987, Estenssoro 810 (GOET!, LPB); Semborreto entre Markilla y Rodeo, 3630 m, 20 June 1987, Estenssoro 819 (LPB); Between Cerro Canto Monte and Mizque along Arani-Mizque road, 3600 m, 17 April 1987, Fjeldså s.n (LPB); ca. 30 Km NW Mizque on road to Arani, 2950 m, 17 August 1991, Kessler 2985 (AAU!, GOET!, LPB); 2988 (AAU!, GOET!); 2989 (AAU!, GOET!); 2996 (GOET!, MO!). Tiraque, 12.8 km W of Koari, highway from Cochabamba to Epizana, 17°27'44"S, 065°41'01"W, 3475 m, 04 May 2007, Nee 55332 (MO!); San Isidro, A Km 88 carretera Cochabamba-Santa Cruz, entrando hacia al norte, 5 km de la comunidad de San Isidro, 17°26'54"S, 065°31'38"W, 4300 m, 18 March 2006, Zárate 2306 (BOLV, MO!); 106.8 km E of Cochabamba on Carretera Fundamental, 4100 m, 05 December 1979, Davidson 3743 (F!, NY); Chapare Yungas de Espiritu, following the abandoned Chapare Road along the NW facing side of the Serrania de Callejas at the head waters of the río Espíritu Santo, ca. 50 km 25 N of W from Cochabamba, 17°12'S, 065°42'W, 4000 m, 01 December 1985, Lewis s.n (F!, LPB, MO!). La Paz: Murillo, Río Minasa, 1.5 km arriba del viejo puente del ferrocarril (ca. 3 km arriba de Villa Fatima, La Paz), 16°27'S, 068°07'W, 4000 m, 18 January 1987, Solomon 15783 (LPB, MO!). Potosí: Charcas, de Ocuri hacia Pajri cuchu (bajando), 4000 m, 12 March 1993, Torrico 119 (LPB). Jose M. Linares, a 2 km de Lajas hacia Tambillo, Serranía de Mataca, 3930 m, 05 April 1993, Torrico 346 (LPB). Capi, March 1890, Bang 769 (F!, G, GH!, MO!, NY, US!, W); Alturas de Chacatilla, 3500 m, 23 August 1980, Erquicia 60 (GOET!); 23 January 1905, Orbigny s.n (MO!).

Figures

Figure 93. Polylepis besseri Hieron A flowering branch B upper leaflet surface C lower leaflet surface D fruit E leaves F habit. Scale bars: 2 cm (A, E); 5 mm (B, C); 2 mm (D). Photographs A, E, F M. Kessler B-D T. E. Boza E.

Figure 94. Polylepis besseri Hieron A flowering branch B stipular sheaths C fruit D lower leaf surface E upper leaf surface (A Kessler 3210 B ERTS 60 C-E Kessler 2988). Scale bars: 5 cm (A); 9 mm (C); 2 cm (D, E). Photographs by T. E. Boza E.

Figure 103. Geographical distribution of the species of subsection Polylepis Besseria Besseria.