Paepalanthus pilosus var. leoniae Hensold, 2016

Hensold, Nancy, 2016, The Andean Paepalanthus pilosus complex (Eriocaulaceae): a revision with three new taxa, PhytoKeys 64, pp. 1-57 : 40-43

5b. Paepalanthus pilosus var. leoniae Hensold var. nov. Figs 11E , 12L

Diagnosis.

Differs from the typical variety by the capitula 2-3 mm in diameter, flowers 5-10 per capitulum, the pistillate flowers with sepals elliptic, uniformly thickened in fruit and dispersed with the fruit; petals of pistillate flowers oblong to oblong-spatulate with broadly rounded to truncate apex.

Type.

PERU. San Martín: Prov. Mariscal Caceres, NW sector Rio Abiseo National Park, grassland in Paredones , [07°40'16.73"S, 77°29'1.78"W], 3600 m, 16 March 1988, B. León & K. Young 1597 (Holotype: MO!) .

Description.

Leaves 5.5-12 mm long × 0.6-1.4 mm wide at midpoint, sharply cuspidate, finely appressed-ciliate near apex when young, early glabrate. Peduncles 3-6.5 mm long, fruiting peduncles the same length in specimens observed, the sheaths 5-7 mm. Capitula 2-3 mm in diameter, the involucres obconic or cupulate in flower and fruit, not opening broadly, the bracts similar to typical variety. Flowers 5-10 per capitulum, the staminate equal in number to pistillate or in fewer-flowered capitula the proportion of staminate flowers may be reduced. Pistillate flowers: Pedicels 0.25-0.35 mm. Sepals elliptic, obtuse to rounded, 1.35-2.4 mm long × 0.65-0.8 mm wide at middle, 0.25-0.35 mm wide at base, pale brownish, tinged dusky-brown on shoulders, becoming uniformly thickened and cymbiform at maturity, enclosing the fruit and dispersed with it. Petals oblong to oblong-spatulate, with apex broadly rounded to truncate, retuse or apiculate, 1.5-2.0 mm long × 0.65-0.85 mm wide, 2.2-2.5 times longer than wide, pilose as in the typical variety or with trichomes restricted to subapical tufts, uniformly thickening in fruit, as the sepals. Gynoecium with style base 0.5-0.65 mm long, nectaries 0.65-1.0 mm long, papillae at upper margin colorless, stiff, globose (Leon 1597) to linear (Young 4368); style branches 0.75-1.7 mm. Seeds not seen but mature ovary locules 0.65 mm (Young 4368), 0.75 mm (Leon 1597). Staminate flowers: Pedicels 0.25-0.35 mm. Sepals 1.35-2.1 mm long, fused 35-55 % of their length. Corolla 1.55-2.05 mm long, with the anthophore 0.85-1.15 mm long, comprising 45-75% the length of the whole corolla, ca. 0.1-0.25 mm in diameter at base, the tube and lobes 0.4-1.05 mm long. Filaments brownish toward apex; nectaries reaching corolla sinuses.

Etymology.

Named in honor of Dr. Blanca León, of the Universidad Nacional Mayor de San Marcos and the University of Texas, a generous and accomplished botanist whose many contributions include ecological and taxonomic study of Rio Abiseo National Park.

Phenology.

Collected in March and July. A mild dry season occurs June to August ( Young and Leon 1988).

Distribution.

Endemic to Peru, San Martín, Prov. Mariscal Caceres, Rio Abiseo National Park. (Fig. 6 )

Habitat.

From high-elevation grasslands, at 3450-3800 m. Young and León (1988) compare the habitat to the wet páramos of southern Ecuador, and note that the U-shaped valleys at high elevations where this variety was collected were glaciated as recently as 12,000 years ago.

Conservation status.

Endangered, Criteria B1ab(iii) ( IUCN 2014). This variety is known from only two sites 10 km apart in the protected area of Rio Abiseo National Park In recent years, cattle-grazing, which may have been a threat, has ceased (B. León, pers. comm.) However, the very small distribution, and the fact that this variety represents the southernmost occurrence of a wetland páramo species suggests vulnerability to climate fluctuations.

Discussion.

This variety is found at the southernmost and highest elevation station for the species in Peru. It occurs above 3400 m at the very south end of the Amotape-Huancabamba floristic zone as characterized by Weigend (2004), in the drainage of the Rio Huallaga. This compares to the typical variety collected at up to 3400 m, in the drainage of the Rio Marañón.

The uniformly thickened fruiting perianth of this variety is similar to that of Paepalanthus caryonauta , complicating the otherwise tidy distinction between the two species. However the size and shape of the leaves, the dwarf peduncles, the pale greenish involucres, and the large rigid nectary papillae, all suggest Paepalanthus pilosus , and the type specimen in particular looks nearly identical to populations of typical Paepalanthus pilosus from adjacent southern Amazonas. In fact, these populations are partly intermediate in floral morphology between the two varieties, as discussed under the typical variety. Given the variation in Paepalanthus pilosus in Peru and the contiguity of distribution, it seems best for now to treat this taxon as a variety of that species.

The specimen Young & León 4368, collected ca. 10 km from the other two, is marked by the very small size (5.5-7 mm) of the dark green leaves. The flowers and seeds are also smaller. The habitats of the two localities differed, with the type locality a typical patchy wet páramo among outcrops, while the small-leaved plant was in a broad boggy area bordered by small trees, where cattle once pastured (B. León, pers. comm.)

Additional specimens examined.

Perú. San Martín: Prov. Mariscal Caceres. Puerta del Monte, northwest corner of Rio Abiseo National Park; high elevation grassland on bottom of u-shaped valley; [7°39'30.20"S; 77°28'13.67"W], 3450 m, 10 Jul 1987, K. Young & B. León 4368 (F); Pastizales de Empedrada , entre manojos de Calamagrostis , [07°40'17"S, 77°29'2" W], 3750-3785 m, 27 Jul 2000, B. León & K. Young 4579 (USM [photo!]) .

Figures

Figure 6. Distribution of Paepalanthus caryonauta and suspected hybrids, Paepalanthus pilosus var. pilosus, Paepalanthus pilosus var. leoniae, and Paepalanthus " Species A. "

Figure 11. Habits of Paepalanthus pilosus varieties and " Paepalanthus sp. A. " A-D Paepalanthus pilosus var. pilosus. (A Soderstrom 1346 B Sagastegui 12242 C Cano 16840 D Larsen 237.) E Paepalanthus pilosus var. leoniae (Leon 1597) F-G " Paepalanthus sp. A " (Cuadros 3732) F Habit G Capitulum. In D arrows indicate flowering (fl) and fruiting (fr) capitula.

Figure 12. Pistillate flowers and fruits of Paepalanthus pilosus varieties. A-K Paepalanthus pilosus var. pilosus (A-B Jorgensen 2366 C-F Cano 16840 G Cuatrecasas 25574 H MacDougal 4463 I Wurdack 1616 J Ollgaard 9557 K Boeke 2133) A-B Flower in anthesis with detail of gynoecial nectaries C Flower in anthesis D Gynoecium E Petal F Seed G Diaspore with detached calyx H Sepal (fr) I Diaspore releasing seed J-K Seeds after wetting L Paepalanthus pilosus var. leoniae. Mature diaspore, sepals and petals intact. (Leon 1597).