Pilea nidiae Dorr & Stergios, 2014

Dorr, Laurence J. & Stergios, Basil, 2014, Four new species of Andean Pilea (Urticaceae), with additional notes on the genus in Venezuela, PhytoKeys 42, pp. 57-76 : 62-65

Pilea nidiae Dorr & Stergios sp. nov. Figure 4

Pilea sp. D, Dorr et al., Contr. U.S. Natl. Herb. 40: 147. 2000 [2001].

Diagnosis.

Similar to Pilea flexuosa Wedd. from which it differs by its asymmetrically elliptic to narrowly-elliptic or obovate (versus broadly ovate) laminae that are asymmetrically cuneate (versus rounded or cordate) at the base.

Type.

VENEZUELA. Trujillo: Mpio. Boconó: Parque Nacional Guaramacal, sector vertiente sur, 2800-2900 m, 25-30 Jul 2002, B. Stergios & R. Caracas 19810 (holotype: PORT [85861]: isotypes: K, MO, US [00772535]).

Description.

Herb, to 1.25 m tall; terrestrial; dioecious. Stems erect or prostrate (fide Stergios & Caracas 19810), succulent, branched, drying reddish-brown, dull purple (fide Steyermark 55533) or almost black, glabrous, cystoliths punctiform or short fusiform, often clustered at nodes, internodes 0.8-3.5 × 1-4 mm (shorter distally), terete in cross-section, angulate when dry, nodes constricted (at least when dry). Stipules 6-11 mm long, narrowly triangular, drying pale brown or tan, persistent. Leaves petiolate, distichous; petioles at the same node unequal by a ratio of 1:11.5-13.5 (-23), canaliculate above, glabrous; major petioles 2.3-2.7 cm long; minor petioles ca 1-2 mm long; laminae of leaves at each node unequal by a ratio of 1:1.7-2.2, major laminae in a pair 6.5-9.5 × 1.5-3.2 cm, asymmetrically elliptic to narrowly-elliptic or obovate, membranous, 3-nerved with lateral nerves diverging from midrib 1-6 mm above the base, forming pocket domatia where the 3 nerves join, midrib and lateral nerves prominent below, slightly impressed (or not) above, lateral nerves visible almost the entire lamina length but disappearing below the apex, secondary nerves 8-14 pair, borne 70-90° to the midrib and then curved distally, upper surface dark green, drying dark brown, glabrous except for scattered, minute peltate scales, cystoliths fusiform or absent, lower surface pale green drying dark brown, glabrous except for scattered, minute peltate scales, base cuneate, asymmetrical, margin coarsely toothed entire length, apex long acuminate; minor laminae in a pair 3-5 × 0.8-1.5 cm, otherwise as major laminae. Inflorescences 1-10 per stem, unisexual, green suffused with maroon; bracts ca 2 mm long; bracteoles ca 1 mm long. Staminate inflorescences 1 per axil, 2.8-3.5 cm long, bearing ca 50 flowers in a compact head-like cyme; peduncles 2-3 cm long, glabrous with minute, scattered peltate scales, occasionally cystoliths present; pedicels ca 0.25 mm long. Staminate flowers ca 1.5 × 1-1.25 mm (mature flowers not seen); tepals 4, ca 2 mm long, notched inside; stamens 4. Pistillate inflorescences 1 or 2 per axil, ca 5 mm long, bearing ca 50 flowers in a ± loose cyme; peduncles ca 2 mm long, glabrous; pedicels minute. Pistillate flowers ca 0.5-0.75 mm long, cucullate tepal ca 0.5 mm long, ± lanceolate; lateral tepals minute. Infructescences 1-2.5 cm long, frequently including receptive pistillate flowers; peduncles 0.7-1.8 cm long; achenes ca 1.25 × 1 mm, compressed, asymmetrically ellipsoid or lachrymiform, verrucose, margin narrowly thickened with a very narrow hyaline wing.

Distribution and ecology.

Known only from the Andes of Venezuela (Lara and Trujillo states) where it is found in the moist, shaded understory of montane forest; 2285-2900 m.

Etymology.

This species is named in honor of Nidia Cuello, Director of Herbario PORT, UNELLEZ, Guanare, and expert on the vegetative ecology of Guaramacal National Park.

Specimens examined.

VENEZUELA. Lara: Mpio. Morán: Trail from Humocaro to Buenos Aires ( caserío) below Páramo Los Rosas (ca 09°40'N, 070°05'W), 2750 m, 25 Jul 1979, R. Liesner et al. 8158 (MO, VEN); Between Buenos Aires to Canyon of El Callado, above Humocaro Alto, 2285-2740 m, 12 Feb 1944, J.A. Steyermark 55533 (NY, US). Trujillo: Mpio. Boconó: Páramo Guaramacal, 20-21 km beyond jct. with hwy. NE of Boconó, ca 09°13'N, 070°13'W, 2640-2700 m, 14 Mar 1984, J.L Luteyn & E. Cotton 9705 (MO, NY, PORT, VEN).

Discussion.

Pilea nidiae belongs in the Heterophyllae group of Weddell (1869). Its 3-nerved, toothed leaves that are unequal in size at each node and conspicuous, persistent stipules place it in the Flexuosae group of Killip (1936, 1939). We have not encountered any other Andean species from Venezuela with stipules that are as large as those of Pilea nidiae .

The leaf laminae of one of the paratype collections (Steyermark 55533) are narrower than in the type of Pilea nidiae and densely covered in cystoliths above and below (the type mostly lacks cystoliths). All other characters (leaf shape, venation, toothing, etc.) agree with our concept of this new species.

Conservation status.

Using IUCN criteria ( IUCN 2001) we tentatively consider Pilea nidiae to be Endangered (E). The known range of the species is less than 5000 km2 (IUCN criterion B1) and there are only four known populations and of these only two are in a protected area (IUCN criterion B1(a)). We know nothing, however, about the dynamics of these populations and whether or not they are declining.