Pilea nicholasii 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 : 60-62

Pilea nicholasii Dorr & Stergios sp. nov. Figure 3

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

Diagnosis.

Most similar to Pilea hydrocotyliflora Killip from which it can be distinguished by the distinctly asymmetrical laminae that are pruinose (i.e., with a waxy, powdery, whitish bloom) below.

Type.

VENEZUELA. Trujillo: Mpio. Boconó: Parque Nacional Guaramacal, Laguna de Agua Negra - parte alto [sic] de la Qda. Salvaje, 2000-2100 m, 14 Apr 2003, B. Stergios & L.J. Dorr 20208 (holotype: PORT [86924]; isotypes: BM, G, K, MO, NY, P, US [00728426]).

Description.

Herb, to 50 cm tall; terrestrial or hemiepiphytic; monoecious. Stems erect, ascending or spreading, rarely trailing, branched or not, succulent, drying brown or dark reddish-brown, glabrous, younger stems often with minute peltate glands, cystoliths fusiform or absent, internodes 6-50 × ca 1-3 mm (shorter distally), terete, ± flattened when dry, fragrant when crushed (fide Licata & Culleo 233). Stipules ca 1-1.25 mm long, broadly deltate, drying dark brown, persistent. Leaves petiolate, distichous; petioles at each node unequal by a ratio of 1:4.3-17 (-33); major petioles 12-33 mm long, canaliculate above, glabrous; minor petioles 1-4 mm long or subsessile, canaliculate above, glabrous; laminae of leaves at each node unequal by a ratio of 1:1.2-3.2; major laminae in a pair 3.7-9 × 1.4-3.2 cm (laminae usually larger distally), ovate or obovate, asymmetrical, subcoriaceous, 3-nerved from the base or lateral nerves diverging from midrib 1-2 mm above the base, sometimes forming flap-like domatia where the 3 nerves join, midrib and lateral nerves prominent or not, lateral nerves visible almost the entire length but disappearing just below the apex, secondary nerves 6-9 (-20) pair, often becoming obscure or fading distally, borne 60-80 (-90)° to the midrib, often strongly curved distally, upper surface dark green, drying dark brown or reddish-brown, glabrous or with minute, peltate scales, cystoliths fusiform, varying in length, lower surface pruinose, pale green, drying whitish with scattered dark spots and minute, peltate scales, cystoliths sometimes present, base cuneate or less commonly truncate, asymmetrical, margin regularly toothed, sometimes teeth overlapping the lamina, apex acute to shortly acuminate, sometimes asymmetrical; minor laminae in a pair 1.4-3.5 × 0.8-1.6 mm, otherwise as major laminae. Inflorescences 1-5 per stem, unisexual; bracts ca 1 mm long; bracteoles ca 1 mm long. Staminate inflorescences 1 per axil, 33-50 mm long, bearing (18-) 40-60 flowers in a ± compact to loose cyme; peduncles 25-45 mm long, equal to or exceeding major petioles in length, glabrous except for minute, peltate scales, occasionally cystoliths present; pedicels 0.5-1.25 mm long, glabrous. Staminate flowers ca 1 × 1.5 mm immediately prior to anthesis, white, creamy-white, greenish-white or greenish-red; tepals 4, ca 1 mm long, glabrous, occasionally cystoliths present and also often minute, peltate scales, apices ca 0.25 mm long, glabrous; stamens 4. Pistillate inflorescences 1 per axil, 1-12 mm long, bearing 15-30 flowers in a ± compact head-like cyme; peduncles 0.5-8 mm long, glabrous; pedicels ca 0.25-1 mm long, glabrous. Pistillate flowers ca 1.25 mm long, cucullate tepal ca 1 mm long, elliptic or ovate, lateral tepals minute. Infructescences 23-28 mm long; peduncles 19-25 mm long; achenes 1-1.5 × ca 1 mm, slightly compressed, ± ellipsoid, verrucose, margin narrowly thickened.

Distribution and ecology.

Known only from the Andes of Venezuela (Lara, Portuguesa, and Trujillo states) where it is found in the understory of montane and cloud forest; 1900-2800 m.

Etymology.

This species is named for Nicholas Dorr who assisted with field work in the Venezuelan Andes, but clearly prefers the rigors of Chichiriviche to those of the mountains.

Specimens examined.

VENEZUELA. Lara: Mpio. Morán: SW-facing slopes at Los Aposentos, above Las Sabanetas, above Humocaro Bajo, 2500-2530 m, 3 Feb 1944, J.A. Steyermark 55213 (NY, US, VEN); Pica que va desde Buenos Aires a Páramo Las Rosas, 09°34'N, 070°06'W, 2300-2600 m, 15 Nov 1984, H. van der Werff & R. Rivero 7963 (PORT). Portuguesa: Mpio. Sucre: Fila del Helechal, en el límite con el Edo. Lara, 80 km al NO de Guanare, al N de Chabasquén, ca 2000 m, 09°32'N, 069°58'30"W, 9 Feb 1984, B. Stergios et al. 6722 (PORT, US). Trujillo: Mpio. Boconó: Guaramacal, 20 km al E de Boconó, ca 09°14'N, 070°11'W, 1900-2300 m, 7 Feb 1987, G. Aymard et al. 5226 (PORT); Parque Nacional Guaramacal, vertiente sur, ca 09°12'45'N, 070°09'51"W, 2350 m, 21 Apr 1998, N. Cuello et al. 1416 (NY, PORT, US); Parque Nacional Guaramacal, trail from la Laguna de las Aguas Negras to la Qda. Salvaje, N slope of mountain, 09°19'N, 070°11'W, 27 Oct 1998, L.J. Dorr et al. 8279 (PORT, US); Parque Nacional Guaramacal, road from Boconó to Guaramacal, SE of Boconó, ca 15 km from the post of the park guards, S slope of mountain, 09°13'N, 070°12'W, 3 Nov 1998, L.J. Dorr et al. 8455 (K, MO, PORT, US), Ibid., L.J. Dorr et al. 8471 (G, K, MO, P, PORT, US); Parque Nacional Guaramacal, trail from El Cafenol (E of Mosquey) to Fila Los Recostaderos, 1790-2200 m, 12 Jun 2001, L.J. Dorr et al. 8872 (G, K, MO, P, PORT, US); Parque Nacional Guaramacal, en la vertiente norte, 2300 m, 27 May 1995, A. Licata & N. Cuello 158 (PORT, US), Ibid., 09°14'59.78"N, 070°12'43.36"W, 2100 m, 19 Jun 1995, A. Licata & N. Cuello 233 (PORT, US); Camino al Cerro Guaramacal via la laguna de "Los Cedros," 21 Mar 1981, B. Stergios 2544 (PORT); P.N. Guaramacal, vertiente norte, 2100 m, Mar 2003, B. Stergios 19986 (PORT, US); Parque Nacional Guaramacal, sector trocha Laguna Negra - quebrada del Salvaje, 1850-2100 m, 15 Jun 2002, B. Stergios & R. Caracas 19671 (MO, PORT, US); Fila de Agua Fria, 09°16.70'N, 070°8.65'W, 2700-2800 m, Jan-Feb 1996, B. Stergios & L. Zambrano 17701 (PORT, US); Cerro Guaramacal, Boconó, 09°15'N, 070°13'W, ca 2000 m, 29 Nov 1983, B. Stergios et al. 6561 (NY, PORT); Parque Nacional Guaramacal, trail from Casa Vicuyal toward Páramo de Vicuyal, 2200-2600 m, 10 Apr 2003, B. Stergios et al. 20074 (G, K, MO, NY, PORT, US); Parque Nacional Guaramacal, NE slopes of Cerro Guaramacal between Laguna de Los Cedros and the summit of the road to Guaramacal, 09°15'N, 070°125'W, 21 Sep 2003, B. Stergios et al. 20639 (PORT, US). Mpio. Carache: Entre La Peña y Agua de Obispo, 22-28 km de Carache, 2400-2500 m, 1 Mar 1971, J.A. Steyermark 104972 (US-2 sheets).

Discussion.

The majority of collections of Pilea nicholasii have either staminate or pistillate inflorescences on a stem. Several collections, including the type (Stergios & Dorr 20208), however, have both staminate and pistillate inflorescences on the same stem, and at least one collection (Cuello et al. 1416) has both staminate and pistillate inflorescences arising from the same leaf axil. This suggests to us that the species is monoecious rather than dioecious.

Sometimes the pedicels on staminate inflorescences are sterile. The cause of this is not clear: it may be that some male flowers are caducous or, as suggested by one of the reviewers of this manuscript, the consequence of fungal infection. A number of the pistillate inflorescences, especially on specimens with conspicuous staminate inflorescences, are very cryptic with very short peduncles. Other pistillate inflorescences have pronounced peduncles. In any case, there appears to be a bias toward collecting specimens with either staminate inflorescences or infructescences probably because these plants are more visible and manifestly fertile.

Pilea nicholasii belongs in the Heterophyllae species group of Weddell (1869). Its placement in one of the species groups proposed by Killip (1936) is somewhat problematic as depending upon which pair of leaves at a single node are measured Pilea nicholasii falls into either Killip’s Centradenioideae species group with major leaf laminae more than twice as long as minor leaf laminae or his Capitellatae species group with the major leaf laminae less than twice as long as the minor ones. Among species placed in the former group, Pilea nicholasii is similar to Pilea hydrocotyliflora Killip, which was described from Colombia (Norte de Santander). However, the undersurface of the laminae is pruinose in the former and glabrous in the latter species. This makes the leaves of Pilea nicholasii look lighter below than above while those of Pilea hydrocotyliflora are uniformly green. In addition, the major laminae of the former are markedly asymmetrical whereas in the latter they appear to be ± symmetrical.

Pilea nicholasii also bears a superficial resemblance to Pilea pichisana Killip, another species in the Centradenioideae group that is known only from Peru ( Junín). The major leaf laminae of Pilea pichisana , however, are smaller than those of Pilea nicholasii (2-2.8 × 1-1.3 versus 7-9 × 1.4-3.2 cm) and the cystoliths are different (punctiform versus fusiform).

Pilea nicholasii does not appear to have any close allies in the Capitellatae species group of Killip (1936). It keys to a group of three species that are monoecious, but none of these three species has the pruinose undersurface of the leaf laminae found in our new species.

Characters for distinguishing Pilea nicholasii from Pilea hydrocotyliflora and Pilea pichisana are given in Table 3 .

Conservation status.

Using IUCN criteria ( IUCN 2001) we could not identify a threat to Pilea nicholasii . We are aware of 15-20 distinct populations, the majority of which are in Guaramacal National Park. The extent of occurrence (EOO) is less than 5000 km2 and the area of occupancy (AOO) is less than 500 km2, which might suggest that the species is Endangered (E) under IUCN criteria B1 or B2, but there are> 5 populations and as with Pilea matthewii we would expect the species to be found in similar habitat along the east-facing slopes of the Sierra Nevada de Mérida.