Pholidostachys dactyloides Moore (1967: 148)

Henderson, Andrew, 2012, A revision of Pholidostachys (Arecaceae), Phytotaxa 43, pp. 1-48 : 11

2. Pholidostachys dactyloides Moore (1967: 148) .

Calyptrogyne dactyloides (Moore) Wessels Boer, 1968: 74 . Type:— COLOMBIA. El Valle: Costa del Pacifico , río Yurumanguí, El Papayo, 10–20 m, 5 February 1944, J. Cuatrecasas 15982 (holotype BH!, isotypes COL!, F!, US!) .

Stems 5.4(2.0–10.0) m long, 7.7(4.0–12.0) cm diameter, solitary. Leaves 15(6–25) per stem; sheaths 45.4(14.0–110.0) cm long; petioles 56.8(20.0–122.0) cm long; rachises 135.4(68.0–231.0) cm long, 13.3(7.9– 20.1) mm diameter; pinnae 10(6–17) per side of rachis; basal pinna 57.9(34.0–92.0) cm long, 2.4(0.7–7.5) cm wide, forming an angle of 53(30–74)° with the rachis; apical pinna 45.0(36.0–58.0) cm long, 15.3(4.5–22.5) cm wide, forming an angle of 13(7–20)° with the rachis. Inflorescences branched 1 order (rarely 2 orders), with a well-developed peduncle, short rachis, and several rachillae, these erect at anthesis; prophylls and peduncular bracts fibrous, covering all or part of the rachillae at anthesis; prophylls 46.0(30.0–59.0) cm long; peduncular bracts 56.7(50.0–65.0) cm long, inserted 6.2(2.5–11.0) cm above the prophyll; peduncles 16.3(8.5–25.5) cm long, 10.4(4.7–19.0) mm diameter; rachillae 9(2–16), 35.5(15.5–75.0) cm long, 6.3(4.5– 9.7) mm diameter; proximal lips of flower pits irregularly shaped, often acute or acuminate, completely covering pits before anthesis; fruits scarcely compressed, obovoid, with obscure longitudinal ridges, 12.2(8.8–16.3) mm long, 7.9(5.8–11.5) mm diameter.

Distribution and habitat. From 8°50’N – 3°11’S and 76°03’– 79°14’W in eastern Panama, western Colombia, and western Ecuador at 444(5–1440) m elevation in lowland or montane rainforest ( Fig. 5 ).

Taxonomic notes. Pholidostachys dactyloides is a widespread and variable species with an unusually wide elevation range.

Subspecific variation. Specimens occur in several different populations. The northernmost specimens, from two localities in eastern Panama, are distinct in their short rachillae and acuminate proximal lips ( Fig. 3A , left).

These Panamanian specimens strongly resemble others from the northern part of the Chocó region of Colombia, where they occur at both high and low elevations. However, some of these have rachillae of the more usual length.

Further south, in the Valle region of Colombia, specimens are similar to those from southwestern Colombia and northwestern Ecuador, and both populations have less acuminate proximal lips ( Fig. 3A , right).

There is a large population in southwestern Colombia and northwestern Ecuador. One specimen from there (Vargas 6108) has inflorescences branched to 2 orders. Regression shows there are significant associations between elevation and four leaf and five inflorescence variables in this population. Squared multiple R for the regression of leaf number on elevation is 0.29, rachis width 0.40, number of pinnae 0.27, basal pinna angle 0.40, peduncle width 0.37, rachilla length 0.30, rachilla width 0.42, fruit length 0.62, fruit diameter 0.51. Values for these variables increase with elevation except for basal pinna angle. Notably, rachillae are thicker at higher elevations.

The southernmost specimens, in southwestern Ecuador, differ slightly from those in southwestern Colombia and northwestern Ecuador. Although there are too few specimens to test for differences, they have shorter and narrower apical pinnae.

Figures

FIGURE 3. A. Proximal lips of flower pits irregularly shaped, often acute or acuminate, completely covering pits before anthesis (Pholidostachys dactyloides; left de Nevers 8402, right Arguëllo 477). B. Proximal lips of flower pits regularly shaped, rounded, completely covering pits before anthesis and not recurved (P. panamensis; de Nevers 6767). C. Proximal lips of flower pits regularly shaped, rounded, completely covering pits before anthesis and not recurved (P. pulchra; left Henderson 712, right Henderson 59). D. Proximal lips of flower pits regularly shaped, rounded, not covering pits before anthesis, recurved (left P. occidentalis, Henderson 138; right P. synanthera subsp. synanthera, Henderson 161). Scale bar = 1 cm.

FIGURE 5. Distribution maps of Pholidostachys amazonensis, P. dactyloides, P. occidentalis, and P. panamensis.