Pholidostachys occidentalis Henderson, 2012

Henderson, Andrew, 2012, A revision of Pholidostachys (Arecaceae), Phytotaxa 43, pp. 1-48 : 12-13

3. Pholidostachys occidentalis Henderson , sp. nov. (Appendix IV, Plates 2–8)

It differs from other species in its branched inflorescences and compressed, obovoid fruits with a pronounced longitudinal ridge on one side.

Type:— ECUADOR. Pichincha: Road from Santo Domingo to Quevedo , 12 km S of Santo Domingo, 0°17’S 79°15’W, 300 m, 24 July 1985, H. Balslev, A. Henderson & F. Skov 60678 (holotype QCA n.v., isotypes AAU!, K!, NY!) .

Stems 5.4(2.5–11.0) m long, 10.4(7.0–15.0) cm diameter, solitary. Leaves 15(12–20) per stem; sheaths 25.3(16.0–40.0) cm long; petioles 51.7(45.0–60.0) cm long; rachises 192.0(150.0–234.0) cm long, 16.3(7.8– 24.4) mm diameter; pinnae 12(8–13) per side of rachis; basal pinna 47.4(34.0–83.0) cm, long, 3.9(1.4–10.0) cm wide, forming an angle of 54(34–67)° with the rachis; apical pinna 42.9(34.0–54.0) cm long, 18.5(10.0– 25.5) cm wide, forming an angle of 25(18–29)° with the rachis. Inflorescences branched 1 order, with an elongate peduncle, short rachis, and several rachillae, these pendulous at anthesis; prophylls and peduncular bracts woody, not covering rachillae at anthesis; prophylls 62.0 cm long; peduncular bracts 59.0 cm long, inserted 7.8(4.0–11.5) cm above the prophyll; peduncles 114.1(72.0–171.0) cm long, 10.1(6.3–12.5) mm diameter; rachilla 8(6–11), 50.8(33.0–64.0) cm long, 7.4(6.3–8.6) mm diameter; proximal lips of flower pits regularly shaped, rounded, not covering pits before anthesis, recurved; fruits compressed, obovoid in lateral view with an asymmetric base, ellipsoid in frontal view, with a pronounced longitudinal ridge on one side and several lesser ridges on opposite side, 17.0(16.2–18.0) mm long, 9.3(8.5–9.8) mm diameter.

Distribution and habitat. From 3°43S’ – 6°45’N and 76°02’– 79°46’W in western Colombia and western Ecuador at 854(300–1600) m elevation in lowland or montane rainforest ( Fig. 5 ).

Taxonomic notes. Borchsenius et al. (1998) were the first to point out the differences between populations of Pholidostachys synanthera from west and east of the Andes. The western population, here recognized at the specific level as P. occidentalis , has inflorescences that are branched to 1 order and have elongate peduncles, short rachises, and several rachillae that are pendulous at anthesis ( Fig. 1B ) (versus P. synanthera with inflorescences that are branched 1–2 orders and have well-developed peduncles and rachises, and several rachillae that are spreading at anthesis). The fruits of the two species also differ. Pholidostachys occidentalis has compressed fruits, obovoid in lateral view with an asymmetric base, ellipsoid in frontal view, with a pronounced longitudinal ridge on one side and several lesser ridges on the opposite side ( Fig. 4B ). Pholidostachys synanthera has scarcely compressed fruits that are ellipsoid with obscure longitudinal ridges ( Fig. 4F ).

Subspecific variation. Pholidostachys occidentalis occurs in scattered localities from southwestern Ecuador to northwestern Colombia, but there are too few specimens to test for differences amongst these populations. Like P. dactyloides , this species has an unusually wide range in elevation.

Figures

FIGURE 1. A. Leaf blade of Pholidostachys occidentalis (Henderson 138). B. Inflorescence of P. occidentalis (Henderson 138). C. Inflorescence of P. dactyloides (Balslev 60677). D. Infructescence of P. panamensis (Henderson 3037).

FIGURE 4. A. Fruits of Pholidostachys dactyloides (Dodson 14491). B. Fruits of P. occidentalis (Balslev 60678). C. Fruits of P. panamensis (Liesner 1255). D. Fruits of P. pulchra (de Nevers 4285). E. Fruits of P. sanluisensis (Juncosa 726). F. Fruits of P. synanthera subsp. synanthera (Couvreur 119). Scale bar = 1 cm.

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