Salacca acehensis Mogea & Zumaidar, 2014

Salacca acehensis Mogea & Zumaidar View in CoL sp.nov.

Type:— INDONESIA. Sumatra: Aceh Province, Southeast Aceh Regency, Gunung Kemiri , hillslope of dipterocarp forest, 900 m elevation, 18 November 1975, J.P.Mogea 568 (holotype BO! , isotypes K! , L! ).

Small palm, with stem to 15 cm tall and leaves 1–2.5 m long. Staminate inflorescences slender and erect, to 7 cm long, with up to 3 branches. Pistillate inflorescenses to 10 cm long, with up to 2 branches. Most similar to S. rupicola J. Dransf. from Borneo, but different in having the apical leaflets composed of ca. 2 united segments (versus 8 in S. rupicola ), and smaller inflorescences (the staminate inflorescence up to 15 cm long and the pistillate ones to 40 cm long in S. rupicola ).

Small, pleonanthic, dioecious palm. Stems clustering, ca. 10–15 cm long, 3–5 cm in diameter, somewhat stilt rooted, obscured by persistent leaf bases. Leaves 5–12 per stem, 1–2.5 m long; sheath 5–6 cm wide at the base, densely covered abaxially with dark brown indumentum, armed in the middle part with comb-shaped groups of spines, each group consisting of 4–5 stout, triangular, yellowish spines, to 25 mm long and 2 mm wide at the base, smaller spines present between the groups; all spines covered in indumentum, especially on adaxial side; petiole slender, 75–125 cm long, ca. 9 mm in diameter at the base, 5 mm in diameter in the middle, triangular, covered in pale brown to dark brown indumentum, especially in abaxial side, armed with scattered groups of short horizontal and reflexed spines arranged in three longitudinal rows; rachis to 60 cm long. Leaflets 10–12 on each side of the blade, irregularly arranged in groups of 2–3 near the base, spreading in several planes, sigmoid to lanceolate, acuminate, margins armed with small curved spines ca. 0.5 mm long inserted at distances of 3–5 mm, pointing upwards, adaxial surface dark green with sparse brown indumentum, abaxial surface yellowish grey, with dark brown indumentum at the base and the margins; middle leaflets to 32 cm long and 6 cm wide, with 3 main longitudinal veins separated by 1–2 cm and 4–7 minor veins in between, adaxially with transverse veinlets conspicuous; apical leaflet 10 cm wide on each side, with ca. 2 main folds.

Inflorescences axillary, piercing the subtending leaf sheath. Staminate inflorescence to 7 cm long, slender and erect, simple or with up to 3 branches to 5 cm long, with flowers borne in dyads, each subtended by a short bracteole. Staminate flowers with sepals 3, membranous, ca. 3 mm long and 2 mm wide, basally united and with a dense indumentum; petals 3, connate in the basal half, pink outside, basally white inside, ca. 2 mm long and 1 mm wide; stamens 6, ca. 1 mm long, filament red, anther ca. 1 mm long with yellow pollen. Pistillate inflorescence and flowers not seen. Young infructescences to 10 cm long, simple or with up to 2 branches, closely sheathed by several peduncular bracts. Developing fruits globose, ca. 7 mm long and 8 mm wide (in dry condition), densely covered with ascendent scales, ca. 3.5 mm long and 1 mm wide.

Paratypes:— INDONESIA. Sumatra; Aceh Province, Southeast Aceh Regency, Gunung Kemiri , near junction of hill dipterocarp forest and lower montane forest, steep valley side, 1200 m elevation, 27 August 1971, J. Dransfield and D. Saerudin 1983 ( K!, KYO) ; same locality, hillslope of dipterocarp forest, 900 m elevation, 18 November 1975, J.P. Mogea 569 ( BO!), 570 (BO!), 572 (BO!), 573 (BO!), 574 (BO!) ; North Sumatra Province, Bukit Lawang Bahorok, Langkat , hill dipterocarp forest, 200 m elevation, 25 February 1973, J. Dransfield 3310 ( BO!) .

Discussion:— Salacca acehensis has the epicarp covered in spine-like scales and thus clearly belongs to section Salacca . Among the species of that section it mostly resembles S. rupicola Dransfield (1980: 36) , with which it shares the small size, pinnate leaves and slender, erect, staminate inflorescences. However, S. rupicola has a narrow, bluish green leaves with flabellate apical leaflets composed of ca. 8 united segments while in S. acehensis they are composed of ca. 2. Furthermore, inflorescences of S. rupicola are larger: the staminate ones are up to 15 cm long (versus 7 cm in S. acehensis ) and the pistillate up to 40 cm (versus 10 cm in S. acehensis ). Salacca rupicola also occurs in limestone habitats in Borneo. Of the remaining species of section Salacca with leaves less than 2.5 m long, two species from Borneo, viz. S. dransfieldiana Mogea (1980: 463) and S. sarawakensis Mogea (1980:473) , and three species from Peninsular Malaysia, viz. S. flabellata Furtado (1949: 387) , S. minuta Mogea (1984: 11) and S. multiflora Mogea (1984: 13) , have bifid, flabellate leaves. The remaining small species, S. bakeriana Dransfield (2009: 168) from Borneo, S. graciliflora Mogea (1984: 6) from Peninsular Malaysia and S. stolonifera Hodel (1997: 35) from Thailand, all have relatively long male inflorescences, up to 0.7–1.2 m long, depending on the species, that are held along the surface of the ground and sometimes produce new shoots at the tip —a character also found in S. flabellata ). This has not been observed in S. acehensis where male inflorescences are small and erect.

A duplicate of the paratype collection J. Dransfield and D. Saerudin 1983 was distributed to BO (J. Dransfield pers. comm.) but was not found there in spite of thorough search.

Conservation status:—Gunung Kemiri, where this new species was first discovered, is part of the large, 1.09 mill. ha. Gunung Leuser National Park in northern Sumatra and hence protected area. The second known locality is located at the eastern edge of that park, some 65 km E of Gunung Kemiri. The habitat is hill dipterocarp forest up to an elevation of ca. 1200 m and Salacca acehensis may occur in large parts of the park. Data are insufficient to perform a proper evaluation of its conservation status according to the IUCN criteria, but given the apparently small total extent of the species’ range, and the high rates of deforestation outside protected area, it may be vulnerable or even endangered.