Palaquium bintuluense P. Chantaranothai, 2014

Chantaranothai, Pranom, 2014, Palaquium bintuluense (Sapotaceae), a new species from Sarawak, Phytotaxa 173 (2), pp. 173-176 : 173-175

Palaquium bintuluense P. Chantaranothai , sp.nov. ( Fig. 1 )

P. bintuluense is similar to P. rufolanigerum van Royen (1967: 580) but differs in having an obtusely acute or rarely retuse leaf apex, a V-shaped patch of pubescence at the top of the corolla lobes, 16 stamens, and eight locules per ovary ( Table 1).

Type: — MALAYSIA. Sarawak: 4 th Division, Nyabau, Bintulu , between heath and dipterocarpaceous types, ca. 100 m elevation, 25 June 1966, Hou 381 (holotype K!, isotypes BO!, KEP!, SAR, SING!) .

Tree up to 25 m tall. Branchlets terete, light brown, glabrous. Leaves mostly at apex of branchlets; lamina coriaceous, spathulate, 8–13 × 2.5–4 cm; apex obtusely acute or rarely retuse; base cuneate, decurrent; both surfaces of leaves glabrous; midrib crested above, rounded below; lateral veins 9–13 pairs, looped; tertiary veins reticulate somewhat subparallel to the lateral veins; petiole 1–1.6 cm long, flat above, rounded in the basal part, brownish woolly, glabrescent; stipules lanceolate, ca. 7.5 × 1.5 mm, glabrous except for brownish woolly on the basal part outside. Flowers 2–10 in axils of fallen leaves; pedicel terete, 9–15 mm long, brownish woolly; sepals 4, broadly ovate; outer sepals 5.8–6.5 × 5.2–5.7 mm, brownish woolly; inner sepals 5–5.5 × 3.5–4.5 mm, brownish woolly except for glabrous central and basal parts inside; corolla 4–4.2 mm long; tube 0.8–1 mm long; lobes 8, oblong, 3–3.2 × 1.6–1.8 mm, glabrous except for reddish-brown woolly pubescence between the stamens and in V-shaped patch at the top of the lobes both outside and inside; stamens 16, 2– 2.2 mm long; filaments very short, 0.2–0.3 mm long, glabrous; anthers oblong-ovoid, 1.9–2 mm long, sparsely hairy; connective acute, ca. 0.2 mm long; ovary conoid, 8-locular, brownish woolly; style exserted, 5.3–7 mm long, glabrous. Fruit unknown.

Distribution and ecology: —Endemic to Borneo and only known from the type locality in Sarawak; elevation 50– 100 m.

Addition collection studied (paratype):— Malaysia, Sarawak: 4 th Division , Nyabau, Bintulu, between kerangas and dipterocarpaceous types, ca. 50 m elevation, 23 June 1966, Hou 350 ( BO!, K!, KEP!, SAR, SING!) .

Phenology: —Flowering June–August.

Etymolog y:—The specific epithet reflects the known occurrence of the species.

Conservation status: —This species is endemic to Sarawak, and also is so far known from two collections from the 4 th Division, Nyabau, Bintulu. The collections were made in a lowland area that is now dominated by plantations. A lack of protection from the existing protected area indicates that this species is highly threatened and with the extent of occurrence is estimated as to be less than 100 km 2. A provisional rating of Critically Endangered (CR B1ab(iii), IUCN, 2001) is merited

Vernacular: —Nyatoh (Iban).

Note: —In habit, Palaquium bintuluense is nearly identical to that of P. rufolanigerum . They also have in common spathulate leaves, and the woolly pubescent on the petioles, pedicels and outside of sepals. Palaquium bintuluense differs by the obtusely acute, rarely retuse leaf apex, V-shaped patch of pubescence on the top of corolla lobes, 16 stamens, shorter filaments, glabrous style and ovary which has 8 locules ( Table 1).

Figures

FIGURE 1. Palaquium bintuluense: A. branchlet with leaves and flowers; B. tertiary nervation of leaf; C. outer sepal, outside; D. inner sepal, outside; part of corolla, outside; E. calyx and gynoecium; F. corolla with stamens; G. stamen (from Hou 381). Drawn by W. Thammarong.