Decalobanthus borneensis (Merr.) A.R.Simões & Staples

3. Decalobanthus borneensis (Merr.) A.R.Simões & Staples View in CoL — Fig. 3 View Fig ; Map 2

Decalobanthus borneensis ( Merr.) A.R. Simões & Staples (2017) View in CoL 569. — Merremia borneensis Merr.(1929) View in CoL 260. — Lectotype (designated here): Elmer 20990 (holo PNH†; lecto UC [ UC312121 *]; isolecto A [00054672]*, BISH [ BISH1001146 About BISH ], F [ F567109 ], G [ G00227276 ], GH [00054673]*, K [ K000830847 ],L [ L 0004222 ], M [ M 0184797 ], MO [MO-694473, MO-694474]*, NY [ NY00336579 ], P [ P03536870 ], SING [ SING0052311 About SING ]*, U [ U 0001428 ]*), ( Malaysia. Sabah,) ‘ British North Borneo, Elphinstone prov., Tawao’ .

Stems and branches (and peduncles) whitish lenticellate, glabrous. Leaves basally attached, orbicular or ovate, 5(–)8–22 by (3.5–) 6–18 cm, ± bullate, bases deeply cordate; secondary veins (6–)8–11 on either side of the midvein. Inflorescences several-flowered, cymosely branched; peduncles 6–12 cm long; bracts caducous. Flower buds ovoid-oblong, acute; sepals elliptic to broadly elliptic, (1.5–) 1.8–2.2 cm long, apically obtuse to slightly emarginate, outer 2 drying leathery, the inner ones ± membranous; corolla broadly tubular-funnelform, 5.5–6 cm long, yellow, glabrous outside, limb 10-lobed, reflexed; stamens included; pistil included. Fruiting calyx slightly accrescent, spreading away from fruit; sepals blackish, leathery. Fruit seemingly indehiscent, berry-like, ovoid, c. 12 mm tall, black, glabrous, mucronate. Seeds oblong-ovoid, c. 6–7 mm long, appressed pilose with pale trichomes.

Previously published illustration — Staples & Syahida-Emiza (2015: 292, plate 38A).

Distribution — Peninsular Malaysia ( Terengganu), Borneo ( Sabah, Sarawak, Kalimantan).

Habitat & Ecology — Tolerant of human disturbance and often reported from logged or burned forest, in secondary regrowth, near homes, in vegetable plots and plantations, along roadsides, always in full sun; seemingly prefers high moisture and reported near rivers, banks of streams, or low-lying wet areas with standing water; on soils including sandstone, shale outcrops, and open, sandy loamsoils; usually at low elevations of 10–340 m, with two collections made from higher elevations, at 1055 and 1500 m.

Vernacular names — Malaysia: Akar larum (Kedayan; Kadir A 2034), balan (Su Pingas; Taleon 101), bunga karang hutan ( Rostado 13), lapad (Dusun Kinabatangan; Taleon 101), laran ( Kadir A 2034), pohon lapa gaga ( Rostado 13), sireh-sireh (Banjar; Taleon 101), tangau (Dusun; Jusimin D. JD 285).

Note — Decalobanthus borneensis is similar to D. pulcher , which differs primarily in larger flower size. Both species share the lenticellate stems, bullate leaves, and black, evidently indehiscent fruits. Perhaps further investigation in the field and application of suitable molecular tools will clarify the relationships; for now, I maintain both species. Furthermore, I restrict D. borneensis to Borneo and use the name D. sumatranus exclusively for Sumatran plants.