Decalobanthus pacificus (Ooststr.)A.R.Simões & Staples

15. Decalobanthus pacificus (Ooststr.)A.R.Simões & Staples View in CoL — Fig. 11 View Fig ; Map 3 View Map 3

Decalobanthus pacificus (Ooststr.) A.R. Simões & Staples (2017) View in CoL 571. — Merremia pacifica Ooststr. (1939a) View in CoL 263. — Type: A.C. Smith 1690 (holo BISH [ BISH1001149 About BISH ]; iso GH [00054679], K [ K000195199 ], L [ L 0004238 ], NY [ NY00336584 ]), Fiji, Vanua Levu , Mbua, Mt. Seatura.

Stems and branches glabrous, not lenticellate. Leaves basally attached, suborbicular, 10.5–22 by 8–22 cm, bases cordate; secondary veins 8–10 on either side of the midvein. Inflorescences umbelliform, 7–30-flowered; peduncle 13–34 cm long; bracts deciduous; pedicels 5-angled, thickened apically, grooved around calyx base. Flower buds ellipsoid-oblong, obtuse; sepals subequal, concave, outer 2 broadly obovate, 1–1.5 cm long, bases with thick medial boss, margins thin; corolla broadly funnelform to campanulate, 3.3–5 cm long, white, yellow inside at tube base, outside minutely golden gland-dotted, limb 5-angled; stamens included, unequal, strongly spiralling; pistil included. Fruiting calyxes persistent, tardily reflexing. Capsules narrowly ovoid-oblong, 1.3–4 cm long, valves splitting into many segments, basally indehiscent. Seeds 6 –7 mm long, black, at first covered in wavy, 7–8 mm long, brown hairs, older seeds ± velvety pubescent.

Previously published illustrations — Van Ooststroom (1939a: 264, f. 1a–g; 1958: 560, f. 4).

Distribution — Widespread in the southwestern Pacific islands: Federated States of Micronesia ( Pohnpei); Papua New Guinea ( Bougainville, Buka, Rossel, East New Britain); Solomon Islands ( Guadalcanal, Vanikoro, Kolombangara, New Georgia, Savo, Faro, San Cristoval); Vanuatu (Maewo); Fiji (Ovalau, Vanua Levu, Viti Levu).

Habitat & Ecology — In margins of primary rain forest, per- manently wet coastal swamps, riversides, along logging roads and in secondary regrowth, along roadsides, in gardens and coconut plantations, on volcanic basaltic clays; elevations from sea level to 500 m.

Vernacular names — Federated States of Micronesia ( Pohnpei): iol wah pwetepwet ( E. A. Amor 66 and 92) . Fiji ( Vanua Levu ): Veliyawa ( A. C. Smith 1690) . Papua New Guinea ( Buka ): Gova ( Petats; Waterhouse 41 B) . Solomon Islands ( Kolombangara ): Ambui ( Kwar‘ae, Bacon PB­1), tabui, tambui ( Kwara‘ae; Whitmore BSIP4420 About BSIP ) – ( San Cristoval) : gapi mafui ( Comins 204) – ( Guadalcanal): tambui ( Morrison 181) – ( New Georgia): mou ( Waterhouse 13) . Vanuatu ( Maewo ): gawe tagwatagwa ( Bourdy 675) .

Notes — Often wrongly identified in herbaria as Merremia peltata . There are several features of D. pacificus that aid in correct recognition of the species: basal leaf attachment; smaller flowers arranged in umbelliform inflorescences; the tiny, glistening golden glands on the outside of the corolla; the capsule splitting into numerous small valves at the apex but remaining firmly fused at the base, the capsule base closely invested at first by the accrescent calyx, which at length reflexes away from the fruit; and the unusually long, silky hairs that initially cover the seeds.

In re-examining Pacific island material, now that more herbarium specimens are available, it has become apparent that the distinctness of the ring or ridge where the pedicel joins the calyx varies considerably; Van Ooststroom (1939a) termed this an ‘epicalyx’. In some cases the ‘epicalyx’ ring is sharply delineated and the groove deep and distinct; in other cases it is barely detectable. These angular ridges of tissue may be an artefact of drying and study of fresh material would elucidate what the shape of the pedicel apex and calyx base region is like in living plants.

The collection Fosberg 58373, from Pohnpei, is a mixture of D. pacificus and D. peltatus : the duplicate in P is D. peltatus while other duplicates seen (in BISH, K, L, US) are D. pacificus . Any additional duplicates of Fosberg 58373 should be examined carefully to ascertain which species they are. Petiole attachment on mature cauline leaves will immediately separate these two species: peltate blade attachment in D. peltatus ; basal blade attachment in D. pacificus .