Decalobanthus calyculatus (Ooststr.) A.R.Simões & Chatrou

5. Decalobanthus calyculatus (Ooststr.) A.R.Simões & Chatrou — Map 3 View Map 3

Decalobanthus calyculatus (Ooststr.) A.R.Simões & Chatrou in Simões et al. (2020) 55: 5. — Merremia calyculata Ooststr. (1939a) 265. — Type: Seemann 324 (holo K [ K000830927 ];iso BM [ BM000884662 ]*,GH [00054678], P [ P00600290 ]), Fiji, ( Taveuni) Vuna (‘ Puna’, see Van Ooststroom 1939a).

Stems and branches lengthwise-striate, not lenticellate, glabrous. Leaves basally attached, suborbicular, 12–15 by 12–15 cm, bases broadly cordate; secondary veins 10 or 11 on either side of the midvein. Inflorescences subumbelliform, branching near apex; peduncles terete, c. 20 cm long; pedicel apices with an ‘epicalyx’ c. 9 mm diam comprising 4 flat triangular lobes. Flowers: sepals equal, convex, membranous, suborbicular, 1.7–2 cm long; corollas campanulate, c. 3.5–4 cm long, white, yellow inside at tube base, glabrous; stamens and pistil included. Fruits and seeds not seen.

Previously published illustration — Van Ooststroom (1939a: 264, f. 1h–t).

Distribution — Fiji.

Habitat & Ecology — No information recorded by collectors. Vernacular name — Wavula ( Seemann 324).

Notes — Decalobanthus calyculatus remains an enigmatic taxon. Staples (2009: 336) speculated that this entity could be an extreme morphological variant of D. pacificus . Study of more material should resolve the ambiguity; unfortunately, the SUVA and BSIP herbaria remain closed so it is not likely any further specimens will be available for study any time soon. Now that a name has been provided for it ( Simões et al. 2020), I provisionally maintain this taxon as a practical consideration but point out the need for locating further material and critical comparison with D. pacificus , which has been shown to be more morphologically variable ( Staples 2009) than was initially described.

The diagnostic characters Van Ooststroom (1939a: 265) used to distinguish D. calyculatus from D. pacificus are: outer sepals 17–20 mm long (vs up to 12 mm in D. pacificus ); the ‘epicalyx’ at the juncture of the pedicel apex/calyx base is composed of 4 triangular, flat, obtuse lobes (vs a wavy, narrow, continuous ring in D. pacificus ). The ‘epicalyx’ character is clearly visible on all sheets of the type gathering, Seemann 324. Van Ooststroom had a good eye for species discrimination in Convolvulaceae and his concepts have almost all been maintained over time; it seems prudent then to maintain this taxon until further specimens can be studied and a more definitive decision reached about the correct status for it.