Decalobanthus distillatorius (Blanco) Staples, 2022

9. Decalobanthus distillatorius (Blanco) Staples View in CoL , comb. nov. — Fig. 6 View Fig ; Map 7

Convolvulus distillatorius Blanco (1837) View in CoL 95. — Merremia distillatori a (Blanco) Merr. (1918) 325. — Neotype (designated here): Quisumbing PNH 8061 About PNH (neo A;isoneo PNH), Philippines, Luzon Island, Quezon Prov., Mt.Ditumabo.

Merremia similis Elmer (1908) View in CoL 335. — Decalobanthus similis (Elmer) A.R. Simões & Staples (2017) View in CoL 571. — Lectotype (designated here): Elmer 7341 (lecto NY [NY 336585]; isolecto E [E00273913]*, G [G00016042], K [K000830840]*, LE*), Philippines, Leyte, Palo.

Stems and branches farinose when young, later glabrescent, not lenticellate. Leaves basally attached, broadly ovate-orbicular, 8.5–20 by 8–20 cm, base broadly cordate; secondary veins 7–10 on either side of the midvein. Inflorescences umbelliform, 2–11-flowered; peduncles to 30(–60?) cm long; pedicels thickened toward apex, with a thick lobed ring at calyx base. Flower buds narrowly ovoid, acute; sepals convex, subequal, 1.5–1.8 cm long, obtuse or slightly retuse; corollas subrotate or broadly funnelform, 3–4 cm long, white or pale pinkish, yellow inside tube base, limb slightly 5-sided, tips of midpetaline bands hairy; stamens protruding, 1.6–1.8 cm; pistils slightly exceeding stamens. Fruiting calyx cupular, enclosing the fruit; sepals to 2 cm long, brown-black abaxially. Capsules 4-valved, ovoid, 1.5–1.8 cm long. Seeds 4, ovoid-carinate, c. 6 mm long, black, sparsely tomentose and densely villous.

Previously published illustrations — Van Ooststroom (1939a: 264, f. 1v, calyx only); Chang (1971: 18, f. 3).

Distribution — Philippines (islands of Cebu, Leyte, Luzon, Mindanao, Negros, Panay, Romblon, Samar, Sibuyan) and southern tip of Taiwan.

Habitat & Ecology — In thickets and secondary forests at margins and in clearings, open areas of cliffs along roadside facing the sea; on rolling limestone hills and on clay loam soil. Elevation: sea level to 400 m.

Vernacular names — Philippines: Anipay ( Madulid et al. ( 1296 [ PNH 118273]); bilángod (Egónget dialect; R.B. Fox PNH 5047); bulacan, buracan (Bisayan dialect, Sulit PNH 14307).

Taiwan: 红花姬旋花 (transliteration = hong hua ji xuan hua; Fang & Staples 1995).

Uses — Blanco (1837) gave the epithet distillatorius based on the use of this liana as a source of potable liquid in the Philippines. Cutting the main stem of the liana near the ground allows a considerable volume of clear liquid to drain from the stems above that point; the liquid can be drunk safely. However, as Blanco (1837: 96) rightly noted, consuming very much of it leads to purging. Similar use is made of other Decalobanthus species on Borneo (Staples, pers. obs. 2011).

There are minor medicinal uses recorded in the Philippines: the flowers are used to treat ugut (boils), simply by placing a flower on the surface of the boil ( R.B. Fox PNH 5047).

Notes — Van Ooststroom (1939b: 360) explicated the ambiguity surrounding the taxon Convolvulus distillatorius and whether it was indeed identical with the taxon Merrill had before him when he made the combination Merremia distillatoria . The specimens cited by Merrill disagree in some minor points with Blanco’s original description. Van Ooststroom therefore set aside this ambiguous name and took up Elmer’s later-published M. similis , for which the typification and original description are quite clear. However, Blanco’s name is validly and legitimately published and it is by far the earliest available epithet; there is no reason under the modern ICN (Turland et al. 2018) to avoid taking it up, with a suitable typification to stabilise the usage. However, I found no authentic original material for this Blanco name. Stafleu & Cowan (1976: 229) mention that 400 Blanco specimens are known to be in MA: an inquiry to the curator at MA brought a reply that there are no Blanco specimens there filed as C. distillatorius or M. similis (García Ibáñez, pers. comm. July 2020). I personally searched the G herbaria during visits (2005, 2010) and found no Blanco specimens there linked to C. distillatorius or M. similis . No original material having been found in MA or the several herbaria at G, I propose a neotype as indicated above.

Chang (1971: 15, 1978: 385) and Lu (1972: 151) recorded Merremia similis from the extreme southern portion of Taiwan on the Hengchun Peninsula. This was the only occurrence of the species outside the Philippines. I searched for the plants in 1996 and failed to locate any. A search in 2010 again failed to locate any D. distillatorius (Yang Sheng-Zehn, pers. comm. 2010) but in December 2021 living plants were found again at Fenshuiling ( Chen et al. 2022).

Likewise, for the Philippines there are few recent herbarium specimens seen for this species. However, photos of an unidentified climber were shared in an online plant forum (Co’s Digital Flora of the Philippines 2020); these showed living plants of D. distillatorius from Romblon Island and (in a separate post) from Mindanao. Based on these photo records we know that D. distillatorius does survive in the Philippines but its conservation status there is unknown. Due to the extensive land clearing and deforestation that has occurred throughout the archipelago this species might warrant conservation protection.