Malesian Euphorbiaceae Descriptions

106. WEDA (Euphorbiaceae)

P.C. van Welzen & K.J. Wurdack

van Welzen, P.C., Arias Guerrero, S., Arifiani, D, Bangung, T.J.F., Bouman, R.W., Eurlings, M.C.M., Gushilman, I., Phillipson, P.B., Tabak, I., Winkel, E., Wurdack, K.J. 2020. Weda, a new genus with two new species of Euphorbiaceae-Crotonoideae from Halmahera (North Maluku, Indonesia) and phylogenetic relationships of the Australasian tribe Ricinocarpeae. Journal of Systematics and Evolution: doi:10.1111/jse.12581.

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Genus description

Key to the species

Species descriptions

Weda Welzen

    Weda Welzen in Welzen et al., J. Syst. Evol. (2020) doi:10.1111/jse.12581. — Type: Weda fragarioides Welzen

Trees, monoecious; latex unknown. Indumentum of pale brown, short, stellate to somewhat lepidote to dendritic hairs, parts also with long, whitish, simple hairs (especially in W. lutea). Stipules absent. Leaves alternate to sub-opposite, simple; petioles long, cylindrical, basally slightly pulvinate, apically hardly thickened; blade at insertion (not peltate) or at base of peltation (blade peltate) with two adaxial large elongate glands, margin entire with an occasional extending gland, surfaces smooth, penninerved or basally palmately nerved, venation raised on both sides, especially beneath, secondary veins looped and closed near the margin, higher order veins laxly reticulate. Inflorescences axillary, erect, cymose, bisexual, but usually unisexial functionally, basically dichotomous and first pistillate with a single, central pistillate flower, after fruit dehiscence, when the more horizontal, scorpioid branches develop, with per branch only staminate flowers with one or two flowering at a time; peduncle long, somewhat flattened, with two leaf-like, slightly subopposite bracts of unequal size at the distal end, lower one smaller, both late caducous during staminate phase; floral bracts either vestigial, hairy enations or acicular and apically glandular. Flowers 5-merous, actinomorphic, pedicellate; sepals four or five, basally united, lobes imbricate, outer three smaller than inner one or two, apices rounded; petals ovate, five or six, contorted, fleshy, glabrous, apex rounded. Staminate flowers stamens either on highly dome-shaped receptacle (W. fragarioides) or filaments partly united in an androphore (W. lutea), densely hairy with simple hairs; disc absent or not obvious to a vague ring around dome/androphore in W. lutea; stamens more than 30, filaments free, thread-like, with few hairs, anthers twothecate, dorsi-basifixed, connective very short and indistinct, thecae almost completely separate, opening extrorsely with longitudinal slits, glabrous; pistillode absent; pollen spheroidal, inaperturate, crotonoid. Pistillate flowers, partly seen in bud and in young fruit; sepals five; petals five; disc not seen; ovary 3-locular, densely hairy, with a single ovule per locule, style short, hairy, stigmas three, broad, mostly bifid, glabrous, smooth, not papillate above. Fruits capsular, ellipsoid, slightly lobed, lobes higher than wide, smooth, dehiscing completely loculicidally and septicidally into six mericarps; wall thin, with a thin exocarp and a woody mesoand endocarp when dry; columella 3-quetrous, persistent. Seeds 3 per fruit, smooth, marbled, naked, with an apical appendage with carunculoid tissue in the young material of W. lutea but without appendage (disappeared) in the mature seeds of W. fragarioides; hilum small; embryo unknown.

    Distribution — The two species are each discovered from three collections made in central Halmahera (Indonesia, N Moluccas).

    Etymology — The genus name refers to Weda Bay where the specimens were collected.

    Note — The leaf blade glands are typical, with the long peduncled inflorescences having two leaf-like large bracts, the highly domed receptacle or androphore of the staminate flowers, and the stellate to dendritic indumentum.

Key to the species

1. Weda fragarioides Welzen 

    Weda fragarioides Welzen in Welzen et al., J. Syst. Evol. (2020) doi:10.1111/jse.12581. — Type: Phillipson, Merello, Sau, Mahroji, Haris 6448 (holotype, L; isotypes, BO, MO), Indonesia, central Halmahera, Weda Bay, Bukit Limber.

Trees, 12m high, dbh at least 7 cm; flowering branches 6–8 mm diameter. Outer bark brown. Leaves spotted brown with stellate hairs when young; petioles 5.5–12 cm long, 2–3 mm thick in middle, with stellate to somewhat lepidote hairs when young, soon glabrescent, gray; blade ovate-oblong to elliptic-oblong, 10.5–30 by 3.8–12 cm, 2.42–4.7 times as long as wide, base rounded to cuneate, shortly attenuate near the basal adaxial (acropetiolar) glands; glands c. 2 by 1.3 mm and c. 1 mm high with long axis perpendicular to petiole; lamina margin recurved to flat, apex acuminate, acumen c. 1.5 cm long, upper surface glabrous, margin and lower surface glabrescent with mainly main veins and margin remaining slightly hairy, venation pinnate, secondary veins 10–14 pairs, basal pair under slightly steeper angle with midrib. Inflorescences: peduncle 7.5–17 cm long, mainly glabrous except apically few stellate hairs (on specimen from Blipek Nu also long, white simple hairs); bracts ovate, 3.7–10.7 by 1.9–5 cm, sessile, without glands, basally emarginate, margin entire, apex acute to acuminate, venation well developed, like leaf blades, but generally fewer secondary veins; other bracts on branches present as vestigial, hairy enations below the flowers. Flowers: petals white. Staminate flowers c. 16 mm diameter, receptacle highly domed; buds green; pedicel up to 10 mm long, with stellate hairs; sepals ovate, fleshy, margins with simple hairs, inside glabrous; outer ones c. 2.2 by 2 mm, externally bearing stellate hairs; inner ones c. 3 by 3 mm, outside lower half with stellate hairs; petals c. 9 by 4.5 mm; disc absent or indistinct, filaments thread-like, c. 1 by 0.1 mm, pale yellow, glabrous or rarely with scattered simple hairs, anthers elliptic, c. 0.7 by 0.7 mm, yellow, glabrous. Pistillate flowers: seen in bud and in young fruit; pedicel c. 6mm long in young fruit, hairy; sepals ovate, c. 1.8 by 1.8 mm, with stellate hairs outside; petals seen young or caducous, somewhat hairy outside when in bud; disc not seen; ovary: styles shortly connate, c. 1 mm high in young fruit, hairy, stigmas c. 3 mm long, bifid except basal c. 0.5 mm, dark gray. Fruits c. 1.3 cm high by 1.5 cm wide when nearly mature, sulcate along sutures, mericarps c. 2 cm high; pedicel 14–18 mm long; wall c. 0.8 mm thick, with brown stellate hairs with central arm longer and setaceous in Bukit Limber material; sepals persistent; columella c. 1.2 cm high, narrowly hour-glass shaped, apically not much widened, trigonous in outline. Seeds seen immature (embryo not developed), ellipsoid but flattened on dorsal side, c. 12 by 7–8 by 5.5–6 mm, light brown and marbled with dark brown irregular spots, apically without appendage.  

    Distribution — Indonesia, N Moluccas (Maluku Utara), Halmahera, north of Weda Bay, Bukit Limber and Blikep Nu, Camp 3.

    Weda fragarioides: dot (lower dot covering 2 specimens); W. lutea: triangle (3 specimens)

    Habitat & Ecology — Common on Blikep in primary to secondary forest along the road at 566–777 m altitude. Flowering in September–October and fruiting in June.  

    Etymology — Due to the arched receptacle in the staminate flowers, the epithet refers to the strawberry (Fragaria L.), where the receptacle becomes a highly domed fruit.  

    Conservation — The known distribution of the new taxon is limited, as exploration of Halmahera and nearby islands is highly incomplete. It appears to be a local endemic and might at least be vulnerable, especially when the planned nickel mine begins operation.  

    Note — The specimen from Blikep Nu is slightly different, as the leaf blades are more elliptic, whereas the specimens of Bukit Limber are more ovate. In addition, the peduncle of the pistillate inflorescence of Blikep Nu has (next to stellate hairs) long simple hairs, not seen in the specimens of Bukit Limber, whereas many stellate hairs on the fruits in Bukit Limber have a central, much longer and stiffer arm, not seen in the fruits of Blikep Nu.

2. Weda lutea Welzen

    Weda lutea Welzen in Welzen et al., J. Syst. Evol. (2020) doi:10.1111/jse.12581. — Type: Bangun, Merello, Gushilman, Haris 118 (holotype, L; isotypes, BO, MO 2 sheets), Indonesia, central Halmahera, Weda Bay, road to Sake South.  

Small trees (reported by Bangun et al. 118 as a 3 m long liana), 10m high, dbh to at least 10 cm; flowering branches 3–5 mm diameter, branchlets rather densely covered with stellate to dendritic hairs, rather persistent, and long (to 2.2 mm) simple hairs, latter caducous. Outer bark brown to brownish gray, rugose; inner bark pale green to red; sap clear or red and oxidizing black. Leaves dark brown from dense indument when young; petioles 8–12.8 cm long, 1–1.8 mm thick in middle, with brown stellate to dendritic hairs and yellow simple hairs; blade ovate-oblong, 8–25.5 by 4.8–16 cm, 1.2–1.7 times longer than wide, base peltate for less than 1 cm or cordate, emarginate, with one or usually two elongated slender glands, often to one side, c. 1.3 by 0.5 mm, often with a flat gland next to the base; lamina margin somewhat recurved, often with several, somewhat shorter glands, apex acuminate, acumen up to 2 cm long and minutely gland tipped, upper surface with stellate and simple hairs when young, stellate hairs persistent on midrib and basal part of major veins, lower surface slightly hairy with stellate to dendritic hairs and simple patent hairs, venation basally palmate, secondary veins 8–10 pairs to apex. Inflorescences: peduncle 8.4–14.4 cm long, with stellate hairs and often long simple hairs and few dendritic hairs; bracts ovate, 4.2–8 by 3.2–5.8 cm, subsessile, petiole up to 5 mm long, basally emarginate, margin entire, apex acuminate, venation well developed, like leaf blades, but fewer secondary veins, indumentum like leaves; branches at least 18 cm long (broken), along with branches acicular bracts, one or two per node, up to 2.5 mm long by 0.2–0.4 mm diam., ending in a globose gland, apically bent downward. Flowers: sepals basally more united than in other species, petals yellow. Staminate flowers c. 12mm diameter, receptacle highly domed or androphore; bud green; pedicel up to 11 mm long, with stellate hairs and some long simple hairs; calyx pale green, c. 3.8 mm long, lobes ovate to oblong, c. 2.3 by 1.2–1.4 mm, fleshy, outside with stellate hairs, especially in middle, inside glabrous; petals c. 7 by 3.5 mm; narrow hirsute band (disc) at base of androecium; stamens yellow, filaments seemingly united in an androphore, free part of filaments thread-like, c. 1 by 0.1 mm, glabrous, anthers elliptic, c. 0.8 by 0.5 mm, glabrous. Pistillate flowers c. 21 mm diameter; pedicel c. 7.5 mm long, hairy; calyx with five lobes, lobes ovate, c. 4.2 by 2 mm, with stellate hairs outside; petals oblong-obovate, c. 11 by 5 mm; disc not observed; ovary densely stellate-hairy, c. 3 mm high, tapering into a hairy style; stigmas c. 4 mm long, seemingly only apically split. Fruits dehiscing, ellipsoid, c. 15 by 14 mm, green, stellate and dendritic hairs brown, hairs with arms all of same length (no longer central arm); wall c. 1 mm thick; sepals persistent; columella c. 1.2 cm high, narrow, apically not much widened. Seeds very immature, apically with an extension of a white 2-lobed caruncle-like structure.  

    Distribution — Indonesia, N Moluccas (Maluku Utara), Halmahera, northeast of Weda, vicinity of Weda Bay at Sake South.  

    Weda lutea: triangle (3 specimens); W. fragarioides: dot (lower dot covering 2 specimens)

    Habitat & Ecology — (Open) secondary forest at 78–103m altitude. Flowering in October and November, fruiting in October.  

    Etymology — The epithet refers to the yellow color of the petals.  

    Conservation — The distribution of the Weda lutea is not adequately known, as species inventories of other areas in Halmahera and nearby islands are incomplete. It appears to be a local endemic and might at least be vulnerable; it is especially at risk because it seemingly occurs only at low altitude and will be especially endangered when the planned nickel mine begins operation.  

    Note — The stamens of W. lutea were difficult to observe due to the very few open staminate flowers. It is unclear as to whether the stamens are inserted on a highly domed receptacle (as is more the case in W. fragarioides) or form an androphore around whose base is a vague circular, very regular annular hirsute disc. The seeds have a poorly understood caruncule-like appendage, not observed in W. fragarioides.