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Weda fragarioides Welzen
& Weda lutea Welzen
in van Welzen, Guerrero, Arifiani, Bangun, Bouman, et al., 2020.
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Abstract
During the environmental impact study for a proposed nickel mine near Weda Bay on Halmahera in North Moluccas (Maluku Utara Province), Indonesia, two unknown Euphorbiaceae were discovered. Morphological comparisons and molecular phylogenetic analyses using four markers (plastid trnL‐F and rbcL, and nuclear ribosomal internal transcribed spacer and external transcribed spacer) indicated that they should be recognized as constituting a new, distinct genus of two species, which are described and illustrated here as Weda fragarioides and Weda lutea. The new taxa are members of the Australasian tribe Ricinocarpeae in subfamily Crotonoideae, and they are most closely related to Alphandia. In contrast with the otherwise mostly sclerophyllous Ricinocarpeae, Weda possesses stellate to dendritic hairs, large, long‐petiolate, glandular leaves, and inflorescences with a pair of large, leafy, subopposite bracts. The two narrowly distributed species are distinguished from each other by vegetative and floral features, molecular data, and elevational preferences. Leaf elemental analysis of Weda indicated manganese, but not nickel, accumulation. Newly resolved generic relationships and potential morphological synapomorphies within Crotonoideae are discussed, and the circumscription of Ricinocarpeae is expanded from 7 to 11 genera.
Keywords: Crotonoideae, elemental analysis, Euphorbiaceae, Malesia, molecular phylogenetics, Ricinocarpeae
Weda Welzen, gen. nov.
Type: W. fragarioides Welzen
Diagnosis: Monoecious trees with stellate to dendritic hairs and often long, simple patent hairs. Stipules lacking. Leaves alternate with long petioles, base of blades with two large, adaxial, basal glands or these at end of narrow lobes, venation raised, very distinct. Inflorescences axillary, cymose, functionally unisexual, with long peduncle and apically two unequal, subopposite, leaf‐like, (sub)sessile, late‐caducous bracts. Flowers with calyx and corolla, apparently lacking a disc. Staminate flowers with highly domed, hirsute receptacle with many short stamens or an androphore with a short free‐filament part per stamen. Pistillate flowers with three‐locular ovary, stigmas split, smooth adaxially. Fruits capsular, smooth, dehiscing loculicidally and septicidally. Seeds naked, marbled.
Distribution: The two species are each discovered from three collections made in central Halmahera (Indonesia, N Moluccas; Fig. 1).
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.
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| Fig. 5: Weda fragarioides Welzen. A, Habit. B, Basal leaf blade glands. C, Staminate flower with front petal removed. D, Pistillate flower with petals removed. E, Partly loculicidally split mericarps and seed. F, Columella remaining after fruit dehiscence. G, Seed, lateral (profile) view. H, Seed, ventral view.
(based on: A–D, Phillipson et al. 6448, L; E–H, Bangun et al. 971, L).
Illustration by Esmée Winkel (2018).
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| Fig. 6: Weda fragarioides Welzen. A, Habit (Gushilman et al. 777, photo IG 5481). B, Branch tip with long petioles, exstipulate developing leaf, stellate hairs and glands at base of leaf blade (Phillipson et al. 6448, photo PBP 5058). C, Bracteate inflorescence with a single developed staminate flower (Phillipson et al. 6448, photo PBP 5079). D, Staminate flower with androecium of many free, short stamens and white petals (Phillipson et al. 6448, photo PBP 5072). E, Bracteate infructescence with young fruit (Phillipson et al. 6448, photo PBP 5059). F, Young fruit with smooth bifid stigmas and brown stellate hairs (Gushilman et al. 777, photo IG 5487). |
Weda fragarioides Welzen, sp. nov.
Diagnosis: Leaf blades not peltate, large glands at blade insertion. Inflorescence branches short, less than 5 cm long. Floral bracts vestigial, hairy enations. Petals white.
Habitat and 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 (see Callmander et al., 2015). 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.
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| Fig. 7: Weda lutea Welzen. A, Habit. B, Peltate leaf base with glandular appendages. C, Basal laminar gland. D, Cymose inflorescence with long branches. E, Staminate bud. F, Staminate flower, two petals removed, showing androecium. G, Young seed with apical caruncule‐like appendage, lateral (profile) view.
(based on A–C, Bangun et al. 199, L; D–F, Gushilman & Haris 178, L; G, Bangun et al. 118, L).
Illustration by Esmée Winkel (2019).
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| Fig. 8: Weda lutea Welzen. A, Habit with hairy, slightly peltate leaves (Gushilman et al. 178, photo IG 820). B, Young shoot with exstipulate developing leaves, stellate (brown) hairs and long white simple hairs (Bangun et al. 199, photo TF 2517). C, Cymose inflorescence with basal young fruit and terminal staminate flowers and buds (Bangun et al. 199, photo TF 2520). D, Staminate flower with yellow petals (Bangun et al. 199, photo TF 2510). E, Pistillate flower (Bangun et al. 118, photo TF 1228). F, Young fruit subtended by sessile bracts (Bangun et al. 199, photo TF 2521). |
Weda lutea Welzen, sp. nov.
Diagnosis: Leaf blades peltate, glands at base of peltation, margin with occasional somewhat smaller glands; venation basally palmate. Inflorescence branches up to more than 18 cm long (broken). Floral bracts acicular, up to 2.5 mm long, ending in a globose gland. Petals yellow.
Distribution: Indonesia, N Moluccas (Maluku Utara), Halmahera, northeast of Weda, vicinity of Weda Bay at Sake South (Fig. 1).
Habitat and Ecology: (Open) secondary forest at 78–103 m 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 (see Callmander et al., 2015). 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.
Peter C. van Welzen, Susana Arias Guerrero, Deby Arifiani, Tjut J.F. Bangun, Roderick W. Bouman, Marcel C.M. Eurlings, Iska Gushilman, Peter B. Phillipson, Iris Tabak, Esmée Winkel and Kenneth J. Wurdack. 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