A TAXONOMIC REVISION OF MALLOTUS SECTION MALLOTUS (EUPHORBIACEAE) IN MALESIA

A revision of Mallotus section Mallotus in Malesia is given. Descriptions, distribution maps, habit drawings and a key to all species are provided. The diagnostic characters for the section are briefly discussed. Four species ( M. barbatus , M. macrostachyus , M. mollissimus , M. paniculatus ) and one variety ( M. paniculatus var. formosanus ) are recognized.


INTRODUCTION
Mallotus Lour. is a genus of shrubs, trees and climbers, with c. 150 species. It is classified in the subfamily Acalyphoideae, subtribe Rottlerinae (Euphorbiaceae s.s.) together with other genera (Radcliffe-Smith, 2001). The genus occurs mainly in (sub)tropical Asia, Australia and the Pacific, with only a few species in tropical Africa and Madagascar (Webster, 1994c).
In the morphological phylogeny of Mallotus by Slik & Van Welzen (2001b) it was suggested that section Mallotus is monophyletic and that Macaranga is closely related to it, but since not all of its species were included in the analysis its monophyly is not certain; the genus Mallotus differs from Macaranga in the presence of stellate and simple hairs (simple in Macaranga), alternate or opposite leaves (alternate in Macaranga), and of 2-celled anthers (4-celled in Macaranga). Until the phylogenetic studies of the genus Mallotus based on molecular and morphological data are completed we accept the traditional sectional delimitations as circumscribed by Airy Shaw (1968).
Distribution -From India (W Bengal) to South China and South Japan, throughout Southeast Asia and Malesia to East Australia and West Pacific (Solomon Islands). KEY  Shrubs to small trees up to 12 m high, dbh up to 15 cm, monoecious or dioecious.
Habitat & Ecology -Locally common in deciduous and evergreen forest, mostly in open, often very disturbed or burned places, along road and river sides; on a large variety of soil types, like shale, limestone, sandstone, and sandy clay. Altitude: sea level up to 1400 m. Flowering and fruiting the whole year through.
Uses -The roots and fruits are used against muscle stiffness. The seeds yield a fatty oil used for making candles.
Uses -The leaves are used as an antidote against snake-poison. The wood is used as firewood.

Mallotus mollissimus (Geiseler) Airy
Habitat & Ecology -Locally common in deciduous and evergreen forest, mostly in open, often very disturbed or burned places, gallery forest, mangrove edges, swamp forest, riparian vegetation, notophyll vineforest, on mountain slopes, open grasslands and along hill and road sides; on a large variety of soil types, like alluvial, basalt rocks, clay, coral limestone, loam, rocky, sandy, ultrabasic, and volcanic. Altitude: sea level up to 1700 m. Flowering and fruiting the whole year through. Observed to be visited by small brown ants.
Uses -The roots are used against headaches and malaria. The inner bark is used as a strap for carrying and for sing sing decorations. The leaves are used as food covering, against stomach cramp, and together with the bark used to cure the spleen. The wood is used for making scabbards, ritual spears, building construction, and as firewood.
Moreover the Staunton collection cannot be the type of M. mollisimus, because there is no evidence that Geiseler ever saw it. It was given by Lambert to De Candolle in 1816, as was written on the label (for additional information see also Miller, 1970: 543).
Since the Crotonis Monographiam from Geiseler (1807) is based on material from Vahl at the Copenhagen Herbarium, by circumstantial evidence, the most likely speci- men to be the type is the Vahl specimen found in C as was actually said by Müller Argoviensis. Like Croizat (1938: 141) we doubt the Chinese origin of this specimen as no other one has come to our attention. The nearest occurrence could be Tu Phap in North Vietnam, but the provenances given by the collector d'Aleizette cannot always be trusted. The specimens cited by Gagnepain (1925: 357) and Poilane 1685 cited by Croizat as well, as far as seen belong to M. metcalfianus.
A letter by Croizat on July 14, 1938, that is after the publication of his paper (April 27, 1938) suggests a possible Indonesian origin and this seems a good suggestion.
2. Croton ricinoides was described from India. The lectotype was collected by Lahaye, who never was in India (cf. Van Steenis-Kruseman, 1950: 307)   Shrubs to small trees up to 15 m high, dbh up to 24 cm, dioecious, rarely monoecious. Bole up to 4 m high; crown up to 4 m long; bark with much tannic acid, outer bark rough to finely fissured or pustular lenticellate, reddish brown with yellowish brown lenticels, up to 10 mm thick; inner bark and wood white. Indumentum tomentose to puberulent. Stipules triangular, 0.8-1.5 by 0.4-0.7 mm, caducous, margin entire, apex acute. Leaves: petiole 30-180 by 0.5-2.5 mm, greenish tawny; blade subpeltate for 1.5 mm, broadly ovate to ovate, 4-23.5 by 3-15 cm, length/width ratio 0.8-2, reddish brown when young, base rounded to cuneate, margin entire to (irregularly) dentate, sometimes 2-lobed at widest part of blade, sometimes hastate, longest lobes up to 30 mm, upper surface dull dark green, basally with 0-2 extrafloral nectaries, 0.8-5 by 0.5-2.5 mm, yellowish green, marginal nectaries 0-11 per side, 2-4 mm from margin, 0.3-0.8 by 0. Note -The criteria used for the recognition of a variety are the slight differences in morphology which partly overlap or are otherwise not of importance for species delimitation and the absence of clear differences in their geographical distribution. Mallotus paniculatus and M. paniculatus var. formosanus slightly differ in their measurements, shape of the leaf margin, and the ending of the nerves (as can be seen in the descriptions), and are both found in Taiwan. Since these two taxa agree with the criteria mentioned above, we decided to maintain var. formosanus. KEY  Leaves: petiole 30-180 by 0.4-0.7 mm; blade 4-23.5 by 3-15 cm, length/width ratio 1.2-2, base rounded to cuneate, margin entire to dentate, sometimes 2-lobed, never hastate, nerves looping, extrafloral nectaries basally 1.8-5 by 1-2.5 mm, marginal nectaries 0.7-0.8 by 0.7-0.8 mm. Fruits 5-12 by 6-14 mm, spines up to 7 mm long; column 3-3.3 by 2-2.2 mm. Seeds 2.5-3 by 2.5-3 by 2-2.5 mm. Distribution -From India to Taiwan, throughout Southeast Asia and Malesia to East Australia and New Guinea.
Habitat & Ecology -Locally common in deciduous and evergreen forest, mostly in open, often very disturbed or burned places, in ravines and on dry sites like plateaus, ridges and slopes, in thickets, and along rivers and roadsides; on a large variety of soil types, like basalt, clay, granite, laterite, limestone, loam, rocky, sandy, ultrabasic, and volcanic. Altitude: sea level up to 1800 m. Flowering and fruiting the whole year through. It grows fast and was observed to be visited by ants and birds eating the fruits.

IDENTIFICATION LIST
The numbers behind the collector numbers refer to the following taxa: