Taxonomy Of The Genus Mallotus (Euphorbiaceae) From China

The tropical and subtropical genus Mallotus Lour.,as traditionally circumscribed,includes 150 species.26 species and four varieties are recorded in China.It occurs mainly in Southeast Asia and the West Pacific,with two species in Africa and Madagascar.Species are predominantly perennial shrubs or small trees and more rarely woody climbers.This genus always distinguished from other genera by whitish to red glandular scales,inflorescences terminal or axillary,paniculatus or racemose,one ovule each ovary and stellate-pubescent.Faced with this number of species and the complicated nomenclature associated with many of them,an initial survey of all species and related literature was carried out in a seach for suites of characters that might indicate natural biological groups.Although some achievements on taxonomic revision have been made by predecessors,some treatments of difficult species are controversial.Based on an extensive literature survey in combination with herbarium and field observations as well as researches of morphology,leaf epidermal micromorphology,palynology and molecular systematics,we accumulated multidiciplinary evidence to solve the problems mentioned.The results are as follows.Micromorphology of leaf epidermis from 22 species as well as one variety indicates that the character combination of epidermal cells,stomatal apparatuses and hairs can provide evidence for infrageneric subdivision.Shapes of epidermal cells are always irregular or nearly isodiametric polygonal,some species have striations or papillae.The stomatal apparatuses exist only in lower epidermis or in both sides.Pollen grains of 12 species of Mallotus from China were examinaed by scanning electron microscope.It can be concluded that the pollen of Mallotus is elliptic or subglobose.Aperture patterns are tricolporate.The exine ornamentation is perforate with scabrae.The difference of pollen size and shapes have some certain taxonomic significance to recognize species in Mallotus.Molecular phylogeny based on four combined DNA sequences(rpsl6-trnQ,psbJ-petA,80F-1300R,PHYC)suggests that the geneus Mallotus is monophyletic.This research provides support of moving Mallotus taoyuanensis into Mallotus paxii.Our study based on extensive literature survey,specimen examination,field observations and experimental evidence indicates that there are 26 species and 4 variations in China.Mallotus taoyuanensis has been moved into Mallotus paxii,Mallotus conspurcatus has been moved into Mallotus barbatus.Mallotus dunnii has been moved into sect.Stylanthus.We corrected errors of typification on Mallotus dunnii and Mallotus oreophilus var.latifolius.Keys and characters are given and names are corrected.Evaluations and descriptions of main characters in this genus are also provided in this paper.