Mallotus bullatus (Euphorbiaceae), a new species from Southwest China based on morphological characters and phylogenetic evidence

<i>Mallotusbullatus</i> M.T.An & J.H.Yu, <b>sp. nov.</b> (Euphorbiaceae), a species new to science discovered in Guizhou, China, is described and illustrated here, and its phylogenetic position among other <i>Mallotus</i> species is presented. Morphological, micro-morphological, and molecular evidence is presented as attestation of its novelty. The new species morphologically resembles M.philippensisvar.reticulatus and M.philippensisvar.philippensis, but it clearly differs by having bullate leaf surfaces (vs. not bullate), leaf margins entire or nearly so (vs. entire or nearly so in M.philippensisvar.philippensis and coarsely serrate in M.philippensisvar.reticulatus), leaf margins sometimes bearing red glands (vs. red glands absent), 5 sepals in staminate flowers (vs. 3-4 in M.philippensisvar.philippensis and 4 in M.philippensisvar.reticulatus), fruits with spines (vs. spines absent in M.philippensisvar.philippensis and present in M.philippensisvar.reticulatus), and abaxial leaf epidermal scattered and clustered vein hairs 0.1-0.8 mm long (vs. 0.04-0.28 mm long in M.philippensisvar.philippensis and 0.05-0.1 mm long in M.philippensisvar.reticulatus). Molecular phylogenetic analysis (BS = 100% / BS = 96%, PP = 1 / PP = 1) provides strong evidence supporting <i>M.bullatus</i> as a new species within the genus <i>Mallotus</i> and supports its placement in M.sect.Philippinenses as sister to <i>M.philippensis</i>.