Morphological and molecular data show an enlarged tropical Australian radiation in Synostemon (Phyllanthaceae, Phyllantheae) previously concealed by heteromorphic species concepts

Abstract

<p><i>Sauropus elachophyllus</i> (F.Muell. ex Benth.) Airy Shaw and <i>S. rigidulus</i> (F.Muell. ex Müll.Arg.) Airy Shaw are revised under the reinstated genus <i>Synostemon</i> F.Muell. (Phyllanthaceae) using morphological and nrITS sequence data. <i>Sauropus decrescentifolius</i> J.T.Hunter & J.J.Bruhl and <i>S. elachophyllus</i> are shown to be conspecific as <i>Synostemon elachophyllus</i> (F.Muell. ex Benth.) I.Telford & Pruesapan and <i>S. elachophyllus</i> subsp. <i>decrescentifolius</i> (J.T.Hunter & J.J.Bruhl) I.Telford & Pruesapan, with <i>Synostemon elachophyllus</i> subsp. <i>latior</i> (Airy Shaw) I.Telford & Pruesapan (syn. <i>Sauropus elachophyllus</i> var. <i>glaber</i> Airy Shaw p.p.) raised in rank. The ‘Top End clade’ has morphological synapomorphies of fused staminal filaments and connectives, and linear, longitudinal anthers. Four new species are named: <i>Synostemon cowiei</i> I.Telford & J.J.Bruhl, <i>S. inaequisepalus</i> I.Telford & J.J.Bruhl, S. kakadu I.Telford & J.J.Bruhl and <i>S. nitmiluk</i> I.Telford & J.J.Bruhl and new combinations are provided: <i>S. crassifolius</i> (Müll.Arg.) I.Telford & Pruesapan, <i>S. ditassoides</i> (Müll.Arg.) I.Telford & Pruesapan, <i>S. dunlopii</i> (J.T.Hunter & J.J.Bruhl) I.Telford & Pruesapan, <i>S. filicinus</i> (J.T.Hunter & J.J.Bruhl) I.Telford & Pruesapan, <i>S. gracilis</i> (J.T.Hunter & J.J.Bruhl) I.Telford & Pruesapan, <i>S. rigidulus</i> (F.Muell. ex Müll.Arg.) I.Telford & Pruesapan, and <i>S. stenocladus</i> (S.Moore) I.Telford & Pruesapan, with <i>S. pinifolius</i> (J.T.Hunter & J.J.Bruhl) I.Telford & Pruesapan also raised in rank.</p>