Phylogenetic and taxonomic studies of six recently-described Stellaria species (Caryophyllaceae) from China, with an additional new species, Stellarialongipedicellata, from Sichuan.

Abstract

The phylogenetic studies of the tribe Alsineae (Caryophyllaceae) have revealed a clearer boundary between the genus Stellaria and related genera, primarily relying on the morphological characteristics of style 3, stamens 10 and petals deeply bifid. However, the newly-published species in China, which have 5 styles or ten or more lobes per petal, challenge this boundary and necessitate further studies. In this paper, we reviewed six newly-published Chinese species of Stellaria, utilising both molecular phylogenetic evidence from nuclear ribosomal internal transcribed spacer (ITS) and four plastid regions (trnL-F, matK, rbcL, rps16) and morphological evidence. Our results demonstrated that the five new species (Stellariaabaensis, S.multipartita, S.pentastyla, S.procumbens and S.zhuxiensis) were nested within the genus Stellaria, but Stellariamotuoensis was sister to the genus Schizotechium. Herein, we accepted four new Stellaria species and proposed a new combination in Schizotechium and a new synonym in Stellaria. Additionally, we described a new species Stellarialongipedicellata from Sichuan Province, China, which was distinguished from the closely-related species Stellariadecumbens by its glabrous body, linear-lanceolate leaves, long pedicellate flowers, prostrate growth habit and flowers nearly equal to or slightly shorter than sepals. Both molecular and morphological evidence support the treatment of S.longipedicellata as a new species of the genus Stellaria.