Taxonomy and distribution of the plant family Podostemaceae in Phitsanulok and Phetchabun provinces, Thailand

Abstract

Recent explorations of Podostemaceae have discovered 2 new species to science (Dalzellia TWA-216 และ Hydrobryum TWA-198) from Phitsanulok Province and 3 more genera and six more species from previously known (2 genera and 4 species). Totally, five genera and 10 species occur in Phitsanulok and Phetchabun provinces. Based on morphological and molecular evidence, the taxa are classified into subfamily Tristichoideae including 2 genera and 3 species (Dalzellia 2 spp. and Terniopsis 1 sp.) and subfamily Podostemoideae consisting 3 genera and 7 species (Hanseniella 1 sp., Hydrobryum 5 spp. and Thawatchaia 1 sp.). The species found in both provinces are Hy. phetchabunense and Hy. tardhuangense while D. kailarsenii is found only in Phetchabun. The plants discovered only in Phitsanulok include Dalzellia TWA-216, Hydrobryum TWA-198, Han. heterophylla, Hy. bifoliatum, Hy. kaengsophense, Th. trilobata and T. minor. Among the species found, Hy. tardhuangense and Th. trilobata are also distributed to the Lao PDR, and the rests are endemic to Thailand.