nrDNA ITS sequences and affinities of Sino-Himalayan Apioideae (Umbelliferae)

The internal transcribed spacers (ITS1 and ITS2) of 18S-26S nuclear ribosomal DNA were sequenced for 13 species of Apioideae from the Sino-Himalayan flora [Apium ventricosum (= Sium frigidum), Arcuatopterus thalictrioideus, Cyclorhiza peucedanifolia, Meeboldia achilleifolia, Notopterygium forbesii, N. weberbauerianum, Pternopetalum delavayi, P vulgare, Pterocyclus rivulorum, Sinocarum cruciatum, Sinodielsia delavayi, Tongoloa elata, and Trachydium simplicifolium], relationships of which are controversial or obscure and unresolved on the basis of morphological data. Phylogenetic trees inferred by neighbor-joining, parsimony analysis, and Bayesian inference are topologically congruent, but not identical. The newly obtained data permit testing of several hypotheses regarding these taxa. Some of the early hypotheses treat local species under well-known European genera (e.g., Apium, Carum, Pimpinella, etc.), but these are not supported by phylogenetic analysis of nuclear rDNA spacer sequences. In particular, Sinodielsia, Meeboldia, Tongoloa, and Pternopetalum are distant from Pimpinella; Pternopetalum, Sinocarum and Tongoloa are remote from Carum; Arcuatopterus is separate from Peucedanum and Angelica; Pternopetalum is distinct from Cryptotaenia; and Notopterygium and Pterocyclus are separate from Pleurospermum. Chinese Notopterygium is shown to be closely related to Siberian and Mongolian Hansenia; this, plus similarity in fruit structure, suggests that they are congeneric. Apium ventricosum, more commonly known as Sium frigidum, appears a close relative of Sinocarum. Affinities of most Sino-Himalayan Apioideae, therefore, are found among taxa from the same and adjacent territories. Wide disjunction between presumptively related taxa has been revealed only in Cyclorhiza and Komarovia. Sinodielsia and Meeboldia are also revealed to be clearly distinct genera.