Abstract
The internal transcribed spacer regions (ITS1 and ITS2) and 5.8S rRNA genes were sequenced in six populations of four
Aspidisca
species, namely
A. leptaspis, A. orthopogon, A. magna
and
A. aculeata
. Phylogenetic trees were constructed by means of Bayesian inference (BI), Maximum Parsimony (MP), Neighbor-Joining (NJ), and Maximum Likelihood (ML) to assess the inter- and intra-species relationships within the genus
Aspidisca
. All trees show similar topologies with stable supports and indicate that: (1) four well known groups, i.e., Oligotrichia, Stichotrichia, Choreotrichia and Hypotrichia, are distinctly outlined within the class Spirotrichea, and all are monophyletic other than Hypotrichia; (2) members of
Aspidisca
can be distinguished well, based on the ITS1-5.8S-ITS2 region sequences, and
A. leptaspis
and
A. magna
shared a closer relationship than other species; (3)
Aspidisca
and
Euplotes
branch early in the subclass Hypotrichia. To compare the phylogenetic relationships based on different genes, SSU rRNA trees were also constructed with nearly the same species inclusion, which revealed different topologies of inter-species, inter-genera and inter-subclasses.