Phylogenetic Placement Ofbotryococcus Braunii(trebouxiophyceae) Andbotryococcus Sudeticusisolate Utex 2629 (Chlorophyceae)1

The phylogenetic placement of four isolates ofBotryococcus brauniiKützing and ofBotryococcus sudeticusLemmermann isolate UTEX 2629 was investigated using sequences of the nuclear small subunit (18S) rRNA gene. TheB. brauniiisolates represent the A (two isolates), B, and L chemical races. One isolate ofB. braunii(CCAP 807/1; A race) has a group I intron atEscherichia coliposition 1046 and isolate UTEX 2629 has group I introns atE. colipositions 516 and 1512. The rRNA sequences were aligned with 53 previously reported rRNA sequences from members of the Chlorophyta, including one reported forB. braunii(Berkeley strain). Phylogenetic trees were constructed using distance, weighted maximum parsimony, and maximum likelihood, and their reliability was estimated using bootstrap analysis for distance and parsimony and Bayesian inference for likelihood. All methods showed, with high bootstrap or credibility support, that the four isolates ofB. brauniiform a monophyletic group whose closest relatives are in the genusChoricystisin the Trebouxiophyceae, whereas the previously reportedB. brauniisequence is from a member of the Chlamydomonadales in the Chlorophyceae and isolate UTEX 2629 is a member of the Sphaeropleales in the Chlorophyceae. Polyphyly of these sequences was confirmed by Kishino‐Hasegawa tests on artificial trees in which sequences were moved to a single lineage.