MITOCHONDRIAL-DNA DIFFERENTIATION BETWEEN 2 CRYPTIC HALICTUS (HYMENOPTERA, HALICTIDAE) SPECIES

Halictus ligatus Say and its cryptic sibling species H. poeyi Lepeleti er were sampled from an area of sympatry and typed for mitochondrial D NA sequence differentiation, as was 1 individual of each species from allopatric populations. Two other species, H. rubicundus (Christ) and H. farinosus Smith, were included to root the tree. Phylogenetic analy sis of the aligned sequences showed that H. ligatus and H. poeyi are s ister species and differ from each other at 33 of the 797 aligned nucl eotide positions. Sequence divergence within species was <0.6%, wherea s that between species exceeded 4%. These data support an earlier repo rt that a ligatus and H. poeyi represent distinct species (based on nu clear allozyme markers) and are sufficient to cast doubt on a recent g laciation-induced speciation event as the cause of the differentiation of these 2 taxa.