Morphological versus molecular identification of avian Haemosporidia: an exploration of three species concepts.

More than 200 species of avian Haemosporidia (genera Plasmodium, Haemoproteus, and Leucocytozoon) have been described based primarily on morphological characters seen in blood smears. Recent molecular studies, however, suggest that such methods may mask a substantial cryptic diversity of avian haemosporidians. We surveyed the haemosporidians of birds sampled at 1 site in Israel. Parasites were identified to species based on morphology, and a segment of the parasite's cytochrome b gene was sequenced. We compared 3 species concepts: morphological, genetic, and phylogenetic. Fifteen morphological species were present. Morphological species that occurred once within our dataset were associated with a unique gene sequence, displayed large genetic divergence from other morphological species, and were not contained within clades of morphological species that occurred more than once. With only 1 exception, morphological species that were identified from multiple bird hosts presented identical sequences for all infections, or differed by few synonymous substitutions, and were monophyletic for all phylogenetic analyses. Only the morphological species Haemoproteus belopolskyi did not follow this trend, falling instead into at least 2 genetically distant clades. Thus, except for H. belopolskyi, parasites identified to species by morphology were supported by both the genetic and phylogenetic species concepts.