Valkiūnas Gediminas, Sehgal Ravinder N M, Iezhova Tatjana A, Hull Angus C
Institute of Ecology, Vilnius University, Akademijos 2, Vilnius 21, LT-08412, Lithuania.
J Parasitol. 2010 Feb;96(1):170-7. doi: 10.1645/GE-2109.1.
The current taxonomy of leucocytozoids (Haemosporida, Leucocytozoidae) is based on the morphology of blood stages of the parasites and on limited information about their specificity. Recent molecular studies have revealed a remarkable genetic diversity of leucocytozoids, indicating that their taxonomic diversity may be greater than in the current classifications. We addressed this issue using morphological data and phylogenetic analysis of the cytochrome b gene of 14 positively identified species of avian haemosporidians. Based on the current taxonomy, Leucocytozoon toddi is the sole species of leucocytozoids parasitizing falconiform birds. However, several distinct haplotypes have been revealed in falconiform birds, suggesting that L. toddi might be a group of cryptic species. We investigated the morphology of blood stages of leucocytozoids of 2 haplotypes (2 lineages from Accipiter spp. and 3 lineages from Buteo spp.) and concluded that these parasites can be readily distinguished due to length of the cytoplasmic processes of their host cells; therefore, they do represent distinct morphospecies. Morphology of the cytoplasmic processes of host cells warrants more attention in the taxonomy of Leucocytozoon species. Leucocytozoon toddi indeed is a species group that currently includes Leucocytozoon mathisi, Leucocytozoon buteonis, and L. toddi; additional morphospecies can be added to this group in the future. It is probable that some other morphospecies of Leucocytozoon also might be groups of closely related species.
白细胞虫类（血孢子虫目，白细胞虫科）目前的分类学是基于寄生虫血液阶段的形态以及关于其特异性的有限信息。最近的分子研究揭示了白细胞虫类显著的遗传多样性，这表明它们的分类学多样性可能比目前的分类更为丰富。我们利用形态学数据以及对14种已明确鉴定的鸟类血孢子虫细胞色素b基因的系统发育分析来解决这个问题。根据目前的分类学，托氏白细胞虫是寄生于隼形目鸟类的唯一白细胞虫类物种。然而，在隼形目鸟类中已发现了几种不同的单倍型，这表明托氏白细胞虫可能是一组隐存种。我们研究了2种单倍型（来自鹰属的2个谱系和来自鵟属的3个谱系）的白细胞虫血液阶段的形态，得出结论：由于其宿主细胞胞质突起的长度，这些寄生虫很容易区分；因此，它们确实代表不同的形态种。宿主细胞胞质突起的形态在白细胞虫物种的分类学中值得更多关注。托氏白细胞虫实际上是一个物种组，目前包括马氏白细胞虫、鵟白细胞虫和托氏白细胞虫；未来可能会有更多的形态种加入这个组。很可能白细胞虫的其他一些形态种也可能是密切相关物种的组。
