Phylogeny of crustacean apicomplexans as inferred from rDNA, with emphasis on a newly described gregarine from an Antarctic benthic amphipod
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Year of publication | 2016 |
Type | Conference abstract |
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Description | Representatives of the group Apicomplexa are well known pathogens causing harmful diseases such as toxoplasmosis, malaria, and cryptosporidiosis in humans and domestic animals. Various aspects of their biology and phylogeny are intensively studied. Less is known about basal apicomplexan groups from invertebrates, namely gregarines. Nevertheless, the knowledge about characters evolution and phylogeny of this group and other related organisms can improve our understanding of evolutionary pathways within Apicomplexa. From the Antarctic, few reports concerning gregarines have ever been published. In this study, a novel eugregarine from a benthic amphipod is described using microscopic and phylogenetic analyses. Head-to-tail syzygies were found: both gamonts were of aseptate morphology and with an oval or lentil-shaped nucleus. The syzygies exhibited gliding motility. The syzygy partners were covered with a three¬membrane pellicle, forming longitudinal epicytic folds, as typical for eugregarines. The attachment site of the primite was convex and the posterior end formed a concave depression in which the cap-like anterior end of satellite plugged in. Furthermore, phylogenetic analyses of rDNA datasets from different coccidia, gregarines and other basal apicomplexans were performed. Selected available sequences of ribosomal genes (SSU and LSU) from different apicomplexans grouped in several main clades. Statistical support in the branches was sometimes low for gregarines that superficially appear to be similar in morphology. On the other hand, gregarines from crustacean hosts clustered together, despite their variable morphological features. |
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