To date, a number of species of Haemogregarina
have been described from different turtle
hosts, mainly based on the morphology of the
developmental stages detected in the host erythrocytes.
The diversity and overlapping morphological
features in the old and recent descriptions has led to
considerable complications in the taxonomy of Haemogregarina
spp. In this study, different stages of
maturity and developing gamonts of a putative new
species of Haemogregarina were detected in erythrocytes
of the Caspian turtle Mauremys caspica
(Gmelin) (Geoemydidae) originating from a southern
province in Iran. Although some of the morphological
characteristics were consistent with Haemogregarina
stepanowi Danilewsky, 1885, some new observations
were made, particularly in the gamont stage. The
phylogenetic analysis based on 18S rDNA sequences
revealed that the present isolate appears as basal to a
large clade of Haemogregarina spp. with sequences
available in the GenBank database. In accordance with
the phylogenetic results, the present Iranian isolate
showed a higher degree of interspecific divergence (up
to 3.3%) compared to the data for the taxa available in
the GenBank database. Thus, molecular data indicate
that this isolate may represent a new species. However,
further genetic analyses are needed as a
complementary tool to the morphological characterisation
in order to elucidate the phylogenetic relationships
of Haemogregarina spp.
