A 50-year-old redescription: molecular and morphometric characterization of Hepatozoon carinicauda Pessôa and Cavalheiro, 1969 in the brown-banded water snake Helicops angulatus (Linnaeus, 1758)

Abstract

The combined use of molecular and microscopic techniques has become an increasingly common and efficient practice for the taxonomic and evolutionary understanding of single-celled parasites such as haemogregarines. Based on this integrative approach, we characterized Hepatozoon found in Helicops angulatus snakes from the Eastern Amazonia, Brazil. The gamonts observed caused cell hypertrophy and were extremely elongated and, in some cases, piriform (mean dimensions: 25.3 ± 1.9 × 8.6 ± 1.3 μm). These morphological features correspond to Hepatozoon carinicauda, described 50 years ago in the snake Helicops carinicaudus in the southeast region of Brazil. Phylogenetic and genetic divergence analyses, performed with the sequence obtained from the amplification of a 590 bp fragment of the 18S rRNA gene, revealed that Hepatozoon in He. angulatus differed from the other lineages retrieved from GenBank, and was clustered singly in both the phylogenetic tree and the haplotype network. The integration of these data allowed the identification of H. carinicauda in a new aquatic host, and increased the knowledge of its geographical distribution. Therefore, the present study included the first redescription of a Hepatozoon species in a snake from the Brazilian Amazon.

Keywords: 18S rRNA; Haemogregarines; molecular description; neotropical snakes; taxonomy.

Graphical abstract

Fig. 1.

Map of the study area, Macapá, Amapá, Brazil, containing the location of the analysed samples, indicated by red circles.

Fig. 2.

Gamonts of Hepatozoon carinicauda infecting erythrocytes of the aquatic snakes Helicops angulatus from the Eastern Amazonia, Brazil (a–f). Arrows indicate parasites; asterisks (*) indicate gamont nuclei; and ‘n’ indicates host cell nucleus. Micrographs are from Giemsa-stained thin blood films. Scale bar = 10 μm.

Fig. 3.

Phylogenetic tree based on an alignment of 615 bp fragment of Hepatozoon spp. 18S rRNA sequences, using ML method and GTR evolutionary model. Numbers beside nodes correspond to bootstrap. Accession numbers are indicated in the sequences. The sequence of Hepatozoon carinicauda detected in the present study is highlighted in bold red.

Fig. 4.

Median Joining Network of 18S rRNA Hepatozoon sequences (461 bp) detected in snakes from Brazil in the present study and in previous studies. While the lines between haplotypes represent mutational steps, the black circles indicate median vectors (hypothetical haplotypes generated by the software to connect all the haplotypes).