Morphology and molecular taxonomy of the tongue worm, genus Raillietiella (Pentastomida) from the lungs of berber skinks Eumeces schneideri (Scincidae): First report

Abstract

In the present study, pentastomids belonging to the order Cephalobaenida were isolated from the lungs of Berber skinks Eumeces schneideri (Famiy: Scincidae), which were morphologically described by light and scanning electron microscopy and taxonomically justified by 18s rDNA molecular analyses of the parasites. Seventeen host specimens were collected from well–vegetated wadis at high altitudes, Jizan, Saudi Arabia as new type locality; twelve specimens (70.59%) were infected. All of the recovered parasites were adults, possessed small broadly triangular cephalothorax flattened on the ventral surface and merged smoothly with a uniformly thick and squat abdomen and terminated in a pair of divergent lobes. The results obtained indicated that the parasites belong to the sharp–tipped posterior–hook Raillietiella spp. distinguished from other raillietiedids of the same group some important characteristic features including annulus number, shape and dimensions of the buccal cadre, copulatory spicules, and anterior and posterior hooks. The anterior hook of the female specimens (n = 5) had a blade length (AB) of 135 ± 5 (110–146) μm and shank length (BC) 158 ± 5 (150–169) μm while the posterior hook was much larger with AB measuring 221 ± 5 (200–236) μm and BC 286 ± 6 (280–289) μm. For the male specimens (n = 5), the anterior hook had an AB of 73 ± 3 (72–75) μm and a BC 102 ± 5 (100–103) μm. The posterior hook was much larger with AB 190.6 ± 5 (190–191) μm and BC 221 ± 5 (280–289) μm. The morphological characterization of the recovered parasites was closely similar to R. aegypti previously isolated from the same host. Sequence alignment by the maximum likelihood analysis for the data obtained from the 18S rDNA analysis of the parasites exhibits identities ranging between 88–95% with pentastomid genera recovered from the GenBank. The phylogenetic tree supported the inclusion of the parasites within the monophyletic Pentastomida clade with maximum identity to the raillietiellid species. The recovered sequences from the present study were deposited in GenBank under Accession number MK970649.1. The present molecular analysis was the first to confirm the taxonomic position of R. aegypti isolated from the host examined.