Zoogeographic distribution may present evolutionary cues for diversity and speciation. Evaluation of zoogeographical distribution together with molecular clues could insight into evolutionary history including probable origin as well. Genus Lamellodiscus (Monogenea: Diplectanidae) may offers great opportunity to analyze the inter-host specifity for understanding molecular conservation and phylogenetic relationship. Members of the genus were integrated in terms of zoographical distribution and diversity. Significant relatedness of species were shown and confirmed from across the globe, irrespective of distant evolutionary relationship. The evolving 18S rRNA structure confirmed the extent of speciation and demonstrated that anomaly in their evolution was accounted mainly due to separation of species into different geographical zones. Representative species of different clades were not well connected either geographically or cladistically but secondary structure proved that they evolved into different individuals/species thousand years ago and maintained the same pattern of origin. Molecular information of evolution pattern was stored and remain conserved in their ribosomal RNAs.