'Molecular approaches to trematode systematics: 'best practice' and implications for future study ', Systematic Parasitology, 93(3), 295-306. The final publication is available at Springer via http://dx.doi.org/10.1007/s11230-016-9631-2.The full details of the published version of the article are as follows: However, since the late-1980s we have seen an increased integration of genetic data to overcome problems encountered when morphological data are considered in isolation. Here, we provide advice regarding the 'best molecular practice' for trematode taxonomy and systematic studies, in an attempt to help unify the field and provide a solid foundation to underpin future work.Emphasis is placed on defining the study goals and recommendations are made regarding sample preservation, extraction methods, and the submission of molecular vouchers. We advocate generating sequence data from all parasite species/host species/geographic location combinations and stress the importance of selecting two independently evolving loci (one ribosomal and one mitochondrial marker). We recommend that loci should be chosen to provide genetic variation suitable to address the question at hand and for which sufficient 'useful' comparative sequence data already exist. Quality control of the molecular data via using proof-reading Taq polymerase, sequencing PCR amplicons using both forward and reverse primers, ensuring that a minimum of 85% overlap exists when constructing consensus sequences, and checking electropherograms by eye is stressed. We advise that all genetic results are best interpreted using a holistic biological approach, which considers morphology, host identity, collection locality, and ecology. Finally, we consider what advances next-generation sequencing holds for trematode taxonomy and systematics.
Phylogenetic analyses of a range of gorgoderid trematodes based on ITS2 and partial 28S rDNA data lead us to propose the Degeneriinae n. subfam. for the genus Degeneria in recognition of its phylogenetic isolation and distinctive morphology and biology. The current concepts of the subfamilies Anaporrhutinae and Gorgoderinae were supported. Within the Gorgoderinae, the large genus Phyllodistomum is shown to be paraphyletic relative to Pseudophyllodistomum and Xystretrum. Notably, the clade of marine Phyllodistomum does not form a clade with the other marine genus, Xystretrum. Distinct clades within the Gorgoderinae correspond variously to identity of first intermediate host, form of cercaria and their marine or freshwater habitat. We are not yet in a position to propose separate genera for these clades.
Species of Proctoeces Odhner, 1911 (Trematoda: Fellodistomidae) have been reported from a wide range of marine animals globally. Members of the genus tend to lack strongly distinguishing morphological features for diagnosis, making identification difficult and the true number of species in the genus contentious. Combined morphological and molecular analyses were used to characterise three species of Proctoeces from Moreton Bay and the southern Great Barrier Reef. Data for two ribosomal regions and one mitochondrial region were generated for specimens collected from Australia. Three unique 18S-genotypes were identified which corresponded to subtle, but reliable, morphological differences. Two species of Proctoeces were identified from fishes of Moreton Bay, Proctoeces insolitus (Nicoll, 1915) Yamaguti, 1953 and P. major Yamaguti, 1934, and a third, P. choerodoni n. sp. from off Heron Island on the southern Great Barrier Reef. Phylogenetic analyses of partial 18S and partial 28S rDNA indicated that these three species differ from the four species reported outside of Australia for which sequence data are available. Phylogenetically, Proctoeces proved to be a reliable concept, with all species of Proctoeces that have been characterised genetically forming a well-supported clade in all analyses. Dramatically different patterns of host-specificity were identified for each of the three Australian species; P. insolitus apparently infects a single species of fish, P. choerodoni n. sp. infects multiple species of a single genus of fish, and P. major infects multiple species of two teleost orders.
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