Fischoederius elongatus might be a cryptic species.
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Classical taxonomic samples are not directly linked to current molecular data.
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The taxonomy of the genus Fischoederius should be revised.
Abstract
Rumen flukes in the genus Fischoederius are neglected foodborne parasites of cattle in Asia. Fischoederius elongatus, first described in 1883 from a sample collected in Indonesia is the type-species of the genus and is found from South to East Asia. In this study Fischoederius spp were collected from cattle in Thailand. The flukes resembled F. elongatus and images of 48 specimens were taken and their DNA was isolated. The mtDNA sequence of the cytochrome c oxidase subunit I (COX1) gene was amplified by PCR and used for restriction analysis with MseI. Nine restriction patterns (A–I) were observed and the COX1 mtDNA sequence for each pattern was determined. Phylogenetic analysis clustered the nine COX1 sequences into five groups with 4.6–9.6 % sequence differences between the groups. This is beyond intragenic variation observed for the COX1 gene in other organisms and suggested that the analyzed specimens represented several species. A comparative transcriptome analysis of specimens with COX1 MseI patterns A, C, E supported this finding. The observed median base differences, both absolute and relative, in the protein coding sequences of 999 orthologs were similar to those between distinct fruit fly species. It is proposed that the genus Fischoederius contains undescribed species that follow the classic description of F. elongatus.
Graphical abstract
SUMMARY: Transcriptome analysis of Fischoederius spp specimens from Thailand suggests a species complex resembling Fischoederius elongates.
Nucleotide sequence data reported in this paper is available in the EMBL, GenBank and DDJB databases under the accession numbers MN176295–MN176303 and BioProject PRJNA723375.
