Interrogation of earthworm (Clitellata: Haplotaxida) taxonomy and the DNA sequence database

Abstract

The DNA sequence database assists us with great potential in species identification because it is practical and affordable to perform. More often, the identification using molecular data helps to identify morphologically variable individuals of same species, including juvenile specimens. In case of earthworms, the classical standards of taxonomy are mainly based on genital structures, while the collection of the sexually agile worm is difficult. Hence, typical barcode marker cytochrome c oxidase subunit 1 was used to explore species richness of the study area. From taxonomic relationship, the valid identification of voucher specimens was taken into consideration for characterization. The species richness of earthworm sp. viz., Metaphire houlleti, Perionyx sp., Drawida minuta, Eudichogaster prashadi, Lennogaster pusillus, Octochaetona beatrix, and Octochaetona prashadi were recorded and analyzed. Less than 1% divergence within species was found, whereas divergence between species was greater than 15% in all cases. The phylogenetic tree(s) was constructed using the best-fitted substitution model of evolution and species delimitation by Automatic Barcode Gap Discovery, operational taxonomic units, and network analysis. The prospective and limitations of molecular taxonomy and the vital role of publicly available nucleotide sequence databases were reviewed to inventor earthworm diversity. The study shows the universality of single locus persists utopian and the use of other typical loci may strengthen earthworm diversity assessment.

Keywords

• ABGD
• COI
• DNA barcoding
• Earthworms
• OTUs