Identification Of Earthworms Research Articles

Identification of earthworms (Clitellata, Oligochaeta) from Kottayam district in Southwestern India: an integrated traditional and barcoding approach

Earthworms from various land uses in the Kottayam district of Kerala, part of the Western Ghats hotspot in India, were studied using an integrative approach that involved morphoanatomical methods and cytochrome c oxidase I (COI) barcoding techniques for the first time here. The study unveiled the presence of nine earthworm species: <i>Drawida ghatensis</i> Michaelsen, 1910; <i>Moniligaster julkai</i> Narayanan and Paliwal, 2022; <i>Glyphidrilus annandalei</i> Michaelsen, 1910; <i>Pontoscolex corethrurus</i> (Müller, 1857); <i>Eukerria kuekenthali</i> (Michaelsen, 1908); <i>Dichogaster bolaui</i> (Michaelsen, 1891); <i>Megascolex cochinensis</i> Stephenson, 1915; <i>M. konkanensis</i> Fedarb, 1898; and <i>Lampito mauritii</i> Kinberg, 1867, belonging to eight genera. The COI sequences of all nine species were deposited in GenBank. Notably, <i>M. julkai</i> and <i>E. kuekenthali</i> are novel additions to the GenBank barcode database. The Bayesian phylogram and maximum-likelihood indicated that the species <i>M. julkai</i> in this study exhibited a closer relationship to <i>D. ghatensis</i> than to other <i>Moniligaster</i> species. This study provides detailed descriptions and illustrations of all nine species, supplemented by their DNA barcodes, to facilitate future species identification.

Molecular phylogeny of Kazimierzus Plisko, 2006 (Clitellata, Kazimierzidae) from the Western and Northern Cape Province inferred from mitochondrial DNA sequences

Species identification of earthworms using morphology can be challenging and inconclusive as homoplasy in many characters is high. The use of molecular DNA technology, such as the use of conserved regions in mtDNA and nuclear DNA has unravelled the phylogenetic background of several earthworm species. The current study utilised the cytochrome c oxidase subunit I (COI) mitochondrial marker to reconstruct the phylogeny of Kazimierzus Plisko, 2006 species from the Western and Northern Cape provinces of South Africa. Phylogenetic reconstructions were implemented using Bayesian Inference, as well as Maximum Likelihood. Both tree building methods adhered to the monophyly of the majority of the taxa. Results showed that species fell into two clades and validated eleven currently known Kazimierzus species (K. circulatus (Plisko, 1998), K. franciscus (Pickford, 1975), K. guntheri (Pickford, 1975), K. hamerae (Plisko, 1998), K. kleinoodi Nxele & Plisko, 2017, K. nietvoorbiji Nxele & Plisko, 2017, K. nieuwoudtvillensis Nxele & Plisko, 2017, K. occidualis (Plisko, 1998), K. pearsonianus (Pickford, 1975), K. phumlani Nxele & Plisko, 2017, K. sophieae (Plisko, 2002)). Cryptic diversity is evident in K. occidualis with genetic divergence greater than 12% amongst populations. Kazimierzus franciscus and K. ljungstroemi (Pickford, 1975) have a low genetic variability suggesting close relatedness or probably conspecificity. A group of specimens from Clanwilliam are morphologically identical to K. sophieae, but are genetically distinct and may belong to undescribed species. This study demonstrates the importance of integrative taxonomy in earthworms in order to present reliable taxonomic and biogeographic data.

DNA-barcoding of invasive European earthworms (Clitellata: Lumbricidae) in south-western Australia

Using DNA-barcoding, we studied the diversity of invasive European earthworms in the south-western corner of Australia. We found six Molecular Operational Taxonomic Units belonging to five morphospecies: Aporrectodea caliginosa, A. trapezoides, Dendrobaena cf. attemsi, Eiseniella tetraedra and Octolasion cyaneum. These were variously collected from indigenous forests and/or alienated land. Two cryptic lineages were found within A. trapezoides, and high intraspecific genetic variation was also found within E. tetraedra-variation that had previously been documented in Europe. Our study demonstrates the usefulness of DNA-barcoding for the identification of earthworms, including cryptic species. Correct identification and high taxonomic resolution is crucial for the monitoring of cryptic diversity, detecting new introductions and monitoring spread of established exotic earthworms.

Comparing four mitochondrial genes in earthworms – Implications for identification, phylogenetics, and discovery of cryptic species

Earthworms play a key role in soil ecology as they can reach high densities, are well known as soil engineers, and occupy a central position in soil food-webs. The identification of earthworms, however, is notoriously difficult and morphologically only possible for well-preserved adult specimens. Molecular markers could facilitate earthworm identification and would be a huge advantage in studies where it is important to species-specifically identify juveniles or where badly preserved specimens and remains of earthworms need to be identified. The aim of this study was to compare four mitochondrial genes (12S rRNA, 16S rRNA, COI, and COII) with respect to their value for identifying earthworms, calculating earthworm phylogenies, and discovering cryptic species. Our results indicate that all four genes are suitable for species identification. However, the genetic distances were approximately twice as high for the protein coding genes than for RNA coding ones. High genetic distances and deep genetic lineages, e.g. for Octolasion lacteum, Lumbricus rubellus and Aporrectodea rosea, indicate the possible presence of cryptic species and hamper molecular identification. The Bayesian analysis based on concatenated sequence data resulted in a phylogenetic tree with high posterior probabilities. The con-specific relationship of Aporrectodea spp. and Allolobophora spp. was not confirmed, underlining the ongoing discussion about the revision of these two genera. In conclusion, our findings suggest using 12S and 16S rRNA sequences as molecular markers for species identification whereas the COI gene is better suited to address genetic lineages and to explore possible cryptic species. Taxonomy and the identification of species are essential for most ecological studies. This study provides the needed molecular sequence information to develop molecular tools that can overcome many hurdles in studies on earthworms, their relationship and their ecology.

A Hypercard program for the identification of biological specimens

A Hypercard-based software tool developed to provide help in the identification of biological specimens is presented. The package implements a matching algorithm that compares alphanumeric strings and runs on Macintosh computers, though its simple architecture can be transferred to other computers and/or other programming environments. The overall performance of the program and its easy customization to specific problems are demonstrated by discussing at length one application in the field of earthworm identification.

Identification of earthworms in mammalian scats

Identification of earthworms in mammalian scats