Search

Earthworms are an important part of terrestrial ecosystems that are often acknowledged for their diverse ecological functions. Mizoram, one of the northeastern regions (NER) of India, was assessed for earthworm diversity and genetic variability based on integrated taxonomical procedures using morpho-anatomical features and sequencing of the COI gene. For species delimitation, three barcoding approaches, i.e., ABGD, BIN, and barcode gap analysis (BGA), were employed, and the K2P intraspecific, as well as interspecific distances, were evaluated in MEGA X. Also, for phylogenetic studies, maximum parsimony (MP) and Bayesian interference (BI) trees were generated. The genetic variability and haplotype analysis were assessed using DnaSP and Network. The morpho-anatomical features revealed 20 species that belonged to 3 families (Moniligastridae, Megascolecidae, and Rhinodrilidae) across 5 genera: Drawida, Amynthas, Metaphire, Perionyx, and Pontoscolex. Furthermore, we reported 12 new earthworm records from Mizoram that includes Amynthas carinensis carinensis, Metaphire anomala, Perionyx rufulus, P. depressus, Pontoscolex corethrurus, Drawida bullata, D. victoriana, D. vulgaris, D. papillifer papillifer, D. nagana, D. periodosa, and D. assamensis species. The mean K2P intraspecific and minimum interspecific genetic distances were 9.59% and 13.97%. Moreover, the species P. depressus and M. houlleti showed deep intraspecific divergence and are composed of several cryptic species. ABGD proposed a barcode gap of 10–12%, whereas BGA suggested around 13%. All the species were strongly supported in MP and BI trees; however, P. depressus appeared polyphyletic and the paraphyly or polyphyly of genera Amynthas and Metaphire were supported. Furthermore, the network revealed 43 haplotypes, and the genetic diversity was highest in P. depressus and M. houlleti.

Taxonomic classification of earthworms based on anatomical features has created several challenges for systematics and population genetics. This study examines the application of molecular markers, in particular mitochondrial cytochrome oxidase (COI), to facilitate discrimination of closely related earthworm species. Molecular markers have also provided insights into population genetics by aiding assessment of genetic diversity, lineage sorting, and genealogical distributions of populations for several species. Phylogeography—a study that evaluates the geographical distribution of these genealogical lineages and the role of historical processes in shaping their distribution—has also provided insights into ecology and biodiversity. Such studies are also essential to understand the distribution patterns of invasive earthworm species that have been introduced in non-native ecosystems globally. The negative consequences of these invasions on native species include competition for food resources and altered ecosystems. We anticipate that molecular markers such as COI and DNA barcoding offer potential solutions to disentangling taxonomic impediments in earthworms and advancing their systematics and population genetics.

Living organisms are naturally bestowed with unique and imitable qualities for maintaining ecological balance and earthworms are no exceptions. These so-called keystone species of terrestrial ecosystems are equipped with wonderful machinery, allowing them to nurture soil beautifully. Earthworm gut represents a potential microbial reservoir, having a complex interdependence with the host. The study aimed to profile bacterial community structure of three earthworm species belonging to two different life forms; Perionyx excavatus and Eudrilus eugeniae (epigeic), Polypheretima elongata (endogeic) respectively. Diversity analysis using 16S amplicon sequencing revealed that the dominant phyla were Proteobacteria (34.17-77.88) followed by Actinobacteria (13.43-35.54%), Firmicutes (1.69-15.45%) and Bacteroidetes (0.51-8.12%). The alpha diversity indices explicit similar gut microbiota of Perionyx excavatus and Eudrilus eugeniae and while higher alpha diversity was recorded in comparison to Polypheretima elongata gut. The taxonomic to the phenotypic annotation of 16S rRNA metagenomes revealed that dominance of Gram-negative bacterial community in all earthworm species while, Polypheretima elongata comprises higher percentage (78%) of Gram-negative bacterial community to Perionyx excavatus (32.3%) and Eudrilus eugeniae (38.3%). The oxygen requirement phenotypic analysis showed that all earthworm species were abundant with aerobic followed by anaerobic bacterial groups. Furthermore, functional metabolism phenotypic analysis revealed that a high abundance of ammonia oxidizers (29.3-80.2%), the gut microbiomes showed the relative abundance of sulphate reducer (22.6-78.7%), nitrite reducer (19.8-73.2%), dehalogenators (12.6-25.1%), illustrating in the role of these microbial communities in various degradation and bioremediation processes. The present study signifies the intrinsic gut microbiota of earthworm species for intensified biodegradation.

Integrative approach of taxonomy drives us to the discovery of three new species of the genus Eutyphoeus Michaelsen 1900, namely Eutyphoeus phawngpuiensis sp. nov., Eutyphoeus serei sp. nov. and Eutyphoeus tawi sp. nov. from protected forests of Mizoram, India. E. phawngpuiensis sp. nov. belongs to the Eutyphoeus hastatus group, and is characterized by holandric male organs, having spermathecal pores at “a or ab”, bidiverticulate spermathecae, and lack of genital marking glands. While, E. tawi sp. nov. has spermathecal pores at b or lateral to b, without lateral intestinal caeca. E. serei sp. nov. belongs to the Eutyphoeus gigas group, and is distinguished by having metandric male organs, lacking female pore of right side, and having spoon shaped tip of penial setae without ornamentation. Molecular characterization using coi gene marker also supports the findings. The maximum intraspecific distances and distance to the nearest neighbour of E. phawngpuiensis sp. nov., E. serei sp. nov. and E. tawi sp. nov. were recorded 3.5%, 9.37%; 2.35%, 14.83%; and 2.28%, 12.86% respectively. The key to Eutyphoeus species of India was also updated.

Gut microbiomes, a consortium of microorganisms that live in the animal gut, are highly engineered microbial communities. It makes a major contribution to digestive health, metabolism management, and the development of a strong immune system in the host. The present study was taken up to answer the long-running question about the existence of truly indigenous microflora of the epigeic earthworm gut. This is due to the general difficulties of culturing many of the microorganisms found in soil or earthworms' gut. Keeping this fact in a view, the metagenomics approach using 16S rRNA marker gene incorporated with amplicon-based sequencing was used to explore microbiota of commercially overriding, diversely fed epigeic earthworm Eudrilus eugeniae (Kinberg) in three varied habitats viz., artificial soil (AS), organic agricultural farm soil (OAFS) and conventional agriculture farm soil (CAFS). There are predominant bacteria that belong to different phyla such as Proteobacteria (29.72-76.81%), Actinobacteria (11.06-34.42%), Firmicutes (6.02-19.81%), and Bacteroidetes (2.40-9.22%) present in the gut of E. eugeniae. The alpha diversity (Observed species, Chao1, ACE, Shannon, Simpson, and Fisher alpha) indices showed that OAFS had significantly higher alpha diversity than AS and CAFS groups. The core microbiota analysis showed that OAFS and AS groups had a relatively similar bacterial panel in comparison to the CAFS group. Various statistical tools i.e. MetagenomeSeq, LEfSe, and Random Forest analysis were performed and the findings demonstrated prevalence of the most significant bacterial genera; Aeromonas, Gaiella, and Burkholderia in CAFS group. Nonetheless, in AS and OAFS groups, the common existence of Anaerosporobacter and Aquihabitans were found respectively. Metagenomic functional prediction revealed that earthworms' gut microbial communities were actively involved in multiple organic and xenobiotics compound degradation-related pathways. This is the first research to use high-throughput 16S rRNA gene amplicon sequencing to show the gut microbiota of E. eugeniae in diverse agricultural systems. The findings suggest the configuration of the gut microbiota of earthworms and its potential role in the soil ecosystem depends on the microbial communities of the soil.

The work was aimed to investigate earthworms species particularly Eutyphoeus endemic to India with the use of DNA barcodes and usual morpho-anatomical standards of earthworm taxonomy from protected areas of Garo Hills, Meghalaya, the north-east region (NER) of India. The study revealed two new records Eutyphoeus kempi Stephenson, E. nepalensis Michaelsen and confirms availability of three known sp. namely E. callosus Gates, E. gammiei Beddard and E. turaensis Stephenson. The neighbor-joining tree was constructed using the K2P substitution model and the genomic signature of each species using COI-1 gene was generated for the first time and were used to reconfirm the identification of species.

The work was aimed to investigate earthworms species particularly