Earthworm Diversity Research Articles

Distribution of earthworm communities in agroecosystems with forested riparian buffer strips: A multiscale study

Knowledge is lacking on the factors controlling the structure and spatial distribution of earthworm communities within agroecosystems. We first hypothesized that forested riparian buffer strips (FRBS) within agricultural landscapes would be a refuge for earthworms, as we predicted higher soil moisture and organic matter inputs in FRBS than in adjacent agricultural fields (treatments = FRBS vs. Field). We further hypothesized that earthworms would be most abundant where the chemical quality of above- and belowground plant litter is high, or where soil disturbance is low. We conducted a field survey to quantify earthworm species abundances in FRBS and adjacent agricultural fields in two bioregions, namely Eastern Canada and Central Europe. At each of 77 sites, we collected and identified earthworms from three plots within FRBS and within adjacent agricultural fields. In each plot, we identified the tree species, understory vegetation, soil drainage class, agricultural crop as well as five soil physicochemical properties. In each bioregion and treatment, we found proportionately more endogeic than anecic or epigeic earthworm species. In Eastern Canada, there were proportionately fewer anecic and more epigeic individuals in FRBS than in fields; in Central Europe there were fewer endogeic and more anecic earthworms in FRBS than in fields. We found significant bioregion × treatment interactions on earthworm abundance and soil moisture. More specifically, in Eastern Canada we found higher earthworm abundance and soil moisture in FRBS, whereas in Central Europe we found higher earthworm abundance in fields and no treatment effect on soil moisture. In both bioregions, we found higher organic matter in FRBS than in fields. In Eastern Canada, earthworm abundance in deciduous and mixedwood stands were higher than in coniferous stands; in Central Europe, earthworm abundance was highest in deciduous stands only. Within FRBS in Eastern Canada, the abundance of the prominent endogeic species, Apporectodea rosea, was correlated with herbaceous plants, notably ferns and graminoids. Conditional regression tree analysis revealed positive relationships between earthworms and soil clay content, pH, moisture and organic matter. Our results suggest that local and landscape patterns in earthworm diversity can be predicted by soil and vegetation attributes, however the relative importance of these factors changes across continental scales due to differences in precipitation patterns and soil moisture availability. Comparing the distributions of earthworms across different scales provides insights into the potential of different species to spread into new habitats with climate change.

A Comparative Study on Earthworm Biodiversity & Species Habitat-Relationship of Hilly and Plain Areas of Sirohi District of Rajasthan, India

Extensive surveys of earthworm diversity were done in different habitats of plain and hilly areas of Sirohi district of Rajasthan, India. Earthworms differed in their ecomorphological characteristics and relative abundances in different habitats. A total twelve species of earthworms Pontoscolex corethrurus, Amynthas morrisi, Lampito mauritii, Metaphire posthuma, Megascolex konkanensis, Metaphire houlleti, Perionyx sansibaricus, Polypheretima elongata, Ocnerodrilus occidentalis, Dichogaster bolaui, Octochaetona beatrix and Gordiodrilus sp. were recorded from hilly and plain areas. Among these, ten species were found from plain area and nine from hilly area. Five earthworm species (M. konkanensis, M. houlleti, P. elongata, O. beatrix, Gordiodrilus sp.) were recorded for the first-time from Rajasthan. The plain area species P. elongata, O. beatrix and Gordiodrilus sp. were replaced by M. konkanensis and M. houlleti in hilly region. This showed the habitat preferences of earthworm species. Few species were present in a particular habitat of plain area, but they were absent in the same type of habitat in hilly area. The relative density, frequency and species diversity index of earthworm species differed in different habitats and areas. Earthworm diversity exhibited differing species-habitat relationship in hilly and plain areas. These findings may be utilized for eco-restoration of degraded land in similar habitats.

Functional diversity of earthworm communities in forests in the south of the Russian Far East

Key species of soil macrofauna – large soil saprophages, i.e. earthworms – have been studied in unique in terms of floristic and faunal diversity, as well as the most preserved forests of the southern Russian Far East. The results of studying taxonomic and functional diversity of earthworms, their biomass and abundance and patterns of temporal spatial distribution in summer seasons, are presented. The complete set of the main functional groups of earthworms (epigeic, epi-endogeic, endogeic and anecic) was found only in the best-preserved valley forests, with no traces of logging and fires over the last century. The earthworm community is not complete (one or two functional groups are missing) in one of valley forest that was partially cut down and affected by fires in recent decades and in hillside forests. Horizontal spatial distribution was analysed for the epi-endogeic and endogeic groups of earthworms, dominating in terms of biomass and occurrence. It was found that, in the summer season, the group of epi-endogeic species showed the "covering" type of distribution (regular distribution without aggregation), whereas the group of endogeic species showed the "spotty" type of distribution (aggregated distribution).

At each site its diversity: DNA barcoding reveals remarkable earthworm diversity in neotropical rainforests of French Guiana

Despite their recognized essential role in soil, earthworms in tropical environments are still understudied. The aim of this study was to re-evaluate the diversity at the regional scale, as well as to investigate the environmental and spatial drivers of earthworm communities. We sampled earthworm communities across a range of habitats at six localities in French Guiana using three different sampling methods. We generated 1675 DNA barcodes and combined them with data from a previous study. Together, all sequences clustered into 119 MOTUs which were used as proxy to assess species richness. Only two MOTUs were common between the six localities and 20.2% were singletons, showing very high regional species richness and a high number of rare species. A canonical redundancy analysis was used to identify key drivers of the earthworm community composition. The RDA results and beta-diversity calculations both show strong species turnover and a strong spatial effect, resulting from dispersal limitations that are responsible for the current community composition. Sampling in different microhabitats allowed the discovery of 23 MOTUs that are exclusively found in decaying trunks and epiphytes, highlighting hidden diversity of earthworms outside of soil.

Plant, soil and faunal responses to a contrived pH gradient

PurposeTo build a more holistic understanding of soil pH change we assessed the synchronised effects of a contrived soil pH change on soil chemistry, vegetation growth and nutrition, and soil faunal abundance and diversity.MethodsWe established a fifteen year old field experiment with a contrived pH gradient (pH 4.3 to 6.3) and measured the effect on soil chemistry, plant biomass and elemental composition and the impact of these changes on soil fauna (earthworms, nematodes, rotifers and tardigrades) and biological indices (based on ecological group structures of earthworms and nematodes). A single 20 × 20 × 20 cm soil block was excavated from each sample site to directly attribute biotic parameters in the block to the abiotic (soil) conditions.ResultsAcidification affected the extractable concentrations of Al, Ca, Mn and P and the C:N ratio of the soil and caused a reduction in plant Ca (rs for pH vs Ca = 0.804 p < 0.01), an increase in plant Mn (rs = −0.450 p = 0.019), along with significant decrease in root:shoot ratio (rs = 0.638, p < 0.01). There was a significant positive correlation between pH and earthworm index (rs = 0.606, p < 0.01), and a negative correlation between pH and nematode index (rs = −0.515, p < 0.01).ConclusionSoil pH influenced the mobility of Ca, Al, Mn and P, which in turn has impacted on plant tissue chemistry and plant biomass ratios. Linked changes in soil chemistry and vegetation had a corresponding effect on the abundance and diversity of nematodes and earthworms in the soil blocks.

Earthworm burrow number and vertical distribution are affected by the crop sequence of a grass-clover rotation system

Grass-clover is an important element in crop rotations due to its beneficial agronomic properties including nitrogen build-up, stimulation of earthworms and their burrowing and maintenance of soil macropores. We studied the relationship between important elements of grass-clover management in a crop rotation and earthworm diversity and macropore depth distribution, diameter and density from the ploughing layer to a depth of 1 m. Treatments included winter rye, 1st year cutting + slurry, 3rd year cattle grazing + slurry, 3rd year cutting + slurry and 3rd year cutting without slurry. The four-species earthworm assemblages and their burrow spatial structure responded distinctly to the temporal sequence of farming system management elements. The relative density of the endo-anecic and epi-anecic earthworm species, Aporrectodea longa and Lumbricus herculeus, was higher in the grass-clover phase of the rotation than under the annual crop, and increased with the age of grass-clover. The same was true for Aporrectodea rosea, but density and biomass of Aporrectodea caliginosa showed the opposite trend. Cattle grazing favours the occurrence of burrows (>5 mm ⌀) made by the anecics, A. longa and L. herculeus, while otherwise decreasing the number of fine-medium macropores (<5 mm ⌀) below the topsoil. Our study reveals the intimate interdependence between the cropping sequence and the earthworm burrow structure with low number of detectable burrows under annual crops, then increasing in number during the grass-clover over 3 years. The highest number of burrows was found at 0.5 m depth in 3rd year cutting ± slurry, presumably because there is no soil disturbance by tillage in this horizon. The density of the endogeic A. caliginosa was negatively correlated with the presence of burrows and sensitive to grazing cattle compacting the topsoil. Positive correlations between burrows and density of L. herculeus indicate that this species was responsible for the burrows at one m depth while the density of A. longa was positively correlated with the burrows in the Ap horizon. We discuss the species composition in the grass-clover rotation system and its influence on soil ecosystem functioning.

The Ecology Underground coalition: building a collaborative future of belowground ecology and ecologists.

Rising to meet global, interconnected challenges, such as food security and ecosystem resilience to global change, requires insights from across the Earth. This is especially true for belowground terrestrial ecological processes. Soil ecologists have answered this call: like mushrooms, large global datasets and databases on soil physics, chemistry and ecology are sprouting up everywhere (e.g. Fine‐Root Ecology Database (Iversen et al., 2018), FunFun (Zanne et al., 2020), GlobalFungi (Větrovský et al., 2020), COntinuous SOil REspiration (Jian et al., 2020), Global distribution of earthworm diversity (Philips et al., 2019) etc.). It is now time to leverage synergies among these datasets to link the continuum of belowground processes to ecosystem functions (e.g. decomposition, nutrient cycling and soil respiration). Built on interdisciplinary and international collaborations, data synthesis that leads to a holistic understanding is one of the best ways of predicting the future of terrestrial ecosystems and for preserving ecosystem services under global change. In 2020, global interconnectedness was on display as we saw a pandemic sweep across the world in weeks. The pandemic allowed the Ecological Society of America (ESA) to enter a new digital era by holding a fully virtual conference. While technology cannot yet replicate all aspects of an in‐person conference, the virtual platform increased accessibility and reduced the climate impact of the annual conference. It also provided an opportunity for early‐career plant and microbial ecologists from five ESA Organized Oral Sessions and one Inspire Session to organize Ecology Underground, a two‐day program of live virtual talks and open discussions on integrative belowground ecology on 4 and 5 August 2020. Ecology Underground was sponsored by New Phytologist, the ESA Soil Ecology Section, the US Department of Energy, Biological and Environmental Research program and the Oak Ridge Institute for Science and Education (ORISE), and gathered 453 participants over two days. The online platform allowed for participation across the globe (37 countries were represented; Fig. 1) and was an opportunity to think creatively about how scientific discussions and global collaborations can take place, now and in the future. Open in a separate window Fig. 1 The online platform of Ecology Underground allowed for participation across the globe.

Effects of temporary grassland introduction into annual crop rotations and nitrogen fertilisation on earthworm communities and forage production

Earthworms contribute to a wide range of ecosystem services in agriculture. Most studies focusing on impacts of annual crop management on earthworm communities are related to soil tillage, fertilisation or pesticides, while the effect of introducing temporary grassland into an annual crop rotation remains largely unknown. In this context, the aims of the present study were to evaluate effects of (i) introducing grassland into a crop rotation, (ii) grassland duration and (iii) grassland fertilisation on earthworm communities and grassland forage production in a long-term experimental station in western France. Three years of highly fertilised (230 kg ha−1 yr−1 of mineral nitrogen) grassland preceded by three years of annual crop rotation was compared to an annual crop rotation without grassland and to six years of grassland either lightly (30 kg ha−1 yr−1 of mineral nitrogen) or highly (230 kg ha−1 yr−1 of mineral nitrogen) fertilised. Grassland introduction into a crop rotation significantly increased earthworm abundance, biomass, and diversity, especially for anecic species, and improved the functional structure of the earthworm community. Grassland duration and fertilisation increased earthworm abundance and biomass, especially for anecics, without affecting endogeic species and earthworm diversity. Grassland duration did not increase forage production, but the increase in fertilisation did. Three years of highly fertilised grassland significantly increased earthworm abundance and biomass, improved the functional structure of the earthworm community and produced as much forage per year as six years of highly fertilised grassland. Overall, the introduction of grassland into annual crop rotations appears an effective way to rapidly increase earthworm community parameters and, given the important role of earthworms in soils, enhance soil functioning.

Response to Comment on "Global distribution of earthworm diversity".

James et al claim that there are areas of concern in our work. We believe that they have misunderstood the methods behind our paper and that differences in scale have been overlooked. Once those misunderstandings have been resolved, their remaining criticisms are either not sustained or agree with our statements. To advance the field, we recommend additional sampling using comparable methodologies in underrepresented areas.

Soil properties, grassland management, and landscape diversity drive the assembly of earthworm communities in temperate grasslands

Earthworms are widespread soil organisms that contribute to a wide range of ecosystem services. As such, it is important to improve our knowledge, still scanty, of the factors that drive the assembly of earthworm communities. The aim of the present study was to conjointly evaluate the effects on the assembly of earthworm communities of i) soil properties (texture, organic matter content, and pH), ii) grassland management (grassland age, livestock unit, and type of fertilization), iii) landscape diversity (richness, diversity of surrounding habitats, and grassland plant diversity), and iv) presence of hedgerows. The study was conducted in temperate grasslands of Brittany, France. Earthworms were sampled in 24 grasslands and, in three of these grasslands, they were sampled near a hedgerow or near a ditch (control without a hedgerow). Soil properties explained the larger portion of the variation in the earthworm community parameters compared to grassland management or landscape diversity. The increase in soil organic matter content and pH were the most favorable factors for earthworm abundance and biomass, in particular for endogeic species. Regarding grassland management, the increase in the livestock unit was the most damaging factor for earthworm communities, in particular for the anecic earthworm biomass and endogeic species richness. Surprisingly, landscape diversity negatively affected the total earthworm abundance and epigeic earthworm biomass, but it was related to an increase in the epi-anecic species. At a finer scale, we also demonstrated that the presence of hedgerows surrounding grasslands enhanced earthworm species richness, especially within the epigeic and anecic ecological categories. This study highlights that the earthworm ecological categories respond specifically to environmental filters; further studies need to be conducted to elucidate the factors that drive the assembly of earthworm communities at this ecological category level. We recommend that policymakers should act on landscape management to favor earthworm diversity in order to improve the ecosystem services they drive.

Earthworm Diversity, Forest Conversion and Agroforestry in Quang Nam Province, Vietnam

The conversion of natural forests to different land uses still occurs in various parts of Southeast Asia with poor records of impact on ecosystem services and biodiversity. We quantified such impacts on earthworm diversity in two communes of Quang Nam province, Vietnam. Both communes are situated within buffer zones of a nature reserve where remaining natural forests are under threat of continued conversion. We identified 25 different earthworm species, out of which 21 were found in natural forests, 15 in agroforestry, 14 in planted forests, and seven each in annual croplands and home gardens. Out of the six species that were omnipresent inhabitants of all observed habitats, Pontoscolex corethrurus largely dominated habitats with intensive anthropogenic activities but was rare in natural forests. Natural and regenerated forests had a much denser earthworm population in the top 10 cm of soil rather than in deeper soil layers. We conclude that the conversion of natural forests into different land uses has reduced earthworm diversity which can substantially affect soil health and ecosystem functions in the two communes. Protection of the remaining natural forests is urgent, while the promotion of a tree-based farming system such as agroforestry can reconcile earthworm conservation and local livelihoods.

Bioturbation by endogeic earthworms facilitates entomopathogenic nematode movement toward herbivore-damaged maize roots

Entomopathogenic nematodes (EPNs) have been extensively studied as potential biological control agents against root-feeding crop pests. Maize roots under rootworm attack have been shown to release volatile organic compounds, such as (E)-β-caryophyllene (Eβc) that guide EPNs toward the damaging larvae. As yet, it is unknown how belowground ecosystems engineers, such as earthworms, affect the biological control capacity of EPNs by altering the root Eβc-mediated tritrophic interactions. We here asked whether and how, the presence of endogeic earthworms affects the ability of EPNs to find root-feeding larvae of the beetle Diabrotica balteata. First, we performed a field mesocosm experiment with two diverse cropping systems, and revealed that the presence of earthworms increased the EPN infection potential of larvae near maize roots. Subsequently, using climate-controlled, olfactometer-based bioassays, we confirmed that EPNs response to Eβc alone (released from dispensers) was two-fold higher in earthworm-worked soil than in earthworm-free soil. Together our results indicate that endogeic earthworms, through burrowing and casting activities, not only change soil properties in a way that improves soil fertility but may also enhance the biocontrol potential of EPNs against root feeding pests. For an ecologically-sound pest reduction in crop fields, we advocate agricultural practices that favour earthworm community structure and diversity.

Earthworm diversity and density as affected by soil and climatic factors in Raymond Mhlaba municipality, Eastern Cape province, South Africa

Earthworms play a key role in improving soil health, and their diversity and density are mainly affected by soil and climatic factors. This study determined the effects of rainfall, temperature and selected soil properties on the diversity and density of earthworms in Raymond Mhlaba municipality of the Eastern Cape, South Africa. Nine sites in the municipality covering the humid, sub-humid, semi-arid and arid regions were sampled. At each site, earthworms were collected for identification and quantification. The relationships between earthworm density and diversity against the selected factors were analysed using analysis of variance and Pearson correlations. Seven exotic earthworm species were identified, namely: Dendrobaena octaedra; (epigeic groups); Aporrectodea caliginosa; Pontoscolex corethrurus (Rhinodrillidae); Allolobophora chlorotica (endogeic groups); Amynthas aspergillum, Lumbricus terrestris and Fimoscolex sporadochaetus (anecic groups). No indigenous earthworms were found. There were significant differences in earthworm density and biomass across all the climatic zones (p < 0.05). Earthworm density and biomass showed positive correlations with soil moisture and rainfall but strong negative correlations with temperature (p < 0.05). Earthworm densities across all sites were lower than the global average. The study concluded that sub-humid environments exhibited the highest earthworm diversity and density while rainfall, temperature and soil moisture influenced earthworm distribution, diversity and density.

Assessment of earthworm diversity and pesticide toxicity in Eudrilus Eugeniae

Pesticides have become an inseparable part of modern agricultural production and technology. Malathion pesticide more than 139,000 MT production capacity annually, with more than 219 technical grade and manufacturing units, and over 4000 formulation units in India. The earthworm survey was carried out in all the five sites at regular monthly intervals. In this present work, a total of six earthworms from five different species were collected from different vegetation such as garden, pond, paddy, edible tubers, and sugarcane field. The organophosphate pesticide malathion is selected as a target compound for toxicity study. The earthworm species Eudrilus eugeniae was used as a model organism. Contact toxicity was studied by filter paper method and to observe the mortality rate of different concentrations of pesticide for 24 and 48 h. The soil toxicity study was done by using artificial soil for 14 days. Surviving worms also had reduced body weight, and in some cases, morphological changes. Enzymatic activities of SOD, CAT, and protease were evaluated in the vermicast of pesticide-treated earthworm. This study refers to the earthworm population between pesticide-contaminated and unpolluted soil. This work will provide information to estimate the toxic level of Malathion against the earthworm.

Large contribution of pulsed subsidies to a predatory fish inhabiting large stream channels

Resource subsidies exert critical influences on recipient habitats with relatively higher perimeter-to-area ratios, such as headwaters in watersheds. However, little is known about how those subsidies contribute to the energy sources in recipient habitats where the perimeter-to-area ratio is low, such as large stream channels. Here, we show that the diet of small Japanese eels (Anguilla japonica) &lt;500 mm in total length inhabiting natural shoreline areas in large stream channels consists largely of terrestrial earthworms (Metaphire spp.). Stable isotopic analyses showed that the earthworms were the prey animal that contributed most to the eels’ diet (45%–47%). Earthworms constituted the largest portion of the eels’ stomach contents (7%–93%). Eels ingested earthworms within 2 days after rainfall during spring, summer, and autumn, and their consumption increased as the precipitation increased. These findings indicate that the pulsed earthworm subsidy that is driven by rainfall could temporarily bias the eels’ diet toward this allochthonous resource, which may explain the large contribution of the subsidy for consumers inhabiting large stream channels. Furthermore, diverse earthworm species could drive multiple pulsed subsidies across seasons and provide the predators with a prolonged subsidy, enhancing the long-term contribution of the subsidy to the predators’ diet.

Impact of water content and dietary organic carbon richness on gut bacteria in the earthworm Lumbricus terrestris.

Many higher and lower animal gut ecosystems have complex resident microbial communities. In contrast, ingested soil is the primary source of the gut microbial diversity of earthworms, invertebrates of fundamental importance to the terrestrial biosphere. Earthworms also harbor a few endemic bacteria including Tenericutes-affiliated Candidatus Lumbricincola of unknown function. Gut microbes are subject to nutrient fluctuations due to dilution effects during gut passage, the nutrient richness of the anoxic gut, and dietary organic carbon, factors that could alter their activity/detection. This study's objective was to assess the potential impact of these factors on the occurrence and activity of ingested and endemic bacteria in gut content of Lumbricus terrestris. Fermentation product profiles of anoxic undiluted and diluted gut content treatments were similar, suggesting that experimental increase in water content and nutrient dilution had marginal impact on fermentation. However, 16S ribosomal Ribonucleic Acid (16S rRNA) sequence abundances indicated that stimulated bacterial taxa were not identical in undiluted and diluted treatments, with dominate potentially functionally redundant phylotypes being affiliated to the Firmicutes, Fusobacteria and Proteobacteria. Although the earthworm-associated Tenericutes were not stimulated in these treatments, the occurrence of three Tenericutes-affiliated phylotypes varied with the organic carbon richness of the earthworm diet, with two phylotypes being associated with high organic carbon richness. 16S rRNA sequence abundances indicated that other dominant gut taxa also varied with dietary organic carbon richness. These findings illustrate that functionally redundant ingested bacteria and earthworm-associated Tenericutes might be influenced by nutrient fluctuations in the gut and organic carbon richness of the earthworm diet.

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

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.

Diversity and Abundance of Earthworms in Different Landuse Patterns: Relation with Soil Properties

Diversity and Abundance of Earthworms in Different Landuse Patterns: Relation with Soil Properties

Earthworm Diversity and Biomass in Different Fallow System in The Kelimutu National Park Areas

Earthworms have a role as bioindicators so that their existence is very sensitive to changes in the environment. The decreasing of land quality caused by continuous use (horticultural agriculture) will also decrease the diversity of earthworms. To anticipate degradation of land quality, the land needs to be rested (bero) so that it will facilitate natural recovery. Indicators of land restoration include the diversity and importance index of earthworms. Therefore, the research aim was to determine the diversity of earthworm in the fallow system lands at Kelimutu National Park areas. The monolith random sampling method at three soil depths was applied to several fields with different fallow periods (5, 10, 15 and 20 years) to measure importance value index, diversity index, evenness, density, and earthworm biomass. The results showed that there were 4 types of earthworms found in the land given, namely Pontoscolex, Megascolex, Lumbricus and Perithima. Pontoscolex dominates which is indicated by the highest importance value index. While the diversity of earthworms was higher in fallow land with a duration period of 5 and 20 years. The duration of the fallow period is also shown to affect populations of earthworms but has no effect on its biomass. For soil depths not seen no effect at each depth. The results of this study further strengthen the evidence that the application of the bero period can improve land quality by increasing the earthworm population so that land productivity can be maintained.

French Mediterranean islands as a refuge of relic earthworm species: Cataladrilus porquerollensis sp. nov. and Scherotheca portcrosana sp. nov. (Crassiclitellata, Lumbricidae)

The area comprising the Pyrenees, Northeast Spain, Southern France and Corsica-Sardinia supports a large part of the diversity of Lumbricidae earthworms, including most species of the endemic genera Prosellodrilus, Cataladrilus and Scherotheca. In this region, the probability of encountering new species for science is significant, especially in scarcely sampled localities. In this study, we describe two unidentified species recently collected in the Hyères Archipelago (France), which we assigned to the genera Cataladrilus and Scherotheca based on morphological characters and molecular phylogenetic analyses. Other species of Scherotheca from Montpellier (including the type species of the genus, Sc. gigas gigas) were included in the analysis to clarify their conflicting systematics. A reduced molecular marker set (COI, 16S, 28S and ND1) proved as successful as larger marker sets for identifying phylogenetic relationships within the Lumbricidae. Remarkable disjunctions between both Cataladrilus porquerollensis Marchán &amp; Decäens sp. nov., Scherotheca portcrosana Marchán &amp; Decäens sp. nov. and their most closely related relatives, suggesting a strong influence of paleogeographic events on the earthworm fauna of the area and a possible role of near-shore islands as refugia for relict taxa. Genetic distances and branch lengths supported the elevation of some subspecies of Scherotheca to specific status as well as the retention of other subspecies, highlighting the importance of testing for such delimitation with molecular methods.