Earthworm Taxa Research Articles

Remarks on the new earthworm taxa described by Aladesida and Owa in 2015 from Nigeria (Clitellata: Megadrili)

Remarks on the new earthworm taxa described by Aladesida and Owa in 2015 from Nigeria (Clitellata: Megadrili)

New and additional records of earthworms (Annelida: Clitellata) from Central Serbia: First finding of Bimastos parvus (Eisen, 1874) in Serbia

This paper includes the summarized knowledge (of more than 40 years) on earthworms in Central Serbia, in the middle part of the Balkan Peninsula. The aim of this paper is to present new data on the earthworms for the study area. Also by analysing the newly reported species together with literature records, we establish the definitive list of known earthworm taxa. The list underlines earthworm diversity and provides a general overview of their distributions, zoogeographical positions, levels of dominance and ecological categories. During the current investigations in the different parts of Central Serbia, 36 earthworm species and subspecies belonging to 10 genera were recorded. Among them, 4 taxa represented the first findings in Central Serbia: Bimastos parvus (Eisen, 1874) Bimastos eiseni (Levinsen, 1884) Aporrectodea cemernicensis Mrsic, 1991 and Lumbricus castaneus (Savigny, 1826). Consequently, the number of the earthworm species recorded for Central Serbia is raised to 46. Surprisingly, the peregrine B. parvus proved to be new species in the fauna of Serbia, including the study area, so now the total number of species for the whole Serbia has risen to 75. With respect to the zoogeographic situation, the majority of them belong to peregrine (36.96%), endemic (19.57%), and trans-Aegean species (13.04%). Summing up the endemics and Balcanic-Alpine species, 30.44% of the total lumbricid fauna in Central Serbia shows an autochthonous character.

No evidence of co-facilitation between a non-native Asian earthworm (Amynthas tokioensis) and invasive common buckthorn (Rhamnus cathartica) in experimental mesocosms

Non-native invasive earthworms are known drivers of forest change in north temperate forests. Much understanding of earthworm invasion is based on species of European origin, but concern about Asian pheretimoid earthworms (e.g. Asian jumping worms, Amynthas spp.) is increasing. Some effects of Amynthas spp. on soil properties and biota have been studied, but little is known about interaction of Amynthas spp. with plants. Potential interaction between Amynthas spp. and invasive buckthorn (Rhamnus cathartica) is of particular interest given hypothesized co-facilitation between R. cathartica and European earthworms—cited by some as components of an “invasional meltdown”. We used reciprocal mesocosm experiments in Wisconsin, USA, to test for co-facilitation between Amynthas tokioensis and R. cathartica. We asked: (1) Are jumping worms more successful in environments invaded by buckthorn? (2) Does jumping worm activity increase buckthorn germination and establishment? Counter to expectations, co-facilitation was not supported, and we found evidence to the contrary. There was no increase in litter loss (indicative of consumption by jumping worms) or jumping worm fecundity in buckthorn-invaded environments, and buckthorn germination was unaffected by increased jumping worm densities. Counter to our hypothesis, jumping worm fecundity was greater in buckthorn-free soils than in buckthorn-invaded soils. Our results show no experimental evidence of co-facilitation by either of these invasive species, and highlight potential differences in ecological impact of non-native invasive earthworm taxa that vary in life-history and functional dynamics.

Two new Cambodian semi-aquatic earthworms in the genus Glyphidrilus Horst, 1889 (Oligochaeta, Almidae), based on morphological and molecular data.

Combining morphological and molecular data is a powerful approach to support the discovery of new species. Here, two new species of the semi-aquatic earthworm genus Glyphidrilus, G. jamiesoni sp. n. and G. kralanhensis sp. n., are described from the Mekong Basin in Cambodia. They are morphologically distinguished by the respective locations of wings and spermathecae; furthermore, G. kralanhensis sp. n. has three pairs of ovaries, probably an autapomorphic trait. In addition, two mitochondrial gene fragments (COI and 16s rRNA) were sequenced of types of the new species and of five further Glyphidrilus species described recently from the Mekong basin in Thailand and Laos. They revealed a high level of genetic divergence of the new species compared to the other earthworm taxa. The evolutionary relationships among the Mekong Glyphidrilus members is discussed with reference to the recent paleogeography of the Mekong River drainage.

Evidence for ongoing introduction of non-native earthworms in the Washington, DC metropolitan area

Earthworm introductions and invasions are ongoing, with significant consequences for ecological characteristics and function where populations of invasive species reach high densities. In North America the influx of people, goods and materials to coastal cities has long been recognized to be related to introduction and establishment of many different invasive organisms. We conducted surveys for soil invertebrates in the Washington, DC area along the Potomac River corridor to examine the influence of historic soil profile disrupting disturbances on the composition of soil invertebrate communities. Here we report three earthworm taxa that either (1) had never been previously reported in North America (Lumbricidae: Helodrilus oculatus), (2) had never been reported from “wild” caught samples in forested soils (Lumbricidae: Eisenia fetida), or (3) represented a notable range expansion for an introduced species (Lumbricidae: Murchieona muldali). All three species reported here have attributes that give reason for concern over their expansion into North American soils, not least of which is their potential for competitive interactions with the remaining native earthworm species.

Allozyme data reveal genetic diversity and isolation by distance in sympatric Glyphidrilus Horst, 1889 (Oligochaeta: Almidae) of the Lower Mekong River Basin

The genus Glyphidrilus, comprised of semi-aquatic freshwater earthworms that live in an ecotone between terrestrial and freshwater ecosystems, are widely distributed along riverbanks and rice paddy systems. Two Glyphidrilus species (Glyphidrilus vangviengensis and Glyphidrilus mekongensis) are endemic in the Lower Mekong River Basin and are sympatric from Northern Thailand to Southern Laos. However, species delimitation among the Mekong Glyphidrilus remains unclear because the key morphological traits in semi-aquatic earthworms are highly polymorphic. This study assessed the distinction between G. vangviengensis and G. mekongensis using allozyme electrophoresis. A total of 752 individuals collected from 33 localities were screened for 10 putative loci from seven enzymatic systems, revealing that G. vangviengensis and G. mekongensis are two distinct species, according to their different allelic patterns and high genetic distance. A low genetic differentiation within each species was indicated by the pairwise Nei's D and FST analyses, and the absence of population structure was detected by AMOVA and Bayesian structure analyses. However, a significant isolation by distance, but not vicariance, was observed, which is probably due to the river current causing translocation downstream and so gene flow between adjacent localities. The genetic diversity of the Mekong Glyphidrilus was relatively high and comparable to other earthworm taxa, and several localities showed deviation from Hardy–Weinberg equilibrium. An additional cryptic species from Ban Hat Khamphi, Loei, Thailand, was inferred.

Does a global DNA barcoding gap exist in Annelida?

Accurate identification of unknown specimens by means of DNA barcoding is contingent on the presence of a DNA barcoding gap, among other factors, as its absence may result in dubious specimen identifications – false negatives or positives. Whereas the utility of DNA barcoding would be greatly reduced in the absence of a distinct and sufficiently sized barcoding gap, the limits of intraspecific and interspecific distances are seldom thoroughly inspected across comprehensive sampling. The present study aims to illuminate this aspect of barcoding in a comprehensive manner for the animal phylum Annelida. All cytochrome c oxidase subunit I sequences (cox1 gene; the chosen region for zoological DNA barcoding) present in GenBank for Annelida, as well as for “Polychaeta”, “Oligochaeta”, and Hirudinea separately, were downloaded and curated for length, coverage and potential contaminations. The final datasets consisted of 9782 (Annelida), 5545 (“Polychaeta”), 3639 (“Oligochaeta”), and 598 (Hirudinea) cox1 sequences and these were either (i) used as is in an automated global barcoding gap detection analysis or (ii) further analyzed for genetic distances, separated into bins containing intraspecific and interspecific comparisons and plotted in a graph to visualize any potential global barcoding gap. Over 70 million pairwise genetic comparisons were made and results suggest that although there is a tendency towards separation, no distinct or sufficiently sized global barcoding gap exists in either of the datasets rendering future barcoding efforts at risk of erroneous specimen identifications (but local barcoding gaps may still exist allowing for the identification of specimens at lower taxonomic ranks). This seems to be especially true for earthworm taxa, which account for fully 35% of the total number of interspecific comparisons that show 0% divergence.

Diversity and a biogeographical review of the earthworms (Oligochaeta: Lumbricidae) of the Balkan Mountains (Stara Planina Mountains) in Serbia and Bulgaria

In this paper we summarize the knowledge on earthworm diversity in the Balkan Mountains (Stara Planina Mountains) based on new findings and published data in order to establish the first list of known earthworm taxa from the entire area of the Balkan Mountains. During investigations in the western part of the Balkan Mountains (western Stara Planina Mountains), 24 earthworm species were recorded altogether. Among them, 10 taxa represented the first findings for the whole territory of the Balkan Mountains (Allolobophora robusta spasenijakaramani, Aporrectodea smaragdina, Dendrobaena byblica, Dendrobaena hortensis, Dendrobaena illyrica, Dendrobaena jastrebensis, Dendrobaena vejdovskyi, Dendrobaena veneta, Helodrilus balcanicus balcanicus, and Helodrilus cernosvitovianus). The complete list of lumbricids from the Balkan Mountains contains 40 taxa belonging to 14 genera. With respect to the zoogeographic situation, the majority of them belong to peregrine, endemic, and trans-Aegean species. Our data show that the degree of endemism for the whole Stara Planina Mountains is relatively high (20%). Summing up the 9 endemics and the Balkanic (Moesian and Illyric) species, 27.5% of the total lumbricid fauna shows an autochthonous character. The impressive earthworm diversity shows that the Balkan Mountains are a territory of considerable species richness.

Checklist of earthworms (Oligochaeta: Lumbricidae) from Bulgaria—a review

Little is known about the diversity, ecology, distribution and habitats of earthworm populations in Bulgaria. In the presentstudy an attempt has been made to collect all scientific works on earthworm species (Lumbricidae) of Bulgaria. Thecomplete list of earthworm taxa of Bulgaria comprises 50 species and subspecies of Lumbricidae, belonging to 15 genera.For the first time, comprehensive information on distribution and habitats of all lumbricids in the country is given. Thepaper is useful for further monitoring studies of earthworm diversity and abundance in relation to environmental issues, land use and climate change.

Termite and earthworm abundance and taxonomic richness under long-term conservation soil management in Saria, Burkina Faso, West Africa

Unsustainable crop and soil management practices are major causes of soil degradation and declining soil biodiversity in West Africa. Identifying soil management practices that favor macrofauna abundance is highly desirable for long-term soil health. This study investigates the effects of long-term conservation soil management on termite and earthworm abundance and taxonomic richness in the central plateau of Burkina Faso. Trials included rotations with 5 Mg ha −1 yr −2 of organic matter added (established in 1960), application of 10 Mg ha −1 yr −1applied with additional organic (manure or straw) and mineral inputs (established in 1980) and different tillage systems (established in 1990) where 10 Mg ha −1 yr −1 of organic matter was also applied. Soil macrofauna was surveyed at the soil surface and in the upper 30 cm using transect and monolith sampling methods, eight weeks after sorghum crop planting. A total of five termite taxa: Trinervitermes sp., Microtermes sp., Odontotermes magdalenae, Macrotermes sp. and Amitermes stephensoni; belonging to the family of Termitidae, and two earthworm taxa: Dichogaster affinis, Millsonia inermis; from the family of Acanthodrilidae were found. Termite taxonomic richness per treatment ranged between 1 and 4, while earthworm taxa ranged from 0 to 2. Under rotation, one termite taxa and no earthworm taxa were identified. In the organic amendment plots, three termite and two earthworm taxa were found. And light tillage (animal or hand) resulted in four termite taxa and one earthworm taxa. The two types of fauna clearly responded differently to the different conservation soil management practices. Under rotation lower recorded macrofauna population was attributed to the lower rate of applied organic matter compared to levels applied in the organic amendment and tillage trials and where more macrofauna were found. Location of food stock (rooting depth of different crops in the rotation) also had a significant effect on termite presence. Effect of rooting depth on earthworms was not observable due to the absence of earthworms in the rotation trials (possibly due to insecticide application. Manure treatments favored earthworms, while sorghum straw treatments favored termites likely due to respective preference for easy versus difficult to digest organic sources. Animal plowing and hand hoeing had similar and significantly positive effects and both termite and earthworm biological components compared to tractor tillage. We conclude that termite and earthworm abundance and taxonomic richness are most significantly affected by the type and amount of organic matter applied and tillage regimes, with rooting depth of rotations crops also playing a significant role. To promote macrofauna abundance and taxonomic richness in soils, integrated conservation soil management practices with attention to the particular needs and preferences of termites and earthworms is needed.

Cross-taxa congruence, indicators and environmental gradients in soils under agricultural and extensive land management

Important steps in developing reliable bioindicators for soil quality are characterising soil biodiversity and determining the response of its components to environmental factors across a range of land uses and soil types. Baseline data from a national survey in Ireland were used to explore relationships between diversity and composition of micro-organisms (bacteria, fungi, mycorrhiza), and micro-, meso- and macro-fauna (nematodes; mites; earthworms, ants) across a general gradient representing dominant land uses (arable, pasture, rough-grazing, forest and bogland). These diversity data were also linked to soil physico-chemical properties. Differences in diversity and composition of meso- and macro-fauna, but not microbes, were clear between agriculturally-managed (arable and pasture) and extensively-managed (rough-grazing and bogland) soils corresponding to a broad division between ‘mineral’ and ‘organic’ soils. The abundance, richness and composition of nematode and earthworm taxa were significantly congruent with a number of the other groups. Further analysis, using significant indicator species from each group, identified potential target taxa and linked them to soil environmental gradients. This study suggests that there is potential surrogacy between the diversity of key soil taxa groups and that different sets of bioindicators may be most effective under agricultural and extensive land use.

Biodiversity and multiple ecosystem functions in an organic farmscape

To increase ecosystem services provided by their lands, farmers in the United States are managing non-production areas to create a more biodiverse set of habitats and greater landscape heterogeneity. Relatively little is known, however, of the actual environmental outcomes of this practice, termed ‘farmscaping’. We inventoried communities of plant and soil organisms and monitored indicators of ecosystem functions in six distinct habitats of an organic farm in California's Central Valley to better understand the ecological costs and benefits of farmscaping. A riparian corridor, hedgerows, a system of drainage ditches, and tailwater ponds supported different plant life history/functional groups and greater native plant diversity than the two production fields. Differences were less pronounced for belowground organisms, i.e., nematode functional groups, microbial communities (based on phospholipid fatty acid (PLFA) analysis) and earthworm taxa. Partial ordination analysis showed that environmental variables, rather than spatial location, explained much of the distribution of soil and plant taxa across the farmscape. Riparian and hedgerow habitats with woody vegetation stored 18% of the farmscape's total carbon (C), despite occupying only 6% of the total area. Infiltration rates in the riparian corridor were >230% higher than those observed in the production fields, and concentrations of dissolved organic carbon (DOC) in soil solution were as much as 65% higher. The tailwater pond reduced total suspended solids in irrigation runoff by 97%. Drainage ditches had the highest N 2O-N emissions (mean values of 16.7 μg m −2 h −1) and nitrate (NO 3 −-N) leaching (12.1 g m −2 year −1 at 75 cm depth). Emissions of N 2O-N and leaching of NO 3 −-N were, however, quite low for all the habitats. Non-production habitats increased biodiversity (particularly plants) and specific ecosystem functions (e.g. water regulation and carbon storage). Extrapolating relative tradeoffs to the entire farmscape showed that greater habitat enhancement through farmscaping could increase both biodiversity and multiple ecosystem functions of agricultural lands with minor loss of production area.

Impact of M1A1 main battle tank disturbance on soil quality, invertebrates, and vegetation characteristics

Military training commonly results in land degradation, but protocols for assessing and predicting long-term environmental impact are lacking. An ability to assess the impact of repeated disturbance and subsequent recovery is needed to balance training requirements against environmental quality. To develop methodology for assessing soil quality, a study evaluating disturbance resulting from tank maneuvers was initiated on Fort Riley Military Installation, Kansas. The objectives were to identify and quantify soil-quality indicators on two soil types exposed to controlled tank traffic. We examined physical, chemical, and biotic indicators after treatments were applied during wet and dry soil conditions. A randomized complete-block design, with three blocks per soil type and three treatments per block, was used. Treatments consisted of disturbance created by a 63-ton M1A1 tank making five passes in a figure-8 pattern during either dry or wet soil conditions. The M1A1 was operated at a speed of approximately 8 km/h. Control plots received no tank traffic. Soil-quality indicators evaluated were soil compaction, soil penetration resistance, rut depth, soil bulk density, soil texture, soil chemical composition, plant biomass, soil microbial diversity, and nematode and earthworm taxa. Soil-quality indicators were sampled within one week after tank disturbance. Preliminary data indicate soil-texture-dependent treatment effects ( p ⩽ 0.05) for bulk density and porosity. Bulk density increased and porosity decreased on trafficked areas, in the silt loam soil, but showed no change in the silty clay loam soil. Disturbance during wet soil conditions raised penetrometer resistance and gravimetric water content more than disturbance during dry soil conditions ( p ⩽ 0.05). A significant difference in disturbance was measured between the outside and inside portion of the same track ( p ⩽ 0.01 and 0.001, respectively). The outside track caused the greatest amount of disturbance, as measured by the height of the disturbed soil ridge above the track bed. Tank disturbance significantly reduced total vegetative biomass ( p ⩽ 0.05) compared with that of un-trafficked areas. Disturbance under wet soil conditions significantly reduced grass biomass ( p = 0.040), whereas disturbance under dry soil conditions significantly reduced forb biomass ( p = 0.0247) compared to un-trafficked areas. Total earthworm abundance ( p = 0.011) was reduced by 82% when disturbance occurred during wet soil conditions regardless of soil type.

The earthworms (Oligochaeta) of Jordan

A new subspecies, Dendrobaena orientalis karak ssp. nov., is described, and four other earthworm species (Eisenia fetida (Savigny, 1826), Octodrilus transpadanus (Rosa, 1884) Microscolex dubius (Fletcher, 1887) and Ocnerodrilus occidentalis Eisen, 1878 (families Lumbricidae, Acanthodrilidae, Ocnerodrilidae respectively)) are recorded as new for the fauna of Jordan. O. transpadanus also represents a new record for the Levantine zoogeographic province. In addition, new data on the distribution of other earthworm taxa in Jordan are presented. The earthworm fauna of Jordan comprises altogether 13 species, of which 7 are thought to be introduced.

Further contribution to knowledge of the earthworms of Sumadija, Serbia

The authors present the results of recent investigations of earthworms from Sumadija. Research was carried out during 1996-2003 and included natural and cultivated biotopes from various parts of Sumadija. We found 27 taxa including six species new for the earthworm fauna of Sumadija: Dendrobaena alpina, Helodrilus cernosvitovianus, Octolasion cyaneum, Octodrilus complanatus, Serbiona serbica, and Serbiona paratuleskovi. Up to 1995, the total number of earthworm taxa in Sumadija was 37. After our present study this number has risen to 43 taxa. As for the zoogeographical position of the earthworms of Sumadija, the established taxa have the following types of distribution: European (11 taxa), cosmopolitan (10), Holarctic (eight) Palearctic (two), South European (five), Balkan (three) and endemic (four).

Physiology of cold hardiness in cocoons of five earthworm taxa (Lumbricidae: Oligochaeta)

Earthworm cocoons are mostly found in the uppermost soil layers and are therefore often exposed to low temperatures during winter. In the present study, cocoons of five taxa of earthworms were investigated for their tolerance to freezing, melting points of cocoon fluids and dehydration of cocoons when exposed to a frozen environment. Embryos of the taxa investigated were freeze intolerant. The melting points of fully hydrated cocoon fluids were high (above −0.3°C) and thermal hysteresis factors were absent. Exposure to a frozen environment caused the cocoons to dehydrate drastically and dehydrated cocoons showed significantly lower super-cooling points than fully hydrated cocoons, reducing the risk of freezing for dehydrated cocoons. It is proposed therefore that the cold-hardiness strategy of the earthworm cocoons is based on dehydration upon exposure to subzero temperatures in the frozen environment. Cocoons of three surface-dwelling taxa, Dendrobaena octaedra, Dendrodrilus rubidus tenuis and Dendrodrilus rubidus norvegicus had lower supercooling points and survived frost exposure better than cocoons of two deeper-dwelling taxa, Aporrectodea caliginosa and Allolobophora chlorotica. One of the investigated taxa, D. r. norvegicus, was collected from a cold alpine habitat. However, it was not more cold hardy than the closely related D. r. tenuis collected from a lowland temperate habitat. D. octaedra was the most cold hardy taxon, its cocoons being able to withstand −8°C for 3 months and −13.5°C for 2 weeks in frozen soil.