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Ovaries in a minute and mainly aquatic clitellates, collectively termed microdriles, are usually tiny paired gonads localized, depending on the family/subfamily, in segments VI, XI, XII, or XIII. Sometimes, two pairs of ovaries are present in consecutive segments, or ovaries are unpaired. Usually, accumulating yolk (vitellogenic) oocytes detach from ovaries and float in the coelom cavity. This study presents the microscopical analyses of unpaired ovaries found in two representatives of the genus Achaeta (family Enchytraeidae). The ovary is an inconspicuous organ composed of germ-line cysts uniting early meiotic cells. Cysts comprise 16 synchronously developing cells interconnected via cytoplasmic bridges to the central cytoplasmic mass, termed cytophore. Each interconnected cell has one bridge connecting it to the cytophore. Clustering germ cells are enveloped by elongated somatic cells. The developmental synchrony within cysts is lost when one cell per cyst forms prominent microvilli, gather vast amounts of nutrients (yolk), and becomes an oocyte. The remaining 15 cells do not form microvilli, grow slowly, and are regarded as nurse cells that supply the oocyte with organelles and probably macromolecules. Such cysts detach from the ovary and float freely in the segmental cavity. Nurse cells and vitellogenic oocyte are still connected to the ball-like cytophore. Vitellogenic oocytes gather vast amounts of reserve material, mainly protein spheres. Finally, oocytes lose contact with the cytophore, and nurse cells no longer accompany them. The ovary organization and oogenesis scenario observed in this study are broadly similar to that described for other enchytraeid species, such as Enchytraeus albidus and Grania postclitellochaeta, and have been classified as the "Enchytraeus" type of ovary. The obtained results show that despite the unpaired nature of the Achaeta ovary and some differences in ovary morphology and oogenesis between different enchytraeid taxa, the ovaries of these clitellates are consistently composed of 16-celled germ-line cysts equipped with cytophore. Moreover, the presence of cysts equipped with cytophore in the ovaries of the studied Achaeta specimens provides the subsequent evidence that the formation of such germ-line cysts is a conserved aspect of oogenesis within the Clitellata. This consistency in the ovarian and oogenic patterns underscores the evolutionary conservation of these reproductive traits within the Enchytraeidae and clitellate annelids., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Chromosomal chaos may have aided their moves to fresh water and land.

There is a gap in our knowledge of microorganization and the functioning of ovaries in earthworms (Crassiclitellata) and allied taxa. Recent analyses of ovaries in microdriles and leech-like taxa revealed that they are composed of syncytial germline cysts accompanied by somatic cells. Although the pattern of cyst organization is conserved across Clitellata - each cell is connected via one intercellular bridge (ring canal) to the central and anuclear cytoplasmic mass termed the cytophore - this system shows high evolutionary plasticity. In Crassiclitellata, only the gross morphology of ovaries and their segmental localization is well known, whereas ultrastructural data are limited to lumbricids like Dendrobaena veneta. Here we present the first report about ovarian histology and ultrastructure in Hormogastridae, a small family of earthworms inhabiting the western parts of the Mediterranean sea basin. We analyzed three species from three different genera and showed that the pattern of ovary organization is the same within this taxon. Ovaries are cone-like, with a broad part connected to the septum and a narrow distal end forming an egg string. Ovaries are composed of numerous cysts uniting a small number of cells, eight in Carpetania matritensis. There is a gradient of cysts development along the long ovary axis, and three zones can be distinguished. In zone I, cysts develop in complete synchrony and unite oogonia and early meiotic cells (till diplotene). Then (zone II), the synchrony is lost, and one cell (prospective oocyte) grows faster than the rest (prospective nurse cells). In zone III, oocytes pass the growth phase and gather nutrients; at this time, their contact with the cytophore is lost. Nurse cells grow slightly, eventually die via apoptosis, and are removed by coelomocytes. The most characteristic feature of hormogastrid germ cysts is the inconspicuous cytophore in the form of thread-like thin cytoplasmic strands (reticular cytophore). We found that the ovary organization in studied hormogastrids is very similar to that described for D. veneta and propose the term "Dendrobaena" type of ovaries. We expect the same microorganization of ovaries will be found in other hormogastrids and lumbricids., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier GmbH. All rights reserved.)

Megascolecid earthworms of the pheretimoid group are dominant detritivores of soil ecosystems in the Japanese Archipelago and East Asia. However, their diversity and phylogenetic relationships are poorly understood. We assembled whole mitogenome sequences for 197 megascolecid earthworms collected throughout Japan to study the phylogenetic relationships, phylogeography, divergence times, and diversification of important morphological characteristics among pheretimoid earthworms. Using 197 mitogenome sequences and 24 published mitogenome sequences from the East Asian mainland (221 sequences in total), we constructed a maximum likelihood tree and found that the pheretimoid earthworms currently assigned to Amynthas, Metaphire, Duplodicodrilus, and Manus are involved in the most senior genus Amynthas; thus, Amynthas can be treated as the sole genus encompassing all of the above genera. Within the Amynthas group, we identified three major lineages that led to four groups of endemic species in Japan. These lineages originated from different lineages on the East Asian mainland and Taiwan Island, indicating multiple colonization events from the East Asian mainland by different ancestral lineages, possibly after the Miocene. We also assembled nuclear ribosomal DNA sequences encompassing the 18S to 28S rRNA genes. The nuclear gene tree showed major groups consistent with the mitogenome tree except for different (and not well-resolved) relationships among major clades. Our molecular data covered 115-158 native and 7 non-native Amynthas group species in Japan in terms of DNA-based species delimitation. Our findings provide a basis for understanding the evolutionary relationships among diversified megascolecid earthworms in the Amynthas group in Japan and adjacent regions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

In this article, the descriptions of four new enchytraeid species (Enchytraeidae, Clitellata) from Jeoksangsan (Deogyusan National Park, Korea) are presented: Decimodrilus bulbosus sp. n., Fridericia jeoksangsaniensis sp. n., Fridericia sphaericoides sp. n. and Mesenchytraeus globiferus sp. n. Validity of these new species was verified by comparative morphological and molecular taxonomic analyses (based on the ITS region, CO1 and H3 genes). Apart from the new species, 13 other enchytraeid species were recorded in the soil samples of Jeoksangsan. In addition, new reference sequences are provided for the previously described Fridericia seoraksani Christensen Dzsa-Farkas, 2012.

The extremely difficult and challenging process is identifying pheretimoid species, genus Metaphire and Amynthas involving increased homoplasy in various morphological characteristics. The molecular identification, phylogenetic relationships, and evolutionary divergence time of earthworms belonging to the pheretimoid complex were investigated in this study using partial mitochondrial COI (cytochrome C oxidase subunit I) gene sequences ranging from 550-680 bp. Results revealed that 86 pheretimoid earthworms were morphologically different from a total of 342 mature worms. Moreover, 11 pheretimoid species were molecularly identified, including Metaphire posthuma (02), M. anomala (01), M. houlleti (02), M. californica (01), M. birmanica (02), Amynthas minimus (01), A. morrisi (01), and M. bununa (01). A phylogenetic tree was constructed with bootstrap values of 95%, which supported a monophyletic lineage of two well-supported clades formed by 12 partial COI sequences and 48 GenBank sequences using Hirudo medicinalis as an outgroup. The monophyly of these obtained genera indicated overall similarity at species level. Today, species like Amynthas, Metaphire and Pheretima have worm diversity in the form of pheretimoid earthworms, which dates to the Late Miocene (11.2-5.3 Mya) and the Pliocene (5.3-2.4 Mya). Compared to all relevant pheretimoid species, genetic p-distance values ranged from 0.0% to 0.57% (less than 1%). These low range values demonstrated that both genera Metaphire and Amynthas, supported the theory, which states that there are shared similarities among the species, despite different morphology. The current study is the first attempt in Pakistan to identify earthworms through DNA barcoding thus providing a genomic stamp. The work explored the significance of COI gene sequences to construct molecular tools that will be useful to overcome the different obstacles in morphologically similar earthworm identification and their phylogenetic study.

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 coelomic cavity is part of the main body plan of annelids. This fluid filled space takes up a considerable volume of the body and serves as an important site of exchange of both metabolites and proteins. In addition to low molecular substances such as amino acids and glucose and lactate, the coelomic fluid contains different proteins that can arise through release from adjacent tissues (intestine) or from secretion by coelomic cells. In this chapter, we will review the current knowledge about the proteins in the annelid coelomic fluid. Given the number of more than 20,000 extant annelid species, existing studies are confined to a relatively few species. Most studies on the oligochaetes are confined to the earthworms-clearly because of their important role in soil biology. In the polychaetes (which might represent a paraphyletic group) on the other hand, studies have focused on a few species of the Nereidid family. The proteins present in the coelomic fluid serve different functions and these have been studied in different taxonomic groups. In oligochaetes, proteins involved antibacterial defense such as lysenin and fetidin have received much attention in past and ongoing studies. In polychaetes, in contrast, proteins involved in vitellogenesis and reproduction, and the vitellogenic function of coelomic cells have been investigated in more detail. The metal binding metallothioneins as well as antimicrobial peptides, have been investigated in both oligochaetes and polychaetes. In the light of the literature available, this review will focus on lipoproteins, especially vitellogenin, and proteins involved in defense reactions. Other annelid groups such as the Pogonophora, Echiura, and Sipuncula (now considered polychaetes), have not received much attention and therefore, this overview is far from being complete.

Semi-aquatic freshwater earthworms in the genus Glyphidrilus from Southeast Asia are characterized by both an extreme morphological crypsis among divergent phylogenetic lineages and a high morphological variability within the same phylogenetic lineages. The present study provides a new taxonomic framework for this problematic genus in SE Asia by integrating DNA sequence and morphological data. When single-locus and multilocus multispecies coalescent-based (MSC) species delimitation methods were applied to DNA sequence data, they usually yielded highly incongruent results compared to morphology-based species identifications. This suggested the presence of several cryptic species and high levels of intraspecific morphological variation. Applying reciprocal monophyly to the cytochrome c oxidase subunit 1 (COI) gene tree allowed us to propose the existence of 33 monophyletic species. Yet, often substantially more molecular operational taxonomic units (MOTUs) were obtained when species delimitation was based on COI and 16S rRNA sequences. In contrast, the ITS1 and ITS2 sequences suggested fewer MOTUs and did not recover most of the monophyletic species from the Mekong basin. However, several of these latter taxa were better supported when MSC species delimitation methods were applied to the combined mtDNA and ITS datasets. The ITS2 secondary structure retrieved one unnamed Mekong basin species that was not uncovered by the other methods when applied to ITS2 sequences. In conclusion, based on an integrative taxonomic workflow, 26 Glyphidrilus candidate species were retained and two remained to be confirmed. As such, this study provides evidence to suggest nine species new to science and to synonymize 12 nominal morphospecies. It also illustrates that the uncritical use of COI as a universal DNA barcode may overestimate species diversity because COI may be unable to distinguish between divergent conspecific lineages and different candidate species., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The bodies of earthworms are composed of repeating deformable structural units, called metameres, that generate the peristaltic body motions required for limbless underground burrowing and above-ground crawling. Metameres are actuated by circular and longitudinal muscles that are activated synchronously by the animals' nervous systems. A significant number of the neural-motor feedback loops function with sensory input gathered by the animals' highly sensitive skins, which are embedded with light, pressure and chemical receptors. In this paper, adopting the basic mechanisms employed by earthworms, we propose a new type of pneumatically-driven soft robot that can travel inside pipes by mimicking the motions and replicating the functionalities of a single metamere. Furthermore, we introduce a sensing scheme for feedback control that mimics the mechanical sensory capabilities of an earthworm's skin, which was developed upon stretchable liquid circuits capable of measuring strain and detecting pressure variations. The suitability of the proposed approach is demonstrated through several controlled locomotion experiments, employing two different robotic prototypes.

Our understanding of the impacts of ongoing global warming on terrestrial species has increased significantly during the last several years, but how climatic change has affected, and will affect, the distribution of earthworms remains largely unknown. We used climate niche modeling to model the current distribution of the giant earthworm Rhinodrilus alatus - an endemic species of the Cerrado Domain in Brazil, which is traditionally harvested and commercialized for fishing bait. R. alatus is sensitive to environmental changes because climate, in synergy with soil attributes, determine its annual reproductive cycle and distribution. The paleoclimatic reconstructions predict important geographical shifts from LGM (~21,000 yBp) to the present potential distribution of R. alatus: range expansion, fragmentation, and shrinkage of the current core area. Further, the 2070 scenarios predict substantial shrink and losses of stable areas. Our results indicate that climate change will not only affect the extent of the distribution, but will also promote significant fragmentation and a geographical shift to outside of the currently recognized geographical boundaries. In this context, populations of R. alatus would decline and traditional harvesting would collapse, requiring immediate implementation of management and conservation measures for the species and economically sustainable alternatives for the local community.

Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), together with polycyclic aromatic hydrocarbons (PAHs), represent highly toxic and persistent organic environmental pollutants, especially due to their capability for bioaccumulation in fatty tissues. To observe the environmentally relevant effect of these compounds on earthworms, two soils naturally contaminated with PCDD/Fs and PAHs were used in our experiments. We focused on the role of CuZn- and Mn-superoxide dismutases. We assembled a full-length sequences of these molecules from Eisenia andrei earthworm and confirmed their activity. We demonstrated the significant reduction of CuZn-SOD on both mRNA and enzyme activity levels and increased levels of reactive oxygen species in earthworms kept in PCDD/F-polluted soil, which corresponds to the observed histopathologies of the earthworm intestinal wall and adjacent chloragogenous tissue. The results show an important role of CuZn-SOD in earthworm tissue damage caused by PCDD/Fs present in soil. We did not detect any significant changes in the mRNA expression or activity of Mn-SOD in these earthworms. In earthworms maintained in PAH-polluted soil the activity of both CuZn-SOD and Mn-SOD significantly increased. No histopathological changes were detected in these worms, however significant decrease of coelomocyte viability was observed. This reduced viability was most likely independent of oxidative stress., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Pontoscolex corethrurus is the most widespread earthworm species in tropical and sub-tropical zones and one of the most studied in soil science. Although, ecological interactions of P. corethrurus with its environment are well documented, the taxonomic status of the species remains unclear. In this study, we investigated phylogenetic relationships within the genus Pontoscolex, in particular focusing on morphologically indistinguishable (i.e., cryptic) lineages. A total of 792 specimens collected from 25 different countries and islands all over the world were analyzed using two mitochondrial (COI and 16S rDNA) and two nuclear (internal transcribed spacers 2 and 28S rDNA) markers, and a total of 11 morphological characters both internal and external were investigated in all genetically characterized lineages. A large-scale multilocus sequence data matrix was also obtained for Pontoscolex spp. specimens using the Anchored Hybrid Enrichment (AHE) method. Multilocus phylogenetic and phylogenomic analyses, combined with species delimitation methods; including single locus (mPTP, ABGD) and multilocus (BPP) approaches, revealed congruent results. Four cryptic species were supported within the P. corethrurus species complex, and four potentially new species within the genus Pontoscolex. One widespread lineage (L1), within P. corethrurus complex was observed in the current population of Fritz Müller's garden where P. corethrurus was first described in 1856. Cryptic lineages were observed in sympatry at several localities. This, in combination with observed heteroplasmy in COI gene in one population raises an important question of reproductive isolation between these species., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Invertebrate immunity is associated with natural mechanisms that include cellular and humoral elements, similar to those that play a role in vertebrate innate immune responses. Formation of extracellular traps (ETs) is a newly discovered mechanism to combat pathogens, operating not only in vertebrate leucocytes but also in invertebrate immune cells. The ET components include extracellular DNA (exDNA), antimicrobial proteins and histones. Formation of mammalian ETs depends on enzymes such as neutrophil elastase, myeloperoxidase, the citrullination of histones and protease activity. It was confirmed that coelomocytes-immunocompetent cells of the earthworm Eisenia andrei-are also able to release ETs in a protease-dependent manner, dependent or independent of the formation of reactive oxygen species and rearrangement of the cell cytoskeleton. Similar to vertebrate leukocytes (e.g., neutrophil), coelomocytes are responsible for many immune functions like phagocytosis, cytotoxicity and secretion of humoral factors. ETs formed by coelomocyte analogues to neutrophil ETs consist of exDNA, histone H3 and attached to these structures proteins, e.g., heat shock proteins HSP27. The latter fact confirms that mechanisms of ET release are conserved in evolution. The study on Annelida adds this animal group to the list of invertebrates capable of ET release, but most importantly provides insides into innate mechanisms of ET formation in lower animal taxa.

Inspired by the morphology characteristics of the earthworms and the excellent deformability of origami structures, this research creates a novel earthworm-like locomotion robot through exploiting the origami techniques. In this innovation, appropriate actuation mechanisms are incorporated with origami ball structures into the earthworm-like robot 'body', and the earthworm's locomotion mechanism is mimicked to develop a gait generator as the robot 'centralized controller'. The origami ball, which is a periodic repetition of waterbomb units, could output significant bidirectional (axial and radial) deformations in an antagonistic way similar to the earthworm's body segment. Such bidirectional deformability can be strategically programmed by designing the number of constituent units. Experiments also indicate that the origami ball possesses two outstanding mechanical properties that are beneficial to robot development: one is the structural multistability in the axil direction that could contribute to the robot control implementation; and the other is the structural compliance in the radial direction that would increase the robot robustness and applicability. To validate the origami-based innovation, this research designs and constructs three robot segments based on different axial actuators: DC-motor, shape-memory-alloy springs, and pneumatic balloon. Performance evaluations reveal their merits and limitations, and to prove the concept, the DC-motor actuation is selected for building a six-segment robot prototype. Learning from earthworms' fundamental locomotion mechanism-retrograde peristalsis wave, seven gaits are automatically generated; controlled by which, the robot could achieve effective locomotion with qualitatively different modes and a wide range of average speeds. The outcomes of this research could lead to the development of origami locomotion robots with low fabrication costs, high customizability, light weight, good scalability, and excellent re-configurability.

The family Lumbricidae is arguably the most well-known and well-studied earthworm group due to its dominance in the European earthworm fauna and its invasion in temperate regions worldwide. However, its North American members, especially the genus Bimastos Moore, 1893, are poorly understood. We revised the systematics of the genus Bimastos and tested the hypothesis of the monophyly of North American lumbricids using morphological characters and eight molecular markers. Phylogenetic analyses based on our extensive sampling of Bimastos and inclusion of Dendrodrilus and Allolobophoridella indicated a well-supported clade containing Bimastos and Eisenoides Gates, 1969, and provided the first evidence supporting that North American lumbricids are monophyletic. Assuming the available divergence time estimations and dating of land bridges are correct, it would suggest that the ancestor of this clade arrived North America through Beringia or the De Geer route during Late Cretaceous, and since then the clade has diverged from its Eurasian sister group, Eisenia. The peregrine genera Dendrodrilus and Allolobophoridella are nested within the Bimastos clade; we propose to treat them as junior synonyms of the genus Bimastos, and, contradictory to the commonly held belief of being European, they are indeed part of the indigenous North American earthworm fauna. Morphological characters, such as red-violet pigmentation, proclinate U-shaped nephridial bladders and calciferous diverticula in segment 10 further support this placement. The East Mediterranean-Levantine Spermophorodrilus Bouché, 1975 and Healyella Omodeo & Rota, 1989 are nested within the Dendrobaena sensu lato clade; therefore their close relationship with the North American Bimastos is refuted. Species fit the revised diagnosis of Bimastos are reviewed and keyed, and a new species, Bimastos schwerti sp. nov., is described.

The infection by Limnodrilus hoffmeisteri Claparède, 1862 (Oligochaeta: Tubificinae) in humans is relatively uncommon. The present report is to describe an incidental human infection with oligochaetes in the nasal cavity of a Chinese man, a 25-year-old man residing in Zhangjiakou city, Hebei province, China presenting with nose bleed, severe itching, continuous sneezing, and rhinorrhea. A lot of oligochaete worms were found in the nasal discharge of the patient. The detected worms were identified as Limnodrilus hoffmeisteri (Annelida: Oligochaeta) based on morphological and molecular characteristics. This incidental L. hoffmeisteri nasal infection is the first case in China and indicates that oligochaete worms can be encountered in humans.

This paper presents a checklist of the freshwater oligochaetes of Croatia, including data related to the ecoregions, river basins and habitat types in which species were recorded. The checklist is based on literature data and new records from unpublished research conducted since 1975. A total of 71 freshwater oligochaete species were recorded at 345 sampling sites. The family Naididae was most species rich (31 species), followed by the family Tubificidae (27 species), Lumbriculidae (6 species) and Pristinidae (4 species). The families Haplotaxidae, Propappidae and Lumbricidae were least diverse, with only one species recorded for each. Approximately two-thirds of the oligochaete species occurred in both the Dinaric western Balkan and the Pannonian lowland ecoregions. Similar patterns in species richness were detected for the Black Sea and the Adriatic Sea basins. Species richness varied between habitat types, with rivers as the most speciose habitats. In comparison to adjacent countries, the Croatian oligochaete fauna was most similar to that of Bosnia and Herzegovina, Hungary and Austria.

A list of the endemic earthworms of the Balkan Peninsula is presented. Comprehensive information on the ecology, distribution on the Balkan Peninsula and zoogeographical type of all endemics is given. The list comprises 90 species and subspecies, belonging to 11 genera of the family Lumbricidae. The largest number of the Balkan endemic earthworms belongs to a narrow range group (63.3%). Broad range endemic species take part with 36.7%. Our study shows that the degree of endemism on the Balkan Peninsula is extremely high (about 40%) suggesting an important process of autochthonous speciation on the Balkan Peninsula. This appearance is attributable to relative isolation of the mountains compared to the lowlands within the context of paleoenvironmental changes.

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.

Three new species of the earthworm genus Zapatadrilus are described from Tamaulipas, Mexico: Zapatadrilus aurelius sp. nov., Zapatadrilus huastecus sp. nov., and Zapatadrilus montezumensis sp. nov. Delimitation of the new species was supported by morphological and molecular (genetic distances) evidence. Diagnostic characters of the three new species include: tubulo-racemose prostates in segments 18 and 20, penial setae absent, typhlosole present and intestine beginning in 17/18. Z. montezumensis sp. nov. is separated by its metandric condition, Z. aurelius sp. nov. by the last hearts in 13 and Z. huastecus sp. nov. by the shape of the spermathecae and patterns of genital markings.

The invasion of the pheretimoid earthworms in North America, especially the genera Amynthas and Metaphire, has raised increasing concerns among ecologists and land managers, in turn increasing the need for proper identification. However, the commonly used keys to this group are more than 30 years old with outdated taxonomic information and are based primarily on internal morphology. The requirement of significant amount of taxonomic expertise and dissection, even from the first entry of the key, has prevented broader use of these keys. As a result, many publications in the United States have used Amynthas spp. to represent the group without identifying the species. We present here a new key and diagnoses for the 16 pheretimoid earthworm species recorded in North America north of Mexico, including four genera: Amynthas (10), Metaphire (4), Pithemera (1), and Polypheretima (1). The descriptions were based on published records with modifications following inspection of specimens archived at the National Museum of Natural History, Smithsonian Institution, Washington, D.C. Photos of external and internal characters, including male pores, spermathecal pores, genital markings, spermathecae, prostate glands, and intestinal caeca, are presented to help identification. A summary of current knowledge about the ecology and historical context is provided for each species. We also highlight the previously overlooked and potentially common and widespread co-occurrence of three species-A. agrestis, A. tokioensis, and M. hilgendorfi-and point out that many recent claims of invasion of A. agrestis need to be re-evaluated for potential misidentification.

A survey of the earthworms of Guadeloupe was undertaken to improve knowledge of the diversity of native and introduced earthworms of the island and to evaluate native species for use in vermicomposting. Twenty-eight species were found, 8 introduced, 4 uncertain, and 16 presumed native. The introduced species are Pontoscolex corethrurus, Pontoscolex spiralis, Amynthas rodericensis, Perionyx excavatus, Polypheretima elongata, Dichogaster affinis, Eudrilus eugeniae, and Drawida sp. Juveniles of the genera Righiodrilus, Glossodrilus and Periscolex were found, but one cannot say if they are introduced or not without a confirmed identification. Omodeoscolex divergens was collected in several locations, with variation in color, size and male sexual function suggestive of long residence on the island, but we are counting this as of uncertain status and tentatively placing all in the same species. Late juveniles of a large endogeic species of a heretofore unknown genus of the Rhinodrilidae were found only in the most remote location sampled and are presumed to be native. Seven previously reported native Dichogaster were found. Eight non-recorded species of Dichogaster were found, five represented by single specimens or juveniles, for which we give only a brief precis. The three described here are Dichogaster spolstoni n. sp., Dichogaster caraibensis n. sp.,.and Dichogaster etaspiqui n. sp. These are compared to and differentiated from previously known Dichogaster species of the world and of Guadeloupe.

A new acanthodriline earthworm species, Lavellodrilus notosetosus sp. nov., is described from tropical rain forests of southern Mexico. The new species is placed within the genus Lavellodrilus by the presence of mesial spermathecal pores. It is separated from other species of the genus by the dorsal location of setae cd in most of the body, last hearts in segment 13, first intestinal segment in 20 and genital setae in segment 12. A preliminary morphological revision of all genera and species of Acanthodrilinae was undertaken in order to: i) evaluate if the mesial spermathecal pores justify the status of Lavellodrilus, ii) determine how common (expressed as percentages of species having the character) the diagnostic characters of the new species are in the subfamily, iii) clarify if these characters exhibit a geographical pattern, and iv) contribute towards a comprehensive analysis of the Acanthodrilinae. In this revision, species were separated in nine geographical regions: USA, northern Mexico, southern Mexico, Caribbean Islands (northern hemisphere), and South America, South Africa, Madagascar, Australia, New Zealand, New Caledonia and Antarctic Islands (southern hemisphere). As a result of the revision it was found that among the 511 recognized species of Acanthodrilinae only 11 species have a mesial location of the spermathecal pores, in two cases probably representing monophyletic groups (Lavellodrilus and a group of South African Parachilota species). It was also found that the distinguishing characters in L. notosetosus sp. nov., notably the location of last hearts, genital setae and the first intestinal segment, are uncommon characters in the acanthodriline earthworm fauna of southern Mexico and Central America, but more frequent in North America, the Caribbean, and the southern hemisphere. We conclude that the acanthodrilines from the northern hemisphere are morphologically more similar to those from Australia, New Zealand, and New Caledonia than to those of South Africa and South America.

The comprehensive checklist of earthworms in Vietnam is presented here listing 24 genera and 212 species arranged in eight families. For each species, bibliographic citations are given, including the original descriptions as well as notable citations affecting taxonomic status or distributional reports of a species. Distributions of each species are also provided. The bibliography contains all relevant papers for Vietnamese earthworms. Of 212 species, 114 have been recorded only in Vietnam, and 25 are cosmopolitan. New combinations are made for Amynthas acalifornicus (Do & Huynh, 1991) comb. nov., A. binhgiaensis (Le, 1994) comb. nov., Metaphire catbaensis (Thai & Le, 1993) comb. nov., M. khoii (Do & Tran, 1994) comb. nov., M. phaluongana (Do & Huynh, 1992) comb. nov., and M. mangophila (Nguyen, 2011) comb. nov., M. tripidoporophoratus (Thai & Nguyen, 1993) comb. nov. Additionally, Pheretima paraalexandri Nguyen, 2011 is treated as a junior synonym of Amynthas polychaetiferus (Thai, 1984).

Earthworm specimens collected from various parts of Thailand were found to contain seven new species of the genus Metaphire Sims & Easton, 1972. These are M. songkhlaensis sp. n. in the octothecal pulauensis species group,                        M. trangensis sp. n. in the octothecal ignobilis species group, M. khaoluangensis sp. n. and M. khaochamao sp. n. in the sexthecal houlleti species group, M. doiphamon sp. n. in the sexthecal peguana species group, M. saxicalcis sp. n. in the quadrithecal planata species group, and the bithecal M. surinensis sp. n. Type material of some established species from Thailand or northern Malaysia was reinvestigated and illustrated to confirm the status of the new species and to facilitate species comparisons: M. pulauensis (Beddard, 1900), M. baruana (Stephenson, 1932), both with newly designated         lectotypes, and M. planata (Gates, 1936), illustrated and redescribed.

The earthworm fauna of North America is still greatly unknown, with undescribed native species and new records of invasive species continually being discovered. The most recent checklists are difficult to reconcile, since they vary in their geographic coverage and taxonomy. Reynolds & Wetzel (2012) state that North America (including all of Mexico, some of the Caribbean, and Hawaii) is home for 256 species of earthworms, from which 188 are considered native or endemic and 68 are peregrine, exotic, and invasive species. Blakemore (2008) listed North America north of Mexico as having 183 earthworm species, of which 59 species are exotic. One Megascolecidae genus, Amynthas, is mostly located in the warmer subtropical and tropical regions of the world, with a few species that are able to survive the winter in the temperate zones of North America (Edwards & Bohlen 1995; Görres et al. 2014). Here we report for the first time the occurrence of Amynthas carnosus (Goto & Hatai, 1899) in the United States. To our knowledge, this is not only the first report of A. carnosus in North America, but also its first report in the Western Hemisphere. The description below is intended to place our specimens in the correct taxon while avoiding future confusion with similar species, without making changes to the existing classification system.

A new Italian earthworm morphologically close to the similarly large and anecic Eophila tellinii (Rosa, 1888) is described. Distribution of Eophila crodabepis sp. nov. extends over 750 km2 from East to West on the Asiago Plateau and Vittorio Veneto Hills, from North to South on mounts Belluno Prealps (Praderadego and Cesen), Asiago, Grappa and onto the Montello foothills. This range abuts that of Eophila tellinii in northern Friuli Venezia Giulia region. Known localities of both E. tellinii and E. crodabepis sp. nov. are mapped. mtDNA barcoding definitively separates the new western species from classical Eophila tellinii (Rosa, 1888).

A new species of the tubificine genus Limnodrilus is described and COI barcoded from Sulphur Cave and associated springs in Colorado, USA. The habitats are characterized by high sulfide concentrations. The new species, L. sulphurensis, is distinguished from all congeners by the elongate, nearly parallel teeth of chaetae in its anterior segments. It has a penis sheath resembling that of L. profundicola; consequently, museum specimens and new collections are examined here to resolve some of the taxonomic confusion surrounding that widespread, but uncommon species.

This paper describes two new species of earthworms belonging to the Amynthas morrisi-group from Hainan Island, China: Amynthas zonarius sp. nov. and Amynthas wuzhimontis sp. nov. Both have two pairs of spermathecal pores in 5/6-6/7, and simple intestinal caeca. Amynthas zonarius sp. nov. has a pad-like male porophore, with flat-topped tubercle surrounded by 5 skin folds distal half of the spermathecal diverticulum dilated into band-shaped seminal chamber. Amynthas wuzhimontis sp. nov. has a seminal chamber constricted into moniliform subchambers and a glandular pad-like elliptical male pore porophore surrounded by the tumid area. Partial COI sequences of the holotypes of the two new species have been submitted to GenBank as DNA barcodes to enable molecular species identification.

Earthworm decerebration causes temporary inhibition of reproduction which is mediated by certain brain-derived neurohormones; thus, cocoon production is an apposite supravital marker of neurosecretory center functional recovery during brain regeneration. The core aim of the present study was to investigate aspects of the interactions of nervous and immune systems during brain regeneration in adult Dendrobaena veneta (Annelida; Oligochaeta). Surgical brain extirpation was combined, either with (i) maintenance of immune-competent coelomic cells (coelomocytes) achieved by surgery on prilocaine-anesthetized worms or (ii) prior extrusion of fluid-suspended coelomocytes by electrostimulation. Both brain renewal and cocoon output recovery were significantly faster in earthworms with relatively undisturbed coelomocyte counts compared with individuals where coelomocyte counts had been experimentally depleted. These observations provide empirical evidence that coelomocytes and/or coelomocyte-derived factors (e.g. riboflavin) participate in brain regeneration and, by implication, that there is close functional synergy between earthworm neural and immune systems., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Many soft-bodied invertebrates use a flexible, fluid-filled hydrostatic skeleton for burrowing. The aim of our study was to compare the scaling and morphology between surface-dwelling and burrowing earthworm ecotypes to explore the specializations of non-rigid musculoskeletal systems for burrowing locomotion. We compared the scaling of adult lumbricid earthworms across species and ecotypes to determine whether linear dimensions were significantly associated with ecotype. We also compared the ontogenetic scaling of a burrowing species, Lumbricus terrestris, and a surface-dwelling species, Eisenia fetida, using glycol methacrylate histology. We show that burrowing species are longer, thinner and have higher length-to-diameter ratios than non-burrowers, and that L. terrestris is thinner for any given body mass compared with E. fetida. We also found differences in the size of the musculature between the two species that may correlate with surface crawling or burrowing. Our results suggest that adaptations to burrowing for soft-bodied animals include a disproportionately thin body and strong longitudinal muscles., (© 2015. Published by The Company of Biologists Ltd.)

We give descriptions of five new enchytraeid species (Enchytraeidae, Oligochaeta) from Korea: Henlea magnaampullacea sp. n., Fridericia sphaerica sp. n., F. cusanicaformis sp. n., F. granulocyta sp. n. and Mesenchytraeus calyx sp. n., with morphological and molecular (mitochondrial cytochrome c oxidase subunit I, nuclear histone 3 genes and nuclear ribosomal ITS region sequences) data. In total, 19 enchytraeid species belonging to seven genera have been found in the studied woodland and agronomical soil samples. Apart from the five new species, three further species are new for the Korean enchytraeid fauna, Enchytraeus christenseni, E. dichaetus, and Achaeta cf. brevivasa. Molecular taxonomical analyses show that the Korean species resembling H. ventriculosa is not identical with the European species, furthermore sequence analysis of individuals morphologically identified as F. seoraksani indicate the possibility of species-complexity and the presence of cryptic species.

Three species of semi-aquatic freshwater Enchytraeidae of the genera Mesenchytraeus Eisen, 1878, Chamaedrilus Friend, 1913 and Globulidrilus Christensen & Dózsa-Farkas, 2012 are described from stream, wet soil or snow habitats in the Ozegahara Mire, an extensive high moor in heavy snowfall area in central Japan. Among Mesenchytraeus speies, Mesenchytraeus nivalis sp. nov. is distinguished by not having enlarged chaetae and spermathecal diverticula, vas deferens with atrial glands 3 or 4 in number and club-shaped, spermathecal ental duct short, with sperm bundles in the sperm sack. Chamaedrilus ozensis sp. nov. closely resembles C. floridae, but the length of the sperm funnel and character of the coelomocytes are different. Globulidrilus helgei Christensen & Dózsa-Farkas, 2012 is recorded for the first time from Japan.

Uktena riparia n. gen., n. sp. has been collected in hyporheic habitats at several sites in North Carolina, southeastern USA. The genus is defined by unusual characters related to reproductive structures, including the formation of encapsulated spermatophores for sperm transfer and large bundles of genital chaetae, both previously unknown in the Lumbriculidae. The simultaneous occurrence of both spermatophores and spermathecae is rare in the microdrile oligochaetes. Uktena spermatophores appear more similar to those reported in leeches than to those in other microdrile oligochaete families. Possible synapomorphies associating Uktena with the genera Kincaidiana and Guestphalinus include a filiform, ringed proboscis, a forward shift of reproductive organs relative to the usual position in the family, and spermathecae in the atrial segment. The new species adds to the already diverse, endemic lumbriculid fauna of the North Carolina Sandhills ecoregion.

Two new earthworm species are described, Periscolex malibu sp. nov. (Rhinodrilidae) and Righiodrilus lebrijae sp. nov. (Glossoscolecidae). They were found in relicts of tropical dry forests surrounding wetlands in the southern department of Cesar, located near the Caribbean coast of Colombia. Periscolex malibu sp. nov. is close to P. fuhrmanni Michaelsen, 1913 by the position of both clitellum and tubercula pubertatis, but differs in the extension of the clitellum and in the presence of five pairs of spermathecae. Righiodrilus lebrijae sp. nov is close to R. paolettii Righi, 1984a by the extension of the clitellum, but differs in the extension of the tubercula pubertatis, the extension of the seminal vesicles, the position of the male pores, the arrangements of setae, and the shape of the spermathecae.

In 2012, we conducted earthworm surveys in Matsu Islands, and described five new species of the genera Amynthas and Metaphire and reported two new records, Desmogaster sinensis Gates, 1930 and Ocnerodrilus occidentalis Eisen, 1878. This paper describes three new species, one of them with two new subspecies, Amynthas nanganensis nanganensis sp. nov. et ssp. nov. and Amynthas nanganensis beiganensis ssp. nov., Drawida beiganica sp. nov. and Drawida dongyinica sp. nov., provides a new record of Drawida koreana Kobayashi, 1938 from the remaining specimens collected in the surveys, reports DNA barcodes (the 5' end sequences of the mitochondrial cytochrome c oxidase subunit 1 gene) from type specimens and further reference specimens of the new species, and lists a total of 27 earthworm species and subspecies found from Matsu Islands. Pheretimoid earthworms made up 66.7% of the total number of the species, with Metaphire matsuensis Shen, 2014 and Metaphire californica (Kinberg, 1867) the most dominant. Our findings indicate that the earthworm fauna of Matsu Islands is more closely related to that of warm temperate China than to Taiwan or tropical southern China.

Recent studies on the ovary organization and oogenesis in Tubificinae have revealed that their ovaries are small polarized structures that are composed of germ cells in subsequent stages of oogenesis that are associated with somatic cells. In syncytial cysts, as a rule, each germ cell is connected to the central cytoplasmic mass, the cytophore, via only one stable intercellular bridge (ring canal). In this paper we present detailed data about the composition of germ-line cysts in Tubifex tubifex with special emphasis on the occurrence and distribution of the cytoskeletal elements. Using fixed material and live cell imaging techniques, we found that the entire ovary of T. tubifex is composed of only one, huge multicellular germ-line cyst, which may contain up to 2,600 cells. Its architecture is broadly similar to the cysts that are found in other clitellate annelids, i.e. a common, anuclear cytoplasmic mass in the center of the cyst and germ cells that are connected to it via intercellular bridges. The cytophore in the T. tubifex cyst extends along the long axis of the ovary in the form of elongated and branched cytoplasmic strands. Rhodamine-coupled phalloidin staining revealed that the prominent strands of actin filaments occur inside the cytophore. Similar to the cytophore, F-actin strands are branched and they are especially well developed in the middle and outermost parts of the ovary. Microfilaments are also present in the ring canals that connect the germ cells with the cytophore in the narrow end of the ovary. Using TubulinTracker, we found that the microtubules form a prominent network of loosely and evenly distributed tubules inside the cytophore as well as in every germ cell. The well-developed cytoskeletal elements in T. tubifex ovary seem to ensure the integrity of such a huge germ-line cyst of complex (germ cells-ring canals-cytophore) organization. A comparison between the cysts that are described here and other well-known female germ-line cysts is also made.

Phytotelmata, or plant-held water bodies, often house complex aquatic invertebrate communities. Microdrile oligochaetes (Clitellata, Annelida) are known to be part of that community, but specimens are rarely identified to species level. Here we report three species of Enchytraeidae and three species of Naididae from a collection sampled in phytotelms of bromeliads in Cusuco National Park, Honduras. Two species of enchytraeids are new to science. Bryodrilus hondurensis sp. nov. is distinguished from other members of the genus by the high number of ventral chaetae, up to 11 per bundle. The genus is Holarctic and this is the southernmost record so far of a Bryodrilus species. Hemienchytraeus phytotelmatus sp. nov. is distinguished by a combination of characters, among which the huge spermathecae and seminal vesicles are most conspicuous. The genus is common in tropical and subtropical soils around the world. A third species of enchytraeids in the collection, Cernosvitoviella atrata (Bretscher), is redescribed, together with three known species of Naididae, Pristina jenkinae (Stephenson), Pristina osborni (Walton) and Pristina terrena Collado & Schmelz. Presence of ingested debris and humus in the intestine of most specimens suggests that the collected animals live and reproduce in the phytotelms. We provide a list of oligochaete species recorded so far from bromeliad pools in Central and South America.

Earthworms belonging to the family Lumbricidae are extremely abundant in terrestrial temperate regions. They affect soil properties and nutrient cycling, thus shaping plant community composition and aboveground food webs. Some lumbricids are also model organisms in ecology and toxicology. Despite the intense research efforts dedicated to lumbricids over the last 130years, the evolutionary relationships and taxonomic classification of these organisms are still subject to great debate. Resolution of their systematics is hampered by the structural simplicity of the earthworm body plan and the existence of cryptic species. We sampled 160 earthworm specimens belonging to 84 lumbricid species (28 genera) and 22 Lumbricoidea outgroups, sequenced two nuclear genes, four mitochondrial genes and seven mitochondrial tRNAs and examined 22 morphological characters. We then applied a combination of phylogenetic methods to generate the first robust genus-level phylogeny of the Lumbricidae. Our results show that the current Lumbricidae classification and the underlying hypotheses of character evolution must be revised. Our chronogram suggests that lumbricids emerged in the Lower Cretaceous in the holarctic region and that their diversification has been driven by tectonic processes (e.g. Laurasia split) and geographical isolation. Our chronogram and character reconstruction analysis reveal that spermathecae number does not follow a gradual pattern of reduction and that parthenogenesis arose from sexual relatives multiple times in the group; the same analysis also indicates that both epigeic and anecic earthworms evolved from endogeic ancestors. These findings emphasize the strong and multiple changes to which morphological and ecological characters are subjected, challenging the hypothesis of character stasis in Lumbricidae., (Copyright © 2014 Elsevier Inc. All rights reserved.)

During the exploration of the enchytraeid fauna in forests and grasslands of Hungarian flat areas, a small enchytraeid species, Hemifridericia bivesiculata Christensen & Dózsa-Farkas, 2006, was found unexpectedly. This species was known previously only from one single location, Bank Island in the Canadian archipelago, and was presumed to be endemic. Here, the distinctive features of the two Hemifridericia species are described based on detailed morphological analyses, which were supported with molecular methods. The results demonstrated that the two Hemifridericia species are very similar morphologically, but can be clearly distinguished from each other by the presence or absence of the oesophageal vesicles and the shape of the brain. Some additional differences were observed between the Hungarian material and the type specimens of H. bivesiculata. The two species were unequivocally separated based on the studied molecular markers, the mitochondrial cytochrome c oxidase subunit I (CO1) gene, the nuclear histon 3 (H3) gene and the nuclear ribosomal ITS region.

We give descriptions of three new Fridericia species (Enchytraeidae, Oligochaeta) from Transylvania, Romania. Fridericia transylvanica sp. n. is a large-sized worm with a maximum of 4 chaetae per bundle. The spermathecae are separate entally and have two sac-like diverticula bent distad with the ampulla forming a common U-shaped sperm-containing chamber. The species was found not only in the Transylvanian Plateau but also in different regions of the Carpathians in Romania and Serbia. Fridericia gyromonodactyla sp. n. is medium-sized with a maximum of 3 chaetae per bundle. There are only four pairs of preclitellar nephridia. The spermathecal ectal duct is contractile and shorter than the body diameter; each ampulla has only one diverticulum, elongate and coiled, and there is one sessile gland at the orifice. Fridericia longeaurita sp.n. is large-sized with 4(5) chaetae per preclitellar bundle but only two or one in postclitellar bundles. The spermathecal ectal duct is shorter than the body diameter, with one small and sessile ectal gland at the orifice. Each ampulla has two long, ear-shaped, and sac-like diverticula. None of the three species were rare at the sites where they occurred.

The paper provides descriptions of three new species of the earthworm genus Polypheretima Michaelsen, 1934 from Dong Nai Province, South Vietnam. They are named Po. cattienensis sp. nov., Po. militium sp. nov., and Po. cordata sp. nov.. All three species are characterized by spermathecal pores in 5/6/7 and the absence of genital markings. Po. cattienensis sp. nov. is distinguished by paired spermathecal pores and seven spermathecae per porus. Po. militium sp. nov. is diagnosed by paired spermathecal pores and a variable number of spermathecae, 21-40 altogether, with 7-17 in 5/6 and 11-23 in 6/7. Po. cordata sp. nov. is recognized by one pair of spermathecal pores in 5/6 and two in 6/7, by only one spermatheca per porus, and by a heart-shaped spermathecal ampulla.

The Eisenia muganiensis species group is established, consisting of a set of Asian earthworm species characterized by elongate, backward placed clitellum and tubercles: Eisenia malevici Perel, 1962; Eisenia muganiensis (Michaelsen, 1910); Eisenia patriciae Szederjesi, Pavlíček, Coşkun & Csuzdi, 2014 and Eisenia transcaucasica (Perel, 1967). The species are shortly reviewed and furthermore, two new species of the E. muganiensis group are described, E. kontschani sp. nov. from Turkey and E. malekae sp. nov. from Iran.

We provide descriptions, with illustrations of internal structures, for 18 new species of Pheretima from Mt. Malindang, Misamis Occidental Province, Mindanao Island, Philippines. Among the 18 species, 11 belong to the P. sangirensis species group, characterized by having a pair of spermathecal pores in the intersegmental furrow of 7/8 and lacking penial sheaths in the copulatory bursae: P. maculodorsalis n. sp., P. tigris n. sp., P. immanis n. sp., P. lago n. sp., P. nunezae n. sp., P. boniaoi n. sp., P. malindangensis n. sp., P. misamisensis n. sp., P. wati n. sp., P. longiprostata n. sp., and P. nolani n. sp. One species, P. longigula n. sp., belongs to the P. montana species group, characterized by having a pair of spermathecal pores in the intersegmental furrow of 7/8 and penial sheaths in the copulatory bursae. Two species, P. vergrandis n. sp. and P. concepcionensis n. sp., are monothecal. Three species, P. adevai n. sp., P. lluchi n. sp., and P. potonganensis n. sp., belong to the P. darnleiensis species group, characterized by having either four or five pairs of spermathecae from vi to ix, with a fifth pair variably present in segment v. One species, P. subanensis n. sp., is athecate. All species described here from the Mt. Malindang Range are probably native rather than introduced, and probably do not represent range extensions of species known from neighboring islands in Southeast Asia. We provide an identification key to the Pheretima species from Mt. Malindang.

Earthworm (Oligochaeta, Lumbricidae) species are used widely in eco-toxicological tests especially with contaminated soils. These long-term tests are reliable, but a high sample size is needed. Magnetic resonance imaging (MRI) can produce fast, robust, sensitive, and longitudinal morphological results using a small sample size. Performing longitudinal in vivo examinations of earthworms using MRI requires the need for anesthetics to completely avoid earthworm's moving. Our goal was to develop a simple and non-invasive method to anesthetize earthworms for in vivo longitudinal imaging studies. We investigated a number of different anesthesia methods and found that propan-2-ol and its vapor was optimal. We used a commercial sequential nanoScan® PET/MRI system (Mediso Ltd, Hungary, Budapest) to explore feasibility of MR imaging in immobilized earthworms. It was possible to visualize via micro MRI the brain, gastrointestinal tract, seminal vesicles, calciferous gland (Morren gland), and main blood vessels of the circulatory system. Our findings show the possibilities to examine changes in morphology using MRI of certain organs using a reversible, long-term immobilization method., (© 2014 Wiley Periodicals, Inc.)

The 'acaecate' Pheretima group from Vietnam is revised, with description of a new species, Polypheretima mekongmontis sp. nov. A total of 18 species of three genera, Metapheretima Michaelsen, 1928, Planapheretima Michaelsen, 1934, and Polypheretima Michaelsen, 1934 has been recorded from Vietnam. Caecate species of Planapheretima are included here as well. Planapheretima arboricola (Rosa, 1890), Pl. lacertina (Chen, 1946), Pl. tenebrica (Chen, 1946), Polypheretima elongata (Perrier, 1872), and Po. taprobanae (Beddard, 1892) are originally recorded from other countries; all remaining species are native to Vietnam. The species Polypheretima tani (Thai, 1996) and Po. tiencanhensis (Pham, 1995) are transferred to the genus Metapheretima. A key to species and distribution maps are also presented.

Earthworms are important soil macrofauna inhabiting almost all ecosystems. Their biomass is large and their burrowing and ingestion of soils alters soil physicochemical properties. Because of their large biomass, earthworms are regarded as an indicator of "soil heath". However, primarily because the difficulties in quantifying their behavior, the extent of their impact on soil material flow dynamics and soil health is poorly understood. Image data, with the aid of image processing tools, are a powerful tool in quantifying the movements of objects. Image data sets are often very large and time-consuming to analyze, especially when continuously recorded and manually processed. We aimed to develop a system to quantify earthworm movement from video recordings. Our newly developed program successfully tracked the two-dimensional positions of three separate parts of the earthworm and simultaneously output the change in its body length. From the output data, we calculated the velocity of the earthworm's movement. Our program processed the image data three times faster than the manual tracking system. To date, there are no existing systems to quantify earthworm activity from continuously recorded image data. The system developed in this study will reduce input time by a factor of three compared with manual data entry and will reduce errors involved in quantifying large data sets. Furthermore, it will provide more reliable measured values, although the program is still a prototype that needs further testing and improvement. Combined with other techniques, such as measuring metabolic gas emissions from earthworm bodies, this program could provide continuous observations of earthworm behavior in response to environmental variables under laboratory conditions. In the future, this standardized method will be applied to other animals, and the quantified earthworm movement will be incorporated into models of soil material flow dynamics or behavior in response to chemical substances present in the soil.

The structural and functional consequences of changes in size or scale have been well studied in animals with rigid skeletons, but relatively little is known about scale effects in animals with hydrostatic skeletons. We used glycol methacrylate histology and microscopy to examine the scaling of mechanically important morphological features of the earthworm Lumbricus terrestris over an ontogenetic size range from 0.03 to 12.89 g. We found that L. terrestris becomes disproportionately longer and thinner as it grows. This increase in the length to diameter ratio with size means that, when normalized for mass, adult worms gain ~117% mechanical advantage during radial expansion, compared with hatchling worms. We also found that the cross-sectional area of the longitudinal musculature scales as body mass to the ~0.6 power across segments, which is significantly lower than the 0.66 power predicted by isometry. The cross-sectional area of the circular musculature, however, scales as body mass to the ~0.8 power across segments, which is significantly higher than predicted by isometry. By modeling the interaction of muscle cross-sectional area and mechanical advantage, we calculate that the force output generated during both circular and longitudinal muscle contraction scales near isometry. We hypothesize that the allometric scaling of earthworms may reflect changes in soil properties and burrowing mechanics with size., (© 2014. Published by The Company of Biologists Ltd.)

In spite of the high relevance of lumbricid earthworms ('Oligochaeta': Lumbricidae) for soil structure and functioning, the taxonomy of this group of terrestrial invertebrates remains in a quasi-chaotic state. Earthworm taxonomy traditionally relies on the interpretation of external and internal morphological characters, but the acquisition of these data is often hampered by tedious dissections or restricted access to valuable and rare museum specimens. The present state of affairs, in conjunction with the difficulty of establishing primary homologies for multiple morphological features, has led to an almost unrivaled instability in the taxonomy and systematics of certain earthworm groups, including Lumbricidae. As a potential remedy, we apply for the first time a non-destructive imaging technique to lumbricids and explore the future application of this approach to earthworm taxonomy. High-resolution micro-computed tomography (μCT) scanning of freshly fixed and museum specimens was carried out using two cosmopolitan species, Aporrectodea caliginosa and A. trapezoides. By combining two-dimensional and three-dimensional dataset visualization techniques, we demonstrate that the morphological features commonly used in earthworm taxonomy can now be analyzed without the need for dissection, whether freshly fixed or museum specimens collected more than 60 years ago are studied. Our analyses show that μCT in combination with soft tissue staining can be successfully applied to lumbricid earthworms. An extension of the approach to other families is poised to strengthen earthworm taxonomy by providing a versatile tool to resolve the taxonomic chaos currently present in this ecologically important, but taxonomically neglected group of terrestrial invertebrates.