A B S T R A C TExotic peregrine earthworms are often considered to cause environmental harm and to have a negative impact on native species, but, as ecosystem engineers, they enhance soil physical properties. Pontoscolex corethrurus is by far the most studied morphospecies and is also the most widespread in tropical areas. The term of morphospecies is used in this review because P. corethrurus may in fact constitute a complex of cryptic species. This earthworm is found in a wide range of habitats, from apparently pristine to any kind of human-disturbed environment. This review synthesizes 265 studies describing the distribution, morphology, biological and ecological traits of this morphospecies, as well as its impacts on soil conditions and communities. We then discuss the characteristics necessary for this specific morphospecies to become a successful colonizer throughout the world and the positive and negative effects it can have on the ecosystems that it has invaded. We emphasize the lack of knowledge of P. corethrurus reproductive mode and ploidy level, of its population genetics, and of the potential existence of cryptic species. To finish, we highlight the fact that data on P. corethrurus interactions with non-earthworm soil macrofauna are scarce.

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.

Following many decades of work on the taxonomy, biology and ecology of the globally-distributed tropical earthworm Pontoscolex corethrurus (Müller, 1857), morphological and molecular data have shown that the stability and effectiveness of nomenclature depends on the designation of a neotype from the type locality. We do that, with all the required justifications, and provide sufficient information to permit the correct identification of this species.

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Pontoscolex corethrurus (Müller, 1857) plays an important role in tropical soil ecosystems and has been widely used as an animal model for a large variety of ecological studies in particular due to its common presence and generally high abundance in human-disturbed tropical soils. In this study we describe the complete mitochondrial genome of the peregrine earthworm P. corethrurus. This is the first record of a mitochondrial genome within the Rhinodrilidae family. Its mitochondrial genome is 14 835 bp in length containing 37 genes (13 protein-coding genes (PCG) 2 rRNA genes and 22 tRNA genes). It has the same gene content and structure as in other sequenced earthworms but unusual among invertebrates it hasseveral overlapping open reading frames. All genes are encoded on the same strand. Most of the PCGs use ATG as the start codon except for ND3 which uses GTG as the start codon. The A+T content of the mitochondrial genome is 59.9% (31.8% A 28.1% T 14.6% G and 25.6% for C). The annotated genome sequence has been deposited in GenBank under the accession number KT988053.

Abstract:Pontoscolex corethrurus (Müller, 1857) plays an important role in soil terrestrial ecosystems and has been widely used as an animal model for a large variety of ecological studies, in particular due to its common presence and generally high abundance in human-disturbed tropical soils. In this study we describe the complete mitochondrial genome of the peregrine earthworm Pontoscolex corethrurus. This is the first record of a mitochondrial genome within the Rhinodrilidae family. Its mitochondrial genome is 14 835 bp in length containing 37 genes (13 protein-coding genes (PCG), 2 rRNA genes and 22 tRNA genes). It has the same gene content and structure as in other sequenced earthworms, but unusual among invertebrates it has several overlapping open reading frames. All genes are encoded on the same strand, most of the PCGs use ATG as the start codon except for NAD3, which uses GTG as the start codon. The T+A content of the mitochondrial genome is 59.9% (31.9% A, 27.9% T, 14.9% G, and 25.3% for C). The annotated genome sequence has been deposited in GenBank under the accession number KT988053.

Pontoscolex corethrurus is a well-known invasive earthworm in tropical zone which is believed to have originated from the Guayana Shield in South America and was described as parthenogenetic. A recent phylogenetic study revealed four cryptic species in the P. corethrurus complex (L1, L2, L3 and L4), among them L1 was particularly widespread and was proposed as P. corethrurus sensu stricto. Here, our aims were to investigate the genetic variation of P. corethrurus L1 in its presumed native and introduced ranges and to examine its reproductive strategy. An extensive dataset of 478 cytochrome oxidase I gene (COI) sequences, obtained in specimens sampled all around the world, revealed a weak COI haplotype diversity with one major haplotype (H1) present in 76% of the specimens. Analyses of the genetic variation of 12 L1 populations were done using both nuclear (226 AFLP profiles) and mitochondrial (269 COI sequences) genetic information. The high AFLP genotype diversity at the worldwide scale and the fact that no genotype was shared among populations, allowed to reject the 'super-clone' invasion hypothesis. Moreover, a similar level of mean genetic diversity indices were observed between the introduced and native ranges, a pattern explained by a history of multiple introductions of specimens from different parts of the world. At last, occurrence of identical AFLPs genotypes (i.e. clones) in several population confirmed asexual reproduction, but recombination was also revealed by gametic equilibrium analysis in some populations suggesting that P. corethrurus L1 may have a mixed reproductive strategy.

Pontoscolex corethrurus (Müller, 1857) plays an important role in soil terrestrial ecosystems and has been widely used as an animal model for a large variety of ecological studies, in particular due to its common presence and generally high abundance in human-disturbed tropical soils. In this study we describe the complete mitochondrial genome of the peregrine earthworm Pontoscolex corethrurus. This is the first record of a mitochondrial genome within the Rhinodrilidae family. Its mitochondrial genome is 14 835 bp in length containing 37 genes (13 protein-coding genes (PCG), 2 rRNA genes and 22 tRNA genes). It has the same gene content and structure as in other sequenced earthworms, but unusual among invertebrates it has several overlapping open reading frames. All genes are encoded on the same strand, most of the PCGs use ATG as the start codon except for NAD3, which uses GTG as the start codon. The T+A content of the mitochondrial genome is 59.9% (31.9% A, 27.9% T, 14.9% G, and 25.3% for C). The annotated genome sequence has been deposited in GenBank under the accession number KT988053.