A numerical revision of the earthworm genus Pheretima auct. (Megascolecidae: Oligochaeta) with the recognition of new genera and an appendix on the earthworms collected by the Royal Society North Borneo Expedition

Four new earthworm species of the genera Amynthas and Metaphire (Oligochaeta, Megascolecidae) from Hunan and Anhui provinces, China

This paper describes four new species earthworms from Hunan and Anhui provinces, China, Amynthasxiangtanensis Qiu & Jin, sp. nov., Amynthastaoyuanensis Qiu & Jin, sp. nov., Amynthasxuanchengensis Jin & Li, sp. nov. and Metaphiredonganensis Jin & Jiang, sp. nov. Amynthasxiangtanensis sp. nov., and A.taoyuanensis sp. nov. belong to the Amynthascorticis group. Both have four pairs of intersegmental spermathecal pores in 5/6-8/9; male pores in segment XVIII, separated by 1/3 of body circumference, each on top of a slightly raised porophore, surrounded by several tiny genital papillae. Amynthastaoyuanensis sp. nov. prostate glands are degenerated. Amynthasxuanchengensis sp. nov. belongs to the Amynthasmorrisi group, it has two pairs of spermathecal pores in 5/6 and 6/7; male pores in XVIII, separated by 1/3 of body circumference, each on top of a slightly raised, circular porophore. Metaphiredonganensis sp. nov. belongs to the Metaphirehoulleti group. It has three pairs of spermathecal pores in 6/7-8/9; male pores in XVIII, separated by 1/3 of body circumference, each on the bottom center of the longitudinal copulatory chamber.

Acceleration of genome rearrangement in clitellate annelids

Comparisons of multiple metazoan genomes have revealed the existence of ancestral linkage groups (ALGs), genomic scaffolds sharing sets of orthologous genes that have been inherited from ancestral animals for hundreds of millions of years (Simakov et al. 2022; Schultz et al. 2023) These ALGs have persisted across major animal taxa including Cnidaria, Deuterostomia, Ecdysozoa and Spiralia. Notwithstanding this general trend of chromosome-scale conservation, ALGs have been obliterated by extensive genome rearrangements in certain groups, most notably including Clitellata (oligochaetes and leeches), a group of easily overlooked invertebrates that is of tremendous ecological, agricultural and economic importance (Charles 2019; Barrett 2016). To further investigate these rearrangements, we have undertaken a comparison of 12 clitellate genomes (including four newly sequenced species) and 11 outgroup representatives. We show that these rearrangements began at the base of the Clitellata (rather than progressing gradually throughout polychaete annelids), that the inter-chromosomal rearrangements continue in several clitellate lineages and that these events have substantially shaped the evolution of the otherwise highly conserved Hox cluster.

Four new terrestrial earthworm species from the northeast Thailand (Oligochaeta, Megascolecidae)

Earthworm specimens collected from Sakon Nakhon and Nakhon Phanom, northeast Thailand, were found to contain four new species in the family Megascolecidae, with one species in the genus Metaphire Sims & Easton, 1972, and the other three in the genus Amynthas Kinberg, 1867. These are herein named Metaphiresongkhramensis Chanabun & Panha, sp. nov. in the sexthecal houlleti species group, and Amynthassakonnakhonensis Chanabun & Panha, sp. nov., A.auriculus Chanabun & Panha, sp. nov., and A.bantanensis Chanabun & Panha, sp. nov. in the sexthecal aelianus species group. Metaphiresongkhramensis Chanabun & Panha, sp. nov. occurs in dark clay soil of the oxbow lake of the river, Amynthassakonnakhonensis Chanabun & Panha, sp. nov. occurs in wetland area, A.auriculus Chanabun & Panha, sp. nov. occurs in dark sandy loam habitats of mixed deciduous forest while the following species, A.bantanensis Chanabun & Panha, sp. nov. occurs in sandy loam habitats of paddy fields. Descriptions of the new species, including illustrations of the external and internal morphological characteristics, are provided.

Origin and diversification of pheretimoid megascolecid earthworms in the Japanese Archipelago as revealed by mitogenomic phylogenetics

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.

The complete mitochondrial genome of the Korean endemic earthworm Amynthas deogyusanensis (Clitellata: Megascolecidae)

The Korean endemic earthworm Amynthas deogyusanensis Hong and James, 2001 (Clitellata: Megascolecidae) is found in the forest area of Deogyu Mountain, South Korea. In this study, the complete mitochondrial genome (mitogenome) of A. deogyusanensis was sequenced, assembled, and annotated. The mitogenome of A. deogyusanensis is a circular DNA molecule, consisting of 15,257 bp with an A + T content of 67.9%. It contains 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and one non-coding region (control region). Phylogenetic analysis suggested that the family Megascolecidae is a monophyletic group with full support, whereas the genus Amynthas is non-monophyletic with the genera Metaphire and Duplodicodrilus.

A new species of New Guinea Worm-Eating Snake (Serpentes, Elapidae, Toxicocalamus Boulenger, 1896) from Western Highlands Province, Papua New Guinea

We describe a new species of New Guinea Worm-Eating Snake (Elapidae: Toxicocalamus) from a specimen in the reptile collection of the Papua New Guinea National Museum and Art Gallery. Toxicocalamus longhagensp. nov. can be easily distinguished from other species of this genus by the presence of paired subcaudals, a preocular scale unfused from the prefrontal scale, a prefrontal distinct from the internasal scale that contacts the supralabials, a single large posterior temporal and two postocular scales. The new taxon is currently known only from one specimen, which was collected from Mt. Hagen Town in Western Highlands Province, Papua New Guinea in 1967. The new species was originally identified as T. loriae, but the unique head scalation and postfrontal bone morphology revealed through micro-computed tomography scanning easily distinguish the new species from T. loriaesensu stricto. This is the first species of this genus described from Western Highlands Province.

Two new Drawida (Oligochaeta, Moniligastridae) earthworms from Vietnam

Two new earthworm species are described, namely Drawidaangiang sp. nov. and Drawidacochinchina sp. nov. The former can be recognized by having male pores on spiniform penises in intersegment 10/11, an erect and sac-shaped spermathecal atrium, glandular prostate, the capsule coiled one round, the vas deferens strongly coiled but small, two large, round, genital markings on segments ix-x, and three gizzards in xiii-xv. The latter species is distinguished in having the male pores placed on highly elevated, backwardly directed, conical penises in 10/11, a slender spermathecal atrium, a glandular prostate, a somewhat folded capsule, the vas deferens strongly coiled as a bunch and equal size to the testis sacs, a pair of genital markings located closely anterior to the penises with 1-3 additional ones in xi-xii, and three or four gizzards in xiii-xvi. The DNA barcode fragment of the COI gene was extracted for each species, and the COI genetic distances and phylogenetic analysis also supported two new species..

DNA Barcoding: Molecular Identification and Phylogenetic Analysis of Pheretimoid Earthworm (Metaphire sp. and Amynthas sp.) Based on Mitochondrial Partial COI Gene from Sialkot, Pakistan

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.

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

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

The megascolecid earthworms (Annelida, Oligochaeta, Megascolecidae) in the Phu Quoc island, Vietnam, with descriptions of three new species

The megascolecid earthworms of the Phu Quoc island are intensively investigated. Twelve species in three genera (Lampito Kinberg, 1867, Amynthas Kinberg, 1867, and Metaphire Sims & Easton, 1972) are recorded. Of these, Metaphiredoiphamon Bantaowong & Panha, 2016 is recorded for the first time in Vietnam, and three species are newly described, namely Amynthascatenatussp. nov., A.phuquocensissp. nov., and A.poropapillatussp. nov. An identification key to 12 megascolecid species is provided as well.

Characterization of the complete mitochondrial genome of Drawida gisti (Metagynophora, Moniligastridae) and comparison with other Metagynophora species

Here, the complete mitochondrial genome (mitogenome) of Drawida gisti was sequenced and compared with the mitogenomes of other Metagynophora species. The circular mitogenome was 14,648 bp in length and contained two ribosomal RNA genes (rRNAs), 13 protein-coding genes (PCGs), and 22 transfer RNA genes (tRNAs). The types of constitutive genes and the direction of the coding strand that appeared in Drawida mitogenome were identical to those observed in other Metagynophora species, except for a missing lengthy non-coding region. The conservative relationships between Drawida species were supported by the overall analyses of 13 PCGs, two rRNAs, and 22 tRNAs. A comparison of the Metagynophora mitogenomes revealed that the ATP8 gene possessed the highest polymorphism among the 13 PCGs and two rRNAs. Phylogenetic analysis suggested that the Moniligastridae contained Drawida, which is a primitive Metagynophora group. Our study provides a step forward toward elucidating the evolutionary linkages within Drawida and even Metagynophora.

Modification by earthworms of effects of soil heterogeneity and root foraging in eight species of grass

Spatial heterogeneity of soil nutrients and earthworm activity can each increase the performance of plant species, but their interactive effects have been little studied. The ability of plants to forage for nutrients by concentrating roots where nutrients are concentrated can partly explain the positive effects of nutrient heterogeneity, but whether root foraging can help explain the positive effects of earthworm activity is untested. We conducted a greenhouse experiment in which we grew eight species of Poaceae in homogeneous and heterogeneous soils with or without the earthworms Eisenia fetida and Metaphire guillelmi and measured net accumulation of plant mass and tillers. Effects of heterogeneity and earthworms on plant performance were positive in most species. The presence of earthworms reduced the directly measured effect of heterogeneity on total mass in some grass species. Most species showed root foraging ability. Ability showed no relationship to effects of heterogeneity or earthworms on final total dry mass. However, earthworms reduced foraging in some species, possibly by lessening heterogeneity. Earthworm activity in heterogeneous soil may thus reduce the benefits of root foraging for nutrients in plants.

Three new species and one subspecies of the Amynthas corticis-group from Guangxi Zhuang Autonomous Region, China (Oligochaeta, Megascolecidae)

Three new species and one subspecies of the genus Amynthas are described from Guangxi Zhuang Autonomous Region, China: The new species are: Amynthas maximus Qiu & Dong, sp. nov. and Amynthas tortuosus Qiu & Dong, sp. nov., and Amynthas shengtangmontis Dong & Jiang, sp. nov., the subspecies is Amynthas shengtangmontis minusculus subsp. nov. All have four pairs of spermathecal pores in 5/6-8/9, which indicates that they should belong to the corticis-group. Their morphological characteristics are compared to other similar species in the corticis-group from China and other Asian countries, such as Amynthas pulvinus Sun & Jiang, 2013, Amynthas homosetus (Chen, 1938), Amynthas corticis (Kinberg, 1867), Amynthas dorsualis Sun & Qiu, 2013, and Amynthas carnosus (Goto & Hatai, 1899). In addition, the results presented are confirmed by the pairwise comparison of COI barcode sequences. The pairwise distances between each new species and the other eighteen corticis-group species are greater than 14.7% on average. Furthermore, the pairwise distance between A. shengtangmontis shengtangmontis and A. shengtangmontis minusculus is 10.7-11.4%.

Nguyen. Three new "caecate" earthworm species from Sulawesi, Indonesia (Oligochaeta, Megascolecidae)

Three new earthworm species are described from Sulawesi, Indonesia. Two belong to the genus Pithemera Sims & Easton, 1972, namely P.suwastikai Fahri, Amaliah & Atmowidi, sp. n. and P.tadulako Fahri, Amaliah & Atmowidi, sp. n. The new species, P.suwastikai sp. n. is distinguished by a medium size (135-165 mm long, 4.5-6.5 mm diameter), four pairs of spermathecal pores in 5/6/7/8/9, 7-12 setae between male pores, no genital markings, holandry, and simple intestinal caeca. Pithemeratadulako sp. n. is recognized by a large size (217-340 mm long, 13-15 mm diameter), two pairs of spermathecal pores in 7/8/9, no setae between male pores, no genital markings, holandry, and simple intestinal caeca. Another new species, Metaphirerusydii Fahri, Amaliah & Nguyen, sp. n., is diagnosed by its large size (250-280 mm long,12-16 mm diameter), two pairs of spermathecal pores in 7/8/9, no setae between male porophores, presence of genital markings in the male region, holandry, and complex intestinal caeca. Additionally, an identification key to "caecate" species is provided to the Sulawesi's fauna.

Structural equation model of the relationship between metals in contaminated soil and in earthworm (Metaphire californica) in Hunan Province, subtropical China

Earthworms have the ability to take up heavy metals in soil and partition them in different subcellular compartments. In this study, we used a structural equation model (SEM) to investigate the two-step causal relationship between environmental availability (EA) and environmental bioavailability (EB) of heavy metals (Cd, Cu, Zn, and Pb), as reflected by their levels in soil fractions and in earthworms from field-contaminated areas in Southern China. In the SEM, the correlation between EA and EB reflected the bioavailability of Cd, Zn, and Pb. For Cd, the causal relationship between the latent variables EA and EB was reflected by DTPA fractions in soil as well as by earthworm internal and subcellular cytosol fractions. The extractable and oxidizable fractions of Zn in soil influenced Zn concentrations in the cytosol and debris. The DTPA and reducible Pb fractions were bioavailable to earthworm internal Pb concentrations and those in cytosol fractions. These results implied that the DTPA, extractable, oxidizable, or reducible fractions of different metals could be the bioavailable sources to earthworm internal metals and partitioned in their subcellular compartments.

Phylogenetic evaluation of Amynthas earthworms from South China reveals the initial ancestral state of spermathecae

Our knowledge of the phylogeny of the earthworm genus Amynthas under the family Megascolecidae, which is comprised of a huge number of species, is very limited compared to the better-known and much smaller family Lumbricidae. In order to investigate the phylogenetic relationships among the species within the genus Amynthas, which is the largest genus of the Megascolecidae family, nuclear and mitochondrial DNA sequences of 77 species, including 76 in-group Amynthas species collected from South China and 1 out-group species, were analyzed. A 5402bp segments composed of whole nuclear 18S rDNA and the mitochondrial genes COI, COII, ND1, 12S, and 16S was assembled from 77 species. Maximum Likelihood and Bayesian analyses of the concatenated sequences were performed. The results revealed evolution of two geographically independent lineages, both showing the ancestral state of two pairs of spermatheca (Sp.p 7/8/9). We found the species groups described by Sims and Easton (1972) to be non-monophyletic, and the origin of the parthenogenetic species group to likely be a quadthecal ancestor. These results provide modest evidence in support of an Indochinese peninsula origin of the Chinese Amynthas species and divergence of the genus once it had spread to mainland China. The findings of this study are consistent with a divergence scenario that resulted in at least one branch spreading to the Southeast of China and another branch spreading to the Southwest of China, but further research is required to confirm this interpretation of the Amynthas phylogeny.

Land-use change on Mount Gede, Indonesia, reduced native earthworm populations and diversity

The conversion of natural forest to agroforestry plantations and annual cropping systems alters the soil habitat and food resources for biota, including earthworms. Native earthworm species may disappear whereas exotic species with greater tolerance of disturbance and less niche specialisation may thrive. The objective of the study was to compare the earthworm diversity in managed forest and agroforestry systems, which were cultivated for mixed plantation and annual crop production on Mount Gede, Indonesia. All the habitats in the study area were impacted by humans. The forest habitat was a managed forest, with a permanent tree cover, whereas mixed plantation had a partial shrub cover. Meanwhile, homogenous plantation was cultivated with annual crops. Among 3787 individuals collected during July–October 2012, five Oriental earthworm species were identified in the soil communities of Mount Gede: Drawida nepalensis, Notoscolex javanica, Pheretima pura-group, Polypheretima moelleri, and Polypheretima sempolensis. Also, 18 species were found that are reported to be non-Oriental in origin. Anthropogenic disturbance of forests on Mount Gede, due to conversion into plantations, alters the earthworm environment by increasing soil water content, temperature and total phosphorous content, while decreasing organic carbon. N. javanica was the only native species to survive this deforestation, while the exotic Ocnerodrilus occidentalis and Pontoscolex corethrurus thrived, becoming the eudominant species. From the forest area to the mixed and homogenous plantations, the predicted decreasing diversity is evidenced by the lowering trend of Shannon’s diversity index. In conclusion, the land-use change into mixed plantations and annual croplands has reduced earthworm diversity in this region of Mount Gede, Indonesia.

Fifteen new earthworm mitogenomes shed new light on phylogeny within the Pheretima complex

The Pheretima complex within the Megascolecidae family is a major earthworm group. Recently, the systematic status of the Pheretima complex based on morphology was challenged by molecular studies. In this study, we carry out the first comparative mitogenomic study in oligochaetes. The mitogenomes of 15 earthworm species were sequenced and compared with other 9 available earthworm mitogenomes, with the main aim to explore their phylogenetic relationships and test different analytical approaches on phylogeny reconstruction. The general earthworm mitogenomic features revealed to be conservative: all genes encoded on the same strand, all the protein coding loci shared the same initiation codon (ATG), and tRNA genes showed conserved structures. The Drawida japonica mitogenome displayed the highest A + T content, reversed AT/GC-skews and the highest genetic diversity. Genetic distances among protein coding genes displayed their maximum and minimum interspecific values in the ATP8 and CO1 genes, respectively. The 22 tRNAs showed variable substitution patterns between the considered earthworm mitogenomes. The inclusion of rRNAs positively increased phylogenetic support. Furthermore, we tested different trimming tools for alignment improvement. Our analyses rejected reciprocal monophyly among Amynthas and Metaphire and indicated that the two genera should be systematically classified into one.

Notes on Metaphire multitheca (Chen, 1938) (Oligochaeta, Megascolecidae) recorded from Vietnam, with descriptions of two new species

The paper deals with Pheretimamultithecamultitheca Chen, 1938 recorded from Vietnam (non Pheretimamultitheca Chen, 1938 now in Metaphire from Hainan Island). As a result, a new species, Amynthaserroneoussp. n., is revealed from materials which were previously misidentified as Pheretimamultithecamultitheca. The new species is obviously distinguished from other Amynthas species by multiple spermathecal pores lateroventral in intersegments 5/6/7/8/9, and presence of two pairs of crescentic genital markings in xviii. In addition, another new species, Amynthasnhonmontissp. n., is described and easily recognized by multiple spermathecal pores ventral in intersegments 5/6/7/8 and three pairs of genital markings in xvii, xix and xx.

Complete mitochondrial genome of a Pheretimoid earthworm Metaphire vulgaris (Oligochaeta: Megascolecidae)

We have determined the mitochondrial genome of the first Pheretimoid earthworm, Metaphire vulgaris (Chen, 1930). This mitogenome is 15,061 bp in length containing 37 genes typical of other annelid. All genes are encoded by the same strand, ATP8 is not adjacent to ATP6, all 13 PCGs use ATG as a start codon. These features are consistent with first determined earthworm Lumbricus terrestris, but unusual among animal mtDNAs.

Two new Korean earthworms (Annelida, Oligochaeta, Megadrilacea, Megascolecidae)

Two Korean endemic pheretimoid Amynthas Kinberg, 1867 species belonging in family Megascolecidae s. stricto are sketched, dissected and described. Amynthas daeari Blakemore sp. n. has spermathecae in 6/7/8 complying with an Amynthas tokioensis spp-group, whilst Amynthas jinburi Blakemore sp. n. has spermathecal pores in 5 & 6 strictly complying with Sims and Easton's (1972)Amynthas canaliculatus-group. A definitive COI gene barcode is provided for the holotype of Amynthas daeari but the age since collection or preservation of the Amynthas jinburi type in 2000 precluded its mtDNA extraction at this time.

A global survey of the bacteria within earthworm nephridia

Earthworms comprise 16 described families in the Crassiclitellata plus a few other minor groups. Microscopy studies of the early 20th century detected bacteria within the excretory organs, the nephridia, of species within a few of these families. More recent evidence for the consistent and specific association of bacteria with nephridia within the Lumbricidae has been well documented, but the presence and identity of nephridial bacteria among the rest of the Crassiclitellata families had not been explored. The study presented here aimed to identify members of Crassiclitellata families that harbor bacteria in their nephridia, and identify these bacteria based on 16S rRNA gene sequences. Eleven earthworm families were surveyed from countries of six continents, and two island nations. The results revealed members of four bacterial orders commonly occurred within nephridia of genera within nine Crassiclitellata families. Members of the bacterial phyla Bacteroidetes (order Sphingobacteriales), Betaproteobacteria (order Burkholderiales; family Comamonadaceae), and Alphaproteobacteria (orders Rhodospirillales and Rhizobiales) were detected in the nephridia of basal Crassiclitellata, as well as in derived families. Earthworm genera with meronephridia, multiple small nephridia per segment, lacked bacteria, whereas bacteria were often detected in holonephridia, single pairs of large nephridia with a distinct morphology and external excretory pore. The Acanthodrilidae members, a large derived family of earthworms, did not appear to possess nephridial bacteria regardless of nephridial form. Although earthworms from a variety of habitat types were sampled, there were no clear correlations of lifestyle with symbiont types, with the exception of the aquatic earthworms that contained bacteria unrelated to those in any other earthworms. The findings support an evolutionarily long association of bacteria within the Crassiclitellata, and suggest a contribution to nitrogen conservation for the earthworms.

Molecular phylogeny of earthworms (Annelida:Crassiclitellata) based on 28S, 18S and 16S gene sequences

Relationships among, and content of, earthworm families have been controversial and unstable. Here we analyse molecular data from 14 Crassiclitellata families represented by 54 genera, the non-crassiclitellate ‘earthworms’ of the Moniligastridae, plus several clitellate outgroups. Complete 28S and 18S gene sequences and a fragment of the 16S gene analysed separately or in concatenated Bayesian analyses indicate that most previously proposed suprafamilial taxa within the Crassiclitellata are para- or polyphyletic. There is strong support for the Metagynophora, which consists of the Crassiclitellata and Moniligastridae. The most basal within-Clitellata branch leads to the small families Komarekionidae, Sparganophilidae, Kynotidae, and Biwadrilidae, found in widely separated areas. A clade composed of Lumbricidae, Ailoscolecidae, Hormogastridae, Criodrilidae and Lutodrilidae appears near the base of the tree, but Criodrilidae and Biwadrilidae are not closely related because the former is sister to the Hormogastridae + Lumbricidae clade. The Glossoscolecidae is here separated into two families, the Glossoscolecidae s.s. and the Pontoscolecidae (fam. nov.). The Megascolecidae is monophyletic within a clade including all acanthodrilid earthworms. There is strong support for the Benhamiinae (Acanthodrilidae s.l.) as sister to Acanthodrilidae + Megascolecidae, but taxon sampling within other acanthodrilid groups was not sufficient to reach further conclusions. The resulting trees support revised interpretations of morphological character evolution.’

New earthworm species of the genus Amynthas Kinberg, 1867 from Thailand (Clitellata, Oligochaeta, Megascolecidae)

Four new species of terrestrial earthworms from the zebrus-group in the genus Amynthas Kinberg, 1867, are described from Nan province, north Thailand: Amynthas phatubensissp. n., from Tham Pha Tub Arboretum, Amynthas tontongsp. n., from Tontong Waterfall, Amynthas borealissp. n., from Chaloemprakiat district, and Amynthas srinansp. n., from Srinan National Park.After comparing with the two closely related Laos species Amynthas chandyi Hong, 2008 and Amynthas namphouinensis Hong, 2008, the four new species show clear morphological differences, and also it is confirmed that there are no previous records of the species described here. Amynthas phatubensissp. n. is the largest (longest) sized of these earthworms and is the only species that lives in limestone habitats. The genital characters are different among them and also from the two Laotian species. Molecular systematics would be a good method for further analysis of the diversity and species boundaries in SE Asian Amynthas.