Molecular phylogeny and systematics of native North American lumbricid earthworms (Clitellata: Megadrili)

Abstract

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 first combined checklist of earthworms of the Northeastern Mediterranean region (Clitellata: Megadrili).

“…Dendrobaena skipetarica Szederjesi & Csuzdi, 2017in: Szederjesi et al 2017b. Dendrobaena ganglbaeri (part.…”

Population Genetic Structure Reveals Two Lineages of Amynthas triastriatus (Oligochaeta: Megascolecidae) in China, with Notes on a New Subspecies of Amynthas triastriatus

“…In recent research, mitochondrial COI, COII, NDI, 12S rRNA and 16S rRNA have been widely used to study the phylogenetic evaluation, mitochondrial diversity and population genetic diversity of earthworm using multivariate concatenation [18,21,[23][24][25][26][27][28][29]. Complete mitochondrial genomes and genomic features of four pheretimoid earthworms (Amynthas longisiphonus, Amynthas corticis, Amynthas gracilis and Metaphire californica) revealed that mitochondrial ATP8 exhibited the highest evolutionary rate and the NADH gene was second to it [30].…”

Earthworms (Oligochaeta: Lumbricidae) of Interior Alaska

“…Two specimen identifications were made using molecular data: those of Aporrectodea caliginosa and Bimastos rubidus (known as Dendrodrilus rubidus prior to Csuzdi et al (2017)), which correspond with the following DNA barcode records on BOLD (Ratnasingham and Hebert 2007): (MOBIL6686-18) and (MOBIL6651-18) respectively. The latter species was also identified using the key in Reynolds (1977).…”

“…Four of these species were documented from opportunistic collections, with the standardised sampling adding one species, Dendrobaena octaedra . At least four of these species are European, or potentially Asian, introductions to North America (Reynolds 2015, Csuzdi et al 2017). One species, Bimastos rubidus , known from the most sites (n=5), is thought to be native to North America (Schwert 1979, Csuzdi et al 2017).…”

“…At least four of these species are European, or potentially Asian, introductions to North America (Reynolds 2015, Csuzdi et al 2017). One species, Bimastos rubidus , known from the most sites (n=5), is thought to be native to North America (Schwert 1979, Csuzdi et al 2017). All of these species had been previously documented from southeast and/or south-central Alaska (Costello et al 2010, Reynolds 2016).…”