Phylogeny of oligochaetous Clitellata

Abstract

Clitellata, with more than one third of all annelid species described, is briefly introduced, and an overview of the hypotheses of phylogenetic relationships among the groups traditionally referred to as oligochaetes is given. The presentation is placed in a historical context and describes the trend to move from intuitive, narrative approaches to more formal analyses of character patterns. Monophyly of the earthworms (the megadriles, or Metagynophora sensu Jamieson), or at least a major part of them (Crassiclitellata sensu Jamieson), and paraphyly of the 'microdrile' largely aquatic, groups are supported by both morphological and molecular data. Further, DNA sequences as well as spermatozoal ultrastructure corroborate that all leech-like taxa (Hirudinida, Acanthobdellida and Branchiobdellida) constitute a clade derived within 'Oligochaeta', closely related to the family Lumbriculidae. Molecular systematic studies also support relationships already identified on the basis of morphological data, e.g., the position of Naididae within Tubificidae, the position of Phreodrilidae close to, but outside, the same family, and the putative sistergroup relationship between the newly discovered Capilloventridae and the rest of Clitellata. A recent study using 18S rDNA suggests that Enchytraeidae is closely related to Metagynophora, and that these two taxa, which contain all terrestrial oligochaetous clitellates, form a clade derived from aquatic 'microdriles' This refutes a recent hypothesis proposing that the ancestor of Clitellata was terrestrial. To a great extent, however, the basal resolution of the oligochaetous clitellates remains unclear.

Impact of Environmental Conditions on Bottom Oligochaete Communities in Subsidence Ponds (The Silesian Upland, Southern Poland)

“…The fauna of the subsidence ponds studied was composed of eleven benthic groups (Oligochaeta sensu oligochaetous clitellata (ERSÉUS, 2005), Gastropoda, Bivalvia, Hirudinea, Coleoptera, Heteroptera, Trichoptera, Ephemeroptera, Odonata, Diptera, Isopoda) among which oligochaetes predominated (more than 70% of the total benthic fauna). During the study 17 species representing the families Lumbriculidae (1 species), Enchytraeidae (1 species) and Naididae (15 species), in the new sense (ERSÉUS et al, 2008), were collected and identified.…”

Development and embryonic pattern of body wall musculature in the crassiclitellate Eisenia andrei (Annelida, Clitellata)

“…Homology of the lecitotrophic early embryo would imply multiple loss and reversal in the lineages of Crassiclitellata and Hirudinea considering the current and generally accepted view of phylogeny within Clitellata (Erséus, 2005;Jamieson and Ferraguti, 2006;Sidall et al, 2006). For instance, all hirudineans including erpobdelliform leeches, which develop from oligolecithal eggs, form a derived group within the Hirudinea.…”

“…The phylogenetic relationships among Clitellata are still intensively discussed (Erséus, 2005;Jamieson and Ferraguti, 2006). A clitellum, comprising a single layer of cells, very likely represents the plesiomorphic state in Clitellata and is present in small aquatic oligochaetes often referred to as ''microdriles''.…”

Riverine and riparian clitellates of three drainages in southern Sweden

“…Enchytraeidae is often regarded as a primarily terrestrial group, but it is probably the most ubiquitous of all clitellate families, with its more extreme habitats including glacial ice and deep-sea sediments (Erséus 2005). In the present study, the amphibious nature of many enchytraeid species is manifested, and the inclusion of the riparian zone does not only demonstrate that many enchytraeids prefer wet habitats, it also emphasizes the importance of the river banks in estimating the total species diversity of a river system.…”