CLITELLATA (OLIGOCHAETE, LEECH AND BRANCHIOBDELLID)

RELEVANCE TO CLITELLATA View in CoL View at ENA (OLIGOCHAETE, LEECH AND BRANCHIOBDELLID) RELATIONSHIPS

Morphological and molecular support for paraphyly or polyphyly of the Oligochaeta and inclusion within this group of leeches and branchiobdellids has been outlined in the Introduction. Our 28S data are consistent with a leech-branchiobdellid-lumbriculid clade, within the Oligochaeta, less so for a leech-branchiobdellid grouping, considering the variation among methods. Although long branch/rate acceleration/base content has posed problems for the nuclear ribosomal genes analyses, consistency with data of different characteristics (mtDNA and COI) underlines these relationships. The lumbriculid relationship was proposed on morphological grounds by Michaelsen (1928 -1932), Brinkhurst & Nemec (1986), Brinkhurst & Gelder (1989), Brinkhurst (1999a) and, less certainly, by Brinkhurst (1999b) and from molecular data by Siddall & Burreson (1998), Martin (2001) and Siddall et al. (2001). If accepted, the present phylogeny would confirm the Oligochaeta as a paraphyletic group as previously mooted ( Jamieson et al. 1987; Jamieson 1988; Martin 2001), being merely the non-leech, nonbranchiobdellidan clitellates ( Purschke et al. 1993). Inclusion of leeches and branchiobdellids within the Oligochaeta would thus render the name Oligochaeta synonymous with Clitellata (or Euclitellata of Jamieson 1983), as proposed by Siddall et al. (2001) and in a study of molecular phylogeny of the Tubificidae (subsuming the Naididae ) by Erséus et al. (2002).