Glossiphonia group

Glossiphonia group

Mark E. Siddall *

___.__ Alboglossiphonia heteroclita
   |___.___.__ Glossiphonia complanata
       |   |___ Glossiphonia complanata
       |___.___ Torix_baicalensis
           |___.___ Glossiphonia complanata
               |___ Glossiphonia complanata

Based on: CO-I, ND-1, and morphology in Light and Siddall, 1998
Discussion of Relationships

The genera Glossiphonia, Alboglossiphonia, and Torix all are members of a larger clade that also includes Hemiclepsis marginata and Theromyzon species. Noticeably, all leeches in this group have multiple pairs of eyes and three pairs of eyes appears to be the original condition although it has been modified at least twice. There is an increase to four pairs of eyes for Theromyzon species and an apparent reversion to two pairs for T. baicalensis . This leech, endemic to Lake Baikal, was described as having two pair of eyes instead of three (Blanchard, 1849; Sawyer, 1986), but it is clearly positioned within the G. complanata clade. It is possible that the first pair of eyes may be compound rather than one large pair.Following further examination of new specimens, the genus Torix may well fall into synonymy with the genus Glossiphonia.
The fact that T. baicalensis falls out between the European and the North American representatives of G. complanata suggests that these two geographic isolates might be distinct species. There are morphological differences, such as the separation of gonopores, and substantial genetic differences between European and North American G. complanata species. Although no other species disrupts the H. stagnalis clade, the genetic differences between the H. stagnalis from Ohio and from Britain are approximately the same as the genetic differences between European and North American G. complanata . In CO-I, there are 53 nucleotide differences between the two specimens of H. stagnalis whereas there are 65 and 64 nucleotide changes between the two localities for G. complanata (and only five differences between the two European spe cimens and only eight differences between the two North American specimens). Differences from the ND-1 data are similar. Sixty-four nucleotide changes are found between the H. stagnalis specimens from Ohio and from Britain, whereas there are 53 and 56 nucleotide changes between G. complanata from Europe (but only six changes between the two specimens) as compared to G. complanata from North America (with only seven changes between these new world representatives of G. complanata).

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Mark E. Siddall
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