Grube, 1844
Type species Lumbricus variegatus Müller, 1774
Number of species 13(?). One species known from NWE:
Lumbriculus variegatus (Müller, 1774)
Description
Medium-sized to large, pigmented worms. Body cylindrical, prostomium without any proboscis. In each postclitellar segment, a pair of blind, branching transversal blood vessels covered with dark chloragogen cells. Chaetae two per bundle, sigmoid with distal nodulus, with smaller but well distinguished upper tooth diverging at an angle of about 300. Position of reproductive system variable in several species and within the same species, with one to four pairs of male pores between VII and XIII. Male pores surrounded by concentric ridges of body wall. Atria cylindrical, covered with prostatic cells. Penis formed of a bundle of thin extended epithelial cells. Usually several pairs of spermathecae in postclitellar segments. Number, position and shape of different reproductive organs very variable. Externally differs from the other lumbriculids in its diverging upper tooth in chaetae. There exist a number of variants of reproductive system in the genus, in some cases within one population, since sexual organs have lost their evolutional value and hence the control of natural selection. In some regions of North America and East Asia, similar variants may be genetically stable, and have been described as separate subspecies, species, or even genera. Therefore the real number of species is unclear.
Burrowing in sediment, crawling fast on the substratum. Able to swim short distances when irritated.
Distribution
Holarctic, Japan; the peregrine Lumbriculus variegatus introduced into some countries in the Southern Hemisphere.
Ecology
In freshwater, particularly among macrovegetation.
Reproduction
At least some species reproduce mainly in an asexual way, by architomy (fragmentation), while mature individuals are rare. Sexual reproduction seems to be common in some other species inhabiting cooler regions. Eggs laid in cocoons.
Literature
Grube, 1844: 207; Cook, 1971a: 202-203; Chekanovskaya, 1981: 412; Hrabe, 1981: 110-111; Kasprzak, 1981: 205-206.