Branchiodrilus hortensis, een nieuwe exotische borstelworm in Nederland (Annelida: Oligochaeta)

Branchiodrilus hortensis, an exotic worm new for the Dutch fauna (Annelida: Oligochaeta) The peculiar naidid worm Branchiodrilus hortensis (Stephenson, 1910) is recorded new for the Netherlands. In 2002 and 2003 several specimens were collected from three localities in and near the Giessen, a small, slow-flowing river near Gorinchem (province of Zuid-Holland). In 2004 numerous specimens were collected in the small river Aa in the city of Den Bosch (province of Noord-Brabant). These freshwater localities (Cl 50-143 mg/l) are eutrofic, slightly alkaline (pH 7.3-8.6) and with a reasonable oxygen-level (saturation > 70%). Branchiodrilus hortensis is known from southern Asia, Australia and Africa. It is not known how this species has become introduced into the Netherlands, but exotic water plants from gardens are a likely vector. These records are the first in Europe.