Varechaetadrilus fulleri (Oligochaeta: Tubificidae): New record and amendment of morphological description

Abstract

The tubificid worm Variechaetadrilus fulleri (Annelida: Oligochaeta) was described by Brinkhurst and Kathman (1983) from the Green River, Kentucky, the only locality from which the species has previously been reported. In 1982-84, a number of specimens of V. fulleri were found in the lower Mississippi River and in an adjacent oxbow lake (Eagle Lake), about 19 river kilometers northwest of Vicksburg, Mississippi. In the lake, the species was collected in the inshore 1-m depth zone but not at 1.6-m depths offshore, where the waters stratified thermally in July and August and the dissolved oxygen concentration sometimes fell to 0.5 mg/liter in the hypolimnion. The collection of sexually mature worms in the river in May 1982 and in Eagle Lake in January-February 1984 enabled us to describe anatomical details that refine the description of the species.