DESCRIPTION OF THE LIFE-HISTORY STAGES OF AMPHIASCUS-UNDOSUS LANG (COPEPODA, HARPACTICOIDA)

The six naupliar and six copepodite stages of the harpacticoid copepod Amphiascus undosus Lang are described in detail. Thoracic leg segmentation and armature are presented in tabular form for the copepodite stages. The species becomes sexually dimorphic at the fourth copepodite stage. Average egg-to-adult development time is approximately 31.5 days at 22-degrees +/- 1-degrees-C. Up to four successive pairs of egg sacs from a single female are produced in the laboratory, yielding a maximum of 76 progeny. Some discrepancies exist between the original description of the California type specimens and the present British Columbia material, particularly in the adult male maxillule, maxilliped, and first, fifth, and sixth legs, and the caudal setae of the adult female. A brief comparison is made with the developmental similarities and differences of six other diosaccid harpacticoid copepods.