NO. 3570 PANDARIDAE — CRESSET 3 



segment fused ^\dth cephalon. Thoracic segments 2-4 free. Oral 

 area generally as in female. Legs 1-4 biramose, rami always with long 

 plumose setae. Legs 5 and 6 present. Abdomen 1- or 2-segmented. 

 Caudal rami large. 



Discussion. — Members of the family Pandaridae are generally con- 

 sidered to be parasites of elasmobranch fishes. Occasionally investi- 

 gators report these copepods from teleost fish, but occurrence on such 

 hosts is undoubtedly accidental and does not indicate the true host. 

 The copepods are found on the body surface, cloacal apertiu-e, gills and 

 gill arches, mouth, and nasal passages. Those which are found on the 

 body surface are often heavily pigmented; those in more protected 

 areas are devoid of pigment. 



These parasites are well adapted for attachment to the host, the 

 female more so than the male. The principal attachment structure 

 is the maxilliped. In the case of Perissopus the maxilliped becomes 

 cemented to the host. Adhesion pads scattered over the ventral sur- 

 face of the parasite seem to help resist its sliding over the surface of 

 the host. The pads do not actually attach to the host but rather have 

 surface striations for increased friction. 



Locomotion is usually restricted to the males. The swimming legs 

 of the females are often lamelliform (bearing reduced setae) and prob- 

 ably afford increased area for respiration with a reduction in the 

 swimming function. Males are not so modified and undoubtedly 

 move much more freely than the female. 



The life history of pandarid copepods is still unknown. Wilson 

 (1907) has outlined a composite life history of this group based on 

 fragments of information from various representative caligoids. In 

 general, the life history includes the following stages: egg, nauplius, 

 copepodid, chalimus, and adult. The number of molts between stages 

 is completely unknown for this group. The nauplius is of the usual 

 copepod form with 3 pairs of anterior appendages. This stage is 

 apparently free in the plankton and undoubtedly of short duration. 

 The copepod attaches to the host as a copepodid (=:"metanauplius," 

 Wilson 1907). The second antenna of this stage is greatly enlarged 

 and projects anteriorly. The body of the copepodid is divided into 

 a cephalon, 2 thoracic segments, and a fused genital segment-abdomen 

 with rami attached distally. It is not clear whether this stage lasts for 

 more than 1 molt. The chalimus assumes a body form similar to 

 the adult. Wilson (1907) describes the chalimus stage as seen in 

 Perissopus dentatus. The chalimus stage of caligoid copepods is 

 characterized by the presence of a frontal filament. This is produced 

 by glands in the anterior portion of the cephalon and serves to attach 

 the copepod to the host. Wilson's description includes this structure. 

 I have collected occasional chalimus stages in the genera Pandarus 



