20 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



conclude that only one species is involved and that all the specimens 

 represent R. corallophilus. 



Method of collection and eelation to host. — Rhynchomolgus 

 corallophilus apparently lives mside the polyps of the coral. When 

 pieces of the coral were washed intact in alcoholized sea water within 

 one or two hours after being brought into the laboratory, none of 

 these copepods were obtained. After allowing the coral to remain 

 overnight in the alcoholized sea water, considerable numbers were 

 recovered from the sediment. After subsequently crushing the 

 coral, stUl more R. corallophilus were found. 



Systematic position of the new genus. — ^Several features of the 

 female of Rhynchomolgus suggest that the genus belongs to the famUy 

 Lichomolgidae. The mandible is lichomolgid in form, resembling 

 rather closely that of Lichomolgus rhadinus. The second antenna, 

 labrum, first maxilla, second maxilla, and maxilliped are also basically 

 lichomolgid. The 5-segmented first antenna has fewer segments 

 than in most other lichomolgid genera (where the number of seg- 

 ments is commonly seven). Apparently the reduction in the number 

 of segments in Rhynchomolgus has involved the loss of segments 3 and 4, 

 since the arrangement of the setae and aesthetes on the five segments 

 corresponds rather closely (particularly on segments 3-5) to the 

 pattern seen on segments 1, 2, 5, 6, and 7 of the 7-segmented first 

 antenna of Lichomolgus and other lichomolgid genera. 



There are obvious differences in legs 1-4 between the female of 

 Rhynchomolgus and other lichomolgid genera, but these may be 

 attributed to reduction associated with a parasitic way of life. Ke- 

 duction of legs 1-4, so pronounced in both sexes of Rhynchomolgus, 

 is known to occur to a lesser extent in certain other parasitic or 

 associated lichomolgid genera, for example, in Meomicola Stock, 

 Humes and Gooding, 1964, and in a new genus from zoanthid coe- 

 lenterates whose description by Humes and Ho is in press. 



Since the male of Rhynchomolgus lacks mandibles, paragnaths, and 

 first maxillae, it is more difficult in this sex to demonstrate lich- 

 omolgid affinities. The sexual dimorphism seen in the first antenna, 

 second antenna, second maxilla, and maxUliped makes comparison 

 uncertain. However, following our opinion expressed above on the 

 specific identity of the males and females, the males are included with 

 the females as one species in the lichomolgid genus Rhynchomolgus. 

 As far as known, no other genus of the Lichomolgidae lacks mandibles, 

 paragnaths, and first maxillae in the male. 



