FLABELLIFERA • CYMOTHOIDAE 169 



Nalicora rapax Moore, 1901 

 Figure 78 



DIAGNOSIS 6 6.9 mm, ovigerous 9 10.0 mm. Eyes well developed. Frontal 

 lamina basally slender, widening anteriorly, apex subacute. Posterior half of 

 body bearing numerous scattered stiff setae. Pereonites 4-7 with row of low 

 rounded tubercles near posterior margin. Posterior margins of pleonites 3-5 

 faintly tuberculate, more noticeable in S . Pleotelson wider than long; lateral 

 margins faintly sinuous; apex rounded. 



RECORDS Florida Keys, 55 m; Puerto Rico, 50-150 m; Gulf of Mexico off 

 Florida, 37-73 m. 



Family Cymothoidae Leach, 1818 



DIAGNOSIS Antennules and antennae reduced, no clear distinction between 

 peduncles and flagella. Mandibular palp of three articles. Maxilla 1 with four 

 terminal spines. Maxilla 2 apically bilobed, armed with several spines. Max- 

 illipedal palp of two articles, terminal article bearing hooks. All seven pairs of 

 pereopods prehensile, ending in strongly hooked dactyli. Pleopods lacking 

 marginal setae in adults. 



REMARKS The cymothoids are exclusively ectoparasites on marine, fresh- 

 water, and brackish-water fishes. Most cymothoids occur in shallow water, 

 mainly in tropical and subtropical areas. The position of attachment on the 

 host (externally, in the buccal cavity, or in the gill chamber) is usually genus- 

 or species-specific. The body of gill parasites is often asymmetrical, being 

 slightly twisted, perhaps an effect of the position on the host. The mouthparts 

 are highly adapted for the parasitic mode of life, while all seven pairs of 

 pereopods are strongly prehensile. The posterior pereopods of some genera 

 have the basal article expanded and carinate, allowing for increased mus- 

 culature. The secretion of anticoagulants in the juvenile stages further aids 

 the blood-feeding habit. The surface area of the pleopods is often increased 

 by the development of lobes on the bases or the lamellae, providing an in- 

 creased respiratory ability. 



The post-mancal juvenile stages (sometimes referred to as the aegathoid 

 stage) have large eyes, and highly setose pleopods for active swimming. The 

 juveniles will attach themselves indiscriminantly to any convenient fish host, 

 but eventually attach to the preferred host-species. The juvenile then de- 

 velops into a functional male, losing the swimming setae of the pleopods. 

 Both juveniles and males feed actively, drawing blood from the host fish. The 



