FISHERY BULLETIN: VOL. 81, NO. 2 



and the Istiophoridae (Table 7). Three species of the 

 copepod genus Tuxophorus are parasitic on the body 

 surface of species of Scomber vmorus and Acantho- 

 cybium in the Atlantic and Indo-West Pacific Oceans. 

 When the paper by Cressey and Cressey (1980) went 

 to press, these three species, T. cybii, T. cervicornis, 

 and T. collettei, were retained in Tuxophorus because 

 they conformed to the diagnosis of that genus. Subse- 

 quent considerations by the first author lead to the 

 conclusion that they are not members of Tuxophorus 

 but represent a new genus closely related to Gloiopo- 

 tes or are possibly members of Gloiopotes. The pre- 

 sence of frontal lunules on these three species is the 

 only character separating them from Gloiopotes, as it 

 is presently defined. An earlier work on the parasitic 

 copepods of lizardfishes (Cressey and Cressey 1979) 

 gave an example of a caligid genus (Abasia), which 

 showed a transition series of six species with a grad- 

 ual reduction in the frontal lunule from well devel- 

 oped to absent. This indicates the possibility that 

 the presence or absence of the frontal lunule is not 

 always a valid generic character. The genus Tux- 

 ophorus was described by Wilson (1908) for T cali- 

 godes, based on material collected from Atlantic 

 Rachycentron canadus and Echeneis naucrates. The 

 second species, T. wilsoni, was described by Kir- 

 tisinghe (1937) from the carangid, Chorinemus, from 

 Sri Lanka. 



Four of the five species of Gloiopotes are found on 

 the body surface of various species of istiophorids; 

 the fifth, G. hygomianus, is restricted to A, solandri. 

 The occurrence oiGloiopotes on A canthocybium and 

 istiophorids might be used as evidence to support re- 

 lationships between the two groups. The question is: 



TABLE 7. — Host-parasite records for Tux- 

 ophorus cybii, T, collettei, T. cervicornis, and 

 Gloiopotes spp. 



"Are these relationships ecological or phylogenetic?" 

 The morphological similarities between Acanthocy- 

 bium and the Istiophoridae seem best explained as 

 convergences; those between Acanthocybium and 

 Scomberomorus indicate that A canthocybium is the 

 specialized sister-group of Scomberomorus (Fig. 4). 

 Thus, we argue that the presence of Gloiopotes on 

 Acanthocybium and istiophorids is an ecological re- 

 lationship, but that the occurrence of three species of 

 Tuxophorus on Acanthocybium and Scomberomorus 

 reflects shared phylogeny. Support for this argument 

 could come from the presence oiGloiopotes on some 

 open ocean, fast-swimming host but we have no such 

 data. The explanation for the occurrence of species of 

 Gloiopotes only on Acanthocybium and istiophorids 

 must remain uncertain for the present. 



Sardini 



The bonitos consist of eight species placed in five 

 genera (Collette and Chao 1975). Except for Allo- 

 thunnus, the Sardini differ from the Thunnini in lack- 

 ing prominent prootic pits on the ventral surface of 

 the cranium. Collette and Chao (1975:table 14) sum- 

 marized the characters distinguishing the five genera 

 of Sardini. Copepod fauna: 11 species in 5 genera. 

 Caligus bonito has been found on all. Unicolax collat- 

 eral was found in Orcynopsis, Cybiosarda, and two 

 species of Sarda. 



Orcynopsis Gill 



The monotypic Orcynopsis and Cybiosarda show 

 several characters that distinguish them from Sarda 

 and Gymnosarda (Collette and Chao 1975). Orcynop- 

 sis is a short-bodied and short-headed bonito. Orcy- 

 nopsis unicolor (Geoffrey St. Hilaire) is an eastern 

 Atlantic endemic whose range is centered in the Med- 

 iterranean Sea but extends south to Dakar, Senegal, 

 and north to Oslo, Norway (Collette and Chao 1975: 

 fig. 69). Copepod fauna: 1 specimen of U. collateralis 

 and 1 specimen of Caligus bonito. 



Cybiosarda Whitley 



As noted above, the monotypic genera Cybiosarda 

 and Orcynopsis share a suite of characters that differ- 

 entiate them from Sarda and Gymnosarda (Collette 

 and Chao 1975). Cybiosarda elegans (Whitley) is vir- 

 tually an Australian endemic; is found along the 

 northern three-quarters of the continent from Perth, 

 Western Australia, to Sydney, New South Wales 

 (Collette and Chao 1975:fig. 69); and occurs along 

 the south coast of Papua New Guinea (Collette 



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