Table 5.- — Percentage of specimens of 16 marine species of needlefishes infested by 10 species of copepods 



lones is replaced by a derivative species in the east- 

 em Pacific — P. constrietu-s. This copepod is 

 abundant on all six eastern Pacific needlefishes and 

 has also been found on four other sjiecies of in- 

 shore fishes in two different families. These two 

 copepods seem to be found on wliatever needlefish 

 is available and may also occur on non-needlefish 

 hosts. 



Host-Parasite Distribution 



To summarize the known distributions of needle- 

 fishes and their copepods and to contrast the dis- 

 tribution of a ^iven species of needlefish with its 

 associated copepods, 12 maps were prepared. Six 

 maps (figs. 175-180) were made for the needle- 

 fishes: one for each of the four worldwide species 

 {Ahlennes Mams, Platyhelone argalus, Tylosurus 

 acus, and T. crocodil/as) ; one for the 11 marine 

 species of Strmigylura; and one for the fresh- 

 water species of needlefislies and fresh- water pop- 

 ulations of primarily marine si^ecies of 

 StrongyJura. Six maps (figs. 181-186) of copepod 

 distributions were also made: Caligodes 1-acinia- 

 tus; C olohomatus goodingi; Lertuvnthrojnis he- 

 lones and L. tylosvri; the four species of 

 Parabomolochus; Nothohomolochus gibber and IV. 

 digitatus; and the nine species of Ergasilidae. Tiie 

 needlefish maps are based on all of the specimens 

 of needlefishes examined by Collette for his revi- 

 sionary studies. The copepod maps are based on 

 all of the copepods collected for this study. Not 

 all of the needlefishes were examined for copepods 

 so the needlefish maps have greater coverage than 



the copepod maps. Less abundant species of both 

 needlefishes and copepods were not mapped. The 

 75° F. (23.9° C.) or 80° F. (26.7° C.) sea surface 

 isotheres from Hutcliins and Scharff (1947) are 

 plotted on the 10 maps of marine species. These 

 isotheres delimit the ranges remarkably well ex- 

 cept along part of the mainland coasts where in- 

 shore sfjecies of Strongykira can move beyond the 

 limits of the isothere. 



In general, copepod distributions correspond to 

 needlefish distributions. Most of the widely dis- 

 tributed species extend as far north and south 

 as their hosts. Tliere is, however, one striking ex- 

 ception : Colobomatus goodingi is restricted to 

 warmer waters than its hosts— 80° F. (26.7° C.) 

 rather than 75° F. (23.9° C.) isotheres (Hutchins 

 and Scharff, 1947). This difference is clearest in 

 the western Atlantic where Colobomatus is con- 

 fined to the region of the Gulf of Mexico and 

 Caribbean Sea (lat. 10-30° N.— fig. 182). Although 

 one of its primarj' hosts, Sti'ongylura notata (fig. 

 179), has a similar restriction, other major hosts 

 such as ;S^. marina, S. timitcu. and T. e?'ocodiIus 

 (figs. 178, 179) range much farther to the north 

 (past lat. 40° N.) and south (past lat. 20° S.). 



Lernanfhropus belones has an apparent gap in 

 distribution (fig. 183). Both L. belones and L. 

 tylosuri seem to be equally common throughout 

 the world except for the eastern Atlantic and 

 western Indian Oceans wiiere we liavc found only 

 L. tylosuri. We believe this break is primarily due 

 to the lack of proper hosts for L. belones in these 

 /S7/'o«^y?Mra-deticient regions. The eastern Atlan- 



COPEPODS AND NEEDLEFISHES 



409 



