CRESSEY ET AL.: COPEPODS AND SCOMBRID FISHES 



FIGURE 22.— Additive binary matrix based on scombrid relationships. Numbers 1-11 are host taxa and 12-21 are hypothetical 



ancestors represented in Figure 21. 



synplesiomorphous. Node (2) is based on ancestors 

 (2) and (4). Node (1) is an unresolved tricotomy and 

 does not represent a subset of the host phylogeny 

 because it includes Sarda. This node is based on the 

 presence of parasite (4), U. mycterobius. Events 

 which are not shared (autopomorphous) include 

 the acquisition of (1), Unicolax ciliatus in Scomber- 

 omorus; the acquisition of (5), U. reductus and the 

 loss of (2); U. collateralis, in Katsuwonus; and the ac- 

 quisition of (3), U. anonymous, in Euthynnus. The 

 loss of the parasite U. collateralis in Katsuwanus is 

 the only homoplasy in the host by parasite tree. 



The above procedure can also be used to generate a 

 parasite phylogeny by using a data matrix construct- 



ed from information concerning host phylogeny. 

 The parasite host tree (Fig. 25) is rooted at a non- 

 scombrid ancestor based on the assumption that the 

 common ancestor of Unicolax was from a nonscom- 

 brid. This tree (Fig. 25) can be compared with the 

 tree representing parasite phylogeny, which is based 

 on an analysis of parasite morphological characters 

 (Fig. 19). Node (4) on the parasite by host tree (Fig. 

 25) is comparable with node (1) on the parasite phy- 

 logeny (Fig. 19). Unicolax ciliatus is the sister group 

 of all other parasitic taxa in both trees. Node (3) of the 

 parasite by host tree contains all elements of node (2) 

 on the parasite phylogeny; however, U reductus is 

 removed as the sister group of other taxa on the 



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