416 EIGHTH PACIFIC SCIENCE CONGRESS 



To illustrate this concept I give herewith a few examples: Family 

 Acanthuridae, surgeon fishes; Acanthurus triostegus ranges from Pacific 

 American region of Clarion, Clipperton and Cocos Islands to the Afri- 

 can east coast. A. triostegus triostegus (Linnaeus) has the color pattern, 

 consisting of a single dark spot at base of pectoral and this form occurs 

 from the Indian Ocean to the American Pacific with the exception of 

 the Central Pacific and the Hawaiian Islands. A. t. marquesensis occu- 

 pies the Marquesas Islands, whereas A. t. sandvicensis occupies the 

 Hawaiian Islands. 



The family Labridae has a so-called wide-ranging species known 

 in the literature as Thalassoma duperry. My studies of specimens in- 

 dicate that T. lucasanum of the American tropical Pacific is closely re- 

 lated to T. duperry of the Hawaiian Islands and that T. marnae of the 

 central equatorial Pacific differs only statistically from T. lucasanum 

 and represents a subspecies. Thus T. duperry and T. lucasanum may 

 be recognized by slight difference in coloration of head and median fins. 

 T. lucasanum normally averages 13 branched pectoral rays whereas T. 

 dupery has 14. Now T. I. lucasanum averages 1 to 2 gillrakers fewer 

 than T. /. marnae. 



Another common labrid Halichoeres hortulanus, formerly consid. 

 ered to range throughout the tropical Indo-West Pacific, actually repre- 

 sents to subspecies or perhaps full species. H. hortulanus of the tropical 

 West Pacific differs from H. centriquadrus of the East African region 

 by lacking a small black caudal spot, always present in H. hortulanus. 



The Moray eels have similar color differences, for example, the 

 common Echidna nebulosa (Ahl) of the tropical Indo-West-Pacific is 

 represented by a subspecies or population at Cocos Island in the Amer- 

 ican Pacific by E. cocosa German, which is differentiated by the blackish 

 bars meeting more fully on the abdomen than for nebulosa. Another 

 eel genus, Uropterygius shows similar close relationships of its numerous 

 species between the American tropical Pacific and the tropical Indo- 

 Pacific. 



Ichthyologists have scarcely begun the study of the relationships o£ 

 the named genera and species in the vast tropical shore faunas of the 

 three oceans. As evidence gradually accumulates, I predict that more 

 and more subfaunal areas will be established in the species and sub- 

 species level but closer relationships will appear on the generic level, 

 if the generic concept continues to include a group of closely related 

 species. 



