FISHERY BULLETIN: VOL. 69, NO. 3 



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Figure 1. — lago omanensis, from a 565-mm female deposited in U.S. National Museum. Drawing by Mildred 



H. Carrington. 



lago GENUS NOVUM 



Eiigaleus omanensis NORMAN, 1939, 

 TYPE-SPECIES 



Etymology 



This shark, a namesake of the villain of 

 Shakespeare's Othello, is a troublemaker for 

 systematists and hence a kind of villain. 



Diagnosis (Terminology Follows Compagno, 

 1970) 



lago (Figure 1) differs from most carchar- 

 hinoids in the extremely anterior origin of its 

 first dorsal fin. Only Isogomphodon oxyrhyn- 

 chus, a few species of Carcharinus, and the 

 sphyrnid Eusphyra blochii rival lago in this 

 respect. 



lago is morphologically intermediate bet\veen 

 the families Triakidae and Carcharhinidae as 

 defined by Bigelow and Schroeder (1948) and 

 Garrick and Schultz (1963). The characters 

 of lago strengthen the evidence presented by 

 Compagno (1970) against separation of these 

 families on simple nictitating lower eyelid and 

 dental characters advocated by these writers. 



We follow Compagno in uniting, at least provis- 

 ionally, the two families. lago thus falls into 

 the family Carcharhinidae (sensu lato). 



lago is far from the advanced and intermediate 

 carcharhinid genera discussed by Compagno 

 (1970). These genera include Hemigaleus, 

 Hemipristis, Galeocerdo, Scoliodon, Rhizoprioiv- 

 odon, Loxodon, Negaprion, Triaenodon. Lamiop- 

 sis, Isogomphodon, Carcharhinus, Hypoprion, 

 and Aprionodon. lago differs from all of these 

 in having a transitional, not internal, nictitating 

 lower eyelid with edge nearly horizontal; shal- 

 low subocular pouch; teeth with strong basal 

 ledges and grooves; teeth at symphysis only 

 slightly smaller than adjacent ones; no precau- 

 dal pits; pectoral fin skeleton projecting less than 

 halfway into fin ; distal pectoral radials only as 

 long as proximals, with parallel edges and trun- 

 cate tips (not tapered and acute); caudal fin 

 without projecting ventral lobe and lateral un- 

 dulations of its dorsal margin in adults; cran- 

 ium with a complete supraorbital crest (absent in 

 advanced forms); and a spiral, not scroll, in- 

 testinal valve (Hemigalejis and Hemipristis are 

 exceptional in also having spiral valves). 



lago differs from Galeorhinns and HypogaJeus 

 as delimited by Compagno (1970) in having a 

 transitional rather than internal nictitating low- 



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