lago, A NEW GENUS OF CARCHARHINID SHARKS, WITH 

 A REDESCRIPTION OF /. omanensis 



Leonard J. V. Compagno' and Stewart Springer" 



ABSTRACT 



A new genus, lago, is proposed for Eugaleiis omanensis Norman, 1939. /. omanensis, originally de- 

 scribed from a single specimen, is redescribed from 16 additional specimens from the northern Arabian Sea 

 continental shelf and slope between the Gulf of Oman and the Gulf of Kutch. Its presence in areas 

 of low oxygen and the possibility of its occurrence in deeper waters of the Red Sea are discussed. 



Norman (1939) described Eugaleus omanensis 

 from a 280-mm female specimen, taken at 210-m 

 depth in the Gulf of Oman. He placed it in 

 Eugaleus Gill, 1864 ( = Galeorhinus Blainville, 

 1816) with reservations because omanensis dif- 

 fered from all other species of Eugaleus in den- 

 tition and absence of a pronounced ventral 

 caudal lobe. Norman noted that omanensis did 

 not fit Hemigaleus Bleeker, 1852 because of den- 

 tition differences and lack of precaudal pits but 

 he declined to establish a new genus for it. 



Fowler (1941) overlooked Eugaleus omanen- 

 sis in his review of Indo-Pacific elasmobranchs 

 but later (1956) gave a description of the species 

 condensed from Norman's account and allocated 

 it to the genus Galeorhinus. Misra (1949) had 

 earlier placed it in the same genus but this was 

 not mentioned by Fowler. 



Smith (1957) revised Galeorhinus but also 

 overlooked G. o?nanensfs. Compagno (1970) re- 

 viewed the systematics of Hemitriakis, Galeo7'- 

 hinus, and related genera. He considered G. 

 omanensis generically distinct from Galeorhinus 

 but did not propose a new genus in deference 

 to this paper. 



During the International Indian Ocean Expe- 

 dition (IIOE) in 1963, the RV Anton Bruun on 

 Cruise 4B conducted 109 trawling stations in 

 ti'ansects along the continental shelf of the Arab- 

 ian Sea between Bombay and the Gulf of Oman 

 at depths from 15 to 375 m (Woods Hole Ocean- 



' Stanford University, Stanford, Calif. 94305. 

 " National Marine Fisheries Service, National Center 

 for Systematics, Washington, D.G. 20560. 



Manuscript accepted February 1971. 

 FISHERY BULLETIN: VOL, 69, NO. 



ographic Institution, 1965). Sixteen specimens 

 of a small carcharhinid were included in these 

 collections and sent to us through the Smith- 

 sonian Oceanographic Sorting Center. They 

 were tentatively identified by us as Galeorhinus 

 omanensis (Norman). 



Marshall and Bourne (1964, 1967), in photo- 

 graphic surveys of benthic fishes, collected 30 

 photographs of a small carcarhinoid shark 

 (about 2 ft long) at depths between 1115 and 

 2195 m in the Red Sea. They noted that their 

 shark might be either a triakid or a carcharhinid 

 but was not identifiable to genus or species. Com- 

 parison of Marshall and Bourne's photographs 

 and sketch of their "mystery shark" with our 

 specimens and Norman's account of G. omanen- 

 sis led us to suspect that the "mystery shark" 

 might be omanensis. 



We then sent two specimens of the IIOE series 

 to Dr. N. B. Marshall at the British Museum 

 ( Natural History) . At our request he compared 

 them with the holotype, the hitherto only known 

 specimen of Galeorhirms omanensis, and con- 

 firmed our identification of the IIOE specimens. 

 He also agreed that the IIOE omanensis are very 

 similar to the Red Sea "mystery shark" of the 

 photographs, but noted that final identification 

 of the Red Sea species must await capture of 

 specimens. 



Differences between "Galeorhinus" omanensis 

 and members of Galeorhinus, Hypogaleus, Hem- 

 itriakis, and all other carcharhinid genera war- 

 rant the erection of a new genus for "Galeor- 

 hinus" omanensis. 



615 



