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
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