REVISION OF CARCHARHUSriD SHARK GENERA — SPRINGER 597 



Clasper 

 Length 

 Locality T.L. (%) Locality 



Philippines 709 7.6 Senegal 



Philippines 722 8.0 Macassar 



Australia 760 7.3 Australia 



French Equatorial Gulf of Thailand 816 7.3 



Africa 775 7.1 AustraHa 874 6.9 



The largest embryos seen were 409-411 mm. from Senegal; the 

 smallest non-embryos from Senegal were 401-409 mm., and the 

 smallest, from nearby Ghana and Nigeria, 308-320 mm. The smallest 

 non-embryo examined was 242 mm. from the Philippines, where 

 specimens under 300 mm. were not uncommon. The largest specimen 

 examined from the Philippines was 722 mm. whereas the large embryos 

 from Senegal were taken from a female 940 mm. (not seen by me). 

 These figures may indicate that there are geographic populations 

 varying in sizes attained, as well as indicating variation in size at 

 birth in a given localit3^ 



Geographic variation is indicated also in table 9, where groupings 

 of precaudal vertebral numbers seem markedly different from one 

 locality to another. The pattern of this variation is difficult to follow 

 and will necessitate the examination of large numbers of specimens 

 from many localities before it can be resolved. 



Specimens from the Red Sea are noticeable for considerable variation 

 in snout shape, ranging from rather acute to bluntly rounded. Also 

 seen were some small west African specimens that had blunt snouts. 

 Specimens with either acute or bluntly rounded snouts had the same 

 relative snout lengths. 



Some figures are available on the variation of precaudal vertebral 

 counts in embryonic siblings and their mothers. A female from the 

 Persian Gulf had 70 precaudal vertebrae; her two embryos had 68 and 

 72 precaudal vertebrae. A female from the Red Sea had 65 precaudal 

 vertebrae and her three embryos had 68, 68, and 70 precaudal verte- 

 brae. Three embryonic siblings from Senegal had 69, 69, and 70 

 precaudal vertebrae, and three from Durban, South Africa, had 71, 

 72, and 75 precaudal vertebrae. 



Distribution. — This species is widely distributed from the Madeira 

 Islands to Australia and Japan. 



Relationships. — Within the subgenus Rhizoprionodon, R. acutus 

 is most closely related to R. porosus and R. terraenovae, from which 

 R. acutus differs in having a typically longer snout in front of the 

 nostrils (fig. 1) and a higher dorsal-pectoral ratio (table 3). 



Nomenclatural discussion. — The reasoning for placing Scoliodon 

 sorrakowa Bleeker (1853) into the synonymy of R. acutus is given in 

 the nomenclatural discussion of Scoliodon laticaudus (p. 580). Inas- 



