REVISION OF CARCHARHINID SHARK GENERA — SPRINGER 571 



total length: its length 4.1-5.3 percent (usually more than 4.2 percent) of 

 total length; base of first dorsal fin 7.8-10.9 percent of total length (only 

 one specimen out of 70 below 8.3 percent) ; lengths of upper and lower 

 labial furrows combined is more than 1.5 percent of total length. 



3 Rhizoprionodon 



3a. Upper labial furrow short or virtually absent, 0-1.3 percent of total length 

 (rarely more than 1 percent), usually shorter than lower labial furrow; 

 teeth modally fewer (see tables 1-3) 4 



3b. Upper labial furrow longer, always present, more than 1.1 percent of total 

 length (usually more than 1.3 percent), rarely shorter than lower labial 

 furrow; teeth modally more (see tables 1-3) 5 



4a. Total enlarged hyomandibular pores on both sides of head 7-16 (only 2 of 

 54 specimens with more than 14) ; precaudal vertebrae 84-91 (Indo-Pacific 

 north of Australia) Rhizoprionodon oligolinx 



4b, Total enlarged hyomandibular pores on both sides of head 15-22; precaudal 

 vertebrae 73-80 (Australia) Rhizoprionodon taylori 



5a. Total teeth in outer row of both jaws 53-58; total teeth in outer row of lower 

 jaw 26-28; total teeth in outer row of upper jaw 27-30; snout tip to outer 

 nostrils usually longer at any given size (fig. 1), ranging from 4.5-6.0 

 percent of total length (Eastern Pacific) . . . Rhizoprionodon longurio 



5b. Total teeth in outer row of both jaws 47-53 (only 2 specimens out of 74 of 

 R. acutus with 53) ; total teeth in outer row of lower jaw 22-26 (only 1 

 specimen out of 19 of R. terraenovae and 4 of R. acutus with 26) ; total 

 teeth in outer row of upper jaw 23-27 (1 specimen each of R. porosus 

 and R. terraenovae and 7 of R. acutus with 27) ; snout tip to outer nostrils 

 usually shorter at any given size (fig. 1), 3.2-4.5 percent of total length 

 in R. porosus and R. terraenovae, 4.4-5.1 percent in R. lalandei, 4.0-5.4 

 percent in R. acutus (other than Eastern Pacific) 6 



6a. Tip of appressed pectoral fin fails to reach level of middle of first dorsal 

 base; dorsal-pectoral ratio 100-123 (only 1 out of 33 specimens with less 

 than 105) ; clasper length 5.9 percent or more of total length in males 

 500 mm. or larger; largest specimen seen: 640 mm.; precaudal vertebrae 

 79-90 (rarely less than 84), outnumbering caudal vertebrae 5-20 (usually 

 7 or more) ; centra in posterior monospondylous region scarcely longer 

 than those in anterior diplospondylous region (pi. 2b) (Western Atlantic) . 



Rhizoprionodon lalandei 



6b. Tip of appressed pectoral fin reaches to, or beyond, level of middle of first 

 dorsal base (for dorsal-pectoral ratio, see 7a and 7b) ; clasper length 3.9 

 percent or less in males less than 620 mm.; attaining a length of over 1000 

 mm.; precaudal vertebrae 55-79, equal to, or fewer in number than, caudal 

 vertebrae (one specimen of R. acutus with one more caudal vertebra than 

 body vertebrae) ; centra in posterior monospondylous region markedly 

 longer than those in anterior diplospondylous region (pi. 2a) 7 



7a. Snout tip 4.0-5.4 percent of total length, usually greater at any given size 

 (fig. 1); dorsal-pectoral ratio usually larger (91-114, most specimens 100 

 or more, table 3) (Africa to Austraha) Rhizoprionodon acutus 



7b. Snout tip 3.2-4.5 percent of total length, usually smaller at any given size 

 (fig. 1); dorsal-pectoral ratio usually smaller (81-104, few specimens over 

 100, table 3) (Western Atlantic) 8 



8a. Precaudal vertebrae 58-66 (1 specimen out of 74 with 66, North Carolina) 

 (Atlantic and Gulf coasts of the United States and Mexico). 



Rhizoprionodon terraenovae 



8b. Precaudal vertebrae 66-75 (2 specimens out of 58 with 66, Brazil) (Western 

 Atlantic except United States and Mexico) . . Rhizoprionodon porosus 



