NOTE Mollet et al.: Re-identification of a lamnid shark embryo 



873 



We could not resolve other discrepancies. Sanzo (1912) 

 reported four relatively large teeth in files 4-7, the 4th 

 one was more than twice the size of the 3rd one, and the 

 7th tooth was 4 mm (probably including the root). We con- 

 cluded that the four largest teeth were in files 3-6 and we 

 estimated the total height of the largest tooth in file 6 to 

 be about 3 mm (based on E2=2.4 mm). It is possible that 

 Sanzo's ( 1912) minute first tooth was a recessive parasym- 

 physial tooth, which we overlooked or which had disap- 

 peared before we examined the embryo. Our description of 

 the dentition of the Sanzo embryo agrees in general with 

 that in similar-size salmon shark and porbeagle embryos 

 (Lohberger, 1910; Mollet, personal observ.). 



DNA sequencing and mucous denticles 



DNA sequencing should have allowed identification of the 

 Sanzo embryo but provided no useful results. This was 

 likely due to initial fixing of the Sanzo embryo in formalin 

 (which destroys DNA) before transferal to ethanol. 



We did not have SEM at our disposal during the initial 

 stage of the investigation but suggest that the mucous 

 denticles might be suitable to identify lamnid embryos^ 

 Early development of mucous denticles is expected to 

 occur in the oophagous lamnids (Reif 1985; Raschi and 

 Tabit, 1992). Reif (1985) suggested that dermal denticles 

 are family, genus, and in some cases even species specific. 

 Postnatal shortfin makes and white sharks have different 

 mucous denticles (Reif, 1985; Peyer, 1968). 



Capture information 



The capture information provided by the fisherman who 

 caught the Sanzo shark was more consistent with shortfin 

 mako than with other lamnids, based on presently known 

 lamnid reproductive biology (Francis and Stevens, 2000; 

 Mollet et al., 2000). The litter size of 25-30 was estimated 

 and may have been inaccurate, but it does indicate a large 

 litter The large litter size could be the reason that the 

 Sanzo embryo weighed considerably less than the Uchida 

 embryo although they had similar length. Litter size in 

 porbeagles is nearly always four (maximum of five, Fran- 

 cis. 1996; Francis and Stevens, 2000). Maximum litter size 

 in white sharks is at least ten; unconfirmed reports are as 

 high as 14 (Francis, 1996). Shortfin makos have the larg- 

 est litters yet reported in the Lamnidae, reaching at least 

 18 (Branstetter, 1981; Mollet et al., 2000). 



The shark was estimated to weigh 400-500 kg, although 

 this must be considered approximate. The TL of a female 

 of this mass would be 3.58-3.85 m (Stevens, 1983; Mol- 

 let et al., 2000). A shortfin mako of this length would 

 undoubtedly be mature (Mollet et al., 2000) and the maxi- 

 mum reported length is 4 m (Bigelow and Schroeder, 1948; 

 Mollet^). Female white sharks do not mature until about 

 5.0 m (Mollet et al., 2000) with a corresponding mass of 

 -1200 kg (Mollet and Cailliet, 1996). A full-term litter of 

 25-30 shortfin makos would weigh ca. 75 kg, which would 



' Mollet, H.F. 1999. http://homepage.mac.com/mollet/lo/Io_large. 

 html. [Access date: 9 August 2002.1 



be reasonable for a female shortfin mako weighing around 

 500 kg (Mollet et al., 2000). A white shark litter of 25-30 

 would weigh about 500 kg at birth, i.e. the total mass of 

 the female shark caught, which is not possible. 



We conclude that the Sanzo embryo is Isurus oxyrin- 

 chus. This analysis corrects a long-standing error in the 

 literature and should provide the incentive to procure 

 and describe a white shark embryo of similar develop- 

 mental stage to that of Sanzo's embryo. The smallest 

 photo-documented white shark embryos were ca. 1.0-1.1 

 m TL (Uchida et al., 1996) and fully documented white 

 shark embryos were all nearterm and had a TL between 

 1.35-1.51 m (Uchida et al, 1987, 1996; Francis, 1996). 

 The definite identification of the Sanzo embryo suggests 

 that the maximum litter size of the shortfin mako is hkely 

 larger than 18 (Branstetter, 1981; Mollet et al., 2000) and 

 possibly as large as 25-30. 



Acknowledgments 



P. Stipa and A. Young translated Sanzo (1912) which gave 

 this study momentum. A photograph taken by T. Storai 

 led to our rediscovery of the Sanzo embryo. S. Vanni and 

 M. Poggesi allowed a partially destructive examination of 

 the embryo and we are grateful to S. Vanni for the histori- 

 cal identification of the specimen. E. Tavani and G. Sola 

 helped with tooth histological sections and the first body 

 radiographs. G. Bernardi spent much time attempting 

 DNA sequencing. O. Putz, R. G. Gilmore, and J. Moron pro- 

 vided morphometries of embryonic and postnatal shortfin 

 mako embryos. G. Cailliet suggested the use of x-rays. 

 We are grateful to Y. Kamei and S. Uchida for donating 

 a shortfin mako embryo specimen and to A. Dainty and 

 B. Human for help with the dissection. We also thank S. 

 Branstetter, J. Bruner, J. Casey, G. Cliff, I. Fergusson, B. 

 Habrich, R. Lea, G. Notarbartolo di Sciara, T. Otake, R. 

 Phillips, R. Purdy, H. Pratt, O. Putz, J. Stevens, and S. 

 Wintner for data and helpful suggestions and comments. 

 HFM acknowledges computer support provided by the 

 Monterey Bay Aquarium. The comments of three review- 

 ers improved the manuscript. 



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1965. Tooth terminology and variation in sharks with spe- 

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1966. A possible record-sized bonito shark, Isurus oxyrin- 

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