no. 3645 PORTUNIDAE — STEPHENSON, WILLIAMS, LANCE 13 



available for study, full tabular data could not be obtained; P. vocans 

 © is not restricted to American waters, occurring also at Ascension 

 Island in the South Atlantic (Rathbun, 1930). (6) The eastern P. sayi 

 @ is a member of the P. pelagicus group (see p. 15). 



Inspection of the models: From the models, the same eastern 

 species are part of the P. xantusii group: P. gibbesii @, P. ordwayi 

 ©, P. sebae ©, P. spinicarpus |o), P. spinimanus @, and P. ventralis 

 @; however, P. ventralis %, which was a borderline case from the 

 tabular data, now becomes an even more doubtful member of the 

 group. 



Again from the models, the incenter of the 15-species P. xantusii 

 group is approximately equidistant from P. acuminatus ©, P. asper 0, 

 P. xantusii xantusii ®, and P. xantusii affinis ®. While the term "P. 

 xantusii group" implies an oversimplification, it is considered signif- 

 icant that all four of the above "central" species occur in the Pacific. 

 It seems probable that the group originated from a western American 

 ancestor. 



The remaining American species (apart from P. sayi ©) appear 

 in the models to be scattered between the P. xantusii group and the 

 P. pelagicus group (see p. 15), apart from P. depressifrons @, which 

 is somewhat "to one side." While the general arrangement follows 

 that derived from the tabular data, no pairing of species is evident. 

 Relationships among species of Callinectes. — Tabular data: 

 Consideration of the species of Callinectes, each mutually in relation 

 to the remainder, gives mean values as follows : 



C. arcuatus <§), NFD 6.8, TD 2.6; C. bellicosus (§), NFD 9.0, 

 TD 3.0; C. boucourti (§>, NFD 5.5, TD 2.3; C. danae (§), NFD 5.8, 

 TD 2.5; C. exasperatus (§), NFD 6.8, TD 2.6; C. gladiator <§), NFD 

 7.4, TD 2.7; C. latimanus @, NFD 4.9, TD 2.1; C. marginatum @, 

 NFD 8.9, TD 3.0; C. ornatus (§), NFD 6.0, TD 2.4; C. sapidus (§), 

 NFD 5.4, TD 2.3; C. sapidus acutidens @, NFD 5.5, TD 2.2; C. toxotes 

 <§>, NFD 5.2, TD 2.2. The mean overall values of NFD 7.2 and TD 

 2.5 indicate that the genus is very homogeneous. 



The west African species C. latimanus @ is closest to the 

 "morphological center" in this predominantly Atlantic genus. The 

 three western American species differ appreciably from each other, 

 with C. toxotes @ closest to the bulk of the remaining species and 

 particularly close to five Atlantic species (C. boucourti @), C. ornatus 

 ®, C. sapidus acutidens @, and C. latimanus @, all NFD 3; and C. 

 exasperatus @, NFD 4) . On structural and distributional grounds any 

 of the first three could have given rise to C. toxotes (§§) as a result of 

 a Pacific isolate. The second Pacific species, C. bellicosus @, forms an 

 analogous pair with C. danae @), and presumably they had a common 

 origin. 



277-^59—68 2 



