7 



(Mitchell 1975)] as being due to feeding specializations and sexual selection. Both genera 

 were later established as members of monotypic tribes within their respective subfamilies 

 (Burns & Fay 1970; de Muizon 1982a). 



Thus, two subfamilies are typically recognized today - the Monachinae and Phocinae, 

 corresponding roughly to the seals of the southern (plus Monachus spp.) and northern 

 hemispheres respectively - with the previously recognized subfamilies mentioned above 

 largely relegated as tribes within this scheme. Although generally accepted as being 

 paraphyletic, the Cystophorinae are still occasionally referred to, primarily in catalogues 

 of mammalian species (e.g., Ridgway 1972; Hall 1981; Stains 1984; Wilson & Reeder 

 1993). Considerably less attention has been focused below the tribal level, and the work 

 that has been done possesses numerous shortcomings. As well, the utility of the tribal 

 designations within the Monachinae has recently been questioned (Hendey and Repenning 

 1972; King 1983), as has the status of the Monachinae as a whole (Wyss 1988a; see 

 below). 



Points of contention 



Thus, within the taxonomic framework laid out above, we identified five outstanding major 

 problems concerning the systematics of the phocid seals, representing either points of 

 contention or areas that have not been adequately studied. The various opinions expressed 

 by previous workers for each problem may be regarded as hypotheses to be tested here. 



The systematic status and interrelationships of the monk seals (genus Monachus) 



Monachus spp. are nearly universally regarded as the most primitive of the extant phocids, 

 being considerably more primitive morphologically than many fossil forms (Repenning & 

 Ray 1977; Repenning et al. 1979; de Muizon 1982a; King 1983; Wyss 1988a). The three 

 constituent species - M. monachus, M. schauinslandi, and M. tropicalis - are widely 

 separated geographically, being found in and around the Mediterranean, in the vicinity of 

 Hawaii, and in the Caribbean respectively [although M. tropicalis is believed to have been 

 extinct since the early 1950s (Kenyon 1977)]. All three species are poorly known and 

 insufficiently described, especially with respect to their soft anatomy. 

 The distinctly primitive nature of Monachus appears to have contributed to the long 

 standing view that the genus is monophyletic. As well, the differences between the species 

 are apparently so slight that if it were not for their far-flung distribution, all three might 

 be viewed as subspecies of a single species (Scheffer 1958). However, Wyss (1988a) re- 

 cently put forth the novel suggestion that the genus might be paraphyletic and recognized 

 largely on the basis of the possession of phocid symplesiomorphies. M. schauinslandi was 

 held to be the most primitive of the monk seals (and of all phocids), largely on the basis 

 of the anatomy of the ear region (Wyss 1988a). However, this is a relatively recent view 

 [originating with Repenning & Ray (1972)], with earlier researchers, while recognizing 

 the primitive nature of M. schauinslandi, regarding it as sharing a common ancestor with 

 M. tropicalis to the exclusion of M. monachus (King 1956, 1983; Davies 1958b; Kenyon & 

 Rice 1959; King & Harrison 1961; de Muizon 1982a). Altogether, further description and 

 phylogenetic treatment of this genus would be valuable. 



