MYOCASTORINAE, Ameghino, 1902

Carvalho, Guilherme A. S. & Salles, Leandro O., 2004, Relationships among extant and fossil echimyids (Rodentia: Hystricognathi), Zoological Journal of the Linnean Society 142 (4), pp. 445-477 : 469-470

THE MYOCASTORINAE

The phylogenetic position of the genus Myocastor has usually been controversial, with some authors placing it within the Echimyidae ( Patterson & Pascual, 1968; Patterson & Wood, 1982; Vucetich & Verzi, 1991; McKenna & Bell, 1997; Huchon & Douzery, 2001) and others considering it either in association with the Capromyidae ( Tate, 1935; Simpson, 1945; Wood & Patterson, 1959) or in a family of its own, Myocastoridae ( Landry, 1957; Woods, 1993). Recently, Leite & Patton (2002) conducted a phylogenetic analysis of molecular data, which pointed to the placement of Myocastor as the sister-taxon of Capromys , within the Echimyidae .

In the present analysis, the relationships of Myocastor to the capromyids were not addressed. Nevertheless, the inclusion of Myocastor within the Echimyidae is supported. Myocastor emerges as the sister-group of Clade 7, which includes Mesomys , Lonchothrix , the extant echimyines and dactylomyines, and the associated fossil taxa. The association of Myocastor with this clade (forming Clade 6) has, however, ambiguous support in the consensus cladogram. Thus, although the inclusion of Myocastor in Echimyidae is corroborated, its relationships within Echimyidae remain ambiguous. This ambiguity regarding the sister-group of Myocastor is evident in the molecular study of Huchon & Douzery (2001), in which the association of Myocastor either to Proechimys or to Echimys (the only two other echimyids included in the analyses) is not significantly different.

Myocastor , the only extant genus of the subfamily Myocastorinae , is usually associated with some fossil taxa ( Patterson & Pascual, 1968; McKenna & Bell, 1997), of which the most ancient, Prospaniomys and Spaniomys from Early Miocene, were included in the present analysis. Our results do not support the association of Myocastor to these two fossil taxa, as was suggested by Vucetich & Verzi (1991).