Systematics

Two subspecies recognized:

cinereum, described as Harporhynchus cinereus Xantus 1860; type locality Cape St. Lucas, Lower California

Occurs on the southern portion of the Baja California Peninsula; there is an intergrade zone with mearnsi from "near latitude 28º on [the] Pacific slope and from Animas Bay ... on [the] gulf coast southward" (how far southward?) (Miller et al. 1957).

See Detailed Description.

mearnsi, described as Harporhynchus cinereus mearnsi Anthony 1895; type locality San Quintin, Lower California

Occurs on the west side of the Baja California Peninsula, from Ejiddo Eréndira, south of Punta Cabras at ca latitude 31º14' N, south to latitude 28º30' N (Miller et al. 1957, Unitt et al. 1995).

Similar to nominate cinereum, but much darker, the upperparts dark brown; the underparts pale buff, becoming ochraceous buff on the flanks, vent, and undertail coverts; and the black markings on the breast much larger.

Phylogenetic analysis of DNA sequence data, from both mitochondrial and nuclear genes, identifies two clades within Toxostoma: a clade consisting of T. curvirostre (Curve-billed Thrasher), T. ocellatum (Ocellated Thrasher), T. guttatum (Cozumel Thrasher), T. longistrostre (Long-billed Thrasher), and T. rufum (Brown Thrasher); and a second clade consisting of T. redivivum (California Thrasher), T. lecontei (Le Conte's Thrasher), T. crissale (Crissal Thrasher), T. bendirei (Bendire's Thrasher), and T. cinereum (Zink et al. 1999, Lovette et al. 2012). Toxostoma bendirei is the sister species to cinereum ((Zink et al. 1999, Lovette et al. 2012).