The status of Catharus fumosus Ridgway (Turdidae)

The name Catharus fumosus Ridgway, 1888 has traditionally been placed among the synonyms of Black-headed Nightingale-Thrush C. mexicanus (Bonaparte, 1856) and applied at subspecies rank to the population ranging from Nicaragua to Panama (C. m. fumosus). Recent data support species rank for C. fumosus, but the availability of the name is contested. Allan Phillips claimed that the C. fumosus holotype (USNM 101765) was a hybrid with ‘C. fuscater’ (= C. [f.] hellmayri von Berlepsch, 1902, recently elevated to species), then re-described the Central American taxon under the name C. m. carrikeri A. R. Phillips, 1991. World checklists are now in conflict. Here, I review the relevant history and compare USNM 101765 to a geographically widespread sample of study skins of the putative parental forms, yielding little support for the hybrid hypothesis. This is the fourth in a series of papers concerning historical aspects of Catharus taxonomy and nomenclature.