Megascops watsonii (Cassin, 1848)

Guianan Screech-Owl

corujinha-das-guianas (Portuguese)

Ephialtes watsonii Cassin, 1848 (lectotypes at ANSP examined)

Otus watsonii (Cassin, 1848): Cory (1918; part: specimens east of the Negro and Amazon rivers including southern Venezuela, northern Brazil, Guiana, Surinam, and French Guiana).

Otus watsonii watsonii (Cassin, 1848): Chapman (1928); Peters (1940); Marks et al. (1999); Weick (2006): 84 (part: specimens east of the Negro and Amazon rivers including southern Venezuela, northern Brazil, Guiana, Surinam, and French Guiana).

Megascops watsonii (Cassin, 1848): König et al. (1999); König & Weick (2008; part: specimens east of the Negro and Amazon rivers including southern Venezuela, northern Brazil, Guiana, Surinam, and French Guiana).

Megascops watsonii watsonii (Cassin, 1848): Dickinson & Remsen (2013); Clements et al. (2019); Gill et al. (2020) (part: specimens east of the Negro and Amazon rivers including southern Venezuela, northern Brazil, Guiana, Surinam, and French Guiana).

The type locality of this taxon is defined as “Orinoco River, Venezuela ” (Chapman 1928) and it corresponds to Clade A recovered herein as the lineage of the Megascops atricapilla-M. watsonii complex restricted to the Guiana Shield, east of the Branco and Negro rivers, in Brazil, through Venezuela, Guyana, French Guiana, and Surinam. As reported above, sequences obtained from one of the lectotypes of M. watsonii (ANSP 2445) confidently placed it within Clade A (Fig. 5). Statistical support for the reciprocal monophyly and significant coalescence of M. watsonii with respect to the other species in the complex was high in all analyses (Figs. 3 and 4). Average corrected pairwise p-distances between M. watsonii and the remaining species in the Megascops atricapilla-M. watsonii complex were as follows: 6.7% ( M. usta); 6.4 % ( M. stangiae); 6.7% ( M. ater); 6.6 % ( M. alagoensis); and 7.1% ( M. atricapilla).

Dark morphs of this species tend to be darker than individuals from other species in the Megascops atricapilla-M. watsonii complex, except for M. ater (see below), from which it differs mainly in back color. In some individuals of M. watsonii (e. g. MPEG 66635), the back is black. The darker individuals also tend to have wider and bolder underparts striping than in other species of the complex, which distinguishes them from M. ater dark morphs. However, as is usual within this genus, the tremendous individual variation in M. watsonii makes any generalization about diagnostic morphological characters impossible.

Longsong distinguishable from slower-paced longsongs of M. stangiae and M. usta and faster paced longsongs of M. atricapilla (Fig. 9: Tables 6 and 10). Shortsong faster-paced than in M. usta and M. stangiae (Table 8).