596 BIRDS OF THE REPUBLIC OF PANAMA PART 3 



tributed from Mexico south through Central America and South 

 America to BoHvia and southern Brazil. 



In the Isthmus of Panama, where it is common in the Tropical 

 Zone, they show a definite cline in coloration and measurements from 

 darker hue and somewhat larger size near the Costa Rican boundary 

 to brighter color and lesser dimensions in the central lowlands, 

 continuing in the latter form beyond the Colombian boundary. 



Generic status of Pipromorpha as separate from Mionectes is 

 subject to question. The species included differ definitely in plain 

 color pattern from the heavily streaked forms characteristic of 

 Mionectes, a distinction clearly evident even in the juvenile stages 

 of the two groups. Other than this, the adult males of the streaked 

 group differ in the much narrowed ninth primary, a sexual character, 

 and one that becomes evident apparently only at the renewal of the 

 primaries at the second molt. Nest construction in the two groups 

 is similar, and in both the eggs are white with no markings. Both 

 also appear to have a peculiar signal display in which one wing is 

 thrust up for an instant at right angles to the back. Ames (Peabody 

 Mus. Nat. Hist., Bull. 37, 1971, p. 163) reports that the form of 

 the syrinx is the same in both. Close relationship is evident, with 

 the Mionectes group probably the more ancient in view of their 

 greater uniformity, and the definitely plastic Pipromorpha more 

 recent. While Todd (Proc. Biol. Soc. Washington, vol. 34, 1921, 

 p. 175), and Hellmayr (Cat. Birds Amer., pt. 5, 1927, p. 497) 

 mention the resemblances, both continue to use the two generic names 

 in their accounts of the species. Firm decision may come when the 

 two are more fully known, especially as to life history and other 

 details of anatomy. 



PIPROMORPHA OLEAGINEA DYSCOLA (Bangs) 



Mionectes assiniilis dyscolus Bangs, Auk, vol. 18, no. 4, October 1901, p. 362. 

 (Divala, Chiriqui, Panama.) 



Generally similar to the race assimilis, but somewhat smaller ; 

 brighter olive-green above, with the crown concolor with the back ; 

 darker coloration of under surface more extensive on sides and 

 flanks than in assimilis; buff of abdomen and under tail coverts 

 somewhat darker. 



A female, taken at Puerto Armuelles, Chiriqui, March 8, 1966, had 

 the iris dark brown ; cutting edge of basal half of mandible dull 

 brown; rest of bill fuscous-black; tarsus, toes, and claws dull blackish 

 slate. Gape dull honey yellow, inner surface of maxilla and mandible 



