NO. I AVIFAUNA OF PANAMA — WETMORE 7 



III. AN ADDITIONAL RACE OF THE CHESTNUT-BACKED 

 ANTBIRD, MYRMECIZA EXSUL SCLATER 



The chestnut-backed antbird, found widely through the tropical 

 lowlands of the Republic of Panama, is a forest-inhabiting species 

 that still remains in small numbers in inhabited sections since a part 

 of its haunt is in swampy woodlands where the land is too wet to be 

 available for cultivation. Here it still finds suitable habitat when 

 the surrounding forest has been destroyed. Three subspecies have 

 been recorded from Panama. A detailed study of the series now 

 available from the entire isthmus has indicated a fourth that requires 

 description. 



MYRMECIZA EXSUL NIGLARUS subsp. nov. 



Characters. — Similar to Myrmecisa exsul exsid,- but paler above 

 and below ; darker than M. e. occidcntalis Cherrie,^ especially in the 

 female. 



Description. — Type, U.S.N.M. No. 423427, male, from the Rio 

 Chiman about 10 kilometers above Chiman, Province of Panama, 

 collected February 20, 1950, by A. Wetmore and \V. M. Perrygo 

 (original number 15208) : Crown, sides of head, throat, and foreneck 

 black, shading to dark neutral gray on hindneck ; rest of upper 

 surface Mars brown, shading to russet on rump and upper tail 

 coverts ; rectrices fuscous, edged with russet ; bend of wing black, 

 edged with white, the alula being fuscous-black with the outer webs 

 edged with white ; lesser wing coverts with a shaft line of dusky 

 neutral gray, terminating in a slightly expanded tip of the same 

 color ; primaries and secondaries fuscous-black, with the outer webs 

 Mars brown, except the outermost, which has a narrow white outer 

 edge ; black of foreneck shading progressively to deep neutral gray 

 on chest, and neutral gray on lower breast ; under wing coverts 

 dusky neutral gray, mixed scantily with white ; posterior part of 

 sides, flanks, and under tail coverts cinnamon-brown. Bill black ; feet 

 fuscous-brown (from dried skin). 



Measurements. — Males (15 specimens), wing 65.0-70.1 (67.1), 

 tail 42.5-49.7 (45.7), culmen from base 20.2-22.3 (21.4), tarsus 

 27.5-29.7 (28.4) mm. 



- Myrmeciza cvsul P. L. Sclater, Proc. Zool. Soc. London, vol. 26, 1858 

 (Jan.-May 1859), p. 540. ("Panama," type locality hereby restricted to near 

 Gatun, Canal Zone.) 



^Myrmeciza imnmculata occidcnialls Cherrie, Auk, vol. 8, No. 2, April 1891, 

 p. 191. (Pozo Azul de Pirris, Pacific slope of Province of San Jose, Costa 

 Rica.) 



