490 U.S. NATIONAL MUSEUM BULLETIN 288 



anus ; a faint narrow, glandular ridge from posterior corner of eye above 

 tympanic area, ending in front of shoulder; a weak skinfold across 

 chest; a slight ventral disk; a pair of lateral external vocal sacs in 

 the male. 



Dimensions. — Head and body, 15.5 mm.; head length, 5 mm.; head 

 width, 5 mm. ; femur, 6 mm. ; tibia, 7.5 mm. ; foot, 7 mm. ; hand, 3.5 mm. 



Color in alcohol. — Dorsum uniform Vandyke brown; venter and 

 posterior femur bistre, immaculate. Sides of head drab, with some 

 vague bistre spots. 



The Villavicencio frogs (USNM 144911-26) are pale vinaeeous- 

 cinnamon to drab above, with the area between the dorsolateral lines 

 drab to olive, the lines irregularly marked with sepia patches at 

 intervals; the limbs also pale vinaceous-cinnamon with faint drab 

 crossbars, those at elbow and kneecap usually ending in a large 

 dark sepia spot; postfemoral region buff with a wide sepia stripe 

 down the middle; side of head ecru drab with small round sepia 

 dots along borders of lips, venter olive buff with suffused dark dots 

 on throat, chest, and lower femur. 



Remarks. — Parker (1927b) reported this species only from Colombia, 

 but the United States National Museum has specimens from Venezuela 

 also. In Colombia the species is known from Guajira, Magdalena, and 

 Meta. 



The type description states that the tibiotarsal articulation (the 

 "heel") comes to the angle of the jaws, but in USNM 118721 (formerly 

 MZUM 54589, received in exchange as a typical specimen of pusilla), 

 the heel reaches the anterior corner of the eye, as it does in nearly 

 all other examples of the species. The heel tubercle also varies in 

 development, sometimes being sharp and distinct, sometimes a mere 

 knob. 



While their small size and extreme agility would seem to insure 

 their abundance wherever they occur, these tiny frogs seldom are 

 secured in quantity for museum collections. The "discontinuous 

 distribution" of the genus, mentioned by Parker (1927b, p. 454), is 

 probably more apparent than real, as careful collection near Villa- 

 vicencio has turned up many examples of pusilla there, and the known 

 range has been extended into Venezuela by the specimens from 

 Amazonas and Rosario. 



Specimens Examined 

 COLOMBIA 



Gtjajira: Rio Barbacoas, Arroyo de Arenas, USNM 118182, 118721-2. 



Magdalena: Gaira, AMNH 14353-4, MCZ 4757 (paratype). 



Meta: Villavicencio, USNM 123567, 144911-26, 147111-21. 

 VENEZUELA: Amazonas: Puerto Ayacucho near Venado, USNM 80674. 



Rosario: Near Rosario, USNM 115760-6. 



