Cooley dc Kohls: Argasidae of N. America, etc. 99 



Ornithodoros amblus Chamberlin, 1920 

 Plate 10. Fig. 45 



'920. Ornithodoros amblus Chamberlin, original description, pp. 43-44, with figure. 



Sexes similar; adults and nymphs similar. 



ADULT 



Body. — Su'boval, sides nearly parallel, anterior end a little pointed, poster- 

 ior end broadly rounded. Mouth parts and hood not visible from above. Size, 

 6.45 x 4.8 to 5.0 x 3.25. Chamberlin (1920) gave the length as 7.2. 



Mammillae. — Mammillae on the dorsum large, hemispherical, close but 

 not crowded, those on the posterior border largest; tops convex with a few very 

 small pits. Less elevated on the venter and some are oval or irregular in shape; 

 absent or faint on the supracoxal folds. 



Hairs. — Hairs few in number, more numerous on the anterior border and 

 placed between the mammillae. 



Discus. — Large and noticeable, mostly circular, a little depressed. On the 

 venter present only in the grooves and in a median and two lateral depressions 

 posterior to the transverse postanal groove. 



Legs. — Moderate in length and size in the adults, relatively larger in the 

 small nymphs, articles flared at their distal ends; trochanter thickened. Haller's 

 organ notably distant from the distal end. Subapical dorsal protuberances and 

 dorsal humps absent on all legs. Tarsus IV, long and tapering. Hairs few in 

 number and of moderate length. Length of tarsus I, 0.78; metatarsus, 0.6. 

 Length of tarsus IV, 1,2; metatarsus, 0.96. 



Coxae. — Coxae I and II separated; all other coxae contiguous. 



Hood. — Very short and continuous with a short median elevation that 

 connects it with anterior dorsal margin. 



Camerostome. — Deep and terminating anteriorly in the short hood. 



Cheeks. — Small, narrow and attached along their greatest dimension; not 

 overlapping the mouth parts. 



Capitulum. — Basis capituli wider than long; with a group of erect hairs 

 on each side behind. Surface rough and with transverse wrinkles. Palpal article 

 1 swollen and with its surface similar to that of the basis capituli; with a knife- 

 edge flange overlapping the base of the hypostome. Articles 2, 3, and 4 free 

 and smooth. 



Hypostome. — Sides nearly parallel; apex notched. Principal denticles in a 

 2 /2 arrangement. Small denticles numerous in the corona and with a few 

 small ones suggesting a third file on each side. Posthypostomal hairs reaching 

 to about three-fourths the length of the hypostome. 



Folds. — Coxal and supracoxal folds present. 



Grooves. — Prenanal, transverse postanal and median postanal grooves 

 present, broad and deep; the median postanal terminating at the transverse 

 postanal groove. Dorso-ventral groove absent. 



Eyes. — Absent. 



Anus.- — In a nearly circular frame. 



