Trombidiformes 209 



on the same host, one form usually lives beneath the ventral scales and 

 is flattened, being considerably wider than long and having scales in- 

 stead of hairs on the venter. The second form occurring on the same 

 host is usually to be discovered between the claw and pad of the toes, 

 between the laminae of the pad, or between the toes themselves: this 

 form is normally practically spherical in shape and has hairs instead 

 of scales on the venter." Lawrence 1935 states: "Generally speaking, 

 therefore, mite parasites are absent (i) in families of lizards in which 

 scales are entirely absent or which lack imbricating scales, (ii) in gen- 

 era where degeneration of the limbs has taken place, whether these 

 degenerate forms are burrowing as in the Scincidae, or surface living 

 as in the Zonuridae and Gerrhosauridae, and (iii) in certain isolated 

 species of genera in which the majority of forms are parasitized." 



Very little is known about the biology of most of these species. The 

 life cycle of all Pterygosomidae consists of larva, nymphochrysalis, 

 nymph, teleiochrysalis, and adult in the female mites, but only the 

 larva, chrysalis, and adult stages in the male mites. Lawrence 1935 

 figures the larval, nymphal, and adult stages of Zonurobia cordylensis 

 Lawrence. The immature forms are very similar to the adult; larva 

 and nymph each possess a small eye plate or shield containing one 

 seta; the adult does not have such a plate but does have the two eyes. 

 In Pimeliaphilus podapolipophagus Tragardh, a parasite of cock- 

 roaches, all stages are very similar and differences are small. Although 

 this species has been placed in other families by various workers, it 

 is truly related to the lizard parasites, being the more primitive, free- 

 living type. P. isometri Cunliffe is a parasite of scorpions in the Philip- 

 pine Islands. 



In the United States Pimeliaphilus podapolipophagus Tragardh has 

 proved to be a pest in cockroach-rearing cages, at times causing enough 

 damage to hamper rearing. Geckobiella texana (Banks) was described 

 from Sceloporus fioridanus in Texas. Hirstiella trombidiformes Berlese 

 is known from San Luis Potosi, Mexico, although its host is unknown. 



References: 



Hirst, S. 1925. On the parasitic mites of the suborder Prostigmata (Trom- 

 bidioidea) found on lizards. J. Linn. Soc. London, Zool. 36:173-200. 



Lawrence, R. F. 1935. The prostigmatic mites of South African lizards. 

 Parasitol. 27(1): 1-45. 



Lawrence, R. F. 1936. The prostigmatic mites of South African lizards. 

 Parasitol. 28(1): 1-39. 



