Morphologic features of Sancassania berlesei (Acari: Astigmata: Acaridae), a common mite of stored products in China.

OBJECTIVE Sancassania berlesei (S. berlesei) is the leading threatening mite in breeding industry of Eupolyphaga sinensis and public health. METHODS Living specimens of S. berlesei were obtained from the surface of Eupolyphaga sinensis and purified with double-distilled water. The egg, larva, nymph, hypopus, adult male and female of S. berlesei were screened and picked out under microscope. RESULTS Morphological variations of S. berlesei, including its legs, setae, external genitalia and accessories, are clearly identified under SEM. The larva has three pairs of legs, with no leaf-like setae, yet its coxal rod is well-developed. By nymph stage, four pairs of legs and the fourth dorsal seta arise, whereas the genital area looks still under-developed. At hypopus, the claws and tarsules appear well-built, and leaf-like setae, setae of tibia and setae of genu are seen. The sucker plate totally contains nine suckers and four shell-like dimplings in which there are symmetric distributions with 1 pair of central suckers, 2 pairs of side suckers and 1 pair of anterior suckers, respectively. One pear-like posterior sucker is located at the back of sucker plate. All suckers are smooth except for anterior sucker with radial stripe. The genital sense organ of adults exhibits itself with cordiform external aspect and typical ossification texture; whereas the male is dissimilar with the female regarding seta number on the genital sense organ. CONCLUSION Description of the morphological structure in great detail for S. berlesei tends to supply the important information for the taxonomy and further study.