46 Acarology 



5. Stenosternum Kramer, 1898 



Type. Stenosternum bipilosiim Kramer, 1898 



Discussion: The diagnosis given above is based on the genus Megis- 

 thanus. Vitzthum 1942 suggests that all of the genera may not agree 

 with a diagnosis based on Megisthanus, but knowledge of the other 

 genera is too limited for a definite statement to be made. Only the genus 

 Megisthanus has been examined in preparing this work. 



Species of Megisthanus are commonly found on large beetles in 

 moist environments. The best source of Megisthanus in the United 

 States is the patent leather beetle, Popilius dis functus lUiger. The spe- 

 cies found on this beetle is Megisthanus floridanus Banks. As far as 

 is known, megisthanids are of little economic or medical importance. 



References: 



Tragardh, I. 1943. Further contributions towards the comparative mor- 

 phology of the Mesostigmata (Acarina) the Antennophoridae and 

 the Megisthanidae. Arkiv. for Zoologi. 34A. N:o 20:1-10. 



. 1946. OutHnes of a new classification of the Mesostigmata (Aca- 

 rina) based on comparative morphological data. Lunds Universitets 

 Arsskrift. N.F. Avd. 2. 42: No. 4:1-37. 



. 1946. Contributions towards the corriparative morphology of the 



Mesostigmata (Acarina) VII. The praesternal hairs and the male 

 genital aperture. Sartryk ur Entomologsk Tidskrift. Arg. 67. Haft, 

 3:88-108. 



LIROASPINA TRAGARDH, 1946 



The Liroaspina contains only two families of small mites that are 

 similar to the Megisthanina and the Microgyniina in that they lack an 

 epigynial plate. 



Tragardh 1946 in a study of the male genital openings recommends 

 that the two families originally placed in the Liroaspina be further 

 separated so that each is to be placed in a separate group. There is 

 some justification for such a step since the male genital openings differ 

 considerably. However, Tragardh's original plan of basing the classi- 

 fication on the ventral plates of the females will be followed and thus 

 the Liroaspina will not be split. 



