MITES OF SUBFAMILY HAEMOGAMASINAE — KEEGAN 209 



identical in all species of Haemogamasinae ; the large, bifurcate, tarsal 

 seta is a characteristic of the Laelaptidae ; all species possess a con- 

 spicuously stout seta on ventral surface of coxa ; setae may be smooth or 

 barbed and are usually stouter on ventral surface of palp. 



16. Legs. — Possess six segments as in palpi ; vary specifically in na- 

 ture of setation and to some extent in relative thickness ; setae may be 

 smooth or barbed and are usually shorter and thicker on the ventral 

 surface of each leg; length-width ratio of tarsus varies specifically; 

 distal margins of segments with spines in some species ; spurs present 

 on legs of species of Ischyropoda. 



17. Male. — Sexual dimorphism apparent in several respects ; usually 

 smaller than female and with a relatively larger dorsal shield. In 

 H demogamasus and Euhaemogamasus a single ventral shield in- 

 cludes regions covered by sternal, genitoventral, anal, endopodal, and 

 metapodal shields of female ; in Ischropoda the anal shield is separate, 

 as are the endopodal and metapodal shields. Setation and position 

 of pores on ventral shield correspond fairly closely with those of the 

 female of each species ; shape of shield varies specifically. Epistome 

 usually as in female, but in some species may differ slightly. Chelae 

 modified in most species ; dimorphism especially apparent in movable 

 chela, which, according to Michael (1892), serves to transport the 

 spermatophore from the genital aperture of the male to that of the 

 female. Maxillary corniculi frequently blunt rather than pointed as 

 in the female. Legs may be relatively stouter than in the female and 

 may bear conspicuously stout ventral setae or spurs, especially on leg 

 II; Michael (1892) reported that these enabled the male to clutch the 

 female more firmly during copulation. In spite of sexual dimorphism, 

 the males of each species may be readily determined by characteristics 

 common to both sexes. 



18. Larval and nymphal stages. — ^Dorsal shield undivided, but with 

 a slitlike invagination on either lateral margin at the level of coxae 

 IV in several species. Ventral body surface with an anal shield and 

 a ventral shield extending from coxae I to coxae IV ; in most species 

 this shield possesses four pairs of setae, which represent the three 

 pairs of usual sternal setae and the single pair of metasternal setae 

 of the adult. The usual genitoventral setae flank the narrow, bluntly 

 pointed, posterior end of the shield in most species; accessory setae 

 are present on the ventral shield only in genus Ischyropoda; anal 

 shield as in female but usually with fewer accessory setae. Peritremal 

 shield not fully developed. Epistome, chelae, and maxillae are very 

 much as in adult female and offer most easily studied means of identi- 

 fication. Palpi and legs often relatively stouter than in adults. 

 Setae as in adults but may be relatively smaller and less numerous. 



