362 



Mandibles (Figure 481 ) more flattened than in Orthotrichia; distal 

 part of lower blade on the left mandible very short and without teeth; the 

 serrated upper blade of the left mandible with a small basal tooth; brush 

 of chetoids short and situated in the anterior third of the mandible; upper 

 blade of right mandible with a deep rounded notch and with 2 basal teeth 

 near the distal margin; basal setae yellow; seta situated more ventrally 

 curved; second seta straight, shorter and thinner. Maxillolabium 

 (Figure 482) with a broad basal part; submentum rounded posteriorly, with 

 straight anterior margin; its angle setae strong, light, moderately long; 

 cardo with a thin, small, curved seta; setae of stipes short and straight; 

 the distal seta of the palpiger is longer and thinner; median seta small. 

 Sclerites of segments 1—3 of the maxillary palps open and short; sclerite of 

 4th segment with a deep dorsal and ventral notch at the distal margin 

 (as in Orthotrichia). Sensilla of group I at the apex of the galea, short 

 and thin, its apex pear-shaped; setae of galea straight, short and spinelike. 



Pronotum (Figure 483) markedly less convex than in Orthotrichia, 

 slightly narrower in the middle; both anterior -angle setae (primary and 

 secondary) long, the lateral setae slightly shorter and curved; dark 

 secondary anterior-margin setae short ( / 3 of the width of the head), 

 slightly longer than the curved yellow setae; anterior half of sclerite 

 covered with thin, small, anteriorly curved hairlike setae; primary surface 

 setae in the middle of the sclerite, which stand in pairs behind each other. 



The primary angle seta of meso- and metathorax is as long as on the 

 prothorax; 2 of the 4 secondary angle setae are situated near the anterior 

 margin and 2 posterior to the primary seta; anterior-margin setae short; 

 intermediate and lateral primary surface setae situated close together; 

 hairlike setae (like those on the pronotum) present but in smaller numbers. 



Hornlike process of trochantin completely sclerotized, rugose on the 

 ventral side (Figure 484); in addition to the distal primary seta and 

 2 setules, there are short, thin chetoids at the anterior margin of the horn; 

 transverse membranous stripe of epimeron broad in the middle; seta 

 moderately long; episternum of meso- and metathorax is complete; setae 

 of episternum of these segments and of epimeron of mesothorax as long 

 as the anterior -angle seta; seta of epimeron of metathorax half as long. 



Posterior sternite of prothorax (Figure 485) as in Orthotrichia; 

 median sternite of mesothorax rectangular; that of the metathorax square; 

 the sculpture of the sternites ofOxyethira is absent in Ithytrichia. 



Legs (Figure 486) relatively short; ratio of length of 1st-, 2nd- and 3rd 

 pair 72:100:117. 



The basal seta of the coxa of the foreleg forms a yellow spine; postero- 

 dorsal seta longer than the others; basal process of femur absent; ventral 

 setae of femur equally long, situated in the apical and basal thirds of the 

 segment; apical process on tibia of forelegs absent; anteroventral seta of 

 tibia forming a lanceolate spine; the posteroventral seta a strong hook- 

 like spine; tarsus ventrally with a row of short, dense spinules; ventro- 

 distal setae of tarsus yellow and spinelike; claw with a spinule at the base 

 of the basal seta. Basal seta of coxa of midleg pale, curved; it is a straight 

 yellow spine on the hind legs; both other dorsal setae of the coxa of the 

 midlegs and the anterodorsal seta of the coxa of the hind legs are long; 

 One of the distoventral setae of the trochanter, the distodorsal seta of the 

 femur and the posterior distodorsal seta of the tibia very long; the 



402 



