Scanning electron microscopy and morphometrics of all parasitic stages of the tick Haemaphysalis tibetensis Hoogstraal , 1965 (Acari: Ixodidae)

The tick Haemaphysalis tibetensis is endemic to the Qinghai-Tibet plateau of China, but the morphological characteristics of the larva are unknown. Hence, scanning electron microscopy of all the parasitic stages was carried out with specific concern given to the larval stage. Differences between related species are also discussed. Males of H. tibetensis can be distinguished from those of H. warburtoni and H. qinghaiensis by a combination of the following characters: ventrointernal setae on palpal segment II number 4; dental formula 5/5; denticles in inner files 5, outer files 10; spiracular plates subcircular; internal spurs on coxae triangular, terminally blunt on coxae I-III, terminally slender on coxa IV. Females of H. tibetensis can be distinguished by: infrainternal setae on palpal segment II number 5; suprainternal setae on palpal segment II number 3; dental formula 4/4; denticles in files number 9, 12, 14, 14 from inner to outer; spiracular plates subcircular; internal spur on coxa I rounded and blunt, spurs on coxae II-III ridged, coxa IV sub-ridged. Nymphs can be distinguished by: ventrointernal setae on palpal segment II number 2; denticles in each file about 10-12; spiracular plates pyriform; scutum sub-cordiform; internal spur on coxa I triangular, short and stout, ridged on II-IV. Larvae can be distinguished by: scutum pyriform; internal spur on coxa I stout, terminally flat and wide; spurs on coxae II-III short, terminally triangular on coxa II, rounded and blunt on coxa III.