SCANNING ELECTRON MICROSCOPIC STUDIES ON HALLER'S ORGANS OF IMMATURE DERMACENTOR TICKS

JIANG ZAI-JIE (Department of Biology, Beijing Normal University)

haller's organs of immature ticks-Dcrmacentor abaensisD.auralus-D. marqinatus-D.niveus-D. muttalli -D. reticulatus-D. silva-rum-D. sinicus-Boophius microplus-Hacmaphysalis hystrieis-Hyalommadctritum-Ixodcs sincnsis-Rhipiccphalus pumilio

The Halter's organs of eight opeeies of Dermacentor in larval and nymphal stages were observed with scanning electron microscope and comparisons were made with that of larvae (five species) and nymphs (four species) of other genera for expounding the value of using their morphological features in taxonomy. The Sailer's organs of nine species as larvae and eight species as nymphs are described for the first time.The Haller's organs of the examined genera show distinct differences in the shape of capsule aperture, the depth of the anterior pit, the immiber of sensilla in the anterior pit and the position of the porose sensillum. The Haller 's organs of Dermacentor is elliptical and their anterior pit is deep and almost round. There are five sensilla in the anterior pit of the larva and the porose sensillum is long and situated on the distal end. The capsule aperture is T-shaped or pentadactylous. There are two distal and two medial setae, with the thick porose seta located o.n the median line.Marked differences were found among the larvae of D. aumtus distributed in Oriental region and the larvae of palaearctic species. The former possess pentadactylous capsule aperture with very big center. The porose sensillum in the anterior pit bends toward inside and is located on a common basal disc with other sensilla. A proximal os-tium is located outside the medial setae. In the larvae of palaearetie species the porose sensillum is straight and is located on its own basal disc. In D. abaensis the proximal ostium is generally absent, and if present, it is located inside the medial setae. In D. re-ticulatus the capsule aperture is pentagonal, with very big center. The proximal ostium is located between the medial setae and proximal setae on the outside. In the larvae of other species of Dermacentor the capsule aperture is T-shaped and the proximal ostium is located inside the medial setae. The center of capsuel aperture is rather large in the larvae of D. silvarum but the larvae of other four species of Dermacentor have no difference in the shape of their capsule apertures. Like the larvae, the nymphs of D. auratus and palaearetic species differ in their porose sensilla which bend toward inside in the former but are straight in the latter. The capsule apertures in the nymphs of D. reticu-latus and other species are different in shape; in the former it is Pentagonal with a large and round center, while in the latter they are variable and cannot be used to distinguish the species.Based on the morphological features of IIaller's organs of the immature ticks the author has found certain characters useful in tasonomical study. These are the shape and position of the porose sensilla in the anterior pits and the presence and position of the proximal ostia.