The Camel Tick, Hyalomma (Hyalomma) dromedarii Koch, 1844 (Ixodoidea: Ixodidae): Description of the Egg and Redescription of the Larva by Scanning Electron Microscopy

摘要

The present study describes the egg of Hyalomma (H.) dromedarii for the first time and adds more features to the larva using Scanning Electron Microscopy (SEM) in order to extend our knowledge on these acarine stages to be useful for further taxonomical or control studies. With the purpose of presenting exact description of acarine eggs, it is preferable to examine them both with and without SEM processing. SEM processing caused partial removal of the chorion which makes the egg shell clear and easily observed. The study revealed rough surface of egg shell which was surrounded by the chorion. The egg shell was perforated particularly at poles. The chorion appeared as a finely perforated cloth. Different forms of bumps were noticed between egg shell and chorion. Length, width, l/w ratio and pore diameter of the egg were measured. SEM investigation of the larva revealed smooth scutum with slight irregular ornamentation and horizontally folded extensible cuticle with vertical ridges. At least 2 types of cuticular openings were noticed on the extensible cuticle of the idiosoma. The first type was represented by 1 pair on dorsal side and 2 pairs on ventral one. It was surrounded with thick integumental ring and guarded with 2 internal lips. The second type was numerous, slit-like and without rings or lips. Dorsolateral plate of the hypostome carried numerous oval, tile-like and elevated denticles while ventral one carried 4 rows of posteriorly directed retrograde conical denticles. Mouth enclosed 2 cheliceral digits, each terminated with 3 lobes. Each lobe is supported with 2 or 3 conical denticles which were externally directed to the posterior. Haller`s organ on the tarsus of the first pair of legs consisted of anterior pit and posterior capsule. The pit contained 6 conical sensillae while the capsule opening had extensively branched margin. Measurements of the whole body, idiosoma, scutum, eye, capitulum, hypostome, palp, cuticular pores, legs and Haller`s organ sensillae of the larva are also presented.