How to identify a kidney tick? - briefly
A kidney tick is a small, flat, oval arachnid about 2‑5 mm long, dark brown to reddish‑brown, with a distinct shield‑shaped scutum covering the dorsal surface and elongated mouthparts that embed into the host’s skin. It can be differentiated from other parasites by its rapid engorgement into a rounded, balloon‑like shape within a few days of attachment.
How to identify a kidney tick? - in detail
A kidney tick can be distinguished by several morphological characteristics that set it apart from other ixodid species. The adult female measures approximately 5–7 mm when unfed, expanding to 10–12 mm after engorgement. Its dorsal shield (scutum) is oval, dark brown to black, and bears a distinct pattern of pale, raised punctuations arranged in a linear or slightly curved row along the anterior margin. The ventral surface is lighter, with a smooth, glossy cuticle. Legs are relatively short, each bearing a pair of slender palps and a pair of chelicerae; the tarsi display a characteristic dark band near the base.
Key identification points include:
- Capitulum shape: The mouthparts form a short, triangular structure with a well‑defined basis capituli.
- Eyes: Two small, oval eyes are positioned laterally on the dorsal surface, a feature absent in many related species.
- Spiracular plates: Located ventrally, these plates are rectangular with a central aperture, surrounded by a faintly pigmented rim.
- Genital aperture: In females, the posterior margin of the abdomen shows a conspicuous, oval genital opening, while males possess a slightly elongated operculum.
Microscopic examination of the ventral plates and the arrangement of setae on the legs provides additional confirmation. The presence of a distinct, elongated anal groove that runs posterior to the anus is another reliable marker.
When a specimen is suspected, the following steps ensure accurate determination:
- Collect the tick with fine forceps, avoiding damage to the mouthparts.
- Preserve the sample in 70 % ethanol for later laboratory analysis.
- Place the tick on a glass slide with a drop of mounting medium.
- Use a stereomicroscope at 40–60× magnification to assess the scutum pattern, eye placement, and capitulum dimensions.
- Compare observed features with standard taxonomic keys for renal‑associated ixodids.
Molecular techniques, such as PCR amplification of the mitochondrial 16S rRNA gene, can corroborate morphological findings, especially in immature stages where visual cues are less pronounced. Sequencing results should be matched against reference databases to confirm species identity.
By systematically evaluating size, coloration, shield pattern, eye configuration, and ventral structures, a practitioner can reliably recognize a kidney tick and differentiate it from sympatric tick species.