• Characteristics of the Genus Psoroptes:
• Psoroptes species (Psoroptes ovis, P. cuniculi) are non-burrowing surface mites. They pierce the skin with pointed chelicerae at the base of wool/hairs rather than tunneling into the stratum corneum (burrowing mites belong to the family Sarcoptidae, e.g. Sarcoptes scabiei). Statement (A) is False.
• Piercing causes serum exudation, coagulating with mite feces and epithelial debris to form thick scabs (sheep scab). True.
• Long, jointed legs project visibly beyond the body margin with segmented pretarsi bearing trumpet-shaped suckers. True.
• The body is oval without dorsal spines or triangular scales (unlike Sarcoptes which has dorsal spines). True.
• nalysis:
• Statements (B), (C), and (D) are correct. Hence, Option 3 is correct.

• Diagnostic Antigen: Pso o 2 (Psoroptes ovis allergen 2) is a major immunodominant 14.5-kDa recombinant antigen identified and cloned from the sheep scab mite, Psoroptes ovis.
• Clinical Application: Pso o 2 shares substantial structural homology with group 2 allergens from human house dust mites (Dermatophagoides pteronyssinus, Der p 2). It forms the basis of the highly sensitive and specific diagnostic Pso o 2-ELISA, allowing detection of sheep scab antibodies within 1–2 weeks post-infestation before widespread clinical crusted skin lesions appear.
• Differential Mites: Sarcoptes scabiei utilizes Sarcoptes-specific antigens (e.g., Ssag 1, Ssag 2); Psoroptes cuniculi is the ear canker mite of rabbits with related but distinct antigenic profiles.

Correct option: (3) Psoroptes ovis