Histological structure of the food canal in Nematocera (Diptera) imago head. 4. Bibionidae, Scatopsidae, Anisopodidae and general conclusion [Russian]

摘要

The cephalic food canal of bibionid, scatopsid, and anisopodid midges have different structure regardless of the similar trophic specialization. The most plesiomorphic canal is in scatopsids with the cibarium dilator consisting of numerous tubular muscle fibers and the three-radial pharynx devoid of intrinsic circular muscles. The cephalic food canal in Bibionidae belongs to the type previously described in Chironomidae and some Sciaroidea (Keroplatidae and Macroceridae), whose main characteristics are the weak sclerotization of the pharyngeal wall and development of intrinsic pharyngeal circular muscles. Anisopodids possess a weak cibarial pump and combine both plesiomorphic and apomorphic traits in the pharynx structure. Their major plesiomorphies are strong sclerotization of the pharyngeal intima and the three-radial pharyngeal lumen. The so-called oblique muscle of the precerebral pharynx appears to be anisopodid autoapomorphy. It was not found in any other nematocerans and acts as protractor and pharynx dilator. The studies of the cibario-pharyngeal apparatus in representatives of 20 Nematocera families attest to their great diversity within the suborder. It was established: the existence of two principally different structural types of the pharynx; oligomerization of muscle fibers in the cibarial and pharyngeal dilators in most Nematocera families; a shift of the punctum fixum and punctum mobile of dilator muscles depending on the muscle strength and degree of the pharynx wall sclerotization.