The external and internal cephalic morphology of males and females of Axymyia furcata is described and illustrated in detail. The documented features are compared with those of potentially related groups. Axymyia displays a number of apomorphic features of the adult head, like the subdivision of the compound eyes, the absence of several mucles (M. clypeolabralis, M. stipitopalpalis externus, M. palpopalpalis maxillae primus, Mm. palpopalpalis maxillae primus and secundus), the absence of both maxillary endites, and the loss of the salivary pump musculature (M. hypopharyngosalivarialis). Another apomorphic character is the origin of M. tentorioscapalis anterior on the head capsule. Some features are plesiomorphic and probably belong to the groundplan of Diptera: the orthognathous head, three ocelli, 5-segmented maxillary palps, 2-segmented labial palps transformed into medially fused labella, one premental retractor, a dense vestiture of microtrichia on all exposed parts of the head except the labrum, and the presence of an epipharyngeal food channel. The systematic position of Axymyiidae is discussed. Our findings do not provide support for the phylogenetic position of Axymyiidae.

Axymyiidae, Diptera, morphology, head, phylogeny, position