The genus Chymomyza is a genus of about 60 described species, the majority of which are found in the old and new world tropics. This genus is characterized by having the proclinate orbital setae inserted posterior to the anterior reclinate seta (see Markow and O’Grady 2005 for detailed discussion of all morphological characters). Most members of this group also possess femoral spines (see Grimaldi, 1986: 356; 1990:65). Okada (1976) used morphological characters to divide Chymomyza into five species groups: aldrichii, costata, fuscimana, obscura, and procnemis. Grimaldi (1986) described seven new species in the aldrichii species group, all of which are found in the Neotropics, and presented a phylogeny of this group that greatly improves the resolution in this clade over Okada’s tree. The aldrichii species group is notable because at least five species placed in it are hypercephalic.
Many members of the genus Chymomyza are attracted to cut wood, and this may serve as a lek or oviposition site for these species. Grimaldi (1986) considered the use of this substrate to be a specialization, possibly derived from a polyphagous habit. A number of Neotropical Chymomyza species display elaborate courtship behaviors, including male display and aggression (Grimaldi, 1986; Grimaldi and Fenster, 1989).
(excerpted from Markow and O’Grady, 2006, Chapter 1)