Dohrniphora Dahl, 1898

Dohrniphora Dahl View in CoL (total of 32 photos of 13 mating events examined: Figure 3E–H View Figure 3 )

Dohrniphora View in CoL has one of the greatest structural diversifications of the Phoridae View in CoL , with males bearing almost 314 different types of ornamentation and chaetotaxy on the base of the posterior face of their hind femur (nearly one per species, eg figs in Brown and Kung 2010). The males of some Dohrniphora species also have other sexually dimorphic structures such as a patch of differentiated setulae on the forefemur (figs 325, 326 in Brown and Kung 2010), enlarged foremetatarsus (fig. 327 in Brown and Kung 2010) and hind coxal lobes (figs 307–314 in Brown and Kung 2010). Body-size sexual dimorphism seems to be widespread in the genus, with the males being much smaller than the females ( Figure 3E–H View Figure 3 ).

Dohrniphora View in CoL is one of the few genera in the family for which there is a detailed description of its mating habits ( Barnes 1990). Barnes (1990) commented that, during mating, the Dohrniphora cornuta View in CoL male ‘pivoted on the bases of his hind femora’ and that he ‘stretched his hind legs backward and waved them up and down at a rate of about twice per second, causing his entire body to rock’. Barnes (1990) also noted that the females waved their abdomen up and down, raising the males well above them.

Barnes’ observations are corroborated by the photos we examined which show that this behaviour and mating position is widespread in the genus. All photos show the male hind femur modified structures at the level of possible contact with the female terminalia and the males being lifted to different heights ( Figure 3E–H View Figure 3 ). The male hind leg waving noted by Barnes suggests that the hind femur structures could be stimulating the female terminalia. Alternatively, the male lifting characteristic of the genus could be indicating a possible grasping function for the hind femur structures given that, during the lifting, the male’s legs almost do not contact the substrate. Probably also for holding, Dohrniphora View in CoL males cross their hind legs during mating ( Figure 3E–H View Figure 3 ), behaviour not found in any other genera.

The remarkable modifications of the hind femur of Dohrniphora males may include concavities, projections, lobes, spines and various types of setulae ( Brown and Kung 2010). The morphological aspects of these modifications seem to fit both hypotheses of stimulating or grasping the female. We assume that the males’ hind coxal lobes could have a similar stimulatory or grasping function to their hind femur structures. The other male features on the foreleg are harder to explain considering that the males do not have any special contact of this leg with the female in the photos.

Dohrniphora females have a characteristic pair of lateral plates on their abdominal segment 7 (visible in Figure 3F,H View Figure 3 ) which was observed by Barnes (1990) to be contacted by the male hind femur structures during mating. It is unknown whether these female plates are morphologically variable across the genus or if they are under selective pressures related to male hind femur stimulation.