Chaetocnemistoptera Borgmeier, 1923

Ament, Danilo César, 2014, Taxonomic revision of the genus Chaetocnemistoptera Borgmeier (Diptera: Phoridae), with the description of five new species, Zootaxa 3753 (4), pp. 301-322 : 302-304

Genus Chaetocnemistoptera Borgmeier, 1923

Chaetocnemistoptera Borgmeier, 1923b: 51, 1961: 4 ; Brown, 1992a: 52. Type species: Hypocera semifurcata, 1923a (by monotypy).

Diagnosis. Anepisternum dorsally setulose, without long seta; scutellum with six setae; mid and hind tibia with transverse setal ctenidia. Fused surstyli shifted to left lateral of epandrium forming an articulated process. Some specimens examined in this study do not have the wing vein R2+3 and key out to Hypocera instead of Chaetocnemistoptera in Disney’s identification key to world genera ( Disney 1994). These specimens are clearly Chaetocnemistoptera , however, as they present the features of this genus described below.

Synapomorphies. Scutellum with six setae and the transverse rows of enlarged setulae on the mid and hind tibia (as proposed by Brown 1992a); lateral patch on palpus between two rows of setulae ( Fig. 12 ).

Description. Body length, 1.7–2.8 mm. Frons pubescent, punctate, without median furrow. Eyes reddishbrown. Frontal setation 4-4-4, with two dorsally directed supra-antennal setae. Frontal setae arrangement variable, with two distinct combinations possible differing mainly in the position of the ventral interfrontals and frontoorbitals ( Figs. 10, 11 ). Palpus bearing large setae, with lateral oval patch between two rows of setulae. Flagellomere 1 pubescent, oval; arista pre-apical, pubescent. One lower genal and one upper genal tiny setulae. Anepisternum dorsally setulose, without long seta. Scutellum with six setae. Fore and midfemur in some species with oval patch of differentiated setulae ( Figs. 13–18 ). Forefemur with ventral row of four stronger setae near apex of anterior face. Foretibia with one dorsal seta and anterodorsal row of strong setae. Midtibia with one anterodorsal and two posterodorsal large setae, with 2–4 small setae between the two posterodorsal setae and 2–3 setal ctenidia near base ( Figs. 19–20 ). Hind femur large (height/length ratio: 0.43–0.5), with apical darkening, sometimes with ventral lobe or with ventral group of setulae. Hind tibia with one anterodorsal and 3–8 posterodorsal setae and 10–14 dorsal setal ctenidia ( Figs. 21–22 ). Wing relatively uniform within the genus ( Figs. 23–30 ). Costa not swollen (0.39–0.45 of the wing length); R2+3 vestigial, absent or present; M1 concave, curved posteriorly at apex; M2 slightly sinuous; CuA1 sinuous. Tergites usually dark, with lighter posterior band. Tergite 6 twice as long as tergite 5. Hypopygium generally whitish-yellow, elongated dorso-ventrally. Fused surstyli shifted to left lateral forming a process articulated to the epandrium, sometimes with subepandrial setose elevation and subepandrial groups of setae. Epandrial right posterior margin sometimes posteriorly projected, with subepandrial setulose process. Hypandrium divided in two symmetrical lobes, in some species laterally microtrichose or with rounded protuberances. Hypoproct with 0–4 large setae.

Comments. Chaetocnemistoptera species are very difficult to diagnose morphologically. Contrary to the other Neotropical Phorinae genera Coniceromyia and Neopleurophora , that have a relatively high quantity of diagnostic features in male sexually-related structures, Chaetocnemistoptera species show little variation even in the hypopygium. The few species diagnostic characters, however, are present mostly in the male hind femur and hypopygium. The hind and midtibia chaetotaxy is highly variable even in the same species, as in Neopleurophora , and should be used with caution in the taxonomy of the genus. There is a considerable sexual dimorphism in Chaetocnemistoptera , with most of the species diagnostic features only present in the males.

Figures

FIGURES 10 – 22. Chaetocnemistoptera structures. 10. C. nigroscutellata frons; 11. C. lobata, sp. nov. frons; 12. C. trichopoda head in lateral view; 13. C. formosa forefemur; 14. C. nigroscutellata forefemur; 15. C. palpalis holotype forefemur; 16. C. palpalis additional material forefemur; 17. C. palpalis midfemur dorsal view; 18. C. palpalis holotype forefemur posterior view; 19. C. formosa midtibia; 20. C. palpalis midtibia; 21. C. formosa hind tibia; 22. C. palpalis hind tibia.

FIGURES 23 – 30. Chaetocnemistoptera wings. 23. C. formosa; 24. C. nigroscutellata; 25. C. palpalis; 26. C. lobata, sp. nov.; 27. C. magdalena, sp. nov.; 28. C. phaeonota, sp. nov.; 29. C. pityropyga, sp. nov.; 30. C. trichopoda, sp. nov.