Diplonevra gnoma, Corona, Emily M. & Brown, Brian V., 2005

Corona, Emily M. & Brown, Brian V., 2005, The Central American species of Diplonevra Lioy (Diptera: Phoridae), Zootaxa 1050, pp. 21-38 : 26-29

Diplonevra gnoma new species

Figs. 2 , 15 , 21

Recognition. This species does not key easily in Borgmeier’s 1969 key. It keys to couplet 4, which has the alternatives “halter yellow” versus “halter black.” The halter in D. gnoma is light brown, so following the first lead (halter yellow), specimens key to D. nigricauda Borgmeier. The hind femur of D. nigricauda , however, has 3 pairs of setae on the projecting lobe ( Fig. 13 ), whereas in D. gnoma there are only 3 single setae ( Fig. 2 ). If we accept “halter black” at couplet 4, specimens key out to D. gaudialis (= D. setigera in this paper) from which they can be separated by characters in the key.

This species is extremely similar to small specimens of D. setigera , with which it is sympatric in Patagonia, Arizona, USA. It is not clear whether some specimens listed by Borgmeier (1963) as D. gaudialis (= D. setigera ) were this species, as we were not able to examine all of his specimens, but we suspect that this is so based on his description of the cercus as “Anal tube brown or yellowish.”

Description. Male (female unknown). Body length 1.70–1.95 mm. Frons dark brown to black­brown, punctate. Mean frontal width 0.57 head width. Flagellomere 1 brown to dark brown, spherical. Arista brown. Palpus yellow­brown; apex with large, pointed setae that range in length from 0.038–0.075 mm and many small, extremely fine setulae along basal three­quarters. Proboscis yellow and elongate, narrow. Scutum dark brown to blackbrown; scutellum black, anterior scutellar seta two­thirds size of posterior seta. Pleuron shiny, dark brown, tomentose. Forelegs light brown. Mid­ and hind legs dark brown. Posterior face of hind trochanter with dorsomedial dense, extremely fine, shorter setae ( Fig. 2 ); ventrally with 1 long thick seta. Ventrobasal region of posterior face of hind femur with process containing three thick setae. Wing brown, vein R2+3 present, fork small ( Fig. 15 ). Costal length 0.45–0.47 wing length. Costal setae 0.54 mm. Mean costal sector ratio 5.5:1.2:1.0; range 5.1–5.8:1.0–1.3:1.0. Base of radial sector with 1 small seta. Halter light brown. Abdominal tergites black­brown. Venter of abdomen dark gray. Epandrium dark brown. Left side of epandrium tomentose except glossy along entire margin with darkening along basal margin of glossy section; posterior margin with 2 fine setae and 1 long seta. Right side of epandrium ( Fig. 21 ) glossy except tomentose ventrobasally; posterior margin of glossy section darkened; posterior margin setose with several fine subequal setae. Hypandrium dark brown. Left side of hypandrium tomentose except glossy along posterior margin. Right side of hypandrium tomentose except glossy darkening along entire margin. Stalk of cercus dark brown and setose except dorsal oneforth bare; cercus lighter brown.

Geographical distribution. Costa Rica and southwestern USA. This is the only species of Central American Diplonevra that we know has been collected from a lowland site.

Natural history. One specimen in the USNM collection has the label “Host: Spodoptera frugiperda (Smith) , reared in lab.” Presumably this fly was reared from a laboratory colony of its host, the fall armyworm ( Lepidoptera : Noctuidae ). It is not clear whether the fly was actually parasitizing the moth larva, or whether it was a scavenger on an already dead or diseased host.

Derivation of specific epithet. Derived from the Latin term gnomus, for dwarf, referring to the small body size of this species.

Holotype. ɗ, USA: Arizona: Santa Cruz Co., Patagonia, 31.53°N, 110.77°W, 13.viii.1995, B. Brown, E. Wilk, Malaise trap [ LACM ENT 050834] ( LACM).

Paratypes. COSTA RICA: Puntarenas: Palo Verde NP, 10.35°N, 85.35°W, 4ɗ, iii. 1991, P. Hanson, Malaise trap, 10 m ( LACM, MUCR). USA: Arizona: Maricopa Co., Mesa, U of A Experimental Station, 1ɗ, 2.xii.1964, Ayoade, host: Spodoptera frugiperda (Smith) , reared in lab. (puparium mounted on same point as adult specimen) ( USNM); Santa Cruz Co., Patagonia, 31.53°N, 110.77°W, 4ɗ, 24. x.1993, 2 ɗ, 4. xi.1993, 1 ɗ, 25. v.1994, 9 ɗ, 24. vi.1994, 2 ɗ, 8. vii.1994, 6 ɗ, 13. viii.1995, 1 ɗ, 10.ix.1995, B. Brown, E. Wilk, Malaise trap ( EMUS, MCZC, LACM, SEMC, USNM); Texas: Travis Co., Austin, 30.3°N, 97.78°W, 1ɗ, 6–11.xii.1989, C. R. Nelson, Malaise trap ( LACM).

Figures

FIGURE 13. Diplonevra nigricauda Borgmeier. Basal region of posterior face of hind tibia (light microscopy).

FIGURES 1 – 6. Diplonevra spp. Basal region of posterior face of hind tibia and trochanter (scanning electron micrographs). Fig. 1. D. ereba new species. Fig. 2. D. gnoma new species. Fig. 3. D. goliatha new species. Fig. 4. D. hypermeka new species. Figs. 5 – 6. D. setigera (Malloch), Zurquí de Moravia, Costa Rica. Abbreviations: dms – dorsomedial setulae of trochanter; ls – lateral setulae of trochanter.

FIGURES 14 – 19. Diplonevra spp. Left wings.

FIGURES 20 – 25. Diplonevra spp. Male terminalia, right lateral.