Mesorhaga falciunguis, Bickel, Daniel J., 2007

Bickel, Daniel J., 2007, The Mesoamerican Mesorhaga (Diptera: Dolichopodidae), with a taxonomic conspectus of the New World fauna, Zootaxa 1411, pp. 47-67 : 62-63

Mesorhaga falciunguis n. sp. ( Figs 2 b-c)

Type material. Holotype ɗ, paratype Ψ, Mexico: MORELOS: 34 miles south of Cuernavaca, 2600 ft, 4.viii.1954, J.G. Chillcott ( CNC); paratypes: Ψ, 12 miles east of Cuernavaca, 4400 ft, 14.viii.1954, J.G. Chillcott ( CNC); 2 ɗ, Cuernavaca, 12–19.vii.1961, R.R. Driesbach ( CAS); ɗ, Ψ, 6 miles north of Cuernavaca, 8000 ft., 15.viii.1954, R.R. Driesbach ( CAS); 6 ɗ, 2 Ψ, Cuernavaca, 1.viii.1938, L.J. Lipovsky ( CAS).

Additional material. Mexico: DISTRITO FEDERAL: ɗ, Mexico City, 8000 ft., 16.viii.1954, R.R. Driesbach ( CAS). MORELOS: ɗ, Yecapixtla, 11.vii.1970, J. & M. Sedlacek ( BPBM); possible Ψ, Amecameca, 8000 ft, 17.viii.1956, R.R. Driesbach ( CAS).

Description. Male: body length: 3.8–3.9 mm; wing: 3.3 x 1.3 mm.

Head: 2 strong postvertical setae present in line with the postoculars; weak proclinate vertical present on lateral frons; vertex, frons, face, and clypeus metallic blue-green, with some silvery pruinosity; clypeus slightly narrowed distally; palp dark brown, with apical seta; proboscis brown; antenna black; pedicel with long ventral seta; 1st flagellomere subrectangular; arista dorsal; l postcranium ventrally with pale setae.

Thorax: metallic green with bronze reflections; pleura with some grey pruinosity; ac absent, present as single pair long setae anteriorly, or as single pair of anterior setae and 2–3 unpaired setae posteriad; lateral scutellar setae about quarter length of medians.

Legs: all coxae, trochanters, FI and FII almost to apices, and all leg III dark brown; femoral apices, tibiae and basitarsi I and II yellowish; distal tarsomeres I and II dark brown; CI and CII with pale anterior hairs and black anterolateral setae; CIII with black lateral seta and some shorter whitish setae; all tibiae bare of major setae, but covered with short, almost erect setae. I: 3.6; 3.4; 3.0/ 0.8/ 0.4/ 0.2/ 0.3; FI with pale ventral setae on basal three-quarters; It5 with posterior claw ( Fig. 2 c) greatly enlarged and curved (MSSC). II: 4.6; 5.5; 3.5/ 1.5/ 1.0/ 0.7/ 0.5; FII with white av and pv setae. III: 5.5; 6.5; 2.7/ 2.1/ 1.3/ 0.7/ 0.5; FIII with white av and pv setae.

Wing: with faint brown wash over wing anteriad of vein R4+5; M with right-angle curve at 1/3 between dm-cu crossvein and wing apex; CuAx ratio: 0.8; lower calypter yellow, with black rim and fan of black setae; halter black.

Abdomen: terga 1–4 metallic blue-green with bronze reflections, covered with short dark setae dorsally and pale setae laterally; tergum 1 with posterolateral black setae; terga 5–6 black, with bronze reflections, expanded and rounded ventrally with abundant black setae; hypopygium ( Fig. 2 b) dark brown; phallus and hypandrium elongate and narrow; epandrial lobe ovate, with setae at 3/4 and apex, strong seta basally; surstylus with 2 arms and setae as figured; cercus slightly curved and tapering, apically clavate.

Female: similar to male except: 4 postvertical setae present; vertical seta strong; ac also with single pair of anterior setae and 4 unpaired almost uniseriate setae posteriad; femora ventrally bare; tibiae also bare of major setae and covered with short, almost erect setae; claws of leg I unmodified; halter yellow.

Remarks. Mesorhaga falciunguis occurs above 800 m in the Central Plateau of Mexico, from the Federal District to Morelos. Males have a long, sickle-shaped posterior claw on leg I ( Fig 2 c), hence the specific epithet from the Latin, falci for sickle, unguis for claw. Also of interest, neither sex has strong setae on the tibiae, unusual for the genus.

A badly damaged series of 3 males [ Mexico: west slope of Popocatepetl, 2400 –2600 m, 10.vii.1970, J. & M. Sedlacek (BPBM)] is close to M. falciunguis , but the male posterior claw on leg I is short. Either these specimens represent a related undescribed species, or M. falciunguis shows intraspecific variation in the claw length of leg I.

Figures

FIGURE 2. Mesorhaga adunca Van Duzee a. hypopygium, left lateral. M. falciunguis n. sp.: b. hypopygium, left lateral; c. male distal tarsus I, posterior. M. villanuevi n. sp.: d. hypopygium, left lateral.