Callomyia argentea Cumming

Cumming, Heather J. & Wheeler, Terry A., 2016, Revision of the Nearctic species of Callomyia Meigen (Diptera: Platypezidae) and phylogeny of the genus, Zootaxa 4111 (5), pp. 501-554 : 509-511

Callomyia argentea Cumming sp. nov.

( Figs 4 , 15 , 47 , 53 , 55 , 65 , 70 )

Diagnosis. This western Nearctic species is characterized by silver-grey markings on abdominal tergites 1−5 and male terminalia with a molar-like surstylus. Callomyia argentea is similar in appearance to the western Nearctic species C. corvina and C. gilloglyorum because of its similar abdominal colour pattern, but can be distinguished from these species by its molar-like surstylus (versus broadly lamellate surstylus), hyaline wings (versus yellowishbrown tinted wings), and stronger stouter posteroventral seta on the base of the hind femur. Callomyia argentea has similar male terminalia to C. velutina from eastern and western North America, but its terminalia differ by a ventral inner surstylus cusp that is more extended and rounded in lateral view and truncate in posterior view (versus more pointed in lateral view and narrowly truncate in posterior view), a postgonite that is truncate apically (versus rounded apically), and a phallus that is gradually hooked towards the apex (versus a sharp extended hook apically).

Description. Male ( Figs 4 , 15 ). Body length 3.7–4.2 mm; wing length 3.7–4.1 mm. Head dark silver-grey; mouthparts brownish-yellow to brown with palpus brown to dark brown; antenna with scape, pedicel, first flagellomere and arista dark brown. Antenna with first flagellomere short-oval (as in Fig. 41 ).

Thorax mainly dark brown to black, velvety black in some specimens; notopleuron and supra-alar area of scutum silver-grey dusted in some specimens; propleuron, mesopleuron and metapleuron mainly silver-grey dusted; mediotergite and laterotergite silver-grey dusted. Scutum with 6 notopleural setae.

Legs light brown to brown, hind leg darker with tibia and tarsomeres dark brown. Mid tibia with median anterodorsal seta absent, median dorsal seta present (as in Fig. 50 ); base of hind femur with strong stout posteroventral seta ( Fig. 53 ). Hind tarsomere 1 slightly expanded, subequal to apical width of hind tibia, length approximately 2.5X width.

Wing hyaline ( Fig. 47 ) with cell sc faintly yellow, whitish in some specimens. Halter with stem brown; knob orange, yellow in some specimens.

Abdomen dark brown to black with lateral silver-grey markings on tergites 1 and 2; ventrolateral silver-grey markings on tergites 3–5; tergite 6 silver-grey dusted; tergite 7 entirely grey; sternites light brown, sternite 8 grey.

Terminalia ( Figs 55 , 65 ) with epandrium grey; surstylus black; hypandrium brown; hypandrial process and cercus brownish-yellow. Epandrium with short broad ventral lobe, rounded at apex; apical process moderately long, pointed at apex. Surstylus molar-like, with 2 large cusps moderately excavated in between; dorsal outer cusp broadly rounded in lateral view; ventral inner cusp narrow and extended, rounded at apex in lateral view, truncate and minutely serrate medially in posterior view ( Fig. 65 ). Hypandrium with moderately long apical process; process trifid, with 2 short apical projections and short broad triangular basoventral lobe. Postgonite long, slightly expanded apically, truncate at apex. Phallus gradually hooked towards apex. Cercus short.

Female. Unknown.

Type material. HOLOTYPE, ♂ labelled: “ SilverLake/ MonoCo. Cal./ VI.19.61; “T 86/ 12:45/ FC 50/ RH24%/ E7200; E.L. Kessel/ Collector; “ Callomyia / velutina / Johnson/ Det.Kessel; “HOLOTYPE ♂/ Callomyia argentea / H.J. Cumming [red label] [dissected] ( CAS). PARATYPES: CANADA: BRITISH COLUMBIA: Kleanza Creek Province Camp Ground, Highway 16 , 31.vii.1962, E.L. Kessel (1 ♂, CAS); USA: CALIFORNIA: Donner Summit , 2227m, 16.viii.1999, 3920.55’N12020.44’W, sweep vegetation, J. Savage (1 ♂, LEMQ); Mono County, Silver Lake , 19.vi.1961, E.L. Kessel (1 ♂, CAS); OREGON: Lake County, Drews Creek at Highway 66, 21.ix.1963, E.L. Kessel (1 ♂, CAS); Umatilla County, Woodward Forest Camp , Highway 204, 25.viii.1962, E.L. Kessel (2 ♂, CAS).

FIGURES 1−3. Callomyia habitus and morphology. 1. C. venusta , female on leaf (photograph by Andrew Young). 2. C. calla , male wing (from Kessel 1987, fig. 50.4). 3. C. gilloglyorum , larva (from Kessel 1987, fig. 50.32). Abbreviations: A1+CuA2— anal vein and second branch of anterior cubital vein; CuA1—first branch of anterior cubital vein; M1+2—first branch of media; R1—first branch of radius; R2+3—second branch of radius; R4+5—third branch of radius; Sc—subcosta; sg—segment.

Geographical distribution and seasonal occurrence ( Fig. 70 ). Callomyia argentea is currently known from western North America (British Columbia, Oregon and California). Adults have been collected from late June to late September.

Etymology. This species name is derived from the Latin argentea for silvery, in reference to this species’ similar appearance to C. velutina , but with more silver on the abdomen.

Figures

FIGURE 70. Known distribution of C. argentea.

FIGURES 4 − 8. Callomyia males, lateral view. 4. C. argentea. 5. C. arnaudi (abdomen removed). 6. C. arnaudi abdomen in glycerin (coloured markings more metallic bluish-white than depicted). 7. C. browni. 8. C. bertae.

FIGURES 15 − 18. Callomyia males, dorsal view. 15. C. argentea. 16. C. arnaudi (abdomen removed). 17. C. bertae. 18. C. browni.

FIGURES 45 − 48. Callomyia thoracic bristles and wings. 45. C. velutina, female (scutum with 3 presutural intra-alar setae). 46. C. venusta, female (scutum with 2 presutural intra-alar setae). 47. C. argentea, male wing. 48. C. corvina, male wing.

FIGURES 49 − 54. Callomyia legs. 49. C. proxima, male mid leg (with tibial setae). 50. C. velutina, male mid leg (with tibial seta). 51. C. proxima, female mid leg (with tibial seta). 52. C. velutina, female mid leg (with tibial seta). 53. C. argentea, male hind leg (with femoral seta). 54. C. corvina, male hind leg (with femoral seta). Abbreviations: ad s—anterodorsal seta; d sdorsal seta; pv s—posteroventral seta.

FIGURES 55 − 58. Callomyia male terminalia, lateral view. 55. C. argentea. 56. C. arnaudi. 57. C. bertae. 58. C. browni. Abbreviations: ap prj—apical projection; bv lb—basoventral lobe; cerc—cercus; d lb—dorsal lobe; d o csp—dorsal outer cusp; d prj—dorsal projection; epand—epandrium; epand ap proc—epandrial apical process; epand v lb—epandrial ventral lobe; hypd—hypandrium; hypd proc—hypandrial process; i proc—inner process; o proc—outer process; pgt—postgonite; phphallus; sur—surstylus; v i csp—ventral inner cusp; v prj—ventral projection; v proc—ventral process. Scale bar = 0.1 mm.

FIGURES 63 − 69. Callomyia male terminalia, lateral view (63 − 64); surstyli, posterior view (65 − 69). 63. C. velutina. 64. C. venusta. 65. C. argentea. 66. C. browni. 67. C. calla. 68. C. velutina. 69. C. venusta. Abbreviations: d o csp—dorsal outer cusp; v i csp—ventral inner cusp. Scale bar: Figs 63 − 64 = 0.1 mm; Figs 65 − 69 = 0.05 mm.

FIGURES 41 − 44. Callomyia antennae. 41. C. calla, male antenna (first flagellomere short-oval). 42. C. gilloglyorum, male antenna (first flagellomere elongate-conical). 43. C. venusta, female antenna (first flagellomere short-oval). 44. C. gilloglyorum, female antenna (first flagellomere subtriangular).