Callomyia venusta Snow

Callomyia venusta Snow

(Figs 1, 14, 24, 32, 40, 43, 46, 64, 69, 77)

Callomyia venusta Snow, 1894: 151. Type locality: Magdalena Mountains, New Mexico, USA.

Diagnosis. This widespread Nearctic species is characterized by yellow and silver-blue markings on the abdomen (reduced in some males) and male terminalia with a molar-like surstylus and apically truncate postgonite. The male of C. venusta is most similar to the southwestern Nearctic species C. browni, but differs in abdominal colour, posteroventral seta somewhat longer and thinner on the base of the hind femur, width of hind tarsomere 1, and the terminalia, as indicated in the key to species. The male of this species also has similar terminalia to C. velutina from eastern and western North America, but the postgonite is truncate and slightly pointed apically (versus rounded apically). The female of C. venusta is very similar to C. velutina because of similar thoracic and abdominal markings. However, C. venusta can be distinguished from C. velutina by a complete silver-blue marking on abdominal tergite 5 (versus a silver-blue marking that is interrupted by a median dorsal dark band) and one less presutural intra-alar seta on the scutum.

Description. Male (Figs 14, 24). Body length 4.0– 4.8 mm; wing length 3.55–4.3 mm. Head silver-blue to silver-grey, occiput dark silver-grey; mouthparts including palpus brownish-yellow to brown; antenna with scape, pedicel, first flagellomere and arista brown to dark brown. Antenna with first flagellomere short-oval (as in Fig. 41).

Thorax dark brown to velvety black with silver-grey dusting on postpronotal lobe, presutural scutum and supra-alar area of scutum; silver-grey to silver-blue markings usually on lateral portion of presutural scutum, notopleuron, posterior portion of postsutural scutum and postalar callus; propleuron, mesopleuron, metapleuron, mediotergite and laterotergite silver-grey; postpronotal lobe yellowish-brown posteroventrally. Scutum with 6 notopleural setae.

Legs yellowish-brown to dark brown, hind leg darker with apex of femur, tibia and tarsomeres dark brown; apex of femur and base of tibiae brownish-yellow; coxae silver-grey dusted in most specimens. Mid tibia with median anterodorsal seta absent, median dorsal seta present (as in Fig. 50); base of hind femur with strong stout posteroventral seta (as in Fig. 53). Hind tarsomere 1 slightly expanded, subequal to apical width of hind tibia, length approximately 2.5X width.

Wing hyaline with cell sc yellowish-brown in most specimens. Halter yellow with base of stem brown.

Abdomen dark brown to black with tergites 1–3 yellow, yellow reduced in some specimens (only on tergites 1 and 2, or only 2); lateral silver-white dusting on tergites 1 and 2; lateral to anterolateral silver-blue marking on tergite 5, marking silver-grey or absent in some specimens; posterior silver-grey dusting on tergite 6 in some specimens; tergite 7 entirely brown to grey; sternites pale yellow to light brown, sternite 8 brown to grey.

Terminalia (Figs 64, 69) brown to grey, surstylus darker; hypandrial process and cercus brownish-yellow. Epandrium with short broad ventral lobe, rounded at apex, anteriorly directed; apical process moderately long, broad basally, pointed at apex. Surstylus molar-like, with 2 large cusps widely excavated in between; dorsal outer cusp broadly rounded in lateral view; ventral inner cusp slightly rounded in lateral view, truncate and minutely serrate medially in posterior view (Fig. 69). Hypandrium with moderately long apical process; process trifid, with 2 short apical projections and short stout rounded basoventral lobe. Postgonite long and wide, somewhat truncated and pointed at apex. Phallus with sharp extended hook at apex. Cercus short.

Female (Figs 1, 32, 40). Body length 3.25–4.25 mm; wing length 3.65–4.25 mm. Head silver-blue with occiput silver-grey to silver-brown; mouthparts including palpus pale yellow to brownish-yellow; antenna with scape and pedicel yellowish-brown to brown, first flagellomere and arista brown to dark brown. Antenna with first flagellomere short-oval (Fig. 43).

Thorax mainly black to velvety black with silver-blue markings on postpronotal lobe, entire lateral portion of presutural scutum, notopleuron, most of postsutural scutum and postalar callus; propleuron, mesopleuron, metapleuron, mediotergite and laterotergite silver-blue dusted; postpronotal lobe posteroventrally, supra-alar area of scutum, postalar callus anteriorly and posterior margin of anepimeron pale yellow to yellowish-brown. Scutum with 2 presutural intra-alar setae (Fig. 46).

Fore leg and mid leg pale yellow to yellowish-brown with tarsomeres 2–5 brown; hind leg darker with apex of femur, tibia and tarsomeres dark brown; coxae silver-blue dusted in most specimens. Mid tibia with median dorsal seta absent.

Wing hyaline with cell sc yellowish-white in some specimens. Halter yellow.

Abdomen dark brown to black with tergites 1–3 yellow; lateral silver-white markings or dusting on tergites 1 and 2; tergite 4 usually dark brown to black, yellow or silver-blue in a few specimens; tergite 5 entirely silver-blue; sternites white to light brown.

Terminalia with segment 8 and epiproct brown to dark brown, silver-grey dusted; hypoproct and cercus brownish-yellow.

Type material. LECTOTYPE (designated by Kessel & Buegler 1972), ♂ labelled: “Magdelena./ New Mexico; “ Type.; “ Callomyia / venusta /Snow [handwritten on thick red label]; “ Callomyia / venusta / Snow/ Det. Kessel; “ LECTOTYPE / Callomyia / venusta Snow / labeled by PHArnaud I-1979 / Designated by Kessel/ + Buegler (1973) 1972 [handwritten on pinkish hand-coloured label] (SEMC). PARALECTOTYPES: USA: NEW MEXICO: Hop Canyon, Magdalena Mountains, viii.1894, W.A. Snow (2 ♀, 1 ♂, SEMC).

Additional material examined. CANADA: ALBERTA: Banff, Johnston Canyon, 4700’, 18.vii.1962, K.C. Herrmann (1 ♀, 1 ♂, CNC), same except W.R.M. Mason (1 ♀, CNC), same except 6.viii.1962, Malaise trap, W.R.M. Mason (1 ♀, CNC); Cypress Hills, Bear Creek Trail, 15.vii.1980, S.A. Marshall (1 ♀, DEBU); Waterton Lakes Nat. Pk., 7-12.vii.1980, H.J. Teskey, CNC DIPTERA 192201 (1 ♀, CNC); BRITISH COLUMBIA: Canadian Customs, Haines Highway, 21.vii.1962, E.L. Kessel (1 ♀, CAS); Fernie Provincial Camp Ground, 9.viii.1963, E.L. Kessel (1 ♂, CAS); Glacier National Park, ca. 1.6 km N. Glacier, 14.vii.1974, P.H. Arnaud Jr. (1 ♀, CAS); Kleanza Creek, 14 miles E. of Terrace, 17.vi.1960, J.G. Chillcott (1 ♀, CNC); Liard Hot Springs, Mile Post 496, 8.viii.1959, E.L. Kessel (1 ♂, CAS); Mile Post 104, Alaska Highway, 5.viii.1957, E.L. Kessel (1 ♂, CAS), same except 5.viii.1959, E.L. Kessel (1 ♂, CAS); Richter Pass Rd., 7 mi. W. Osoyoos, 2.vi.1958, H. & A. Howden (1 ♀, CNC); Robson, 31.v.1947, H.R. Foxlee (1 ♀, CNC), same except 6.vi.1947 (1 ♀, CNC), same except 1.vi.1952 (1 ♀, CNC); Terrace, 24.vii.1960, W.R. Richards (1 ♀, CNC); Vancouver Is., 2.3 km from Lk. Cowichan, 19-28 vii.1985, I.M. Smith (1 ♂, CNC); Whiskers Province Park, 2.ix.1959, E.L. Kessel (1 ♀, CAS), same except 3.ix.1959 (1 ♀, CAS); NEW BRUNSWICK: Barber D., 24.vi.1914, J.D. Tothill (1 ♀, CNC); QUEBEC: James Bay Rte. km 133.7, 5029’52N, 7725’11W, black spruce/Sphagnum, yellow pans, 7-16.vii.2001, M. & B. Buck, JSS25815 (1 ♀, DEBU); Laniel, 18.vi.1944, A.R. Brooks (1 ♀, CNC); YUKON TERRITORY: Alaska Highway and Morly River, 24.vii.1962, E.L. Kessel (1 ♂, CAS); Dawson City, 18.vi.1962, E.L. Kessel (1 ♀, CAS); Mayo, 12.vi.1962, E.L. Kessel (1 ♀, CAS); Mile Post 102, Klondike Highway, 18.vi.1962, E.L. Kessel (1 ♀, CAS); USA: ALASKA: Bedrock Creek Camp Ground, 24.vi.1962, E.L. Kessel (1 ♀, CAS); Chatanika River Camp Ground, 21.vi.1962, E.L. Kessel (1 ♀, CAS); Chickaloon River and Glenn Highway, 1.vii.1962, E.L. Kessel (1 ♀, CAS); Clearwater, Alcan Camp Ground, 19.vi.1962, E.L. Kessel (1 ♂, CAS); Haines, 11.viii.1959, E.L. Kessel (1 ♀, 4 ♂, CAS); same except 20.vii.1962 (3 ♀, CAS), same except 21.vii.1962 (2 ♀, CAS); Hyder, Camp Run-A-Muck, 5.viii.1996, 0 1604, Arnaud Flight Trap, P.H. Arnaud Jr. & M.M. Arnaud (2 ♀, CAS); 4 mi. S. of Livengood, 26.vi.1962, E.L. Kessel (2 ♀, CAS), same except 27.vi.1962 (3 ♀, 3 ♂, CAS); Mile 290, Richard Highway, 19.vi.1951, W.R.M. Mason (1 ♀, CNC); Mile Post 1254, East of Tetlin Junction, Alaska Highway, 14.vii.1962, E.L. Kessel (1 ♀, CAS); Moon Lake Camp Ground, 19.vi.1962, E.L. Kessel (1 ♂, CAS); Moose Creek, 1.vii.1962, E.L. Kessel (1 ♀, CAS); Mosquito Lake, 27 miles N. of Haines, 16.vii.1962, E.L. Kessel (2 ♀, 2 ♂, CAS), same except 17.vii.1962 (2 ♂, CAS); Richardson Highway, 27 miles N. of Delta Junction, 29.vi.1962, E.L. Kessel (1 ♀, 1 ♂, CAS); Seward, 26.vii.1921 (1 ♂, USNM); Seward Highway, 41 miles N. of Seward, 2.vii.1962, E.L. Kessel (1 ♂, CAS); Spenard, 17.viii.1959, E.L. Kessel (1 ♀, CAS); 9 miles E. of Valdez, 11.vii.1962, E.L. Kessel (7 ♀, 3 ♂, CAS), same except 12.vii.1962 (8 ♀, 3 ♂, CAS); ARIZONA: Cochise County, Pinery Center, 11.viii.1964, E.L. Kessel (1 ♀, CAS); Coconino County, Oak Creek Canyon, 8.viii.1964, E.L. Kessel (1 ♂, CAS); White Mountains, Coulter Ranch, 28.vi.1947, J.L. Sperry (1 ♂, USNM); COLORADO: Chaffee County, 2 miles E. of Garfield, 20.viii.1964, E.L. Kessel (1 ♀, CAS); 9 mi. N. Dillon Summit County, Blue River FC, 24.viii.1964, E.L. Kessel (1 ♀, CAS); Doolittle Ranch, Mt. Evans, 9000’, 23.vii.1961, S.M. Clarke (1 ♂, CNC); Gilpin County, 3 mi. W. Rollinsville, 7.viii.1973, D.D. Wilder (1 ♂, CAS); Jefferson County, 6 mi. N.W. of Conifer, 22.viii.1964, E.L. Kessel (5 ♂, CAS); Lake County, 4 mi. W. of Twins Lakes, 22.viii.1964, E.L. Kessel (1 ♂, CAS); Peaceful Valley, viii.1926 (1 ♂, USNM); Pitkin County, 4 mi. E. of Aspen, 23.viii.1964, E.L. Kessel (1 ♂, CAS); Rio Grande County, 8000’ South Fork, 20.vi.1972, Malaise trap, W.W. Wirth (1 ♀, USNM); IDAHO: Kootenia County, Hwy 97, St. Joe National Forest, Forestry Rd. 438, 600 m, N4736.392’ W11640.099’, tribs Beauty Ck., 19.vi.2014, B.J. Sinclair (1 ♂, CNC); Moscow Mt., 17.vi.1918, A.L. Melander (1 ♀, USNM); Priest Lake, 4 mi. Camp, viii.1920, A.L. Melander (1 ♀, USNM); Waha, 30.v.1924, A.L. Melander (1 ♀, USNM); MAINE: Mt. Katahdin, 10.vii.1959, H.C. Huckett (1 ♀, CNC); MONTANA: Sanders County, 9 mi. E. of Paradise, 31.viii.1962, E.L. Kessel (1 ♀, CAS); NEW MEXICO: Grant County, Pinos Altos Mountains, 28.viii.1951, E.L. Kessel (1 ♀, CAS); NEW YORK: Adirondacks, Avalanche Trail, 30.vii.1929, A.L. Melander (2 ♀, USNM); Chittenango, 7.ix.1970, D.J. Peckham (4 ♂, USNM); West Ridge McLean Reservoir, 22.viii.1924, collector unknown (1 ♀, CUIC); UTAH: Cache County, Logan Cyn., Bunchgrass Creek, 19-23.vii.1986, Hanson & Knowlton (1 ♀, LACM); Cache County, Logan Cyn., Twin Creek, 1-6.vii.1979, W.J. Hanson (1 ♀, LACM), same except 23-30.viii.1979 (1 ♂, LACM), same except 1-8.vii.1988 (1 ♀, LACM); Cache County, Logan Cyn., Tony Gr., 27.vi-6.vii.1987, N. Youssef (1 ♀, 1 ♂, LACM); Cache County, Tony Grove Creek, 1-6.viii.1990, W.J. Hanson (1 ♂, LACM), same except 8-15.vii.1994 (1 ♂, LACM); Summit County, Bear River R.S. 3 mi. S.E., 5- 12.viii.1971, Malaise trap, Hanson & Knowlton (1 ♀, LACM); Uinta Mountains, Cub Creek, 17.vii.1952, G.F. Knowlton & G.E. Bohart (2 ♀, LACM); WASHINGTON: Chimacum, 23.viii.1910, A.L. Melander (1 ♂, USNM); Friday Harbor, 25.vi.1909 A.L. Melander (1 ♀, USNM); Olympic National Park, Boulder Lake, 21.vii.1953, K.M. Fender (1 ♂, CAS); WYOMING: Grand Teton N.P., Jackson Lake Village, 23.vii.1971, G.C. Steyskal (1 ♀, USNM); MEXICO: Durango, 3 mi. E. El Salto, 8200’, 1.vii.1964, J.F. McAlpine (1 ♀, CNC); Durango, 10 mi. W. El Salto, 9000’, 8.vi.1964, J.F. McAlpine (2 ♂, CNC), same except 14.vi.1964, H.F. Howden (1 ♀, CNC), same except 19.vi.1964 (3 ♀, CNC), same except 21.vi.1964 (1 ♀, CNC), same except 30.vi.1964, R.M. Mason (1 ♀, CNC), same except 1.vii.1964 (1 ♀, CNC); Durango, 14 mi. S.W. El Salto, 8000’, 26.vi.1964, J.F. McAlpine (1 ♂, CNC).

Geographical distribution and seasonal occurrence (Fig. 77). Callomyia venusta is a widespread North American species that ranges from Alaska to New Brunswick south to Mexico. Adults have been collected from late May to early September.

Remarks. This species exhibits variation in abdominal colour and male terminalia. Some male specimens, with diagnostic morphological features characteristic of C. venusta, have reduced yellow markings on the abdomen (yellow only on tergites 1 and 2 instead of tergites 1–3) and reduced silver-blue on tergite 5 (marking sometimes completely absent). A few female specimens also have abdominal tergite 4 yellow instead of dark brown to black. In addition, an eastern series of four male specimens from Chittenango, New York show some variation in the hypandrial process of the terminalia. These specimens are the only male representatives of C. venusta from eastern North America (all other eastern specimens are females). Three of these males have a reduced basoventral lobe on the hypandrial process, whereas the fourth male, which was collected on the same day as the others, has the same sized basoventral lobe as more western male specimens of C. venusta. Additional collecting of eastern C. venusta males is required to determine the extent of variation in the terminalia and whether it represents intra or interspecific variation. Fresh material from both eastern and western populations would also be useful to obtain DNA barcode data, which could help determine if C. venusta is a single species or perhaps a species complex.

Two female specimens of C. venusta yielded COI barcode sequences (CNC DIPTERA 192201 and JSS25815) (Table 1). These two specimens clustered closely together with <2% genetic divergence in the Neighbour-joining tree (Fig. 78). Two additional female specimens that were initially identified as C. venusta also yielded barcodes but these females clustered with a male specimen of C. velutina (see “Remarks under C. velutina.)