Calyxochaetus frontalis
Creators: name: Runyon, Justin B.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Dolichopodidae
Calyxochaetus
Calyxochaetus frontalis

description: Calyxochaetus frontalis (Loew)
(Figs 8–10, 12, 112, 129, 135, 146)
Sympycnus frontalis Loew, 1861: 67.
Calyxochaetus frontalis: Parent (1930: 107).
Type material examined. LECTOTYPE (designated here to fix identity of the species), ♂ from Pennsylvania, USA, labeled: “Loew/ Coll.”; “Type/ 4/ 12924 [red label]”; “LECTOTYPE/ ♂ Calyxochaetus / frontalis (Loew) / des. J.B. Runyon [blue label]” (MCZ) [photos examined].
Other material examined. CANADA: Ontario: Niagara Falls, 6.viii.1929, ALM (1♂, USNM); Niagara Glen, 1.viii.1957, J.R. Vockeroth (1♂, CNC); Ottawa, 5.vi.1946, G.E. Shewell (1♂, CNC); Ottawa, 27.vi.1991, damp shaded ditch in Acer wood, J.R. Vockeroth (1♂, CNC); same data except, 31.viii.1993 (2♂, CNC); Normandale, 42°42′ -80°19′, 2.vi.1956, J.R. Vockeroth (1♂, CNC); St. Ignace II, Sturgeon Bay, v.1959, wooded ravine, J.G. Chillcott (1♂, CNC); Waterdown, Grindstone Creek, 43°19′47″N 79°53′13″W, 17.vi.2023, B.J. Sinclair (1♂, CNC). Quebec: Old Chelsea, 9.vii.1959, J.R. Vockeroth (1♂, CNC); Lac Phillipe, 45°37N 76°W, 22.viii.1959, J.R. Vockeroth (1♂, CNC); Hull, Fairy Lake Creek, 29.ix.1959, J.F. McAlpine (1♂, CNC). USA: Alabama: Lauderdale County: West Fork Anderson Creek, 0.3 mi S Grassy, 7.viii.1992, RLH (1♂, 7♀, MTEC). Connecticut: Fairfield County: Redding, 1–11.vi.1929, ALM (4♂, USNM), same data except, 31.viii.1930 (1♂, USNM); Candlewood Lake, 30.viii.1941, ALM (1♂, USNM). District of Columbia: Rock Creek Park, stream, 38.91922° -77.05605°, 30.v.2016, JBR (4♂, MTEC). Florida: Alachua County: 3 mi. E Gainesville, 4.viii.1988, RLH (1♀, MTEC). Georgia: Dade County: Cloudland Canyon State Park, near Trenton, 24.iv.1989, J.M. Cumming (1♂, 1♀, CNC). Illinois: Hancock County: Nauvoo, 25.vii.1972, FCH (3♂, FSCA); Pope County: Burden Falls, 20.v.1991, B.J. Sinclair (2♂, CNC); Vermillion County: Windfall Creek, 700 ft, N40°11.63′ W87°42.33′, 26.viii.2006, JBR (1♂, 1♀, MTEC). Indiana: Crawford County: Hoosier National Forest, Hemlock Cliffs, trickling stream, 19.v.1991, B.J. Sinclair (4♂, 6♀, CNC); Lawrence County: Spring Mill State Park, small stream, 19.v.1991, B.J. Sinclair (1♂, CNC); Marion County: Indianapolis, 18.vii.1943, FCH (1♂, FSCA); same data except, 4.vi.1944 (1♂, FSCA); same data except, 4.vii.1944 (1♂, FSCA). Iowa: Allamakee County: 3 mi. NW Lansing, 6.viii.2002, RLH (2♂, 2♀, MTEC). Kentucky: Edmonson County: Mammoth Cave National Park, 23.viii.1981, J.R. Vockeroth (2♂, CNC); Letcher County: Poor Fork Cumberland River, N37°04.37′ W82°45.05′, 2.vi.2008, JBR (1♂, MTEC); Pike County: Russell Fork River, 850 ft, N37°17.891′ W82°19.414′, 3.vii.2006, JBR (7♂, 1♀, MTEC). Mississippi: Adams County: 9 mi NW Kingston, 17.viii.1981, RLH (2♂, MTEC). Missouri: Camden County: Climax Springs, 10.viii.1992, RLH (1♂, 6♀, MTEC); St. Louis County: Saint Louis, 15.vi.1952, FCH (1♂, FSCA); same data except, 6.vii.1952 (1♂, FSCA). New York: Steuben County: Canisteo, 2.viii.1957, J.R. Vockeroth (2♂, CNC); Suffolk County: Cold Spring Harbor, 7.vii.1927, ALM (1♂, USNM); Tompkins County: Ringwood, 2.vii.1928, H.A. Scullen (1♂, FSCA); Ithaca, 15.viii.1928, ALM (1♂, USNM); Westchester County: Peekskill, 11.vi.1927, ALM (2♂, USNM). North Carolina: Madison County: Big Laurel Creek, 2900 ft, N35°54.614′ W82°32.613′, 2.vii.2006, JBR (1♂, 1♀, MTEC); Macon County: Wayah Bald, 5300 ft, 14.vii.1957, J.G. Chillcott (1♂, CNC); Swain County: Great Smoky Mountains National Park, N35°36′ W83°25′, Malaise, 24–27.v.1999, L.W. Quate (1♂, MTEC). Ohio: Geauga County: Novelty Township, Chagrin River, 6.viii.1982, R.S. Zack (1♂, 2♀, WSU). Oklahoma: Latimer County: Robbers Cave State Park, 5 mi. N Wilburton, 21.v.1993, along Rough Canyon Creek, J.M. Cumming (1♂, CNC); Robbers Cave State Park, creek at Ash Creek Road, N35°0′8″ W95°21′26″, 2.vi.2019, B.J. Sinclair (1♂, 1♀, CNC). Pennsylvania: Cambria County: Prince Gallitzin State Park, Crooked Run, N40°40.201′ W78°34.032′, 16.vi.2007, JBR (1♂, MTEC); Centre County: Little Fishing Creek, 6 mi. E Bellefonte, 22.iv.2005, JBR (1♂, 1♀, MTEC); Elk Creek, 2 mi N Millheim, 5.vi.2005, JBR (1♂, MTEC); Black Moshannon State Park, Moss-Hanne Trail, Shirks Run, 1900 ft, 12.viii.2007, JBR (1♂, MTEC); Clearfield County, DuBois, 3.ix.1927, ALM (1♂, USNM); Mineral Springs, 5.ix.1927, ALM (1♂, USNM); Huntingdon County: Shavers Creek, 0.25 mi. E Perez Lake, 23.viii.2003, JBR (1♂, MTEC); Perez Lake, 31.viii.2003, JBR (3♂, 1♀, MTEC); Luzerne County: Choke Creek, 3.4 mi. SW Thornhurst, 22.vii.1991, RLH (4♀, MTEC); Union County: Lewisburg, 26.viii.1981, J.R. Vockeroth (4♂, 1♀, CNC); Whitedeer, 26.viii.1981, J.R. Vockeroth (1♂, CNC); Venango County: Richey Run, 0.5 mi. E Emlenton, 23.viii.2003, JBR (1♂, 1♀, MTEC). South Carolina: Pickens County: Easley, Middle Branch Brushy Creek, N34°47.724′ W82°33.201′, 30.vi.2006, JBR (3♂, 2♀, MTEC). Tennessee: Sevier County: Great Smoky Mountains National Park, Elkmont campground, roadcut seep, 14.vi.1990, B.J. Sinclair (1♀, CNC); same data except, Ramsay Cascade Trail, 35°42′40″N 83°23′02″W, 13.vi.2008 (1♂, CNC); Unicoi County: 2.2 mi. NW Erwin, state route 81, stream, 18.v.2000, JBR (1♂, 5♀, MTEC). Virginia: Albemarle County: Briar Fork, 2 mi NE Schuyler, 20.vii.1991, RLH (6♂, 7♀, MTEC); Augusta County: Staunton, Gypsy Hill Park, 6.vii.2006, JBR (1♂, 1♀, MTEC); Dickenson County: Cranesnest River, N37°08.5′ W82°25.3′, 10.v.2000, JBR (7♂, 5♀, MTEC); same data except, 29.vi.2006 (2♂, MTEC); same data except, 30.v.2008 (2♂, MTEC); same data except, 18.vii.2008 (1♂, MTEC); same data except, 12.v.2011 (2♂, MTEC); same data except, 26.xii.2015 (1♂, MTEC); 6 mi. SE Clintwood, small stream, 1865 ft, 13.v.2011, JBR (4♂, MTEC); Lick Branch, 2.5 mi. E Clintwood, N37°09.50′ W82°24.15′, 9.vi.2008, JBR (2♂, MTEC); Ramey Fork, 3 mi. N Clintwood, 15.viii.2008, JBR (1♂, MTEC); Camp Branch Creek, N37°16.283′ W82°17.678′, 19.vii.2008, JBR (1♂, MTEC); Georges Fork, N37°10.83′ W82°28.97′, 20.viii.2008, JBR (1♂, MTEC); Holly Creek, N37°09.264′ W82°25.158′, 11.v.2015, JBR (2♂, MTEC); McClure River at McClure, 10.v.2000, JBR (1♀, MTEC); Pound River campground, 11.v.2000, JBR (3♂, MTEC); Fairfax County: Turkey Run, 9.x.1921, W.L. McAtee (1♂, USNM); Falls Church, Holmes Run, 2.vi.1962, light trap, W.W. Wirth (1♂, USNM); Floyd County: Pine Creek, 7 mi. NW Endicott, 12.vii.1987, RLH (1♂, 2♀, MTEC); Giles County: Stony Creek, 2000 ft, 26.v.1962, J.G. Chillcott (3♂, 3♀, CNC); Montgomery County: Blacksburg, 2100 ft, 28–29.v.1962, J.G. Chillcott (1♂, 1♀, CNC); Nelson County: Dillard Creek at Lovingston, 19.vii.1991, RLH (1♂, 1♀, MTEC); Page County: Luray, 24.vi.1933, ALM (1♂, USNM); Tazewell County: Plum Creek, 4 mi. S Tazewell, 4.viii.1992, RLH (1♂, 2♀, MTEC); same data except, 6 mi S Tazewell (1♂, 1♀, MTEC); Wise County: High Knob Lake, 13.v.2000, JBR (2♀, MTEC); Norton Reservoir, 18.v.2000, JBR (2♀, MTEC). West Virginia: Braxton County: Birch River, 5.5 mi NW Erbacon, 19.vii.1991, RLH (3♂, 7♀, MTEC); Greenbriar County: Harts Run, N37°45.42′ W80°21.31′, 13.viii.2008, JBR (1♂, 1♀, MTEC); Putnam County: 1 mi S Hurricane, 3.viii.1992, RLH (9♂, 9♀, MTEC); Tucker County: Davis, Blackwater Falls State Park, 30.v–2.vi.1990, B.J. Sinclair (1♂, CNC).
Diagnosis. This eastern North American species is distinguished by the unmodified arista-like stylus (Fig. 112) and hind tibia with ventral row of small close-set setae with those near base thin apically and curved downward (Fig. 135).
Redescription. Male. Wing length 2.4–2.8 mm. Head: Frons with large glabrous shiny blue-violet spot on either side of ocellar tubercle. Face white-silver, very narrow, 1–2 ommatidia wide at narrowest. Antenna (Fig. 112) dark brown; scape shorter than postpedicel; postpedicel elongate oval, length variable from 1.5–2.0X as long as wide; arista-like stylus unmodified, evenly tapered to apex. Palpus small, elongate oval, brown with apex yellow. Thorax: Pleura brown with thick gray pruinosity and blue tinge; metepimeron mostly to wholly yellow. Scutellum with distinct blue-violet reflections medially. Legs: Foreleg: Yellow, except tarsus becoming brown from apex of tarsomere 3. Tibia slender, sometimes with small posterodorsal seta near 1/3. Tarsomere 1 very short, slightly longer than wide. Tarsomere 2 half tibia length, less than combined length of tarsomeres 3–4. Tarsomere 3 half tarsomere 2 length, with longer dorsal microsetulae at apex. Tarsomere 4 1.5X tarsomere 3 length, dorsal surface with short hooked microsetulae and row of slightly larger microsetulae across apex. Midleg: Yellow, except tarsus brown from near apex of tarsomere 1. Tarsus (Fig. 129) slightly longer than tibia. Tarsomere 1 about half tibia length, slightly longer than combined length of tarsomeres 2–5. Tarsomere 2 subequal to combined length of tarsomeres 3–5, scarcely broadened apically, with very small anteroapical projection bearing a few longer pale microsetulae. Tarsomeres 3–4 short with short anterior pale microsetulae; tarsomere 3 nearly round, tarsomere 4 slightly longer than wide. Tarsomere 5 subequal to combined length of tarsomeres 3–4. Hindleg: Yellow, except tarsus brown beyond apex of tarsomere 1. Tibia (Fig. 135) with ventral row of short close-set setae, those near base thin apically and curved downward. Wing: Evenly tinged brown. Elongate oval and rather narrow, with anal area reduced. Distal section of M 4 about 3X longer than crossvein dm-m. Abdomen: Tergites 2–3 usually mostly yellow (sometimes brown dorsally and along margins). Tergite 4 sometimes yellow at base, remaining tergites dark brown. Hypopygium (Figs 8–10, 12): Postgonites with apical lobes broadly rounded, translucent light brown, with sclerotized brown rod along dorsal edge.
Female. Wing length 2.8–3.1 mm. Similar to male except as follows: Head: Face wider (subequal to postpedicel width), nearly parallel-sided, gray-silver. Antenna with postpedicel about as wide as long, rounded but with apex weakly flattened. Palpus larger, triangular, rounded apically, brown at base and broadly yellow apically. Thorax: Proepimeron with cluster of 1–4 small white hairs. Legs: Unmodified, without specialized setae. Hind tibia with ventral row of very short (less than tibia width) close-set setae. Wing: Broader with larger anal area. Distal section of M 4 about 2.5X longer than crossvein dm-m. Abdomen: Tergites 2–3 with less yellow, sometimes reduced to lateral spots, remaining tergites dark brown.
Distribution and seasonal occurrence. Widespread in the eastern USA and southern Ontario and Quebec, Canada (Fig. 146). Adults have been collected from late April to September. I collected one male in southwest Virginia in late December following an unusually warm autumn.
Remarks. I have often seen adults at shaded wetlands and streams on low vegetation and on moist soil and rocks. An aberrant male (collected in Tazewell County, Virginia) had clear signs of demasculinization (Runyon 2022) including a wider face, shorter postpedicel, fore tarsomere 1 three-quarters tarsomere 2 length, mid tarsus unmodified, and a broader wing. The abdomen was dissected, and no nematodes were found, but the number and density of tracheoles were unnaturally high. Whether this was caused by nematodes (that had exited the adult), some other type of infection, or a developmental disorder, is unknown.
There are three paralectotypes (of unknown sex) in the MCZ that were not examined.
description: Published as part of Runyon, Justin B., 2024, Revision of the genus Calyxochaetus Bigot (Diptera: Dolichopodidae: Sympycninae), pp. 1-74 in Zootaxa 5539 (1) on pages 56-58, DOI: 10.11646/zootaxa.5539.1.1, http://zenodo.org/record/14240426