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

description: Calyxochaetus distortus (Van Duzee)
(Figs 33, 45, 51, 54, 61, 74)
Sympycnus distortus Van Duzee, 1930: 55.
Sympycnus monticola Van Duzee, 1932: 20. Preoccupied by Sympycnus monticolus Becker, 1919.
Calyxochaetus distortus: Foote et al. (1965: 528).
Calyxochaetus monticola: Foote et al. (1965: 528).
Calyxochaetus millardi Meuffels & Grootaert, 1999: 290. New name for Calyxochaetus monticola (Van Duzee) syn. nov.
Type material examined. Sympycnus distortus: HOLOTYPE ♂, labeled: “Soldier Summit/ 7454 ft Utah ”; “ Sympycnus / distortus / Holotype. Van Duzee ”; “ Nothosympyc / nus / n. sp.” (USNM).
Sympycnus monticola: HOLOTYPE ♂, labeled: “ Electra Lake Colo./ VI 28–VII 1, ‘19/ F.4367E.”; “ About 37°33’ N./ 107°48’ W./ 8400 ft. ”; “ Calyxochaetus / monticola / Holotype.VanDuzee” (AMNH). PARATYPES: USA: Colorado: Same data as holotype (1♂, 1♀, CAS; 2♂, 2♀, AMNH).
Other material examined. USA: Colorado: Boulder County: Nederland, 9.vii.1962, FCH (1♂, FSCA); same data except, seepage area, 8300 ft, 5.vii.1961, J.G. Chillcott (1♂, CNC); Ward, 25.vi.1962. FCH (3♂, FSCA); Clear Creek County: Mount Evans, Echo Lake, 10600 ft, 12.viii.1961, C.H. Mann (1♂, CNC); Conejos County: Cumbres Pass, 22.vii.1959, FCH (2♂, FSCA); La Jara, 26.vii.1963, FCH (1♂, FSCA); Gunnison County: Youman, 13.vi.1961, FCH (1♂, FSCA); Jackson County: Gould, 8.viii.1961, FCH (1♂, FSCA); La Plata County: Marvel, 10.vi.1960, FCH (2♂, FSCA); Larimer County: Rocky Mountain National Park, 29.vi.1959, FCH (3♂, FSCA); Parvin Lake, 25.v.1974, FCH (2♂, FSCA); Swamp Creek, 25.v.1974, FCH (3♂, FSCA); Red Feather Lake, 26.v.1974, FCH (2♂, FSCA); Mesa County: Glade Park, 8.vii.1953, Gurney (2♂, USNM); Rio Grande County: South Fork, 8000 ft, 20.vi.1972, Malaise, W.W. Wirth (1♂, USNM); Saguache County: Valley View Springs, ca 7 mi. E Mineral Hot Springs, on W foot of Sangre de Cristo range, 8500 ft, 13.viii.1965, H.B. Leech (1♂, CAS); Summit County: Winifred, 27.vii.1963, FCH (1♂, FSCA). Idaho: Franklin County: Preston, 28.vii.1945 (1♂, FSCA). Montana: Beaverhead County: Pioneer Mountains, Canyon Creek Road, hillside spring, 1884 m, N45.6571° W112.7933°, 8.viii.2020, JBR (1♂, CNC; 5♂, 3♀, MTEC); Deer Lodge County: Georgetown Lake, Grassy Point, 6400 ft, 17.viii.2002, RLH & JBR (3♂, 5♀, MTEC); Gallatin County: Blackmore Creek at Hyalite Reservoir, 20 mi S Bozeman, 6800 ft, 24.vii.2000, RLH & JBR (1♂, 1♀, MTEC); Meadow Creek, 45.06987° -111.26913°, 4.viii.2019, JBR (1♂, MTEC); Granite County: Flint Creek, 3.1 mi. N Philipsburg, 5300 ft, 25.vii.2000, RLH & JBR (2♂, 3♀, MTEC); same data except, 17.viii.2002 (2♂, 2♀, MTEC); Jefferson County: Milligan Canyon, Milligan Creek, 6 mi W Three Forks, N45°53.26′ W111°40.72′, 20.vii.2002, RLH & JBR (1♂, MTEC); same data except, 16.vii.2011, JBR (1♂, MTEC); Madison County: 5.4 mi. E of Alder, 5400 ft, 17.viii.1993, RLH (1♂, 3♀, MTEC). Utah: Duchesne County: Uinta Mountains, 17.vii.1952, G.F. Knowlton & G.E. Bohart (1♂, LACM); Millard County: Kanosh, 10.vii.1939, G.F. Knowlton & FCH (1♂, LACM); same data except, 24.vii.1939 (1♂, LACM); Uintah County: Vernal, 18.viii.1942, G.F. Knowlton & C.F. Smith (1♂, FSCA); Big Brush Creek, 22 mi. N Vernal, marshy meadow, 8000 ft, 8.vii.1961, J.G. Chillcott (2♂, CNC); Wasatch County: Soldier Summit, 29.vii.1938, G.F. Knowlton & FCH (1♂, 1♀, LACM); same data except, 14.viii.1939 (3♂, LACM); Washington County: Pinto, 21.vi.1940, G.F. Knowlton & FCH (1♂, LACM). Washington: Thurston County: Olympia, 8.viii.1962, FCH (1♂, FSCA).
Diagnosis. Males of this species can be distinguished from others in the C. cilifemoratus species group by the following combination of characters: wing very narrow (Fig. 61); hind femur without long, erect anterior and posterior setae (in dorsal view) and with distinct posterior preapical seta (Fig. 54); face narrow (2 ommatidia wide at narrowest); and midleg with combined length of tarsomeres 2–5 longer than tarsomere 1 (Fig. 45).
Redescription. Male. Wing length 2.8–3.2 mm. Head: Frons with brown pruinosity, only slightly thinner on either side of ocellar tubercle, not glabrous. Face gray becoming whitish ventrally, narrowly triangular, about 2 ommatidia wide at clypeus. Antenna (Fig. 33) dark brown; scape long, subequal to combined length of pedicel and postpedicel; postpedicel oval, slightly longer than wide; arista-like stylus longer than height of head, apical half with denser, slightly longer microtrichia, apical lamella elongate and subtriangular with apex varying from pointed to narrowly rounded. Palpus small, oval, dark brown with brown-yellow setulae. Proboscis brown. Thorax: Pleura dark brown with gray pruinosity; metepimeron concolorous with pleura, usually yellow just above hind coxa. Legs: Foreleg: Yellow, except tarsomere 1 narrowly brown dorsally at apex, tarsus brown from apex of tarsomere 2. Tibia slender, without outstanding setae. Tarsus slender, 1.5X tibia length. Tarsomere 1 very short, about as wide as long. Tarsomere 2 about two-thirds length of tibia, subequal to combined length of tarsomeres 3–4, without anterior setae at apex. Tarsomere 3 about two-thirds length of tarsomere 4. Tarsomere 4 slightly bowed, with slightly longer pale dorsal setulae on apical third (in some pinned specimens, this tarsomere collapses, appearing dorsoventrally flattened). Tarsomere 5 dorsoventrally flattened, slightly wider than tarsomere 4. Midleg: Yellow, except coxa infuscated with yellow ground color visible, tarsus brown from apex of tarsomere 1. Femur with very short slender yellow ventral setae (length half femur width or less). Tibia slender, very slightly bowed, without specialized setae. Tarsus (Fig. 45) very slender, subequal to tibia length. Tarsomere 1 about three-quarters combined length of tarsomeres 2–5; apex with 2 fine curved anterior setae. Tarsomere 2 with basal third slightly swollen, bearing 3 fine curved pale anterior setae. Tarsomeres 2–4 subequal in length and relatively long (each slightly less than half tarsomere 1 length). Tarsomere 4 with a few slightly longer setae (length subequal to tarsomere width) along anterior edge; long (slightly greater than half of tarsomere length) fine curved pale anterior seta at apex. Tarsomere 5 about one-third tarsomere 4 length, with about 3 short fine setae along anterior edge. Hindleg: Yellow, except coxa faintly infuscated at base, femur brownish dorsoapically, tibia becoming brown on apical one-third, tarsus brown. Apical half of femur (Fig. 51) with anteroventral row of long yellow setae, apical-most seta in this row shorter and black, with posteroventral row of short setae on apical half, posterior preapical seta present (Fig. 54). Tibia with row of finer, denser ventral setae on basal half (length subequal to tibia width). Wing (Fig. 61): Very narrow and elongated with anterior half or more light brown-tinged. Very narrow at base, anal lobe markedly widening opposite apex of R 1, widest part of wing just basal to crossvein dm-m with slightly longer hairs along posterior margin, posterior margin flattened at apex of M 4. Distal section of M 4 about 4X longer than crossvein dmm. Abdomen: Tergite 2 usually mostly yellow (yellow-brown in one specimen). Tergite 3 often with some yellow laterally but sometimes wholly brown. Basal sternites yellow, distal sternites brown. Hypopygium: Postgonite apical lobes uniformly dark brown, nearly black.
Female. Wing length 2.9–3.2 mm. Similar to male except as follows: Head: Face wide, nearly parallel-sided, gray. Clypeus light gray. Antenna with postpedicel short, wider than long, rounded with slightly flattened apex; arista-like stylus unmodified. Palpus much larger, triangular, rounded apically, dark brown with gray pruinosity and yellow setulae and setae. Thorax: Proepimeron with 2–3 small white hairs. Metepimeron lightly infuscated with yellow ground color visible. Legs: Unmodified, without specialized setae. Hind femur yellow. Hind tibia yellow, becoming light brown apically. Hind tarsomere 1 yellow on basal half. Wing: Broader, but still elongate and narrow, with narrow anal lobe, not petiolate at base, evenly brown-tinged. Posterior margin evenly rounded except slightly flattened near apex of M 4. Distal section of M 4 about 3X longer than crossvein dm-m. Abdomen: Mostly dark brown, tergite 2 with some yellow at base, often appearing as faint yellow spot.
Distribution and seasonal occurrence. This species is known from Colorado, Utah, southeastern Idaho, southwest Montana, and from one male collected near Olympia, Washington (Fig. 74). Adults have been collected in May through August.
Remarks. Van Duzee (1932) distinguished C. monticola from C. distortus based on the scape having hairs at the tip, arista-like stylus as long as fore tarsus (shorter than fore tarsus in C. distortus), and midleg with tarsomere 4 longer than tarsomere 3 (shorter in C. distortus). However, there is no difference in these characters between the types: both have the scape bare and the lengths of the arista-like stylus and tarsomeres do not differ.
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 26-28, DOI: 10.11646/zootaxa.5539.1.1, http://zenodo.org/record/14240426