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

description: Calyxochaetus pennarista (Harmston & Knowlton)
(Figs 11, 96, 98, 100, 101, 103)
Sympycnus pennarista Harmston & Knowlton, 1940: 399.
Calyxochaetus pennarista: Pollet et al. (2004: 74).
Type material examined. HOLOTYPE ♂, labeled: “ Manila, Utah / 9-5, 1939/ G.F. Knowlton / F.C. Harmston ”; “Type No/ 54299/ USNM”; “HOLOTYPE/ Sympycnus / pennarista / n. sp. F.C.H. - G.F.K”; “ Sympycnus / pennarista / Det. 1940 F.C. Harmston” (USNM).
Other material examined. CANADA: Alberta: Cypress Hills, Spruce Coulee Reservoir, 31.viii.2002, JBR (1♂, CNC; 3♂, MTEC). Manitoba: 9 mi. W Forrest, 29.vii.1958, R.L. Hurley (1♂, CNC); Brandon, light trap, 31.vii.1958, J.G. Chillcott (1♂, CNC); 2 mi E Douglas, along small stream, 27.vii.1958, N.B. Chillcott (1♂, CNC); 5 mi. SW Shilo, floodplain community near tamarack bog, 7.vii.1958, R.L. Hurley (2♂, 1♀, CNC). USA: California: Mono County: Mammoth Lakes, 29.vii.1940, L.J. Lipovski (1♂, MTEC). Colorado: Larimer County: Fort Collins, 20.viii.1972, FCH (2♂, FSCA); Park County: Fairplay, 8.viii.1968, FCH (1♂, CAS; 1♂, FSCA); Summit County: Winifred, 27.vii.1963, FCH (1♂, CAS). Montana: Broadwater County: Williams Ditch, 12 mi WSW Toston, 4300 ft, 21.vii.2001, RLH & JBR (1♂, MTEC); Carbon County: Pryor Mountains, Sage Creek campground, 21.vi.2003, JBR (1♂, MTEC); Gallatin County: Gallatin River at Central Park, 29.vi.2000, RLH & JBR (1♂, MTEC); Madison River, side ponds, 1 mi. NE Three Forks, 4030 ft, 16.vi.2002, RLH & JBR (1♂, MTEC); Cherry River fishing access, 1 mi. N Bozeman, 7.vii.2002, JBR (6♂, 4♀, MTEC); Bozeman, Mill Creek at Lindley Park, 8–10.vii.2002, JBR (5♂, MTEC); Granite County: Flint Creek, 3.1 mi. N Philipsburg, 5300 ft, 25.vii.2000, RLH & JBR (1♂, MTEC); Jefferson County: Milligan Canyon, Milligan Creek, 6 mi. W Three Forks, N45°53.26′ W111°40.72′, 6.vii.2002, RLH & JBR (10♂, MTEC); same data except, 20.vii.2002 (1♂, MTEC); same data except, 14.vi.2003 (1♂, MTEC); same data except, 26.vi.2010, JBR (8♂, 2♀, MTEC); same data except, 16.vii.2011 (6♂, MTEC); Wheatland County: Musselshell River, Harlowton, N46°25.75′ W109°50.27′, 7.vii.2016, JBR (2♂, 1♀, MTEC). Utah: Piute County: Marysvale, 20.vi.1940, G.F. Knowlton & FCH (1♂, LACM; 1♂, MTEC).
Diagnosis. Males can be recognized by having fore tarsomere 1 about half the length of fore tarsomere 2 (Fig. 98). The long, fuzzy, twisted arista-like stylus that is of nearly equal width throughout (Fig. 96) and hind femur with long ventral setae on basal half further separate males from other Calyxochaetus species.
Redescription. Male. Wing length 2.5–2.8 mm. Head: Frons with thick brown pruinosity, hardly sparser on either side of ocellar tubercle. Face silver-gray, narrow, triangular, about one ommatidium wide at clypeus. Antenna (Fig. 96) brown with scape and pedicel brown-yellow; scape laterally flattened, flared apically, longer than combined length of pedicel and postpedicel; postpedicel elongate oval with ventral margin curved, dorsal margin nearly straight, about 1.5X as long as wide; arista-like stylus long, densely pubescent with microtrichia, twisted, slightly thickened and of nearly equal width throughout; article 1 rather thick and longer than postpedicel length. Palpus small, elongate oval, brown with paler apex and small whitish setulae. Thorax: Pleura brown with gray pruinosity, sclerite below the halter yellowish; metepimeron wholly yellow. Legs: Foreleg (Fig. 98): Yellow, except apex of tarsomere 1 brown, tarsus brown from apex of tarsomere 2. Tibia not swollen, a few specimens have very small posterodorsal seta near 1/3. Tarsomere 1 about half length of tarsomere 2. Midleg: Yellow, except coxa infuscated, tarsus brown from about apical third of tarsomere 1. Femur with 4–6 fine ventral setae near base (length subequal to femur width). Tibia slightly bowed in anterior view, with longer than normal anterodorsal setae (near 1/3 and 1/2), about 2X length of posterodorsal seta (near 1/3), with row of slightly longer anteroventral setae (subequal to tibia width) and posterior row of short black setae on apical half. Tarsus directionally asymmetrical (Figs 100, 101). Right side of body with tarsomere 1 slightly longer than left tarsomere 1, both slightly bowed in dorsal view, with posteroventral row of about 6 small black setae on basal half. Right tarsomeres 2–4 each slightly broadened, nearly round in dorsal view whereas left tarsomeres 2–4 not broadened and twice as long as wide, both sides with ventral surfaces slightly flattened and dense anterior and ventral setulae. Right tarsomere 5 about 1.5X longer than tarsomere 4, left tarsomere 5 subequal in length to tarsomere 4. Hindleg: Yellow, except tibia becoming brown on apical third, tarsus brown. Femur with 2–5 slender ventral setae on basal half, at least as long as femur width. Tibia without specialized ventral setae near base. Tarsomere 1 subequal in length to tarsomere 2. Wing: Mostly tinged with light brown, hyaline on approximately posterior third of wing. Elongate oval and narrow with anal lobe gradually narrowed at base; posterior margin evenly rounded. Distal section of M 4 straight, about 3X longer than crossvein dm-m. Abdomen: Tergites 2–3 mostly yellow, usually brown dorsally and along posterior margins. Tergite 4 sometimes narrowly yellow at base. Hypopygium (Fig. 11): Postgonites with apical lobes narrow, rather pointed, usually darker brown along dorsal edge.
Female. Wing length 2.6–2.9 mm. Similar to male except as follows: Head: Face wider (subequal to postpedicel width), nearly parallel-sided, gray. Antenna with scape as long as combined length of pedicel and postpedicel; postpedicel slightly wider than long, weakly pointed apically near dorsal edge, ventral margin curved; arista-like stylus unmodified. Palpus much larger, triangular, rounded apically, dark brown with light gray pruinosity and yellow setae. Thorax: Proepimeron with 3–5 small white hairs. Legs: Unmodified, without specialized setae, bilaterally symmetrical. Mid tibia with anterodorsal setae (near 1/3 and 1/2) about 1.5X longer than posterodorsal seta (near 1/3). Hind tibia light brown apically. Hind tarsomere 1 subequal in length of tarsomere 2. Wing: Mostly tinged with light brown. Anal lobe broader, more rounded at base. Abdomen: Tergite 2 almost wholly yellow, narrowly brown along posterior margin. Tergite 3 about half yellow laterally, brown dorsally and posteriorly, remaining tergites dark brown.
Distribution and seasonal occurrence. Most specimens are from the central and northern Rocky Mountains of the USA with outlying records from eastern California and southern Alberta and Manitoba, Canada (Fig. 103). Adults have been collected June to early September.
Remarks. I have collected adults by sweeping through grasses and rushes along waterways in open habitats. Several Manitoba specimens were collected from a floodplain community near a tamarack bog. The directed asymmetry in the mid tarsus of males is unique in Calyxochaetus and very rare in insects (see Discussion).
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 49-50, DOI: 10.11646/zootaxa.5539.1.1, http://zenodo.org/record/14240426