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

description: Calyxochaetus oreas (Wheeler)
(Figs 79, 85, 90, 94)
Nothosympycnus oreas Wheeler, 1899: 55.
Calyxochaetus oreas: Parent (1930: 107).
Sympycnus spatulatus Harmston & Knowlton, 1940: 398; synonymized by Harmston (1947: 99).
Type material examined. Nothosympycnus oreas: HOLOTYPE ♂, labeled: “Buck/ Creek,/ Wyo/ VIII.14.95”; “W. M. Wheeler/ Collection.”; “Type” (AMNH).
Sympycnus spatulatus: HOLOTYPE ♂, labeled: “Hanksville, Ut./ 8-1-1939 / G.F. Knowlton / F.C. Harmston ”; “Type No/ 54301/ USNM”; “ HOLOTYPE / Sympycnus / spatulatus / n. sp. F.C.H. -G.F.K.”; “ Sympycnus / spatulatus H&K/ Det. 1940 F.C. Harmston ” (USNM). PARATYPES: USA: Utah: Box Elder County: Grouse Creek, 30.viii.1939, G.F. Knowlton & FCH (1♂, LACM).
Other material examined. CANADA: Alberta: Cypress Hills, Reesor Lake, 30.viii.2002, JBR (1♂, 1♀, CNC); Cypress Hills, Battle Creek, 6 km E Reesor Lake, 31.viii.2002, JBR (1♂, 1♀, MTEC). Northwest Territories: Norman Wells, 15.viii.1969, G.E. Shewell (1♂, CNC). USA: Arizona: Apache County: Springerville, Little Colorado River, 1.vii.1953, W.W. Wirth (1♂, USNM). California: Del Norte County: Smith River, 25.vii.1932, J.M. Aldrich (1♂, USNM). Idaho: Bonneville County: Fall Creek Falls, 1615 m, N43°26.46′ W111°22.64′, 9.vii.2018, JBR (1♂, MTEC); same data except, 16.vii.2018 (1♀, MTEC). Montana: Broadwater County: Limestone Hills area, biodiversity study, N46°17.32′ W111°35.22′, 12.vii.1996, sweeping vegetation, M.A. Ivie, L.L. Ivie & D.L. Gustafson (4♂, 2♀, MTEC); Gallatin County: Gallatin River, 17 mi. S of Big Sky, 6725 ft, 13.viii.2005, JBR & RLH (2♂, 3♀, MTEC); Jefferson County: Milligan Canyon, Milligan Creek, 6 mi. W Three Forks, N45°53.26′ W111°40.72′, 6.vii.2002, RLH & JBR (5♂, MTEC); same data except, 20.vii.2002 (1♂, MTEC), same data except, 16.vii.2011, JBR (1♂, MTEC); Powder River County: Holiday Springs, 12 mi. NE Ashland, 24.viii.2002, JBR (1♂, 3♀, MTEC). Utah: Daggett County: Manila, 17.vii.1940, FCH & G.F. Knowlton (1♂, CNC); Grand County: Castleton, 20.vii.1968, Malaise, W.J. Hanson (1♂, LACM); Piute County: Kingston, 15.vi.1950, FCH (1♂, CAS); San Juan County: Monticello, 23.vii.1940, G.F. Knowlton & FCH (1♂, CNC); same data except, 8.viii.1940 (2♂, 1♀, CAS; 1♂, CNC); unknown county: Baher, 28.iv.1940, G.F. Knowlton & FCH (1♂, USNM). Wyoming: Lincoln County: Lost Creek, 13.1 mi. NE Geneva, 7000 ft, 17.viii.1991, RLH (1♂, MTEC); Salt Creek, 10 mi. NE Geneva, 6650 ft, 12.viii.2005, JBR & RLH (1♀, MTEC); Uinta County: Evanston, 4.vii.1968, FCH (1♂, CAS).
Diagnosis. Males can be recognized by the strongly swollen fore tibia (Fig. 85), wing excavated and nearly always folded before apex of M 4 (Fig. 90), and arista-like stylus very slender and sharply pointed at apex with very narrow subapical lanceolate expansion (Fig. 79).
Redescription. Male. Wing length 3.2–3.4 mm. Head: Frons brown pruinose, sparse on either side of ocellar tubercle revealing green-blue ground color, not glabrous. Face silver, very narrow, triangular, one ommatidium wide or less at clypeus. Antenna (Fig. 79) brown; scape laterally flattened, flared apically, slightly shorter than postpedicel; postpedicel elongate oval, about 2X as long as wide; arista-like stylus with very short microtrichia, long, slender, sharply pointed at apex, with very narrow subapical lanceolate expansion. Palpus small, oval, brown with white setulae. Thorax: Pleura brown with dense gray pruinosity; metepimeron concolorous with pleura, becoming yellowish just above hind coxa. Legs: Foreleg (Fig. 85): Yellow, except coxa usually infuscated at base, tarsus brown from near middle of tarsomere 2. Tibia strongly swollen, narrowest at base and broadest subapically, with small slender posterodorsal seta at 1/3. Tarsomere 1 very short, about as long as wide. Tarsomere 2 with distally directed anterior seta at apex. Tarsomere 3 slightly bowed with apex broadened, with dense white dorsal microsetulae on apical third. Tarsomere 4 with dense white dorsal microsetulae. Midleg: Yellow, except coxa infuscated and gray pruinose with yellow ground color visible, tarsus brown from apical third of tarsomere 1. Femur with very short, slender, yellow ventral setae on basal half (longest about half femur width), with small erect black ventral preapical seta, usually subtended by smaller ventral seta. Tarsus with tarsomere 1 subequal to combined length of tarsomeres 2–5. Tarsomere 2 slightly shorter than combined length of tarsomeres 3–5 with apex very slightly widened, pointed anteriorly, bearing a few longer anteroapical setulae (subequal to tarsomere width). Tarsomere 3 subtriangular, about as long as wide, with shorter anterior setulae than tarsomeres 2 and 4. Tarsomere 4 about twice as long as tarsomere 3, broadest at base, tapering to apex, concave anterodorsally, with 1–2 longer anterior setulae at base (subequal to tarsomere width). Hindleg: Yellow, except coxa infuscated and weakly gray pruinose with yellow ground color visible, femur brown on apical third, tibia becoming brown apically (almost wholly brown in a couple of specimens), tarsus brown from near middle of tarsomere 1. Femur ventrally with very short brown to black setae, with larger (subequal to femur width) ventral seta below anterior preapical seta. Tibia with ventral setae small, without conspicuous ventral setae near base. Wing (Fig. 90): Posterior margin excavated before apex of M 4 and opposite crossvein dm-m, this excavation enhanced by adjacent crease that usually folds wing margin. Crossvein dm-m with strong longitudinal crease that crimps crossvein near M 4. Distal section of M 4 apically fading and slightly arching toward wing tip, about 4X longer than crossvein dm-m. Abdomen: Often mostly or wholly brown, but sometimes with tergites and sternites 2–4 partly to mostly yellow. Hypopygium: Postgonites with apical lobes sharply pointed, translucent, light brown.
Female. Wing length 3.0– 3.4 mm. Similar to male except as follows: Head: Face wider but relatively narrow (subequal to postpedicel width), nearly parallel-sided, slightly narrowing to clypeus, gray. Antenna with postpedicel short, wider than long, with round apex; arista-like stylus unmodified. Palpus much larger, triangular, rounded apically, dark brown to black with gray pruinosity, with longer yellow to brown setae. Thorax: Proepimeron with 3– 4 very small white hairs. Legs: Unmodified, without specialized setae. Hind femur light brown dorsoapically. Hind tibia yellow. Hind tarsomere 1 mostly yellow. Wing: Elongate oval, posterior margin evenly rounded. Crossvein dm-m without obvious longitudinal crease adjacent to M 4. Distal section of M 4 not fading apically or arching toward wing tip, about 3X longer than crossvein dm-m. Abdomen: Usually wholly dark brown, rarely tergites 2–3 with small lateral yellow spot.
Distribution and seasonal occurrence. Known from Northwest Territories, south to Arizona with a disjunct record from northwest California (Fig. 94). Most adults were collected in July and August.
Remarks. Adults occur in shade of vegetation or stream banks in open habitats.
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 43-44, DOI: 10.11646/zootaxa.5539.1.1, http://zenodo.org/record/14240426