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

description: Calyxochaetus arizonicus (Harmston)
(Figs 27, 50, 56, 70)
Sympycnus arizonicus Harmston, 1968: 24.
Calyxochaetus arizonicus: Pollet et al. (2004: 74).
Type material examined. HOLOTYPE ♂, labeled: “Sta.[Santa] Catalina MTS./ VI.10.1938 Ariz. / Bryant Lot 21”; “Holotype—male/ Sympycnus / arizonicus H.”; “California Academy/ of Sciences/ Type No. 9951” (CAS).
Other material examined. USA: Arizona: Cochise County: Southwestern Research Station, Portal, 23.vi.1968, V.D. Roth & FCH (1♂, MTEC); same data except, 5 mi. SW Portal, 5400 ft, 23.v–5.vi.1967, Malaise, C.W. Sabrosky (1♂, USNM); 6 mi. W Portal, 23.vi.1968, FCH (2♂, MTEC); Pima County: Madera Canyon, 23.vi.1982, RLH (1♂, 2♀, MTEC); Santa Cruz County: Tubac, 29.ix.1972, FCH (11♂, FSCA, MTEC). Colorado: Lake County: Independence Pass, 21.vii.1962, FCH (1♂, FSCA); Park County: Fairplay, 8.viii.1968, FCH (1♂, FSCA); San Juan County: Molas-Elk Creek Trail, near Silverton, 8900–10000 ft, 26–29.vii.1985, J. & J. Jenkins (3♂, 2♀, WSU). New Mexico: Catron County: Luna, 25.vi.1968, FCH (8♂, FSCA, MTEC); Reserve, 25.vi.1968, FCH (1♂, CNC; 4♂, FSCA); Gila Cliff Dwellings National Monument, Cliff Dweller’s spring, 29.v.1991, B.J. Sinclair (1♂, 1♀, CNC); Grant County: Silver City, 25.vi.1968, FCH (1♂, FSCA); Pinos Altos, Cherry Creek, 22.vi.1953, W.W. Wirth (2♂, USNM); Gila National Forest, Cherry Creek, 14 mi. NE Silver City, 7400 ft, 5.vi.1991, B.J. Sinclair (1♂, 2♀, CNC); 20 mi. N Silver City, Meadow Creek, 32°57.2′N 108°10.3′W, 16.viii.2007, ca. 7100 ft, spring, ~ 100 m E of creek, sweep, S.E. Brooks (3♀, CNC).
Diagnosis. The mitten-shaped postpedicel (Fig. 27) will distinguish males from other known species of the genus.
Redescription. Male: Wing length 2.2–2.6 mm. Head: Frons with glabrous shiny blue-violet spot on either side of ocellar tubercle. Face silver-white, narrowing to about 3 ommatidia wide at clypeus.Antenna (Fig. 27) dark brown; scape long, laterally flattened, slightly flared apically, subequal in length to postpedicel; postpedicel mitten-shaped, with distinct ventral notch near 1/2; arista-like stylus with apical one-fifth slightly widened, narrowly oblanceolate. Palpus small, oval, brown. Thorax: Scutum with acrostichal setae uniseriate but appearing irregularly biseriate in 3 specimens. Pleura brown with weak blue reflections and gray pruinosity; metepimeron yellow on ventral half or less. Legs: Foreleg: Coxa, femur and tibia wholly yellow, tarsus brown from apex of tarsomere 2. Tarsomere 1 very short, barely longer than wide. Tarsomere 2 slightly longer than combined length of tarsomeres 3–5, with small (half tarsomere 3 length), yellow-brown, distally directed anterior seta at apex. Tarsomeres 3–5 decreasing in length apically. Midleg: Coxa infuscated at base, yellow apically, femur and tibia wholly yellow, tarsus brown from apical third of tarsomere 1. Femur with anteroventral row of slender yellow to yellow-brown setae on basal two-thirds, those near base short, 4–5 setae near middle longest (slightly longer than femur width), with small disjunct subapical anteroventral seta in this series; with ventral row of short yellow setae on basal two-thirds. Tibia with posteroventral row of 2–3 short black setae near apex. Tarsomere 1 with a few short (subequal to tarsomere width) fine ventral setae on basal half, with 2 fine sinuous yellowish anterior setae at apex. Tarsomere 2 with basal half slightly swollen and bearing 4 fine sinuous yellow anterior setae. Tarsomere 4 with a few longer (slightly less than tarsomere length) anterior setae, apical-most seta usually longest. Tarsomere 5 with a few small (subequal to tarsomere width) anterior setae. Hindleg: Coxa mostly yellow often infuscated at base, femur yellow but light brownish dorsoapically, tibia yellow, tarsus mostly brown with tarsomere 1 yellow at base. Femur (Fig. 50) with anteroventral row of slender yellow to yellow-brown setae, those near base short, 4 setae near middle very long (about 2X femur width), with small disjunct subapical anteroventral seta in this series, posterior preapical seta absent. Tibia with ventral row of short setae (subequal to tibia width), those on basal half slender. Wing (Fig. 56): Oval, hyaline. Anal lobe relatively well-developed, evenly rounded. Distal section of M 4 about 3X longer than crossvein dm-m. Abdomen: Tergite 1 brown. Tergite 2 yellow, sometimes partly brown. Tergite 3 usually with some yellow basally, rarely brown. Tergites 4–6 brown. Hypopygium: Postgonites with apical lobes pointed, light brown.
Female. Wing length 2.4–3.0 mm. Similar to male except as follows: Head: Face wide, very slightly narrowing to clypeus, silver-gray. Antenna shorter; postpedicel short, rather round, apicoventral margin usually slightly flattened to weakly indented (reflecting notch in male postpedicel); arista-like stylus unmodified. Palpus much larger, triangular, pointed apically, dark brown to black, with white setulae and yellow-brown to brown setae. Thorax: Proepimeron with 3–4 small white hairs. Legs: Unmodified, without specialized setae. Hind femur with anteroventral row of small setae (corresponding to long setae in male) that slightly increase in size apically (largest near 2/3, less than half femur width). Wing: Anal lobe slightly broader. Abdomen: Tergite 2 mostly brown, usually with some yellow laterally, remaining tergites brown.
Distribution and seasonal occurrence. This species is known from Arizona, Colorado and New Mexico (Fig. 70). Adults have been collected from late May to September.
Remarks. Specimens have been collected from riverine habitats in southern Arizona (ca 975 m) to high elevations in Colorado (ca 3650 m).
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 19-20, DOI: 10.11646/zootaxa.5539.1.1, http://zenodo.org/record/14240426