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

description: Calyxochaetus desertus sp. nov.
(Figs 5, 6, 106, 123, 141, 146)
Type material. HOLOTYPE ♂,labeled:“ ARIZONA: Pima Co. / Cienega Creek Preserve / N32°01.09′; W110°38.58′ / 3APRIL2016; JB Runyon ”; “HOLOTYPE/ Calyxochaetus / desertus / J.B. Runyon [red label]” (USNM) (Fig. 141). PARATYPES: USA: Arizona: Same data as holotype (2♂, CAS; 2♂, CNC; 15♂, MTEC; 2♂, USNM); Santa Cruz County: Madera Canyon, 5100 ft, 25.iv.2001, R. Hurley & J. Runyon (2♂, 6♀, MTEC).
Other material examined. USA: Arizona: Cochise County: Ramsey Canyon, 15 mi. S Sierra Vista, Huachuca Mts, 5200 ft, 8.iv.1967, Malaise, R.F. Sternitzky (1♂, CNC); same data except, 6000 ft, v.1967 (1♀, CNC); 6 mi. S Portal, 23.vi.1968, FCH (1♂, FSCA); Southwestern Research Station, Portal, 23.vi.1968, V.D. Roth & FCH (9♂, FSCA); same data except, 2.vi.1969, B.A. Foote (3♂, 3♀, EMEC); same data except, 23.v–5.vi.1967, Malaise, C.W. Sabrosky (3♂, USNM); same data except, 5–9.vi.1972, W.W. Wirth (4♂, USNM); Coronado National Forest, Chiricahua Mts, Pinery Canyon campground, 7000 ft, 2.v.1991, B.J. Sinclair (1♂, 4♀, CNC); same data except, East Turkey Creek, 6500 ft, 1.vi.1991 (4♀, CNC); same data except, Cave Creek Canyon, Cave Creek at Herb Martyr Dam, 3.vi.1991 (6♂, 5♀, CNC); same data except, Idlewilde campground, 30.vii.1983, P.H. Arnaud, Jr (3♂, CAS); South Fork Cave Creek, N31°52.70′ W109°10.69′, 6.iv.2011, JBR (3♂, MTEC); same data except, N31°52.43′ W109°10.98′, 5.iv.2016 (5♂, MTEC); Garden Canyon, Huachuca Mts, 5300 ft, 16.iv.2003, JBR & RLH (6♂, MTEC); San Pedro River, 4 mi. E Sierra Vista, 4025 ft, 23.iv.2002, RLH & JBR (1♂, MTEC); Guadalupe Canyon at corral, 4300 ft, 31°20.62′N 109°3.48′W, 21.ix.2008, J.E. O’Hara (1♂, 4♀, CNC); Pima County: Sabino Canyon, 5.v.1942, ALM (2♂, USNM); Madera Canyon, 23.vi.1982, RLH (6♂, 7♀, MTEC); Santa Cruz County: Tubac, 29.ix.1972, FCH (1♂, FSCA); Sycamore Canyon, Ruby Road, 11–13.vi.1982, W.J. Hanson (6♂, 4♀, LACM); Sonoita Creek near Patagonia Lake inlet, 3775 ft, N31°29.95′ W110°50.69′, 3.iv.2016, JBR (9♂, MTEC). California: San Bernardino County: Granite Mts, 4050 ft, Sc17T8NR13E, 22–25.v.1983, T.L. Griswold (1♂, LACM). Nevada: Clark County: Red Rock Canyon NCA, Fern Canyon, 4200 ft, N36°07.46′ W115°29.62′, 25.iv.2014, JBR (1♂, 2♀, MTEC); Nye County: Nevada Test Site near Mercury, code 12CI(H), 18.vi.1964 (3♂, 1♀, USNM). New Mexico: Catron County: Reserve, 25.vi.1968, FCH (4♂, 2♀, FSCA); Grant County: Silver City, 25.vi.1968, FCH (13♂, FSCA). Texas: Brewster County: Big Bend National Park, Oak Spring, 4500 ft, 1.v.1959, J.F. McAlpine (7♂, 5♀, CNC); same data except, Pine Canyon, 5000–6000 ft, 10.v.1959 (1♂, CNC); same data except, Pulliam Canyon, 5500–6500 ft, 12.v.1959 (4♂, 1♀, CNC).
Diagnosis. This species belongs to a subgroup with C. pictipes and C. sobrinus. Males in this subgroup have a similarly formed mid tarsus (Figs 123–125), a moderately wide face, infuscated coxae and metepimeron, hind tibia without specialized ventral setae and wing with well-developed anal angle. The arista-like stylus distinguishes males of these species (Figs 106–108).
Description. Male. Wing length 2.9–3.3 mm. Head: Frons brown pruinose with large glabrous shiny blue-violet spot on either side of ocellar tubercle (as in Fig. 6). Face white-silver, nearly parallel-sided on ventral half, moderately wide, about 3–4 ommatidia wide at narrowest. Antenna (Fig. 106) dark brown; scape slightly shorter than postpedicel; postpedicel elongate oval, about 1.5X as long as wide; arista-like stylus with narrow lanceolate expansion on distal half, apex narrowly rounded to sharply pointed. Palpus small, elongate oval, brown with apex yellow. Thorax: Pleura brown with thick gray pruinosity; metepimeron concolorous with pleura, sometimes with yellow ground color visible on ventral half or less. Scutellum (Fig. 5) with distinct blue-violet reflections medially. Legs: Foreleg: Yellow, except coxa infuscated near base (sometime mostly so in anterior view), tarsus becoming brown from apex of tarsomere 2. Tibia slender, often with small posterodorsal seta near 1/3. Tarsomere 1 very short, nearly round. Tarsomere 2 slightly shorter than tibia and subequal to combined length of tarsomeres 3–4. Tarsomere 3 subequal in length to tarsomere 4. Tarsomere 4 with dorsal surface clothed in whitish apically hooked microsetulae, with row of slightly larger dorsal setulae across apex. Midleg: Yellow, except coxa infuscated on basal half or more, tarsus brown from apical third of tarsomere 1. Coxa with anterodorsal seta brown to yellow-brown (depending on viewing angle). Tarsus longer than tibia. Tarsomere 1 two-thirds tibia length and longer than combined length of tarsomeres 2–5. Tarsomere 2 1.25X longer than combined length of tarsomeres 3–4, slightly broadened apically with small anteroapical projection bearing a few longer pale setulae. Tarsomeres 3–4 about as long as wide with longer pale anterior setulae; tarsomere 4 slightly larger than tarsomere 3. Tarsomere 5 about 2X as long as wide, slightly shorter than combined length of tarsomeres 3–4 (Fig. 123). Hindleg: Yellow, except coxa infuscated on basal half or more, femur brown on about apical third, tibia sometimes brownish near apex, tarsus brown from near apex of tarsomere 1. Coxa with lateral seta brown to yellow-brown (depending on viewing angle). Tibia without specialized setae. Wing: Evenly tinged light brown. Anal lobe and anal area well-developed. Distal section of M 4 about 3X longer than crossvein dm-m. Abdomen: Tergite 1 dark brown, weakly gray pruinose. Tergites 2–3 yellow laterally, brown dorsally and along margins. Tergite 4 sometimes with yellow at base, remaining tergites dark brown. Hypopygium: Postgonites with apical lobes translucent light brown, slightly curved with apex rounded.
Female. Wing length 2.8–3.2 mm. Similar to male except as follows: Head: Face wider (subequal to postpedicel width), nearly parallel-sided, gray-silver. Antenna with postpedicel wider than long, rounded but weakly pointed dorsoapically; arista-like stylus unmodified, except apex blunted. Palpus much larger, triangular, rounded apically, brown with gray pruinosity and yellow setae. Thorax: Proepimeron with cluster of 2–4 small white hairs (Fig. 6). Legs: Unmodified, without specialized setae. Hind femur wholly yellow or light brown at apex. Hind tibia yellow. Hind tarsus brown from apex of tarsomere 1. Wing: Anal lobe broader with anal angle closer to base. Distal section of M 4 about 3X longer than crossvein dm-m. Abdomen: Tergites 2–3 with smaller yellow lateral spots, remaining tergites dark brown.
Distribution and seasonal occurrence. Known from waterways of the deserts and mountains of the southwestern USA from far southeastern California and neighboring Nevada to west Texas (Fig. 146). Most adults have been collected from April to June.
Remarks. I have often collected adults at rivers and creeks in the shade of large rocks with some vegetation. In 2016, adults were abundant in the shade of willows on low vegetation and on algae-covered stagnant water of a small side-pool of Sonoita Creek (Fig. 3).
Etymology. The specific epithet is Latin and refers to this species being found across the deserts of the southwestern USA.
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 54-56, DOI: 10.11646/zootaxa.5539.1.1, http://zenodo.org/record/14240426