Calyxochaetus longitarsus, Runyon, 2024

Runyon, Justin B., 2024, Revision of the genus Calyxochaetus Bigot (Diptera: Dolichopodidae: Sympycninae), Zootaxa 5539 (1), pp. 1-74 : 15

Calyxochaetus longitarsus sp. nov.

( Figs 17, 22–25 )

Type material. HOLOTYPE ♂, labeled: “USA: NM: Grant Co., 20mi. / N Silver City, Meadow Crk./ 32°57.2′N 108°10.3′W / 16.viii.2007, ca. 7100ꞌ, spring/ ~ 100m E of creek, swp./ S.E. Brooks ”; “ HOLOTYPE / Calyxochaetus / longitarsus / J.B. Runyon [red label]” (CNC) ( Fig. 24 ) . PARATYPE: USA: Arizona: Cochise County: Chiricahua Mts, creek near Ash Spring , 5800–6100 ft, 31°52.3′N 109°14.0′W, 17.viii.2007, sweep, S.E. Brooks (1♂, CNC) .

Diagnosis. Males are distinguished from other known species of Calyxochaetus , except C. angustipennis and C. tripilus , by having a long fore tarsomere 1 ( Fig. 22 ). Males can be distinguished from C. angustipennis and C. tripilus by having an unmodified mid tarsus ( Fig. 23 ). This is the only known species of Calyxochaetus whose males have an unmodified mid tarsus.

Description. Male: Wing length 3.0 mm. Head: Frons with two large glabrous, shiny violet spots on either side of ocellar triangle, with brown pruinosity on, above, and below ocellar triangle. Occiput dark brown pruinose with weak band and lateral area of silver pruinosity around uppermost postocular setae. Face silver, narrowing to about 2 ommatidia wide at clypeus. Antenna ( Fig. 17 ) brown; scape distinctly shorter than combined length of pedicel and postpedicel; postpedicel oval, about as long as wide; arista-like stylus unmodified. Palpus brown with apex slightly paler, small, elongate oval. Proboscis brown-yellow. Thorax: Pleura brown with gray pruinosity, yellowish below halter and along sutures; metepimeron yellow. Scutellum without distinct blue-violet reflections. Legs: Foreleg: Coxa, femur and tibia wholly yellow, tarsus brown from near apex of tarsomere 2. Femur with short yellow-brown ventral setae on basal half (longest subequal to half femur width). Tibia without outstanding setae. Fore tarsus ( Fig. 22 ) unmodified with tarsomere 1 about 1.5X length of tarsomere 2. Midleg: Coxa, femur and tibia yellow, tarsus brown from near apex of tarsomere 1. Femur with ventral row of erect yellow setae, with longest 5–6 setae near middle (subequal to femur width). Tarsus unmodified ( Fig. 23 ). Hindleg: Yellow, except tibia light brown apically, tarsus brown with base of tarsomere 1 yellowish. Femur without specialized setae, posterior preapical seta absent. Tibia with ventral row of short setae (subequal to tibia width), last seta in row (near 2/3) largest. Wing: Similar to C. tripilus ( Fig. 19 ), except slightly broader. Calypter with apex narrowly light brown. Abdomen: Tergite 2 mostly yellow. Tergite 3 yellow at base. Basal sternites yellow with sternites 4–5 becoming brown. Hypopygium: Postgonites with apical lobes sharply pointed, white with narrowly black apex.

Female. Unknown.

Distribution and seasonal occurrence. Known from two males collected in August in the mountains of southeastern Arizona and southwestern New Mexico ( Fig. 25 ).

Etymology. The specific epithet refers to the relatively long fore tarsomere 1 in males ( Fig. 22 ), which is unusual for the genus.

Figures

FIGURES 13–25. Calyxochaetus tripilus species group. 13. C. tripilus (Van Duzee), male habitus. 14. C. tripilus, female habitus. 15. C. angustipennis (Aldrich), male antenna, lateral view (photo by Duncan Sivell, © Trustees of the Natural History Museum, London). 16. C. tripilus, male antenna, lateral view. 17. C. longitarsus sp. nov., male antenna, lateral view. 18. C. tripilus, male head, anterodorsal view. 19. C. tripilus, male wing. 20. C. tripilus, male fore tarsus, ventral view. Arrow shows fore tarsomere 1. 21. C. tripilus, male mid tarsus, ventral view. 22. C. longitarsus sp. nov., male fore tarsus, anterior view.Arrow shows fore tarsomere 1. 23. C. longitarsus sp. nov., male mid tarsus, ventral view. 24. C. longitarsus sp. nov., habitus of male holotype. 25. Known geographical distributions of C. longitarsus sp. nov. and C. tripilus. Scale bars = 1.0 mm.