Calyxochaetus clavicornis (Van Duzee)

Runyon, Justin B., 2024, Revision of the genus Calyxochaetus Bigot (Diptera: Dolichopodidae: Sympycninae), Zootaxa 5539 (1), pp. 1-74 : 23-24

Calyxochaetus clavicornis (Van Duzee)

( Figs 30, 43 , 71 )

Sympycnus clavicornis Van Duzee, 1930: 55 .

Calyxochaetus clavicornis : Foote et al. (1965: 528).

Type material examined. HOLOTYPE ♂, labeled: “ Mono Lake , Cal./ July 23, 1911 ”; “ JM Aldrich / coll”; “ Sympycnus / clavicornis / Holotype. Van Duzee” ( USNM) . PARATYPES: USA: California: Same data as holotype (1♂, 1♀, USNM) .

Other material examined. USA: California: Nevada County: Sagehen Creek near Hobart Mills , 15.vii.1964, R.M. Bohart (1♂, UCD); Sagehen campground , N39°26′00.3″ W120°15′24.6″, 11.vii.2012, swept along creek, S.E. Brooks (1♂, CNC); Sagehen Creek Field Station , 39°25′54.60″N 120°14′26.0″W, 10.ix–15.x.2012, Malaise, C.J. Borkent, J.M. Cumming, S.E. Brooks (1♂, CNC); same date except, 39.431833°N 120.240556°W, 10.viii– 10.ix.2012 (1♂, CNC); San Bernardino County: Sugarloaf Mountain , 15.vii.1946, J.L. Sperry (1♂, USNM); San Bernardino Mountains , 1000 Springs, 1.vi.1947, ALM (1♂, USNM); Trinity County : Coffee Creek Ranch , 3000 ft, 8.vii.1969, J. Powell (1♂, EMEC) .

Diagnosis. The shape of the lamella on the arista-like stylus of males, which is narrowly spatulate with ventral margin slightly concave ( Fig. 30 ), is distinctive. This species is most similar to C. syilx sp. nov. but differs in the shape of the lamella on the arista-like stylus, foreleg with tarsomere 3 1.5X the length of tarsomere 4 ( Fig. 43 ) (tarsomeres 3 and 4 subequal in length in C. syilx ), wing with distal section of M 4 about 4X longer than crossvein dm-m (3X longer in C. syilx ), and with narrower anal lobe.

Redescription. Male. Wing length 2.5–2.8 mm. Head: Frons brown pruinose, usually with small glabrous area with weak blue-violet reflections on either side of ocellar tubercle (two specimens have very sparse pruinosity); glabrous area with small striations. Face gray becoming whitish ventrally, narrowly triangular, about 1 ommatidium wide at clypeus. Antenna ( Fig. 30 ) dark brown; scape long, subequal to combined length of pedicel and postpedicel; postpedicel oval, 1.5X longer than wide; arista-like stylus longer than height of head, with apical lamella relatively long and narrowly spatulate and ventral margin slightly concave (ventral margin indistinctly concave in one specimen). Palpus small, oval, brown and becoming pale yellow at apex. Proboscis yellow-brown. Thorax: Pleura dark brown with gray pruinosity; metepimeron concolorous with pleura, usually yellowish just above hind coxa. Legs: Foreleg: Yellow, except tarsomere 1 narrowly brown at apex, tarsus light brown from apex of tarsomere 2. Tibia slender, sometimes with very small indistinct posterodorsal seta near 2/5. Tarsus ( Fig. 43 ) with tarsomere 1 very short, about as wide as long. Tarsomere 2 about 2/3 length of tibia, with 2 fine anterior setae at apex (slightly greater than half tarsomere 3 length). Tarsomere 3 about 1.5X longer than tarsomere 4, with longer pale setulae dorsally near apex. Tarsomere 4 with slightly longer pale dorsal setulae. Tarsomere 5 dorsoventrally flattened. Midleg: Yellow, except coxa infuscated with yellow ground color visible, tarsus brown from apex of tarsomere 1. Femur with very short slender yellow ventral setae with 1–2 near middle longest and subequal to femur width. Tibia without specialized setae. Tarsus slightly longer than tibia. Tarsomere 1 subequal to combined length of tarsomeres 2–5, apex with 2 fine curved anterior setae (subequal to tarsomere 2 length). Tarsomere 2 with basal half slightly swollen and bearing 3 fine curved pale anterior setae. Tarsomere 4 with a few slightly longer setae (longest subequal to tarsomere width) along anterior edge; long (subequal to tarsomere length) fine curved pale anterior seta at apex. Tarsomere 5 with about 3 short fine setae along anterior edge. Hindleg: Yellow, except coxa infuscated from base, becoming yellow-brown apically, femur with apical fifth light brown, tibia yellow-brown and becoming browner apically, tarsus brown.Apical half of femur with anteroventral row of long (longest greater than femur width) yellow setae; apical-most seta in row black, posterior preapical seta absent. Tibia with row of finer, denser ventral setae on basal half (length subequal to tibia width). Wing: Similar to C. hardyi ( Fig. 58 ) except: Anal lobe slightly larger and more evenly rounded basal to crossvein dm-m, forming very shallow anal angle. Wing slightly narrower beyond apex of M 4 with wing apex more pointed. Distal section of M 4 about 4X longer than crossvein dm-m. Abdomen: Tergite 2 yellow laterally. Tergite 3 usually brown, sometimes yellow-brown. Hypopygium: Postgonite apical lobes light brown, narrowly dark brown along dorsal edge.

Female. Wing length 2.6 mm. Similar to male except as follows: Head: Face wide, nearly parallel-sided, gray. Clypeus light gray. Antenna with postpedicel short, wider than long, rounded with slightly flattened apex; arista-like stylus unmodified. Palpus much larger, triangular, rounded apically, dark brown with gray pruinosity and yellow setulae and setae. Thorax: Proepimeron with 3–4 small white hairs. Legs: Unmodified, without specialized setae. Hind femur yellow. Hind tibia yellow, becoming light brown apically. Wing: Anal lobe broader. Posterior margin evenly rounded except slightly flattened at apex of M 4. Abdomen: Tergite 2 with small yellow lateral spot, remaining tergites brown.

Distribution and seasonal occurrence. This species is widely distributed in mountainous areas of California ( Fig. 71 ). Adults have been collected from June through October.

Figures

FIGURES 26–44. Male antennae (lateral view) and male forelegs of the Calyxochaetus cilifemoratus species group. 26. C. anisoaristus sp. nov. 27. C. arizonicus (Harmston), inset shows lateral view of mitten-shaped postpedicel. 28. C. brooksi sp. nov. 29. C. cilifemoratus (Van Duzee). 30. C. clavicornis (Van Duzee). 31. C. celatus sp. nov. 32. C. coloradensis sp. nov. 33. C. distortus (Van Duzee). 34. C. hardyi (Harmston & Knowlton). 35. C. harmstoni sp. nov. 36. C. isoaristus (Harmston & Knowlton). 37. C. luteipes (Van Duzee). 38. C. syilx sp. nov. 39. C. anisoaristus, anterior view. 40. C. brooksi sp. nov., posterior view. 41. C. celatus, posterior view.Arrow shows very short tarsomere 1. 42. C. cilifemoratus, posterior view. 43. C. clavicornis, anterior view. 44. C. coloradensis sp. nov., ventral view. Scale bars = 0.5 mm; arista-like styli approximately 1 mm long.

FIGURES 70–73. Known geographical distributions of species in the Calyxochaetus cilifemoratus group. 70. C. arizonicus (Harmston).71. C.anisoaristus sp. nov., C. clavicornis(Van Duzee), C. coloradensis sp. nov., C. hardyi (Harmston& Knowlton), C. harmstoni sp. nov. and C. syilx sp. nov. 72. C. cilifemoratus (Van Duzee). 73. C. celatus sp. nov.

FIGURES 56–63. Male wings of the Calyxochaetus cilifemoratus species group. 56. C. arizonicus (Harmston). 57. C. celatus sp. nov. 58. C. hardyi (Harmston & Knowlton). 59. C. cilifemoratus (Van Duzee). 60. C. isoaristus (Harmston & Knowlton). 61. C. distortus (Van Duzee). 62. C. luteipes (Van Duzee). 63. C. harmstoni sp. nov. Scale bars = 1.0 mm.