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

description: Calyxochaetus cascadia sp. nov.
(Figs 77, 82, 88, 92, 94)
Type material. HOLOTYPE ♂, labeled: “ WASHINGTON / OlympicNat.Park / HohRiver Rain/ Forest— 7VII68 / W.W. Wirth ”; “HOLOTYPE/ Calyxochaetus / cascadia / J.B. Runyon [red label]” (USNM) (Fig. 92). PARATYPES: CANADA: British Columbia: Vancouver Island, Goldstream Provincial Park, Goldstream, 9.vii.1974, P.H.Arnaud, Jr (1♂, CAS). USA: California: Nevada County: Sagehen Creek Field Station, 39°25′54.6″N 120°14′26.0″W, 13–19.vii.2012, Malaise, J.M. Cumming & S.E. Brooks (1♂, CNC); Sagehen Creek, near Hobart Mills, 15.vii.1964, R.M. Bohart (1♀, UCD). Oregon: Clackamas County: Wilsonville, 25.vi.1964, sweeping plants in swamp, K. Goeden (2♂, CAS); same data except, 3.vii.1963 (1♂, CAS); Mt. Hood National Forest, Still Creek campground, N45°17.703′ W121°44.313′, 1150 m, 9.vii.2013, B.J. Sinclair (3♂, 1♀, CNC); Tillamook County: Oceanside, 30.vii.1966, FCH (2♂, MTEC). Washington: Cowlitz County: Castle Rock, 28.viii.1921, ALM (1♂, USNM); Pacific County: Seaview, 26.vi.1925, A. Spuler (1♂, WSU); Ilwaco, 28.vi.1925, ALM (2♂, USNM); Thurston County: Puget, 4.vii.1925, ALM (1♂, USNM).
Diagnosis. Males can be recognized by the swollen fore tibia (Fig. 82), posterior margin of the wing with a large lobe (Fig. 88), dark pleura (Fig. 92), and the shape of the arista-like stylus (Fig. 77).
Description. Male. Wing length 3.2–3.5 mm. Head: Frons with small glabrous shiny blue-violet spot on either side of ocellar tubercle. Face silver-white, very narrow, less than one ommatidium wide on ventral half. Antenna (Fig. 77) brown, scape brown- yellow (usually darker along dorsal edge); scape laterally flattened, flared apically, slightly shorter than postpedicel; postpedicel elongate oval, 1.5–2.0X as long as wide; arista-like stylus thickened and of nearly equal width throughout, pointed apically, with dense microtrichia. Palpus small, oval, brown, concolorous with proboscis. Thorax: Pleura dark brown with gray pruinosity; metepimeron mostly yellow, lightly infuscated dorsally. Legs: Foreleg (Fig. 82): Yellow, except tarsus brown from near middle of tarsomere 3. Tibia swollen, with small slender posterodorsal seta at 1/3. Tarsomere 1 very short, barely longer than wide. Tarsomere 2 with 2 slender, distally directed anterior setae at apex (longest seta about half tarsomere 3 length). Tarsomere 3 slightly bowed with apex slightly broadened, with denser dorsal microsetulae on apical half. Tarsomere 4 with denser dorsal microsetulae on apical half. Midleg: Yellow, except coxa lightly infuscated at base, tarsus brown from near apex of tarsomere 1. Femur with short, slender, yellow ventral setae on basal half (longest near 1/2, subequal to femur width), with cluster of 3–4 small erect ventral preapical setae (apical-most seta largest). Tarsus very similar to C. vegetus (Fig. 87) except with smaller anterior lobe at apex of tarsomere 2. Hindleg: Yellow, except femur becoming light brown on apical third, tibia either yellow or light brown apically, tarsus brown from near middle of tarsomere 1. Femur ventrally with very short brown-yellow to black setae, with longer (slightly less than femur width) ventral seta just before anterior preapical seta; stronger ventral seta just beyond anterior preapical seta. Tibia with ventral row of 4–6 longer ventral setae (slightly longer than tibia width) at base. Wing (Fig. 88): Evenly tinged with light brown. Anal area shallowly scalloped opposite apex of R 1. Posterior margin with large lobe just before and excavation at apex of M 4. R 4+5 parallel with M 1 apically. Membrane of wing with crease running through crossvein dm-m, extending through most of cell m. Distal section of M 4 about 3X longer than crossvein dm-m. Abdomen: Tergite 1 light brown. Tergites 2–3 mostly yellow, remaining tergites dark brown. Sternites 2–3 yellow, sternites 4–5 brown. Hypopygium: Postgonites with apical lobes narrow, apex rounded, evenly dark shiny brown.
Female. Wing length 3.2–3.5 mm. Similar to male except as follows: Head: Face wider but relatively narrow (subequal to postpedicel width), nearly parallel-sided, light gray. Antenna with scape yellowish ventrally; postpedicel short, as wide as long, with round or bluntly rounded apex; arista-like stylus unmodified. Palpus much larger, triangular, rounded apically, brown with slight gray pruinosity, with longer yellow to brown marginal setae. Thorax: Proepimeron with 3–4 very small white hairs. Legs: Unmodified, without specialized setae. Hind femur and tibia yellow. Hind tarsomere 1 mostly yellow. Wing: Elongate oval, posterior margin weakly excavated at apex of M 4. Abdomen: Tergite 2 varying from being yellow laterally to mostly yellow with brown along posterior margin. Tergite 3 with some yellow ventrolaterally.
Distribution and seasonal occurrence. Known from western Oregon and Washington State, and Vancouver Island, British Colombia with a disjunct record in northern California (Fig. 94). Adults have been collected June through August.
Etymology. Named for the Cascadia bioregion and considered a noun in apposition.
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 37-38, DOI: 10.11646/zootaxa.5539.1.1, http://zenodo.org/record/14240426