Lamproscatella arichaeta Mathis 1979

Lamproscatella (Haloscatella) arichaeta

DIAGNOSIS.—Although specimens of L. arichaeta appear to be very similar to those of L. cephalotes, they may be distinguished from the latter by the following combination of characters: Specimens averaging smaller in overall size; setal development much less pronounced; mesonotum generally more brownish. The male terminalia of L. arichaeta males differ markedly from those of L. cephalotes males, being smaller and of a unique conformation, particularly the shape of the surstyli (Figures 3–5).

DESCRIPTION.—Small to moderately small shore flies, length 1.70 to 2.45 mm (averaging 2.00 mm); generally brownish gray, with some extensive brown colored areas.

Head: Head width-to-height ratio averaging 1:0.74; coloration whitish gray to brown. Mesofrons subshiny to shiny with metallic brown to bluish green luster, subtriangular, rounded anteriorly, with 1–2 pair of small setae marginally; parafrons mostly charcoal gray, ocellar triangle pollinose, brown. Anterior fronto-orbital seta large, length at least one-half that of larger, posterior bristles; third fronto-orbital seta much reduced, inserted mesad of line of other bristles, very close to second bristle, oriented at posteroblique angle to other fronto-orbitals. Dorsalmost postocular seta more strongly developed than remaining postoculars, inserted posterolaterad of divergent vertical bristle. Antennal segments dark colored, mostly blackish, pollinose; arista slightly longer than combined length of second and third segments. Face whitish gray, densely pollinose to tomentose, protruding and arched; lateral facial setae larger than median ones, becoming larger toward posteroventral angle of face; setae along oral margin only slightly larger than median facial setae. Eye-to-cheek ratio averaging 1 : 0.47; gena concolorous with face; 2–3 parafacial setae.

Thorax: Dorsum mostly light brown, becoming grayer on pleural areas, especially toward venter. Scutellum lighter brown in coloration than disc of mesonotum. Setation quite pronounced and well developed. Legs becoming darker toward apices; apical tarsomeres mostly black. Wing hyaline to faintly infumated with grayish brown coloration: costal margin only slightly setose; costal vein ratio averaging 1 : 0.17; M1+2 vein ratio averaging 1 : 0.55; posterior crossvein with posterior half slightly angulate laterally, wrinkled in middle.

Abdomen: Generally grayer than dorsum of thorax, but also with considerable brown coloration. Male terminalia with surstyli fused to epandrium and forming open triangle with pocket formed by paired arms U-shaped and shallow (Figures 3–5).

TYPE MATERIAL.—Holotype male is labeled: “WASH Grant Co Soap Lake 5 August 1973 Wayne Mathis/HOLOTYPE Lamproscatella arichaeta W N Mathis (red).” Allotype female and 46 paratypes (10 , 36 ; USNM) have the same locality data as the holotype. Other paratypes are as follows: Oregon, Harney Co., Borax Lake, 7.2 km NE Fields, 29 Jul 1975, W. N. Mathis (1, 1; USNM); Malheur Co., 24.2 km NW Yale, 28 Aug 1965, Kenneth Goeden (1; USNM); Lake Co., Goose Lake State Park, 23 Aug 1970, Karl W. Simpson (1, 3; CU). The holotype is in the National Museum of Natural History, Smithsonian Institution, Washington, D. C., type number 75956.

OTHER SPECIMENS EXAMINED.—UNITED STATES: CALIFORNIA: Kern Co., Onyx, 23 Jul 1940, D. E. Hardy (1 , 2 ; KU, USNM); Lassen Co., Hallelujah Junction, 4 Jul 1949, P. D. Hurd (1 ; USNM). Spauldings, 27 Jul 1949, P. D. Hurd (2; USNM); Mono Co., Mammoth Lakes, 29 July 1949, L. J. Lipovsky (4 ;, KU); Riverside Co., Palm Springs, 24–26 Mar 1918, J. C. Bradley (1 ; CU). MONTANA: Fire Hole River, 27 Aug 1940, A. L. Melander (1 , USNM). NEBRASKA: Cherry Co., Big Alkali Lake, 2 Jun 1969, W. W. Wirth (1 , USNM), Twin Lake, 2 Jun 1969, W. W. Wirth (3 , 11 ; USNM). NEVADA: Churchill Co., Soda Lakes near Hazen, 13 Jul 1911 (1 ; USNM). OREGON: Union Co., North Powder, 13 Jun 1971, R. H. Beamer (1 ; USNM). SOUTH DAKOTA: Yankton Co., Gavins Point, 17 Jun 1969, W. W. Wirth (1 ; USNM). WASHINGTON: Grant Co., O'Sullivan Dam, 23 May 1954, 19 Jul 1955, M. T. James (3; WSU), Soap Lake, 24 July 1919, A. L. Melander (1, 2; USNM), Soda Lake near O'Sullivan Dam, Columbia National Wildlife Refuge, W. L. Turner (1 ; WSU), Warden Lake, Columbia National Wildlife Refuge, 16 Aug 1977, R. S. and V. L. Zack (2; WSU); Stevens Co., Evans, 13 June 1930, R. C. Shannon (1, 1; USNM). WYOMING: Hot Springs Co., Thermopolis, 13 Jun 1969, W. W. Wirth (2; USNM); Teton Co., Yellowstone National Park, U Geyser Basin, 7 Aug 1916, A. L. Melander (3; USNM).

GEOGRAPHIC DISTRIBUTION. (Figure 6).—This species occurs mainly west of the 100th meridian between 32° and 49° north latitude.

ETYMOLOGY.—The epithet arichaeta is a combination of the Greek ari (“very” or “much”) plus chaeta (“bristle”), in allusion to the pronounced setation of specimens of this species.