Pelomyia occidentalis Williston 1893

Pelomyia occidentalis Williston

Pelomyia occidentalis Williston, 1893:258; 1908:307 [key, figures of head, thorax].—Curran, 1934:330 [figure of head, copy of Williston, 1908].—Vockeroth, 1965:726 [Nearctic catalog].—Mathis and Munari, 1996:9 [world catalog].—Irwin et al., 2001:153–156 [key, discussion, biology, figures, list, Germany, Great Britain].

Pelomyia coronata of authors [misidentification].—Melander, 1913b:297 [in part; synonymy]; 1952:193 [in part; revision].—Hendel, 1917:46 [in part; revision]; 1934:51 [in part; revision].—Sturtevant, 1923:7 [in part; list and revision].—Malloch, 1934:456 [discussion].—Hennig, 1939:82 [figure of male terminalia].—Cole, 1969:386 [in part; discussion].—Szadziewski, 1983:47 [list, Poland; ecology, figures of male terminalia].

Pelomyia sleyskali Hardy and Delfinado, 1980:375.—Mathis and Sasakawa, 1989:667 [Australasian/Oceanian catalog].—Roháček, 1992:128–129 [discussion, ecology, Czech Republic, Hungary, Poland, Slovakia].—Mathis and Munari, 1996:9 [world catalog], [New Synonym.]

Pelomyia species.—Zuska and Laštovka, 1969:207 [list, Czech Republic],

DIAGNOSIS.—This species is distinguished from congeners by the following combination of characters: body with brownish gray microtomentum; frons yellowish orange, darker near ocellar triangle; parafrontal setulae few, minute, 1 slightly larger seta near base of antenna; fronto-orbital seta 1, reclinate; antenna mostly brown with distal margin and medial surface of 1st flagellomere orange; oral vibrissae weakly developed but distinct; gena approximately 0.20–0.28 times eye height; mesonotum with 3 faint brownish stripes along line of dorsocentral setae and along midline; dorsal of anepisternum brownish, ventral gray, microtomentose; acrostichal setulae few, minute, in 2 scattered rows; wing crossveins not infuscate; forecoxa white in base color; forefemur moderately swollen; hindfemur barely swollen; tibiae brown to black; forefemoral anteroventral ctenidial comb of setae short (shorter than width of foretibia) but moderately strong; tarsomeres of normal size.

DESCRIPTION.—Body length 2.10–3.00 mm; body generally with brown to brownish gray microtomentum.

Head: Ocellar triangle grayish, microtomentose; frons yellowish orange, extreme margins silvery gray, microtomentose; frontal lunule silvery; parafrontal setulae few, minute, with 1 slightly larger seta near base of antenna; ocellar seta 1, strong, another 2 or 3 minute, weak ocellar setulae; paravertical setae short, weak, widely separated, convergent. Antenna mostly brown, only distal margin and entire medial surface of 1st flagellomere orange. Gena approximately 0.20–0.28 times eye height, with whitish yellow microtomentum and bearing many minute, scattered setulae; shiny chitinous stripe along parafacial and peristomal margins; palpus yellow; clypeus brown.

Thorax: Mesonotum mostly with grayish microtomentum and bearing brown stripe along line of dorsocentral setae and centrally along acrostichal setulae; dorsal of anepisternum with brown microtomentum and ventral with gray microtomentum, remainder of pleural surfaces mostly with gray microtomentum. Wing hyaline; costal section ratios 7.0:1.5:1.0. Forecoxa white in base color, with white microtomentum, with 2 or 3 large setae in addition to a few smaller ones; midcoxa partly yellow, gray basally; hindcoxa gray; forefemur moderately swollen, with gray microtomentum and bearing a row of 6–8 strong setae on both posterodorsal and posteroventral surfaces, distal 2 or 3 sometimes longest, many scattered smaller setae on remainder of posterior surface, otherwise evenly setulose; forefemoral anteroventral ctenidial comb of setae distinct, moderately strong, shorter than width of foretibia; hindfemur barely swollen; mid- and hindfemora gray, evenly setulose with anterior surface of midfemur bearing 1 stronger seta in middle; tibiae with brownish to blackish microtomentum, rarely slightly paler on basal of mid- and hindtibiae, evenly setulose; foretarsus entirely gray, mid- and hindtarsi with basal 3 tarsomeres yellow, distal 2 tarsomeres brown.

Abdomen: With microtomentum brownish dorsally becoming gray laterally, extreme posterior margin of each tergite yellow. Male terminalia (Figure 17): ventral lobe of epandrium deeply bifurcate, anterior margin bare, posterior margin bearing several setulae, anterior tine pointed and curved posteriorly, posterior tine of bifurcation spatulate; surstylus short, spatulate, bearing many setulae distally; aedeagus thick, pubescent; pregonite distinct, long, tapered, pointed, partly fused with postgonite; hypandrium in lateral view narrow; distal portion of postgonite long, tapered, pointed; basiphallus long, pointed, triangular; ejaculatory apodeme moderately flared. Female terminalia: cercus bearing fine setulae only (Figures 18, 19); spermatheca as in Figure 20.

TYPE MATERIAL.—The lectotype female of Pelomyia occidentalis Williston, herein designated to stabilize and make more universal the use of this name, is labeled “Monterey Co. CAL[IFORNIA]./Through C V Riley/TYPE No. A. M. N. H. [red]/Am. Mus. Nat. Hist. Dept. Invert. Zool. No. 20330 [number handwritten]/Pelomyia occidentalis Will. [handwritten; two red submarginal borders]/LECTO-TYPE [circular label with a black border]/LECTOTYPE Pelomyia occidentalis Williston 1893 det. A. Irwin 1983 [handwritten]/LECTOTYPE Pelomyia occidentalis Williston By Foster & Mathis [handwritten except for ‘LECTOTYPE’ and ‘By’; black submarginal border].” The lectotype is double mounted (glued to a thin strip of celluloid), is in poor condition (right wing and several setae missing, thorax cracked), and is deposited in the AMNH (20330). Although A.G. Irwin studied this specimen and attached a lectotype label to it, the designation was never published and is thus invalid. In the original description, Williston also listed a male syntype, which we were unable to locate. Irwin (in litt. to W.N.M., 2001) also searched for this specimen in 1983 and was unable to find it.

The holotype male of Pelomyia steyskali Hardy and Delfinado is labeled “OREGON Curry Co 8miN Gold Beach VI-29-72 [29 Jun 1972] George Steyskal/Holotype Pelomyia steyskali Hardy & Delfinado [red label; handwritten]/Pelomyia steyskali Hardy & Delfinado Det. D. E. Hardy [species name and authors handwritten].” The holotype is double mounted (minuten in a block of white plastic), is in good condition (some cephalic setae are missing), and is deposited in the USNM.

OTHER SPECIMENS EXAMINED.—UNITED STATES. Arizona. Yuma: Yuma, 8 Apr 1947, A.L. Melander (1; USNM). California. Alameda: Bay Farm, 10 May 1921, W.M. Giffard (1; CAS); Berkeley, 4 Oct 1947, W.W. Wirth (1; USNM); San Leandro, 14 Jan-19 Nov 1947, 1948, W.W. Wirth (2; USNM). Contra Costa: Antioch, 18 Oct 1936, R.C. Dickson (1; USNM); El Sobrante, 5 Jun 1949, R.E. Ryckman (1; USNM); Richmond, 16 Feb-28 Dec 1947, 1948, W.W. Wirth (7, 7; USNM). Del Norte: Crescent City, 10 Jul 1930, J.M. Aldrich (3; USNM); Crescent City (18.5 mi N), 28 Jun 1972, W.N. Mathis, G.C. Steyskal (2; USNM); Smith River, 17 Jul 1930, J.M. Aldrich (4 5; USNM). Humboldt: Clam Beach, 21 Jun 1935, A.L. Melander (2; USNM); Dyerville, 20 Jun 1935, A.L. Melander (1; USNM); Orick, 18 Sep 1934, A.L. Melander (1; USNM). Kern: Arvin, 14 Mar 1935, A.L. Melander (4 3; USNM); Bakersfield (19 mi E), 24–26 Mar 1947, P.H. Arnaud (1; USNM); Mojave Desert, Roger Dry Lake, 16 Mar 1935, A.L. Melander (1; USNM). Lake: Clear Lake, 18 Jun 1935, A.L. Melander (1, 1; USNM). Los Angeles: Lovejoy Lake, 10 May 1944, A.L. Melander (2; USNM); San Gabriel Mountains, King Creek, A.L. Melander (1; USNM). Marin: Bolinas, 5 Jun 1949, R.E. Ryckman (1; USNM); China Camp, 16 Jun 1958, F.D. Bennett (l, 1; CNC); McClure's Beach, 8 Jul 1961, C.A. Toschi (l, P. steyskali paratype; CNC). Monterey: Asilomar, 11 Jul-3 Oct 1946, 1954, 1957, 1960, A.L. Melander (9, 6; USNM); Monterey, 1 Jul-25 Sep 1896, 1934, A.L. Melander (2; USNM); Monterey Peninsula (on seashore), 5 Jul 1973, J.R. Vockeroth (1; CNC); Pacific Grove, 13 Jun-28 Jul, 1920, 1940, 1969, B. Hocking, W.H. Mann, A.L. Melander (4 4; CNC, USNM); Pacific Grove, Point Pinos, 13 Jun 1959, P.H. Arnaud (1; USNM). Napa: Calistoga, 28 May 1952, P.H. Arnaud, Jr. (4, 1; CAS); Vallejo (5 mi N), 7 Sep 1952, P.H. Arnaud (7; USNM). Nevada: Donner Lake, 10 Sep 1952, P.H. Arnaud (1; USNM). Orange: Buena Park, 23 Dec 1944, A.L. Melander (2; USNM); Corona del Mar, 13 Aug 1949, A.L. Melander (1; USNM); Huntington Beach, 4 Jun 1945, A.L. Melander (2; USNM); Laguna Beach, 21 Mar-18 Aug, 1943, 1951, A.L. Melander, H.D. Stalker (2; USNM); San Clemente, 5 Jun 1945, A.L. Melander (l; USNM). Riverside: Deep Creek, 25 Jan 1953, A.L. Melander (l; USNM); Indio, 6 Mar 1955, W.R. Richards (1; CNC); Lake Elsinore, 10 May 1950, A.L. Melander (1; USNM); Palm Springs, 20 Nov 1943, A.L. Melander (1; USNM); Palm Springs, Palm Canyon, 15 Mar 1955, W.R. Richards (1; CNC); Riverside, 5 May-9 Jul 1940, 1953, A.L. Melander (2; USNM); Palm Canyon, 12 Jan 1953, P.H. Arnaud (l; USNM); Temecula, 4 Apr-7 Jun 1945, 1949, A.L. Melander, W.W. Wirth (2cf; USNM); Thermal, 14 Mar 1955, W.R. Richards (1; CNC); Thousand Palms, 28 Mar 1955, W.R.M. Mason (l; CNC); 25 Mar 1955, W.R. Richards (l, P steyskali paratype; CNC); Thousand Palms, Thousands Palms Oasis, 10–18 Mar 1955, W.R.M. Mason, W.R. Richards (2, 7; CNC); Thousand Palms, Willis Palms Oasis, 25 Mar-3 Apr 1955, W.R. Richards (3, 1; CNC); White Water Canyon, 6–7 Apr 1949, W.W. Wirth (2; USNM). San Benito: Idria (3500 ft) (5 2; USNM). San Bernardino: Cajon Pass, 28 Apr 1949, A.L. Melander (1; USNM); Crestline, 13 Jul 1944, A.L. Melander (1; USNM); Helendale, 18 May 1955, W.R. Richards (1; CNC); Upper Santa Ana River, 13 Jul 1950, A.L. Melander (1; USNM). San Diego: Borrego, 4 Nov 1949, G. and J. Sperry (l; USNM); Carlsbad, 24 Jun 1954, A.L. Melander (12; USNM); La Jolla, 28 Mar 1946, A.L. Melander (l; USNM); San Diego, Apr-30 Dec 1913, 1934, H.G Dyer, A.L. Melander, E.P. VanDuzee (3, 3; CAS, USNM). San Francisco: San Francisco, 22 Jun-1 Aug 1915, 1947, J.E. Aldrich, A.L. Melander (8, 5; CAS, USNM); San Francisco, Lake Merced, 1 Aug 1964, P.H. Arnaud, Jr. (1; CAS). San Luis Obispo: Cholame Creek (1 mi S Cholame), 1 May 1963, P.H. Arnaud, Jr., H.B. Leech (3, 1; CAS); Morro Bay, 16 Jun-29 Jul 1940, 1945, 1947, A.L. Melander (4; USNM); Pismo, 26 Jul 1940, A.L. Melander (l, 1; USNM); San Simeon, 31 Aug 1945, A.L. Melander (1; USNM); Soda Lake (south end; 15 mi SE Simmler), 2 Apr 1969, H.B. Leech (2, 1; CAS); Tremblor Range (12 mi E Simmler; 3200 ft), 25 Apr 1964, J. Powell (l; CNC). San Mateo: Half Moon Bay, 3–19 Jul 1958, 1959, P.H. Arnaud (l, 1; USNM); Jasper Ridge, 15 Aug 1957, P.H. Arnaud (1; USNM); Redwood City (l, ex flowers Foeniculum vulgare), 3 May-6 Sep 1946, 1947, 1949, 1952, 1953, 1957, P.H. Arnaud (7 4; USNM). Santa Barbara: Carpinteria, 12 Jun-11 Aug 1947, 1950, 1953, 1958, A.L. Melander (5, 3; USNM). Santa Clara: Mount Hamilton, 15 Apr 1947, G Bohart (1; USNM); Stanford: 15 Jul-13 Nov 1952, 1953, 1957, P.H. Arnaud, A.L. Melander (10, 11; USNM). Santa Cruz: Big Basin, 18 Jul 1954, A.L. Melander (5; USNM); Felton, 17–18 May 1947, P.H. Arnaud (1; USNM); Santa Cruz, 30 Aug 1952, P.H. Arnaud (3, 2; USNM). Solano: Maine Prairie (swept from tules), 14 Jun 1921, B.G. Thompson (3; USNM). Sonoma: Bodega Mar. Station, 3 May 1968, D.D. Munroe (12, 23; CNC); Sonoma (2000 ft), J.A. Kushe (1; USNM). Stanislaus: Westley, 1 Apr 1948, P.D. Hurd (l; USNM). Ventura: Hueneme (salt marsh), 17 Jun 1948, W.W. Wirth (2; USNM); San Nicolas Island, Celery Canyon (100 ft), 22–26 Jun 1978, A.S. Menke, R.W. Rust (1; USNM); Sisar Creek, 16 Jun 1948, W.W. Wirth (1; USNM). Hawaii. Oahu: Kailua (at window near beach), 1 Jun 1946, W.W. Wirth (9; USNM). Idaho. Bannock: Tyhee (on Beta vulgaris), 18 Sep 1931, D.E. Fox (1; USNM). Latah: Potlatch, 20 Sep 1919, A.L. Melander (1; USNM). Nez Perce: Lewiston, 5 Jun 1930, J.M. Aldrich (1; USNM). Twin Falls: Castleford (beets), 13 Aug 1929, Gillette (1; USNM); Twin Falls (sugar beet study), 24 Aug–1 Sep 1940 (2, 6; USNM). Nevada. Nye: Ash Meadows National Wildlife Refuge (Crystal Spring; 36°25.2′N, 116°19.8′W), 12 May 2001, D. and W.N. Mathis (1; USNM). Storey: Reno, 23 Jul–3 Nov 1915, H.G. Dyer (4; USNM). Washoe: Pyramid, 4–5 Jul 1947, R.L. Usinger (1; USNM). New Mexico. Otero: High Rolls, 2 Jun 1902 (1; USNM). Ohio. Butler: Oxford, Mallot's Lawn, 26 Sep 1978, B.A. Steinly (1; USNM). Lorain: Beaver Creek (near Amherst; 41 °24.2′N, 82°14.0′W), 30 Jun 1977, B.A. Steinly (2; USNM). Oregon. Linn: Breitenbush Springs (2222 ft), 6 Jul 1934, H.A. Scullen (1; USNM). Tillamook: Sand Lake (2 mi S), 13 Jun 1972, W.N. Mathis (1; USNM). Umatilla: Umapine, 21 Jun 1921, A.L. Melander (1; USNM). Utah. Beaver: Mirror Lake, Wasatch Mountains, 5 Aug 1956, A.L. Melander (1; USNM). Kane: Drip Tank Canyon (37°19.4′N, 111°31.8′W), 15 May 2001, D. and W.N. Mathis (1; USNM). Salt Lake: Salt Lake City, 24 Jun 1940, A.L. Melander (1, 2; USNM). Sevier: Richfield (on Beta vulgaris and Salsola pestifer), 15 Jul–21 Sep 1929, H.E. Dorst, D.N. Fox (1, 2; USNM). Tooele: Flux, 4 Aug 1940, D.G.Hall (2; USNM). Utah: Goshen Warm Spring (6.9 km W Santiquen; 39°58′N, 111°56′W), 4 Aug 1992, D. and W.N. Mathis (5, 2; USNM); Spanish Fork, D.E. Hardy (1, 1; USNM). Washington: Washington, 13 May 1958, G.F. Knowlton (1; USNM); Zion National Park, 20 Apr 1935, A.L. Melander (1; USNM). Washington. Adams: Othello (3.2 km W; 46°50′N, 119°14′W), 23 Jul 1992, D. and W.N. Mathis (5; USNM). Asotin: Clarston, 15 May 1912, A.L. Melander (2; USNM). Benton: Kennewick, 20 May–7 Jun 1916, 1921, A.L. Melander (4, 10; USNM); Prosser, 4 May 1911 (5; USNM). Chelan: Entiat, 26 Jul 1919, A.L. Melander (1; USNM); Lake Chelan, Stehekin, 30 Jul 1919, A.L. Melander (2; USNM). Clallam: Blyn (48°1.3′N, 123°0.4′W), 10 Aug 1921, A.L. Melander (5; USNM); Blyn (salt marsh), 24 Jul 1917, A.L. Melander (1; USNM); Dungeness, 24 Aug 1910 (6 2; USNM); Sequim Bay, 3 Sep 1934, A.L. Melander (4, 7; USNM). Franklin: Ringold (NW of Pasco; 46°30.3′N, 119°15.3′W), 30 Jul 1998, W.N. Mathis (1, 1; USNM). Island: Whidbey Island, near Keystone Ferry, 18 Sep 1975, G.F. Hevel (1; USNM). King: Seattle, 2 Aug 1908 (1; USNM). Klickitat: Klickitat River, 20 May 1921, A.L. Melander (1; USNM). Mason: Dewatto (47°27.1′N, 123°4.3′W), 15 Aug 1910 (1; USNM). Okanogan: Pateros, 3 Aug 1919, A.L. Melander (1; USNM). Pierce: Mt. Rainier, Ohanapecosh, 11 Aug 1940, A.L. Melander (1; USNM). San Juan: Olga, 20 Jul (1; USNM); Orcas Island, North Beach, 19 Aug 1925, A.L. Melander (2; USNM). Snohomish: Mukilteo, Jul 1924, A.L. Melander (2; USNM). Whitman: Almota, 2 Jun 1928, A.L. Melander (1; USNM). Yakima: North Yakima, 19 May 1917, 1941, A.L. Melander, Reeves and Brookman (6; CAS, USNM); Yakima, 18 Jul 1920, A.L. Melander (1, 2; USNM).

CANADA. British Columbia: Chilliwack, MacGillivray Creek Game Preserve, 14 Jul 1953, G.J. Spencer (1; CNC); Cranbrook, 14 Aug 1926, A.A. Dennys (1; CNC); Kamloops, 11 Jun 1972, N.L.H. Krauss (1; USNM); Ladysmith, 2 Jun 1955, R. Coyles (1; CNC); Oliver, 21 May–18 Aug 1923, 1953, C.B. Garrett, J.R. McGillis (2; CNC); Osoyoos, 29 Aug 1924, A.L. Melander (1; USNM); Summerland, 13 May–23 Sep 1931, 1959, 1960, A.A. Dennys, A.N. Gartrell, R.E. Leech (4 9; CNC); Vancouver, Point Grey (on tidal flat), 5 Jul–21 Aug 1972, 1973, J.R. Vockeroth (1, 1; CNC); Vernon, 30 Sep 1926, I.J. Ward (1; CNC). Manitoba: Winnipeg, Brady Road Landfill, 25 Aug 1977 (1, 1; CNC).

MEXICO. Baja California Norte: San Carlos (Agua Caliente; 18.5 km E Maneadero), 6 Jul 1973, P.H. Arnaud, Jr. (1; CAS); San Vincente (0.5 mi N), 21 Apr 1963, P.H. Arnaud, Jr., H.B. Leech (17, 4; CAS); Tijuana (60 km S), 26 Jun 1950, A.L. Melander (1; USNM). Mexico: Toluca, 28 Apr 1965, N.L.H. Krauss (1; USNM).

DISTRIBUTION (Figure 21).—Australasian/Oceanian: Hawaiian Islands (Molokai, Oahu). Nearctic: Canada (BC, MB), United States (AZ, CA, HI, ID, NV, NM, OH, OR, UT, WA). Neotropical: Mexico (BCN, MEX). Palearctic: Czech Republic, England, Germany, Great Britain, Hungary, Poland, Slovakia. (The records from countries of the Palearctic Region are from the literature, as noted in the synonymy, or from A.G Irwin, in litt, to W.N.M., 2001, and Irwin et al., 2001.)

NATURAL HISTORY.—This species occurs in a variety of habitats, often associated with terrestrial habitats that are adjacent to aquatic systems. The water quality in these systems varies tremendously from relatively pristine fresh water, to alkaline or saline, or even highly polluted (Melander, 1952; Vockeroth, 1965; Szadziewski, 1983; Roháek, 1992).

VARIATION.—Variation was noted in the coloration of legs, particularly the tibiae. Occasional specimens exhibit a slightly paler color on the basal half of the mid- and hindtibiae. The legs of P. occidentalis, however, are almost always conspicuously darker than those of P. coronata. Thus, most specimens of both sexes can be separated on the basis of the mid- and hindtibial coloration, which in P. coronata is partially yellow and in P. occidentalis is entirely grayish.

Melander (1952) noted considerable variation in the ventral lobe of the epandrium (his “claspers”) of “P. coronata” (now P. occidentalis). He described continuous variation in form from straight and unforked to deeply bifurcate with branches of different lengths or to having no ventral lobe. Based upon examination of more than 400 specimens from Melander's collection, the variation he observed can be explained.

We observed that the epandrium of this species, after drying, may collapse on itself, causing the bifurcate lobes to dry into many configurations. The configurations vary from clearly bifurcate to appearing as if there were no ventral lobe. The anterior and posterior branches may also appear to vary in length because of the differential bending they may undergo. After maceration and rehydration of the terminalia, however, it is clear that there is very little variation in the shape of the ventral lobe of this species.