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Comprehensive Description ( anglais )

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Scatella triseta Coquillett

Scatella triseta Coquillett, 1902:184.

Parascatella triseta.—Cresson, 1935:358.—Wirth, 1965:757 [catalog].

Scatella (Parascatella) triseta.—Sturtevant and Wheeler, 1954:179.

DIAGNOSIS.—Specimens of this species are closely related to those of S. marinensis as evidenced by their close resemblance, but may be distinguished from the latter and all similar congeners by the following combination of characters: 3 pair of larger fronto-orbital setae, middle pair smaller but at least one-half the length of larger, outer pairs; interfoveal carina brown, contrasting distinctly with grayish white, lower portion of face; mesonotum dull, grayish brown; scutellar disc flat; wing hyaline to very lightly infuscated, white spots inconspicuous.

DESCRIPTION.—Moderately small to medium-sized shore flies, length 2.50 to 3.74 mm; generally dull, pollinose mostly brown but becoming distinctly grayer ventrally and along posterior margins of abdominal segments.

Head (Figure 48): Mesofrons shiny with metallic brown to brassy luster, becoming weakly differentiated anteriorly, equaling parafrons in color and vestiture; parafrons dull, pollinose brown; dorsalmost postocular setae very poorly developed, at most equaling length of postocellars; 3 pair of larger, lateroclinate fronto-orbital bristles, middle much smaller but equal to, or larger than, one-half length of larger, outer pairs. Antennal segments more or less unicolorous; third segment more pubescent; arista approximately equal to combined length of other antennal segments, micropectinate above over most of length. Dorsum of interfoveal carina brown, contrasting distinctly with lower portion that is lacteous to argenteous; facial setae extending ventrad from interfoveal carina to posteroventral corner of face and those along oral margin well developed, obviously larger than remaining facial setae that are uniformly smaller; interfoveal carina with distinct dorsal carina. Gena mostly concolorous with face.

Thorax: Generally dull, pollinose, brown to gray, dorsum darker. Mesonotum gray to grayish brown, becoming darker and browner posteriorly; scutellum concolorous with disc of mesonotum, flat; acrostichal setae sparse and weakly developed. Dorsal portion of mesopleuron and notopleuron concolorous, light brown; lower portion of mesopleuron, pteropleuron, and sternopleuron mostly gray; front coxa silvery gray not contrasting distinctly with sternopleuron. Femora and tibiae more or less concolorous, pollinose, gray to bluish gray; tarsi dark, black dorsally, ventral surfaces paler, often tawny. Wing (Figure 52) mostly hyaline or but slightly infuscated, white spots usually inconspicuous, small, roundish.

Abdomen: Generally dull, gray to brown. Anterior portion of each segment brown, bordered posteriorly with gray band, gray on ventral surface also; segments 2–4 of male specimens more or less subequal in length. Male terminalia as in Figures 49 and 50.

TYPE-MATERIAL.—Female lectotype (here designated): “Williams, 6, 6 Ariz; HBarber, Collector.” One male and 2 female paralectotypes (here designated): with the same label data as the lectotype. The lectotype and paralectotypes are in the National Museum of Natural History, Smithsonian Institution, type number 6646. Cresson's original description lists one additional female specimen, which we have not been able to locate in the collection at the USNM.

SPECIMENS EXAMINED.—404 specimens (133 , 271 ). CANADA. ALBERTA Norton, 49°52'N, 10°24'W (CNC). MEXICO. BAJA CALIFORNIA: Sierra San Pedro Martir-La Grulla, 6900' (CA, USNM). UNITED STATES. ARIZONA: Cochise Co., Chiricahua Mtns (USNM), Chiricahua Mtns-Rustlers Park, 8200' (USNM), Douglas (USNM), Herb Martyr Park (WNM), Huachuca Mtns (AMNH), SW Research Sta–5 mi W Portal, 5400' (WNM); Coconino Co., Grand Canyon, S Rim (USNM), Williams ANSP, USNM); Pima Co., Greaterville (CA), Tucson-Saguaro Nat'l. Mon. (USNM); Pinal Co., Superior (USNM); Santa Cruz Co. Sycamore Canyon-Yank's Spring–Tumacacori. CALIFORNIA: Andrea Canyon (USNM); Coachella Valley (CA); Green Valley (USNM); Monarch Pass, 8000' (USNM); Morongo Valley (USNM); Scotland (USNM); Sentence Canyon (USNM): Stoddard Well (USNM); Alameda Co., Berkeley Hills (ANSP); Inyo Co., Big Pines (USNM); Los Angeles Co., Claremont, near mountains (USNM), Los Angeles (CA), Los Cerritos (ANSP), Mojave Desert-Lovejoy Springs (USNM), Pasadena (USNM), Rosemead (USNM), Valyermo (USNM): Mono Co., Mono Lake (CA, USNM), Topaz Lake (CA, USNM): Monterey Co., Asilomar (USNM); Riverside Co., Cathedral Canyon (USNM), Cathedral City (USNM), Indio (CNC), Mag. Spring Canyon (USNM), Mag. Spring near Indio (USNM), Palm Springs (USNM), Whitewater Canyon (USNM); San Bernardino Co., Barton Flat, E of (USNM), Barton Flat, S Fork Camp (USNM), Crestline (USNM), Helendale (CNC), Herkey Camp (USNM), San Bernardino Mtns-Sugarloaf (USNM), South Fork Santa Ana River (USNM), Upper Santa Ana River (USNM), Upper Santa Ana River-Lost Creek (USNM), Wrightwood (USNM); San Diego Co., Agua Caliente (CNC), Borego Desert-Tubb Canyon (USNM), Desert Edge (ANSP, CA); San Mateo Co., Corte de Madera vic Portola (CA), Redwood City (USNM); Santa Barbara Co., Sant Cruz Island (USNM); Tulare Co., Sequoia Park, 6200' (USNM); Tuolumne Co., Yosemite (USNM); Ventura Co., Santa Paula (USNM). COLORADO: (USNM); Mt Evans-timberline, 11,600' (CNC); Clear Creek Co., Idaho Springs, 6 mi SW (CNC); Eagle Co., Tennessee Pass, 10,240' (ANSP, USNM); El Paso Co., Colorado Springs (ANSP, CA). IDAHO: Lake Vaha (USNM). KNASAS: Douglas Co., Lawrence Nat. Hist. Res (WNM). NEBRASKA: Cherry Co., Pelican Lake (USNM), Snake River (USNM). NEW MEXICO: Dartford (USNM); Catron Co., Glenwood, 32 mi E (WNM); Grant Co., Cherry Creek-Pinos Altos (USNM); Otero Co., Alamogordo (ANSP), Cloudcroft (CNC), Cloudcroft, 2.5 mi E (WNM), Penasco River-Mayhill (USNM); Sandoval Co., Cuba, 11 mi SE (WNM), Jemez Springs, 7.5 mi N (WNM), Rabbit Mnt (USNM), 7 Springs Ranger Sta (WNM); San Miguel Co., Las Vegas, 6400' (USNM); Socorro Co., Bear Trap Camp, 28 mi SW Magdelena (AMNH), Magdelena Mtns (AMNH), Magdelena (AMNH); Torrance Co., Tajique (USNM). NORTH DAKOTA: Mountrail Co., White Lake (UNSM). OKLAHOMA: Alfalfa Co., Gt. Salt Plains (USNM). SOUTH DAKOTA: Custer Co., Custer, 7 mi W (WNM) Lawrence Co., Savoy, 2 mi W (WNM). TEXAS: (USNM); Brewster Co., Big Bend Nat'l. Park-Pulliman Canyon; Gillespie Co., Pedernales River (USNM); Presidio Co., Shafter near old silver mine (USNM); Randall Co., Palo Duro Canyon (USNM); Sonora Co., Sonora (USNM), Sonora Exp. Sta (USNM); Travis Co., Austin (ANSP, USNM). UTAH: Utah Co., Goshen Pond (WNM); Washington Co., Santa Clara, 6 mi W (WNM), Zion Park (USNM). WASHINGTON: Okanogan Co., Brewster (USNM); Walla Walla Co., Walla Walla (USNM); Whitman Co., Almota (ANSP). WYOMING: Teton Co., Yellowstone Lake (USNM), Yellowstone Park Falls (USNM), Yellowstone Park, U Geyser Basin (USNM).

GEOGRAPHIC DISTRIBUTION. (Figure 51).—Scatella triseta occurs in most states west of the Mississippi River, as far north as Norton, Alberta, and southward to Big Bend National Park (Brewster County), Texas. It is likely that this species also occurs throughout the high plateau region of northern Mexico.

NATURAL HISTORY.—Deonier (1965) collected specimens of this species commonly in stream rock and freshet-seep habitats in Boone County, Iowa. He characterized the stream-rock habitat as the moss- and alga-covered shoal or riffle rocks that project above the surface of shallow riffles. The exposed rocks are covered with bryophytes and diatoms, the latter being very abundant and constituting most of the microflora. Deonier found that this habitat is restricted to forested areas and that is one of the most stable shore fly habitats in Iowa. The freshet-seep habitat is more ephemeral, depending on seepage that is governed by rainfall. Deonier described it as a microhabitat, consisting of small seepage areas on embankments. The flora includes species of Nostoc and other Cynophyta plus mosses; these grew on the seepage areas and around small pools at the bases of embankments.

PHYLOGENETIC RELATIONSHIPS.—Scatella triseta is the sister species of S. marinensis. This relationship is established by the joint possession of acrostichal setae that are reduced in size and by the color of the interfoveal carina that is brown to golden brown, contrasting distinctly with the bottom portion of the face. Both of these character states are synapomorphous.
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citation bibliographique
Mathis, Wayne Neilsen and Shewell, G. E. 1978. "Studies of Ephydrinae (Diptera: Ephydridae), I: Revisions of Parascatella Cresson and the Triseta group of Scatella Robineau-Desvoidy." Smithsonian Contributions to Zoology. 1-44. https://doi.org/10.5479/si.00810282.285

Scatella triseta ( néerlandais ; flamand )

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Insecten

Scatella triseta is een vliegensoort uit de familie van de oevervliegen (Ephydridae).[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1902 door Coquillett.

Bronnen, noten en/of referenties
  1. Mathis and Zatwarnicki, 1995, World Catalog of Shore Flies, p. 278.
Geplaatst op:
18-06-2013
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