Scatella albilutea Mathis & Wirth 1981

Scatella (Neoscatella) albilutea

DIAGNOSIS.—Specimens of this species are most similar to those of S. bicolor and S. tasmaniae but may be distinguished from them and other congeners by the following combination of character states: frons uniformly and densely pollinose; lateroclinate fronto-orbital bristles subequal in length; dorsum of interfoveal carina moderately explanate, not creased, with short median sulcus; distance between antennal bases about equal to length of third antennal segment; face of both sexes more or less unicolorus and uniformly setulose with subequal small setulae except for 1 pair of large, slightly dorsally curved setae toward posteroventral angle; orientation of eye distinctly oblique to plane or oral margin; scutum and disc of scutellum more or less concolorous brown to slightly grayish brown, scutum lacking a distinct median stripe; setae of front coxa and femur similar in both sexes; tarsi yellowish, contrasting with gray femora and tibiae; first costal section of male wing uniformly thickened; brownish coloration of male wing slightly darker than that of female wing, but pattern and shape of white spots similar in both sexes; larger white spot in cell R3 subquadrate, extending across width of cell; apical white spot in cell R5 wide, subquadrate.

DESCRIPTION.—Moderately small shore flies, length 2.03 to 2.64 mm; mostly gray, with some whitish to lightly tannish coloration; almost entirely pollinose, appearing dull.

Head (Figure 2–3): Head width-to-height ratio averaging 1 : 0.67; frons entirely and uniformly pollinose, appearing dull whitish to very faintly tannish gray, some specimens with ocellar triangle and areas immediately laterad and posteriad of ocellar triangle tannish; lacking distinctly colored mesofrons and parafrons, but latter also distinguished; lateroclinate fronto-orbital bristles subequal in length. Antenna uniformly concolorous with frons; third segment as long as combined length of first and second segments; distance between antennal bases greater than length of third segment; arista mostly appearing bare, setae small, sparse, hairlike. Faces of both sexes concolorous or nearly so, at most slightly darker than frons; dorsum of interfoveal carina only slightly explanate, with short median sulcus; 1 pair of porrect to slightly upcurved larger bristles toward posteroventral angle of face, otherwise facial setae uniformly small, pale, and inconspicuous. Clypeus slightly more shiny and whitish. Eye wider than high, eye width-to-height ratio averaging 1 : 0.89; oriented at oblique angle to plane of epistomal margin. Gena high, eye-to-cheek ratio averaging 1 : 0.51.

Thorax (Figure 4): Mostly pale gray except for partially to mostly brownish dorsomedian area between dorsocentral bristles and extending length of the mesonotum (including scutellum), but not distinctly vittate, brownish coloration on scutellum usually darker. Legs, except tarsi, nearly concolorous with remainder of thorax, sometimes less pollinose and tending to be slightly amber colored at femoral-tibial articulation; tarsi yellowish, contrasting distinctly with grayish tibiae and femora, apical 2–3 tarsomeres becoming blacker. Wings sexually dimorphic (Figures 6–7); male wing differing as follows: costal margin thickened, especially first costal section; and infuscation darker; otherwise pattern as described in diagnosis.

Abdomen: Mostly unicolorous, whitish to silvery gray; lateral margins of terga 3–5 of some specimens with faint to obviously light brown areas.

TYPE MATERIAL.—Holotype male is labeled: “Thomas Riv estuary Esperance Distr WA [Western Australia] 5 Nov. 1977 D. H. Colless (Malaise Trap)/HOLOTYPE Scatella (Neoscatella) albilutea Mathis & Wirth [handwritten, red].” Allotype female and 36 paratypes (14, 22) have the same locality data as the holotype. Other paratypes as follows: NEW SOUTH WALES: COILA LAKE, Tuross Hds., 19 July 1973, Z. Liepa (5, 9; ANIC, USNM); CUTTAGEE LAKE, inlet, 8 km S Bermagui, 21 Jul 1973, Z. Liepa (1; ANIC); LAKE CURALO, Eden (nr. sandbar), 3 Aug 1973, Z. Liepa (8, 15; ANIC, USNM); LAKE MUMMUGA, Dalmeny, 20 Jul 1973, Z. Liepa (1; ANIC); MERIMBULA LAKE (nr. sandbar), 3 Aug 1973, Z. Liepa (4, 1; ANIC); NARRABEEN LAGOON, 12 Oct 1956, W. W. Wirth (3, 6; USNM); POTATO POINT, 9.5 km E Bodella, 20 Jul 1973, Z. Liepa (4, 1; ANIC); ROYAL NATIONAL PARK (nr. Sydney), 13 Aug 1971, D. K. McAlpine (1, AM); WALLAGA LAKE, Bermagui, 15–21 Jul 1973, Z. Liepa (2, 3; ANIC). VICTORIA: LAKES ENTRANCE, North Arm, 5 Aug 1973, Z. Liepa (4, 5, ANIC); MALLACOOTA INLET, SE Genoa, 4 Aug 1973, Z. Liepa (7, 6; ANIC, USNM); MARLO, Snowy River (estuary), 5 Aug 1973, Z. Liepa (3; ANIC); MORUYA RIVER (estuary), 19 Jul 1973, Z. Liepa (1; ANIC). The holotype, allotype, and most of the paratypes are in the Australian National Insect Collection, Canberra. The holotype specimen is doubled mounted (minute nadel in polyporous block) and is in excellent condition.

GEOGRAPHIC DISTRIBUTION (Figure 5).—Southern coast of New South Wales, eastern coast of Victoria, and south-central coast of Western Australia.

ETYMOLOGY.—The species epithet albilutea is of Latin derivation and means “whitish yellow,” referring to the facial color of specimens of this species.