Scatella norrisi Mathis & Wirth 1981

Scatella (Neoscatella) norrisi

DIAGNOSIS.—Specimens of this species are similar to those of S. immaculata and S. austrina but may be distinguished from them and other congeners by the following combination of character states: frons pollinose although more thinly so anterolaterad of ocellar triangle; lacteroclinate fronto-orbital bristles subequal in length; dorsum of interfoveal carina narrowly developed; distance between antennal bases about equal to length of second or third antennal segment; coloration of face in both sexes similar, light grayish yellow; marginal facial setae distinctly larger than those along median surface, with two to three pair of large, slightly dorsally curved setae aligned between interfoveal carina and posteroventral corner of face; orientation of eye at slight oblique angle to plane of oral margin; scutum with brownish median stripe along acrostichal track, contrasting distinctly with grayish coloration on rest of scutum; disc of scutellum gray to bluish gray; setae of front coxa and femur similar in both sexes; tarsi blackish brown, concolorous with femora and tibiae; first costal section of male wing thickened, thickened portion becoming gradually narrower apically; larger white area in cell R3 subquadrate in female wing, in male wing weakly developed or lacking, if present narrow and attenuated medially, appearing more or less as two spots; apical white area in cell R5 narrowly rectangular in both sexes.

DESCRIPTION.—Small to moderately small shore flies, length 1.97 to 2.34 mm; mostly gray, but with considerable yellowish gold to brown coloration; mostly pollinose, appearing dull.

Head (Figures 27–28): Head width-to-height ratio averaging 1: 0.67; frons entirely pollinose, more sparsely so laterad of ocellar triangle, appearing subshiny; coloration of frons mostly gray to tannish gray, mesofrons separated from parafrons by faintly charcoalish, greenish gray, more membranous appearing wedges, ocellar triangle darker than mesofrons, distinctly brownish; lateroclinate fronto-orbital bristles subequal in length. Antenna with first and second segments faintly blackish gray; third segment more brownish gray; length of third segment subequal or slightly longer than combined length of first and second segments; arista with short, hairlike setae dorsally, mostly appearing bare; distance between antennal bases short, less than length of third segment. Face mostly unicolorous, light yellowish gray; facial setae distinct, those along margin stronger, with 3–4 longer setae aligned between interfoveal carina and posteroventral angle of face. Eye subelliptical to round, eye width-to-height ratio averaging 1 : 1; oriented at almost perpendicular angle to plane of epistomal margin. Gena moderately low, eye-to-cheek ratio averaging 1 : 0.21, more whitish gray, but becoming more yellowing posteriorly. Clypeus generally concealed.

Thorax (Figure 29): Mostly gray, but with considerable light brown to brown coloration; mesonotum gray except for median brown stripe (through acrostichal area), some specimens with faint indication of a narrow stripe along dorsocentrals tract; mesopleuron and anterior portion of pteropleuron grayish brown; ventral pleural areas mostly gray. Legs concolorous, gray to blackish; femora mostly gray; tibiae mostly grayish black to black, becoming darker toward apices; tarsi blackish. Wings sexually dimorphic (Figures 34–35); wing of male differing as follows: Costa thickened, especially first costal section; infuscation darker brown; light areas in middle of cell R3 as 2–3 semiseparate areas, attenuated medially to completely separate, not forming a large quadrate area; otherwise wing similar to that of female as described in diagnosis.

Abdomen: Mostly gray, but with considerable brownish coloration; anterior margin of each terga tending to be more brownish, considerably so in some specimens, other specimens with a distinct to less distinct dorsomedian brownish area, lateral margins of terga usually with some brownish coloration.

TYPE MATERIAL.—Holotype male is labeled: “Thomas Riv estuary Esperance Distr WA 7 Nov. 1977 D. H. Colless (At Light)/HOLOTYPE Scatella (Neoscatella) norrisi Mathis and Wirth [handwritten, red].” Allotype female and five paratypes (1, 4), have the same label data as the holotype. Other paratypes as follows: WESTERN AUSTRALIA: MIMMIGARRA STN., 23 Oct 1941, K. R. Norris, (1, 2; ANIC). The holotype, allotype, and most of the paratypes are in the Australian National Insect Collection, Canberra. A male and female paratype are in the National Museum of Natural History, Smithsonian Institution, Washington, D. C. The holotype specimen is double mounted (minute nadel in polyporus block) and is in excellent condition.

GEOGRAPHIC DISTRIBUTION (Figure 36).—South-central coast of Western Australia.

ETYMOLOGY.—The species epithet norrisi is a genitive patronym to honor Dr. K. R. Norris, CSIRO, Canberra, Australia.