Anasimyia diffusa Locke, Skevington and Vockeroth

Skevington, Jeffrey H., Young, Andrew D., Locke, Michelle M. & Moran, Kevin M., 2019, New Syrphidae (Diptera) of North-eastern North America, Biodiversity Data Journal 7, pp. 36673-36673 : 36673

Anasimyia diffusa Locke, Skevington and Vockeroth sp. n.

Materials

Type status: Holotype. Occurrence: catalogNumber: CNC_Diptera102201 ; recordedBy: D.Blades; individualCount: 1; sex: male; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Ontario; locality: Oliver Bog, 3km, S Galt ; decimalLatitude: 43.3168; decimalLongitude: -80.283; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 1988-05-03/26; year: 1988; month: 5; day: 3; verbatimEventDate: 3-26.v.1988; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC640314 ; recordedBy: D. Beresford; individualCount: 1; sex: female; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Nunavut; locality: Akimiski Island ; decimalLatitude: 53.105; decimalLongitude: -80.957; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 2013-07; year: 2013; month: 7; verbatimEventDate: vii.2013; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC640356 ; recordedBy: D. Beresford; individualCount: 1; sex: female; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Nunavut; locality: Akimiski Island ; decimalLatitude: 53.105; decimalLongitude: -80.957; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 2013-07; year: 2013; month: 7; verbatimEventDate: vii.2013; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC640369 ; recordedBy: Alex Howard & Stan Vasilauskas; individualCount: 1; sex: female; lifeStage: adult; otherCatalogNumbers: 1101721B-2012-088-00008; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Ontario; locality: District: 2E-1 Albany River ; decimalLatitude: 51.6492; decimalLongitude: -81.848522; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: samplingProtocol: Malaise trap; eventDate: 2012-06-17; year: 2012; month: 6; day: 17; verbatimEventDate: 17.vi.2012; habitat: Forest, Closed Treed cover, Eco District 2E-1 Albany River; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC640425 ; recordedBy: Ian Fife & Stan Phippen; individualCount: 1; sex: male; lifeStage: adult; otherCatalogNumbers: 1094706-2011-089-00002; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Ontario; locality: District: 1E-3 Winisk River ; decimalLatitude: 54.4712; decimalLongitude: -88.5649; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: samplingProtocol: Malaise trap; eventDate: 2011-06-21; year: 2011; month: 6; day: 21; verbatimEventDate: 21.vi.2011; habitat: Forest, Bryophytes, Herbaceous plant cover, Eco District 1E-3 Winisk River; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC641362 ; recordedBy: David Beresford; individualCount: 1; sex: male; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Nunavut; locality: Akimiski Island ; decimalLatitude: 53.105; decimalLongitude: -80.957; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: samplingProtocol: Malaise trap; eventDate: 2017-07-17; year: 2017; month: 7; day: 17; verbatimEventDate: 17.vii.2017; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC641363 ; recordedBy: David Beresford; individualCount: 1; sex: male; lifeStage: adult; otherCatalogNumbers: 30/27; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Nunavut; locality: Akimiski Island ; decimalLatitude: 53.105; decimalLongitude: -80.957; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: samplingProtocol: Malaise trap; eventDate: 2014-07-21; year: 2014; month: 7; day: 21; verbatimEventDate: 21.vii.2014; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC641364 ; recordedBy: David Beresford; individualCount: 1; sex: male; lifeStage: adult; otherCatalogNumbers: 45/27; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Nunavut; locality: Akimiski Island ; decimalLatitude: 53.105; decimalLongitude: -80.957; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: samplingProtocol: Malaise trap; eventDate: 2014-07-21; year: 2014; month: 7; day: 21; verbatimEventDate: 21.vii.2014; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC_Diptera102200 ; recordedBy: S.J.Miller; individualCount: 1; sex: male; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: New Brunswick; locality: Kouchibouguac National Park ; decimalLatitude: 46.85; decimalLongitude: -64.97; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 1978-06-15; year: 1978; month: 6; day: 15; verbatimEventDate: 15.vi.1978; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC_Diptera245059 ; recordedBy: A. Borkent; individualCount: 1; sex: male; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: British Columbia; locality: 6 km E[ast of] Salmon Arm ; decimalLatitude: 50.7; decimalLongitude: -119.3; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 1992-06-30; year: 1992; month: 4; day: 30; verbatimEventDate: 30.iv.1992; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC_Diptera284501 ; recordedBy: CANPOLIN; individualCount: 1; sex: male; lifeStage: adult; otherCatalogNumbers: UG: SYRPH: 10763; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Manitoba; locality: O'day ; decimalLatitude: 57.582; decimalLongitude: -94.069; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: samplingProtocol: Malaise trap; eventDate: 2011-07-07/19; year: 2011; month: 7; day: 7; verbatimEventDate: 7-19.vii.2011; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC_Diptera284505 ; recordedBy: CANPOLIN; individualCount: 1; sex: male; lifeStage: adult; otherCatalogNumbers: UG: SYRPH: 01075; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Manitoba; locality: Herchmer ; decimalLatitude: 57.378; decimalLongitude: -94.195; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: samplingProtocol: Malaise trap; eventDate: 2011-07-07/19; year: 2011; month: 7; day: 7; verbatimEventDate: 7-19.vii.2011; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC_Diptera44602 ; recordedBy: H.J. Teskey; individualCount: 1; sex: male; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Alberta; locality: Waterton Lakes National Park ; decimalLatitude: 49.083314; decimalLongitude: -113.916733; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 1980-07-07/12; year: 1980; month: 7; day: 7; verbatimEventDate: 7-12.vii.1980; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC_Diptera44629 ; recordedBy: A. Borkent; individualCount: 1; sex: male; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: British Columbia; locality: 6 km East of Salmon Arm ; decimalLatitude: 50.7; decimalLongitude: -119.2; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 1990-05-16; year: 1990; month: 5; day: 16; verbatimEventDate: 16.v.1990; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC_Diptera44630 ; recordedBy: A. Borkent; individualCount: 1; sex: male; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: British Columbia; locality: 6 km East of Salmon Arm ; decimalLatitude: 50.7; decimalLongitude: -119.2; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 1990-05-16; year: 1990; month: 5; day: 16; verbatimEventDate: 16.v.1990; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC_Diptera4972 ; recordedBy: Cooper, Wood; individualCount: 1; sex: female; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Ontario; locality: Carleton Co. 8 km S Richmond fen ; decimalLatitude: 45.069536; decimalLongitude: -75.854558; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 1983-08-02; year: 1983; month: 8; day: 2; verbatimEventDate: 2.viii.1983; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC_Diptera4974 ; recordedBy: S.J. Miller; individualCount: 1; sex: female; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: New Brunswick; locality: Kouchibouguac National Park ; decimalLatitude: 46.85; decimalLongitude: -64.97; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 1978-06-14; year: 1978; month: 6; day: 14; verbatimEventDate: 14.vi.1978; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: CNC_Diptera91228 ; recordedBy: J. Fletcher; individualCount: 1; sex: male; lifeStage: adult; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Manitoba; locality: Aweme ; decimalLatitude: 49.7; decimalLongitude: -99.6; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 1907-08-25; year: 1907; month: 8; day: 25; verbatimEventDate: 25.viii.1907; Record Level: language: en; institutionCode: CNC; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: Jeff_Skevington_Specimen17433 ; recordedBy: D. Blades; individualCount: 1; sex: male; lifeStage: adult; otherCatalogNumbers: accession#026W; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Ontario; locality: Oliver Bog, 3km, S Galt ; decimalLatitude: 43.3168; decimalLongitude: -80.283; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: samplingProtocol: pan trap; eventDate: 1988-05-03/26; year: 1988; month: 5; day: 3; verbatimEventDate: 3-26.v.1988; habitat: pt2 expanse hollow; Record Level: language: en; institutionCode: DEBU; basisOfRecord: PreservedSpecimen Type status: Paratype. Occurrence: catalogNumber: Jeff_Skevington_Specimen17434 ; recordedBy: D. Blades; individualCount: 1; sex: male; lifeStage: adult; otherCatalogNumbers: accession#026W; Taxon: scientificName: Anasimyiadiffusa Locke, Skevington and Vockeroth; kingdom: Animalia; phylum: Arthropoda; class: Hexapoda; order: Diptera; family: Syrphidae; genus: Anasimyia; specificEpithet: diffusa; taxonRank: species; scientificNameAuthorship: Locke, Skevington and Vockeroth; vernacularName: Smooth-legged Swamp Fly; nomenclaturalStatus: new species; Location: country: Canada; stateProvince: Ontario; locality: Oliver Bog, 3km, S Galt ; decimalLatitude: 43.3168; decimalLongitude: -80.283; Identification: identifiedBy: Michelle M. Locke; dateIdentified: 2019; Event: eventDate: 1988-05-03/26; year: 1988; month: 5; day: 3; verbatimEventDate: 3-26.v.1988; habitat: pt2 expanse hollow; Record Level: language: en; institutionCode: DEBU; basisOfRecord: PreservedSpecimen

Description

Size: Body length 7.6 to 10.7 mm; wing length 5.6 to 7.4 mm

Male: Head: Face yellow, covered in yellow pollen and fine yellow pile, sides of face black, shining and bare, small medial tubercle, lower face projecting forwards along the oral margin; gena black, covered in yellow pollen and fine yellow pile; frons black dorsally, yellow ventrally, sometimes narrowly so just along ventral edge and across dorsum of antennal socket, dense yellow pollen often obscures ground colour, narrow shining spot dorsal to the antennal socket, yellow pilose, sometimes with a few black pili; vertex black, mostly black pilose with some yellow pile; antenna wholly yellow to orange, scape and pedicel with short, black pile, pedicel slightly longer than scape, postpedicel round; eye bare.

Thorax: Scutum dull black with two medial, narrow, yellow pollinose stripes, lateral edges yellow pollinose from postpronotum to postalar callus, yellow pilose; postpronotum black, covered in yellow pollen and yellow pile; postalar callus black, covered in yellow pollen and yellow pile; scutellum yellow with black lateral edges and narrowly black along anterior edge, yellow pilose with some black pili admixed; pleuron black, covered in yellow pollen, anterior anepisternum, katepimeron and meron bare, posterior anepisternum, katepisternum and anepimeron yellow pilose; metasternum black, yellow pollinose, yellow pilose; pro- and mesolegs with coxae and trochanters black, yellow pilose, femora black on basal ½, yellow on apical ½, black extends almost to apex anteroventrally, sometimes more or less extensively black, anteroventral basal patch of black setulae, yellow pilose; protibia yellow, usually brown to black anteriorly on apical ¼ -⅓, covered in short, yellow pile, protarsus brown anteriorly, yellow posteriorly, similar in colour to apex of protibia, covered in short yellow pile, few black pili anteriorly; mesotibia yellow, sometimes brown, yellow pilose; mesotarsus yellow basally, brown to black apically, tarsomeres 1 and 2 yellow, 3 yellow or brown, 4 and 5 brown, all yellow pilose with black setulae posteriorly; metaleg with coxa black, yellow pollinose, yellow pilose; metatrochanter without tubercle, black, shining, long yellow pile anteriorly, some short yellow pile posteriorly; metafemur enlarged, yellow, anteromedial spot ranging from obscure brown to black spot ~⅕ the length of the metafemur to large black spot on medial ½ of femur, posterior side ⅔- ¾ black medially, dorsally extending to apex, apical end of metafemur narrowly black, metafemur yellow pilose, small patch of black setulae anterobasally, black setulae along ventral side; metatibia brown to black basally and apically, yellow on medial ¼ -⅓, with ventral carinate ridge, yellow pilose, apical end projected forwards slightly beyond end of tibia not formed into noticeable spur; metatarsus brown to black, black pilose anteriorly, yellow pilose posteriorly; wing entirely densely microtrichose; halter yellow; calypter yellow.

Abdomen: Black, yellow pilose with few black pili admixed; tergite 1 pollinose anterolaterally; tergite 2 yellow laterally, widely on anterior ¾ -⅘, usually narrowly on posterior ⅕- ¼, yellow extending medially on to tergite and tapering to a point about ¼ -⅓ from lateral edge, yellow cuticle covered in yellow pollen, sometimes extending slightly on to black cuticle medially where it tapers to a point; tergite 3 with anterolateral yellow spots ½ length of tergite, often narrowly yellow laterally on posterior half, pair of yellow to grey curved pollinose markings medially; tergite 4 similar to tergite 3 but lateral edges only narrowly yellow, no anterolateral yellow spots, narrowly yellow posteriorly (tergite 3 sometimes very narrowly yellow posteriorly as well); tergites 2-4 shining on posterior ⅕- ½, typically more widely shining on tergites 3 and 4; sternite 1 black on anterior ¾, yellow on posterior ¼, black area convex; sternite 2 yellow, often with brown to black spot posteromedially, spot often obscure, sternite 3 often brown to black with posterior edge narrowly yellow, sometimes yellow on anterior ½; sternite 4 brown to black with posterior edge narrowly yellow; all sternites yellow to grey pollinose with yellow pile.

Genitalia: Epandrium longer than wide, narrows slightly dorsally, with apicodorsal ridge adjacent to cerci; cercus with laterally compressed, subquadrate, sclerotised outer portion covered in long pile and membranous inner portion; surstylus long and wide, bent, with small patch of setae on ventral inner surface at bend, apical end bilobed and curved inwards, dorsal and ventral lobes covered in setae; basal hypandrium convexly curved ventrally, with two low, parallel ridges ending with several posterior-facing, curved setae at apicoventral end (one pair of setae larger than other setae); apical hypandrium split into two complex, multi-lobed arms; phallapodeme long, rod-like structure, laterally compressed and curved dorsally at base; phallus is difficult to distinguish, hidden between the multi-lobed hypandrial arms, small, short, with two pairs of lobes, basal lobes broad and directed laterally, distal lobes narrow and directed apically, with separate dorsal conical structure, pointed at apex (possibly secondarily derived from surrounding membrane).

Female: Differs from male in the following ways: frons black with narrow yellow ventral edge including dorsum of antennal socket, black pilose; scutellum often entirely yellow pilose, sometimes with few black pili admixed; pro- and mesofemora black on basal ⅓- ½, yellow on apical ½ -⅔, black extends almost to apex ventrally, sometimes less extensively black basally with black not extending entirely around femur; metafemur with brown anterior spot smaller than in male, sometimes completely absent; metatibia similar to male but often more yellow with brown areas reduced especially basally; abdomen with short subappressed yellow and black pile; tergite 1 entirely pollinose, with short, yellow subappressed pile; tergite 2 yellow anterolaterally, sometimes with yellow extending narrowly along lateral margin, with pair of curved pollinose markings beginning anterolaterally and curving inwards medially, pile subappressed with some long pile on anterolateral edge, yellow pilose on anterior ¾ or more, black pilose on posterior ¼ or less, posterior edge shining; tergites 3 and 4 similar to tergite 2, sometimes with posterior edge narrowly yellow and with small medial pollinose marking posteromedially, often more extensively black pilose on posterior ½ or less, pile uniformly short, no long pile anterolaterally, tergites 3 and 4 not as long as tergite 2; tergite 5 smaller than other tergites, black anteriorly, yellow posteriorly, tergite almost entirely pollinose except along anterior edge and narrow medial stripe, yellow pilose with few black pili posteriorly; sternites pollinose and yellow pilose; sternite one black; sternite 2 mostly yellow with black medial triangular marking; sternites 3 and 4 mostly black with narrow yellow lateral and sometimes posterior edges.

See Fig. 1 & Fig. 2.

Diagnosis

Male metatrochanter without tubercle, with fine, yellow pile anteriorly ( Fig. 1 e); metatibia without spur ( Fig. 1 d) and tergite 4 with large pair of curved pollinose markings.

Etymology

The word diffusa is Latin, meaning spread out, extended, dispersed. This is the name given to this species by J.R. Vockeroth, presumably with reference to the wide distribution.

Distribution

This species is known from 20 specimens from New Brunswick to British Columbia.

Ecology

Anasimyia diffusa is often collected in the same location as the much more common A. anausis (Walker 1849). They appear to both have a broad distribution and a long flight season, with A. diffusa collected from mid-April to late August. Some specimens have been collected in bogs but it is unclear if it is a bog specialist or not.

Taxon discussion

Differences in the metatrochanter are the easiest way to distinguish A. diffusa from A. anausis . The metatrochanter of A. anausis has short black setuale anteroventrally. In some specimens these setulae appear to be broken off but their insertions into the cuticle give the metatrochanter a rough texture. Anasimyia bilinearis (Williston 1887) can be differentiated from A. diffusa by its mostly dark abdomen with reduced pollinose markings. There is no tubercle on the metatrochanter of A. diffusa as there is in Anasimyia Group 2 males (see Skevington et al. 2019). Females are similar to other Group 1 females (see Skevington et al. 2019) and cannot be distinguished from similar species. Five females of A. diffusa were identified using the barcoding region of COI. These specimens in the paratype series clustered in a neighbour-joining tree with four males that were morphologically identified to A. diffusa . DNA sequences of this species are available in the public BOLD dataset "New Species of Syrphidae from Field Guide - DS-NSSFG" and in GenBank (Table 2 ). They are genetically most similar to A. anausis but consistently separable with DNA barcodes.

Common Name

The common name given to the species by Skevington et al. (2019) is Smooth-legged Swamp Fly.