Dasysyrphus intrudens (Osten Sacken, 1877)

Locke, Michelle M. & Skevington, Jeffrey H., 2013, Revision of Nearctic <i> Dasysyrphus </ i> Enderlein (Diptera: Syrphidae), Zootaxa 3660 (1), pp. 1-80 : 36-39

publication ID	https://doi.org/ 10.11646/zootaxa.3660.1.1
publication LSID	lsid:zoobank.org:pub:95ADD39C-98BE-4879-B070-34A5D86BD67B
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treatment provided by	Felipe
scientific name	Dasysyrphus intrudens
status

Treatment

Dasysyrphus intrudens View in CoL species complex (Osten Sacken)

Figures: 7A–F, 20B

Synonyms and References:

Syrphus amalopis Osten Sacken 1875: 148 View in CoL (in part, description)

Syrphus intrudens Osten Sacken 1877: 326 View in CoL (original description)

Syrphus amalopis Osten Sacken View in CoL :

Williston 1887: 69 (in part; redescription)

Syrphus disgregus Snow 1895: 233 View in CoL (original description; comb. nov.)

Curran 1925: 180 (discussion)

Syrphus laticaudatus Curran 1925: 176 View in CoL , Pl. XI Fig. 152 (original description; comb. nov.)

Syrphus osburni Curran 1925: 177 View in CoL , Pl. XI Fig. 153 (original description; comb. nov.)

Metasyrphus amalopis (Osten Sacken) :

Fluke 1933: 110 (in part, includes disgregus and intrudens ; key, redescription and transfer to Metasyrphus )

Metasyrphus laticaudatus (Curran) :

Fluke 1933: 111 (key, redescription and transfer to Metasyrphus )

Metasyrphus osburni (Curran) :

Fluke 1933: 112 (key, redescription and transfer to Metasyrphus )

Dasysyrphus amalopis (Osten Sacken) :

Stone et al. 1965: 563 (in part; includes intrudens , catalogue and move to Dasysyrphus )

Dasysyrphus disgregus (Snow) :

Stone et al. 1965: 563 (catalogue and move to Dasysyrphus )

Dasysyrphus laticaudatus (Curran) :

Stone et al. 1965: 563 (catalogue and move to Dasysyrphus )

Dasysyrphus osburni (Curran) :

Stone et al. 1965: 564 (catalogue and move to Dasysyrphus )

Dasysyrphus venustus (Meigen) :

Vockeroth 1986: 203 (in part, includes disgregus , intrudens , laticaudatus and osburni ; lectotype designation for disgregus and intrudens and discussion)

Vockeroth 1992: 70 (in part, includes intrudens , disgregus , laticaudatus and osburni ; key and redescription)

Diagnosis: Abdominal maculae cross abdominal margin; maculae on tergite 2 large (>⅓ width of tergite) ovalshaped; maculae on tergites 3&4 arcuate or lunulate, usually strongly constricted medially, sometimes dividing maculae in half, with medial edge swollen, never meeting medially, maculae reach abdominal margin, usually broadly contacting edge of abdomen ( Figs 7A–E View FIGURE 7 ). Has previously been confused with D. venustus , however, species in this complex have maculae that are arcuate, lunulate and/or greatly constricted medially, whereas in D. venustus they are more transverse and much less constricted medially ( Fig. 17A View FIGURE 17 ).

Redescription:

Body Length: 7.0– 11.7mm; Wing Length: 7.0– 10.7mm

Head: Frons dark with light pollenose fascia (in males it runs along ventral edge of where eyes meet, in females it is ¼–½ the length between the antennae and ocelli and narrowly to widely separated medially) and dark pile; face light with dark vitta ¼–½ the width of the face, usually reaching antennal socket, face with dark or light pile, sometimes with a both light and dark pile; gena dark with light pile; occiput dark, covered in light pollen, pile light; scape and pedicel light to dark, flagellomere usually light basally and darker apically, sometimes mostly dark.

Thorax: Scutum dark, may appear shiny or metallic, pile light; scutellum light with darker anterolateral edges, light pile some with varying amounts of dark pile posteriorly; cell c usually densely microtrichose but sometimes bare basally, r 1 is usually bare at the base, but can be entirely microtrichose, br and bm range from densely microtrichose to extensively bare, but often with some bare areas, cup either densely microtrichose or bare at base and/or along CuP; haltere light; pro- and mesofemora ⅓–½ dark basally, ½–⅔ light apically, metafemur ⅔–¾ dark basally, ¼–⅓ light apically, tibiae light, metatibia and rarely pro- and/or mesotibiae with dark band ¼ of the way from the apex, tarsi light, sometimes dark anteriorly.

Abdomen: Maculae on tergite 2 large and oval, sometimes with anterolateral edge extending to edge of abdomen, maculae on tergites 3&4 arcuate or lunulate, usually strongly constricted medially, sometimes dividing maculae in half, with medial edge swollen, never meeting medially, maculae reach abdominal margin, usually broadly contacting edge of abdomen ( Figs 7A–E View FIGURE 7 ); sternite 2 either all light, with dark oval macula or with dark fascia (usually distinct, sometimes faint), sternites 3&4 light with dark fasciae.

Male Genitalia: Surstylus more or less triangular in shape in lateral view, flattened anteroposteriorly with long pile on posterior side and spines on anteroventral side, similar to D. venustus ( Fig. 17D View FIGURE 17 ) and D. limatus ( Fig. 9D View FIGURE 9 ); cercus oval with long pile over entire surface; gonostylus is pointed ventrally, dorsally flattened at base then it expands dorsally towards apex, oblique ridge near apex, with ends of ridge projecting into points; pile on dorsal surface; basiphallus is basally bent at about a 90 degree angle towards the dorsum, at apical end it is curved ventrally, fully sclerotized all the way around with no pile or spines; distiphallus is long with no enlarged area basally, shaft sometimes with small bump dorsally near base, apical end flared out into horn with the dorsal side flattened slightly, which is mostly sclerotized but membranous at apex with setulae dorsally ( Fig. 7F View FIGURE 7 ).

Intraspecific variation: The abdominal maculae are highly variable ( Figs 7A–E View FIGURE 7 ), likely because multiple, unresolved species lie within this complex. Tergites 3 & 4 have maculae that can be arcuate or lunulate, usually strongly constricted medially, sometimes dividing maculae in half, medial edge swollen but degree of swelling varies, maculae usually broadly contact edge of abdomen, but in few specimens they end just past margin and do not contact edge; sternite 2 colouring variable, either all light, with dark oval macula or with dark fascia (usually distinct, sometimes faint); wing cells vary in microtrichia density with c usually densely microtrichose but sometimes bare basally, r 1 is usually bare at the base, but can be entirely microtrichose, br and bm range from densely microtrichose to extensively bare, but often with some bare areas, cup either densely microtrichose or bare at base and/or along CuP; distiphallus shaft sometimes with small bump dorsally near base.

Etymology: Presumably comes from the Latin, intrudo, meaning enter without invitation or permission.

Distribution: Canada (AB, BC, NF, NS, ON QC, YT) and US (AK, AZ, CA, CO, ID, MA, MD, ME, MI, NC, NH, NM, NY, OR, PA, TN, UT, VA, WA, WV, WY), also widespread over Europe and Asia ( Fig. 20B View FIGURE 20 )

Ecology: Collected on great camas ( Camassia leichtlinii (Baker) S. Watson , Liliaceae ), common camas ( Camassia quamash (Pursh) Greene , Liliaceae ), Carolina spring beauty ( Claytonia caroliniana Michaux , Portulacaceae ), small-flowered woodland-star ( Lithophragma parviflorum (Hooker) Nuttall ex Torrey & A. Gray , Saxifragaceae ), heart-leaved foamflower ( Tiarella cordifolia Linnaeus , Saxifragaceae ), birch ( Betula Linnaeus , Betulaceae ), common cowparsnip ( Heracleum maximum W. Bartram , Apiaceae ), cowparsnip ( Heracleum Linnaeus , Apiaceae ), blackberry ( Rubus Linnaeus , Rosaceae ), Pacific blackberry ( Rubus ursinus Chamisso & Schlechtendal , Rasaceae), Pacific silver fir ( Abies amabilis (Douglas ex Loudon) Douglas ex J. Forbes , Pinaceae ), Labrador tea ( Ledum Linnaeus , Ericaceae ), spotted-water hemlock ( Cicuta maculata Linnaeus , Apiaceae ), blueberry ( Vaccinium Linnaeus , Ericaceae ), dogwood ( Cornus Linnaeus , Cornaceae ), jack pine ( Pinus banksiana Lambert , Pinaceae ), mountain maple ( Acer spicatum Lamarck , Aceraceae ), nannyberry ( Viburnum lentago Linnaeus , Caprifoliaceae ), beachgrass ( Ammophila Host , Poaceae ), herb-Robert ( Geranium robertianum Linnaeus , Geraniaceae ), slender phlox ( Microsteris gracilis (Hooker) Greene , Polemoniaceae ), spreading groundsmoke ( Gayophytum diffusum subsp. parviflorum F.H. Lewis & Szweykowski , Onagraceae ), chokecherry ( Prunus virginiana , Rosaceae ), bristly bearberry ( Arctostaphylos columbiana Piper , Ericaceae ), slender stitchwort ( Minuartia tenella (J. Gay) Mattfeld , Caryophyllaceae ), hairy cat’s ear ( Hypochaeris radicata Linnaeus , Asteraceae ). Habitats listed on labels include “ Ainus– Populus – Picea ” or “Alder–Poplar–Spruce”, “along creek in forested ravine”, “along roadside”, “ Betula woods”, “birch & fir”, “black spruce forest”, “canopy gap in hardwood forest”, “dry sand beach ridge”, “gap in Mh/Be forest”, “hardwood forest”, “hemlock forest”, “hot springs”, “in clearing near river”, “ Ledum - Kalmia bog”, “low vegetation and leaf litter at campsite”, “marshy meadow”, “on tide flats”, “ Picea forest”, “pine forest”, “ Pinus - Salix forest”, “riverbank scrub”, “ Salix-Picea ”, “scrub poplar and low vegetation”, “seepage area”, “fen”, “sphagnum bog”, “ Vaccinium wood” and “wet, scrubby clearing”. This species complex is also collected from hilltops. Collected January to November, although much more frequently collected in May to August. Collected from elevations from sea level– 4000m.

Discussion: Dasysyrphus intrudens is most certainly a complex of multiple species. However, the boundaries between these species are still unclear. The COI clusters produced in the NJ tree ( Fig. 4) yielded no clues to the number of species existing in this clade. When sorting the specimens by barcodes, no consistant morphological patterns were visible. Sometimes characters were similar between two or more clusters and sometimes within one cluster there were multiple character states. As the barcoding region of COI appears to be of little help to sort this complex into species, other markers should be sequenced to look for insight into species boundaries. Fresh material collected into absolute alcohol will be required to sequence the necessary genes.

Note that this group has been referred to as the friuliensis group in conference abstracts, but never in a refereed publication. The oldest group name, intrudens , best serves as the name for the complex.

Type Material: “Lagunitas Creek, Cal./ April 15. O. Sacken ”, “Osten/ Sacken/ Coll.”, red label “Type/ 875”, yellow label “ LECTOTYPE / Syrphus / intrudens O.S./ Desig. Thompson 1977”, “ Syrphus / intrudens O.S.”, J. Skevington / Specimen #/ 23783”, ♂, deposited in the Museum of Comparative Zoology , Harvard University ( MCZ). Both basoflagellomeres and right metaleg missing. Genitalia have been removed at some point and are not associated with the specimen (presumed to be lost). (examined)

Material Examined: There were 2138 specimens from throughout the Nearctic ( Fig. 20B View FIGURE 20 ) that were examined for this study. Because this is a complex and species boundaries need to be resolved, it is of little use to list all information for material examined. Database records for each specimen examined may be obtained from the authors.