Dasysyrphus amalopis (Osten Sacken)

Locke, Michelle M. & Skevington, Jeffrey H., 2013, Revision of Nearctic <i> Dasysyrphus </ i> Enderlein (Diptera: Syrphidae), Zootaxa 3660 (1), pp. 1-80 : 29-32

Dasysyrphus amalopis (Osten Sacken)

Figures: 5A–D, 20A

Synonyms and References:

Syrphus amalopis Osten Sacken 1875: 148 (original description)

Curran 1925: 179 (discussion, amalopis s.l.)

Metasyrphus amalopis (Osten Sacken) :

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

Dasysyrphus amalopis (Osten Sacken) :

Stone et al. 1965 (in part): 563 (catalogue and transfer to Dasysyrphus )

Vockeroth 1986: 202 (lectotype designation and discussion)

Vockeroth 1992: 63 (in part; redescription)

Diagnosis: Abdominal maculae do not meet abdominal margin; maculae on tergites 3&4 are constricted medially and usually not divided ( Figs 5A & B ). Wing cells are densely microtrichose ( Fig. 5D ). Surstylus without a prominent posterolateral edge ( Fig. 5C ). Similar to D. occidualis , but D. occidualis has maculae on tergites 3&4 either divided or undivided ( Figs 12A & B ), cell br usually with a small bare area above base of spurious vein and a prominent posterolateral edge on the surstylus ( Fig. 12D ).

Redescription:

Body Length: 7.8–10mm; Wing Length: 7.7–8.7mm

Head: Frons dark with light pollenose fascia (in males it runs along ventral edge of where eyes meet, in females it is continuous, ¼–½ the length between the antennae and ocelli) and dark pile; face light with dark vitta ¼–⅓ the width of the face sometimes reaching antennal socket, face with dark pile; gena dark with pile light to dark; occiput dark, covered in light pollen, pile light; scape, pedicel and flagellomere dark.

Thorax: Scutum dark, may appear shiny or metallic, pile varying from all dark to mixed to all light, more light anteriorly and posteriorly; scutellum light (dark yellow) to dark with darker lateral edges, light pile along anterior edge and dark pile elsewhere; wing completely densely microtrichose ( Fig. 5D ); haltere light; femora ⅔–¾ dark basially, ¼–⅓ light apically, tibiae dark with very basal end light, tarsii dark.

Abdomen: Maculae on tergite 2 large and oval, usually with slight narrowing medially, ⅓–<½ the width of tergite 2, maculae on tergites 3 & 4 are oblique, constricted medially and usually not divided, posterior edge of maculae straight, maculae do not reach abdominal margin ( Fig. 5B ); sternite 2 light with a dark triangular macula, usually not connecting with the lateral edges of the sternite, sternites 3 & 4 are light with dark fasciae.

Male Genitalia: Surstylus more or less triangular in shape in lateral view, flattened posteriorly, long pile on dorsal, laterodorsal and posterodorsal sides, row of spines on posteromedial edge; cercus oval with long pile over entire surface; gonostylus claw-shaped, pile on dorsal surface; basiphallus elongate, basally bent at about a 90 degree angle towards the anterodorsum, apical end curved ventrally with a widened apex and is partly membranous dorsally, with spines on posterodorsal side, apex; distiphallus elongate, apical end flared out into horn, which is mostly sclerotized but membranous at apex with minute setulae dorsally, basally bent towards dorsum and slightly enlarged ventrally at bend ( Fig. 5C ).

Intraspecific variation: From the specimens we have had the chance to observe the maculae on tergites 3 & 4 are usually not divided ( Fig. 5A ). Sometimes only the maculae on tergite 3 are divided and sometimes they are divided on both tergites 3 & 4. The lectotype male has entire maculae, whereas the paralectotype female has divided maculae.

Etymology: From the Greek, amalos meaning soft, tender, weak and – opis, meaning having the appearance of, like.

Distribution: Northern Canada (MB, NL, QC, YK) and Northeastern USA (NH) ( Fig. 20A )

Ecology: Collected from June–July at elevations from sea level– 1006m.

Discussion: In addition to the two specimens selected as lectotype and paralectotype by Vockeroth (1986), Osten Sacken (1875) discussed a third specimen and included it in his description of the species. This third specimen has abdominal maculae that cross the abdominal margin. This third specimen is not a specimen of D. amalopis but a specimen of the D. intrudens complex, and has caused much confusion over the name D. amalopis . Vockeroth (1986) pointed out that Fluke (1933) discussed many specimens of D. amalopis with maculae reaching the margin. Vockeroth stated that he believed those specimens belonged to his concept of D. venustus . We argue that specimens described as D. amalopis that have maculae that cross the abdominal margin belong to the D. intrudens complex. Fluke (1933) does have D. amalopis key out in two places in his key. The D. amalopis keyed out in couplet 54 pertains to D. amalopis s.s. and D. occidualis , while the D. amalopis keyed out in couplet 56 pertains to the D. intrudens complex.

The lectotype and paralectotype are the only known specimens of this species from eastern North America south of northern Quebec and Labrador. Our new species, Dasysyrphus occidualis , has been confused with D. amalopis . However, the COI sequences and male genitalia characters provide evidence for these being two distinct species with an identical habitus. Dasysyrphus amalopis ranges from southern Yukon to northern Labrador ( Fig. 20A ), while D. occidualis ranges from Alaska, south to Colorado ( Fig. 21B ). Specimens referred to as D. amalopis from western Canada or the US are most likely that of D. occidualis and in the overlap zone in southern Yukon male genitalia and/or COI sequences should be used to confidently identify specimens. Despite the long standing use of the name D. amalopis , the similar new species, D. occidualis , has been much more frequently collected.

It is not known why no other specimens are known from as far south as the lectotype and paralectotype. They were both collected in the White Mountains, in New Hampshire. The date of their collection is unknown, however their description by Osten Sacken was published in 1875, so they would have been collected previous to that. It is possible that they are rare and have thus not been collected again or that their habitat or climatic conditions have changed resulting in their extirpation. More collecting should be done in the Appalachians at high elevation to see if this species still exists that far south.

Type Material: “White Mts./ Austin”, “Osten/ Sacken/ Coll.”, red label “Type/ 4092”, “ Syrphus / amalopis/ Type Species O.S.”, yellow label “ LECTOTYPE / Syrphus / amalopsis O.S./ Desig. Thompson 1971”, “ Jan.–July 2003 / MCZ Image/ Database”, J. Skevington/ Specimen #/ 23785”, ♂, deposited in the Museum of Comparative Zoology, Harvard University (MCZ). Missing head. (examined)

Material Examined:

Paralectotype: United States of America: New Hampshire: Gorham , [44.387788, -71.17313], ♀, JSS 23786 ( MCZ) . Other Material Examined: Canada: Manitoba: CHURCHILL REGION: Weir , [58.4026, -94.129], ♂, 25.vii.2007, ♀, 07 PROBE 4723 , L.E. Roscoe ( CNC); Burn site North of Twin lakes, [58.61861111, -93.82888889], 5.vii.2007, ♂, CNCD 9607 , J. Skevington ( CNC); Twin Lakes , [58.63, -93.819], 14m, 19.vii.2009, ♀, 09 PROBE 176 , ( CNC), 26.vi.2010 – 2.vii.2010, ♂, 10 PROBE 13673 , 5.vii.2010 – 9.vii.2010, ♀, 10 PROBE 13805 , J. Wang ( USNM); Goose Creek , [58.649, -94.193 W], 19.vii.2009, ♀, 09 PROBE 25 , A. Thielman ( CNC); Farnworth Lake ( Landing L), [58.7045, -94.0525], 14m, 14.vii.2010, ♀, 10 PROBE 14269 , 14.vii.2010 – 19.vii.2010, ♂, 10 PROBE 15042 , 28.vi.2010, ♂, 10 PROBE 10909 , 28.vi.2010 – 6.vii.2010, ♀, 10 PROBE 15283 , J. Wang ( CNC) . Newfoundland and Labrador: Nain, Anatalak Bay , [56.5429, -61.689989], 16.vii.1928, ♂, JSS 19248, A.C. Weed ( FMNH) . Quebec: Indian House Lake , [56.328482, -64.720845], 19.vii.1954; ♀, CNCD 13616 , 25.vii.1954, ♀, CNCD 13618 ,W. R. Richards ( CNC); 22.vii.1954, ♀, CNCD 13617 , R . Coyles ( CNC) . Yukon Territory: La Force Lake , [62.683333, -132.333333], 1006m, 26.vi.1960, ♂, CNCD 13587 , J.E.H. Martin ( CNC) .

Figures

FIGURE 5. Dasysyrphus amalopis: A: female (CNCD 13616) dorsal habitus, T = tergite; B: female (CNCD 13616) lateral habitus; C: lateral view of male (CNCD 9607) genitalia; D: wing base (CNCD 13587). Dorsal and lateral habitus scale bar = 1mm, genitalia and wing scale bar = 500µm.

FIGURE 12. Dasysyrphus occidualis: A: female (CNCD 60043) dorsal habitus; B: male (OSU 0000133386) dorsal habitus; C: male (OSU 0000133386) lateral habitus; D: lateral view of male (JSS 20804) genitalia; E: wing base (CNCD 60046). Dorsal and lateral habitus scale bar = 1mm, genitalia and wing scale bar = 500µm.

FIGURE 20. Dasysyrphus species range maps (symbols indicate specimen point data). A: D. amalopis (squares) and D. creper (circles); B D. intrudens complex; C: D. laticaudus (circles) and D. richardi (squares); D: D. limatus.

FIGURE 21. Dasysyrphus species range maps (symbols indicate specimen point data). A: D. lotus (squares) and D. nigricornis (circles); B: D. occidualis; C: D. pacificus; D: D. pauxillus (circles) and D. pinastri (squares).