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wrote:<BR><BR> <BLOCKQUOTE type= <html> <head> </head> <body> <br> <br> Christopher Majka wrote:<br> <blockquote type="cite" cite="mid:23D10FBD-7EA2-459C-AF71-236FD612483B@ns.sympatico.ca"> <div> <div> <div><br class="khtml-block-placeholder"> </div> <div><span class="Apple-style-span">On the basis of the photograph, and examining specimens of both species, I couldn't tell which it might be. The two genera are differentiated (from Curran 1965) according to whether the femorae have patches of setulae on the anterior part of the base, and whether the third vein of the wing is strongly or only moderately curved into the apical cell - characters I can't make out from the photograph.</span></div> <div><br class="khtml-block-placeholder"> </div> <div>All the best,</div> <div><br class="khtml-block-placeholder"> </div> <div>Chris</div> </div> </div> </blockquote> Hi Chris, Angus & All, Sept 2, 2006<br> For what it may be worth, the key in Nearctic Diptea distinguishes <i> Helophilus</i> and <i>Eristalis</i> on a key character that can be seen in the right wing of the picture [that yellow background brings out veins very well]; the union of R1 and R2 +3 before the wing margin (<i>Eristalis </i> and the picture) as opposed to R1 and R2+3 each reaching the wing margin independently (<i>Helophilus</i>). <br> <br> DIGRESSION: The authors, incorrectly I think, refer to this as cell r2+3 being closed or open to the wing margin, when it is really cell r1 that is open or closed, but it is clear from their Figures (e.g. 58 & 60) which cell is intended: END OF DIGRESSION<br> <br> <i>E. tenax </i>as illustrated in Swann & Papp has a dark, squat wineglass figure, & distal to this, a thin pale band on visible tergite 1 and insect length is given as 0.6". I have two numbers (A212 & A218; 15 mm & 14 mm long respectively) that compare well with Swan & Papp's illustration. <br> <br> In contrast, in the photo taken by Angus, [what is it Jim Angus' photo or Angus's photo ?] the dark area in tergite 1 is shaped like a broad vase and has no pale distal band. My A325 has a similar dark area on tergite 1 and is 10 mm long. <br> <br> Based on the above I still lean to <i>Eristalis</i> but rule out <i>E. tenax</i> and would guess Angus' yellow flower, which I don't recognize, to be about 25 mm wide. In some situations a specimen is worth a thousand pictures. <br> <br> Yours truly, Dave Webster, Kentville<br> <br> <br> </body> </html>
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