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B. sandersoni & B. vagans

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  • Paul Williams
    Hi Sam and Doug re: B. sandersoni & B. vagans As you know, bumblebees are often very variable in colour pattern (perhaps even more so outside of eastern North
    Message 1 of 3 , Sep 25, 2010
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      Hi Sam and Doug

      re: B. sandersoni & B. vagans

      As you know, bumblebees are often very variable in colour pattern (perhaps even more so outside of eastern North America), so it is much safer to use morphological characters to make identifications.  In this case, the face shape (length to breadth of the malar area) is the most reliable character.  It seems that both of these species can have the pile of the face and top of the head black or with yellow.  Although I haven't seen B. vagans with the pile of the vertex entirely black, they may yet be found.

      It is very likely that B. sandersoni just does not occur at low elevations in WV, VA, and MD.

      Paul

      Fri Sep 24, 2010 7:41 pm (PDT) From D. Yanega


      Having just spent much of today going over a large assortment of B.
      vagans, I can offer some feedback on the following:

      >Female, B. frigidus, B. sandersoni, B. vagans
      >
      >(note, the below is somewhat controversial, so am looking for some
      >feedback... B. sandersoni is a very uncommon bee in general, but we
      >have been finding it at least somewhat regularly in the Appalachian
      >Mountains and ran into a nice string of about 50 from Mountain Lake,
      >VA thanks to Barbara Abraham's work there.
      >
      >B. sandersoni - T1-T2 usually entirely yellow, some specimens may
      >show scattered black hairs on T2 - Hair on T4 black, but at times
      >with yellow or off-white hair on the far sides - Hair on T5 can be
      >pale yellow, off-white, black, if appearing all black there are
      >usually a few yellow hairs on the far sides - Space from lowest
      >point of eye to mid-point of attachment of mandible varies from
      >roughly equal to width of mandible at base to longer - Hair above
      >the ocelli is almost always largely black but often with scattered
      >yellow hairs - In direct comparison, the black hairs on the scutum
      >take up much of the posterior half of the scutum with yellow hairs
      >simply bordering the junction with the scutellum and near the
      >tegulae, scattered black hairs occur in these yellow areas including
      >in the anterior edge of the scutum near the head
      >
      >B. vagans - Hair on T4-5 always black, except in Newfoundland where
      >the endemic subspecies bolsteri has T5 yellow - Space from lowest
      >point of eye to mid-point of attachment of mandible longer than
      >width of mandible at base - Face appears long, horsey - In direct
      >comparison, the black hairs on the scutum are largely restricted to
      >the center of the scutum creating only a small patch of black amidst
      >a largely yellow-haired scutum, though with scattered black hairs
      >laterally to the tegula - Hairs above the ocelli almost always with
      >extensive amounts of yellow, apparently never all black

      Looking over specimens from WV, VA, and MD, there are a few with pale
      hairs on terga other than 1-2; however, all but one of these has a
      lot of yellow on the vertex, and the malar spaces are no different
      from those of perfectly typical vagans from the same
      dates/localities. The amount of black on the scutum seems to vary a
      fair bit from specimen to specimen, even within series, and not just
      series from the Appalachians. I wouldn't say I could confidently
      classify any of the specimens at hand as sandersoni using the
      criteria you give (especially given that they otherwise are no
      different from other females in the same series) - it could be that
      there are simply no sandersoni in amongst these, but if we assume
      that, given that all of your diagnostic features (other than the
      malar space feature, though I confess to not having an ocular scale)
      appear on some of these specimens, that would mean these features
      can't be used to reliably diagnose sandersoni, at least not the way
      they're phrased, without images to clarify them.

      Peace,
      --



    • Sam Droege
      Doug...Paul Malar space is a reasonable part of the equation of determining B. sandersoni. The problem is that while B. vagans always (or, I suppose almost
      Message 2 of 3 , Sep 25, 2010
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        Doug...Paul

        Malar space is a reasonable part of the equation of determining B. sandersoni.  The problem is that while B. vagans always (or, I suppose almost always is always the qualifier with Bombus) has a long malar space, I have seen things I feel confident are B.sandersoni (in amongst a long string of these species) where I would have classified the malar space as "long."  An issue here is one that comes up often which is: how to characterize distance in morphological characters.  Usually our minds classify things naturally  into categories of longer than, equal to, and shorter than.  The categories of "longer than" and "shorter than" can encompass a large range of  measures or ratios all of which are true, while the term "equal to" is a very narrow absolute term and thus very few things fit absolutely, and so we use qualifiers like about, roughly, near, which are open to interpretation as to what range in ratios these terms equate to,   So, in the cases of "nearly equal"  usually it take experience and specimens to determine the range that "equal" means.  Thus the difference between B. vagans and B. sandersoni is separable, at least partially, using malar space, this is not  the case without looking at other known specimens or using a long string of ancillary characters (also open to variation) to CSI the situation.  This is one of the problems with bee identification in that B. sandersoni is not alone being nearly impossible to key out confidently without a collection nearby (or someone to send specimens to).   Another argument for the continued funding for taxonomists and collections....archaic as they may seem.

        I haven't found B. sandersoni outside of the high elevation portions of the Appalachians.  ... there's a story in there!

        sam

        Sam Droege  sdroege@...                      
        w 301-497-5840 h 301-390-7759 fax 301-497-5624
        USGS Patuxent Wildlife Research Center
        BARC-EAST, BLDG 308, RM 124 10300 Balt. Ave., Beltsville, MD  20705
        Http://www.pwrc.usgs.gov

                Consider the Snail

        The snail pushes through a green
        night, for the grass is heavy
        with water and meets over
        the bright path he makes, where rain
        has darkened the earth's dark. He
        moves in a wood of desire,


        pale antlers barely stirring
        as he hunts. I cannot tell
        what power is at work, drenched there
        with purpose, knowing nothing.
        What is a snail's fury? All
        I think is that if later


        I parted the blades above
        the tunnel and saw the thin
        trail of broken white across
        litter, I would never have
        imagined the slow passion
        to that deliberate progress.


               - Thomas Gunn




        From:Paul Williams <porlw@...>
        To:beemonitoring@yahoogroups.com
        Date:09/25/2010 09:34 AM
        Subject:[beemonitoring] B. sandersoni & B. vagans
        Sent by:beemonitoring@yahoogroups.com





         




        Hi Sam and Doug

        re: B. sandersoni & B. vagans

        As you know, bumblebees are often very variable in colour pattern (perhaps even more so outside of eastern North America), so it is much safer to use morphological characters to make identifications.  In this case, the face shape (length to breadth of the malar area) is the most reliable character.  It seems that both of these species can have the pile of the face and top of the head black or with yellow.  Although I haven't seen B. vagans with the pile of the vertex entirely black, they may yet be found.

        It is very likely that B. sandersoni just does not occur at low elevations in WV, VA, and MD.

        Paul

        Fri Sep 24, 2010 7:41 pm (PDT) From D. Yanega

        Having just spent much of today going over a large assortment of B.
        vagans, I can offer some feedback on the following:

        >Female, B. frigidus, B. sandersoni, B. vagans
        >
        >(note, the below is somewhat controversial, so am looking for some
        >feedback... B. sandersoni is a very uncommon bee in general, but we
        >have been finding it at least somewhat regularly in the Appalachian
        >Mountains and ran into a nice string of about 50 from Mountain Lake,
        >VA thanks to Barbara Abraham's work there.
        >
        >B. sandersoni - T1-T2 usually entirely yellow, some specimens may
        >show scattered black hairs on T2 - Hair on T4 black, but at times
        >with yellow or off-white hair on the far sides - Hair on T5 can be
        >pale yellow, off-white, black, if appearing all black there are
        >usually a few yellow hairs on the far sides - Space from lowest
        >point of eye to mid-point of attachment of mandible varies from
        >roughly equal to width of mandible at base to longer - Hair above
        >the ocelli is almost always largely black but often with scattered
        >yellow hairs - In direct comparison, the black hairs on the scutum
        >take up much of the posterior half of the scutum with yellow hairs
        >simply bordering the junction with the scutellum and near the
        >tegulae, scattered black hairs occur in these yellow areas including
        >in the anterior edge of the scutum near the head
        >
        >B. vagans - Hair on T4-5 always black, except in Newfoundland where
        >the endemic subspecies bolsteri has T5 yellow - Space from lowest
        >point of eye to mid-point of attachment of mandible longer than
        >width of mandible at base - Face appears long, horsey - In direct
        >comparison, the black hairs on the scutum are largely restricted to
        >the center of the scutum creating only a small patch of black amidst
        >a largely yellow-haired scutum, though with scattered black hairs
        >laterally to the tegula - Hairs above the ocelli almost always with
        >extensive amounts of yellow, apparently never all black

        Looking over specimens from WV, VA, and MD, there are a few with pale
        hairs on terga other than 1-2; however, all but one of these has a
        lot of yellow on the vertex, and the malar spaces are no different
        from those of perfectly typical vagans from the same
        dates/localities. The amount of black on the scutum seems to vary a
        fair bit from specimen to specimen, even within series, and not just
        series from the Appalachians. I wouldn't say I could confidently
        classify any of the specimens at hand as sandersoni using the
        criteria you give (especially given that they otherwise are no
        different from other females in the same series) - it could be that
        there are simply no sandersoni in amongst these, but if we assume
        that, given that all of your diagnostic features (other than the
        malar space feature, though I confess to not having an ocular scale)
        appear on some of these specimens, that would mean these features
        can't be used to reliably diagnose sandersoni, at least not the way
        they're phrased, without images to clarify them.

        Peace,
        --





      • Paul Williams
        Hi Sam and Doug re: B. sandersoni & B. vagans As you know, bumblebees are often very variable in colour pattern (perhaps even more so outside of eastern North
        Message 3 of 3 , Sep 25, 2010
        • 0 Attachment
          Hi Sam and Doug

          re: B. sandersoni & B. vagans

          As you know, bumblebees are often very variable in colour pattern (perhaps even more so outside of eastern North America), so it is much safer to use morphological characters to make identifications.  In this case, the face shape (length to breadth of the malar area) is the most reliable character.  It seems that both of these species can have the pile of the face and top of the head black or with yellow.  Although I haven't seen B. vagans with the pile of the vertex entirely black, they may yet be found.

          It is very likely that B. sandersoni just does not occur at low elevations in WV, VA, and MD.

          Paul

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